THE ECOLOGICAL PLANET : AN INTRODUCTION TO EARTH ’S MAJOR ECOSYSTEMS COURSE GUIDE

Professor John Kricher WHEATON COLLEGE The Ecological Planet: An Introduction to Earth’s Major Ecosystems Professor John Kricher Wheaton College

Recorded Books ™ is a trademark of Recorded Books, LLC. All rights reserved. The Ecological Planet: An Introduction to Earth’s Major Ecosystems Professor John Kricher

Executive Producer John J. Alexander

Executive Editor Donna F. Carnahan

RECORDING Producer - David Markowitz Director - Matthew Cavnar

COURSE GUIDE Editor - James Gallagher Design - Edward White

Lecture content ©2008 by John Kricher Course guide ©2008 by Recorded Books, LLC

72008 by Recorded Books, LLC #UT119 ISBN: 978-1-4361-0596-5 All beliefs and opinions expressed in this audio/video program and accompanying course guide are those of the author and not of Recorded Books, LLC, or its employees. Course Syllabus

The Ecological Planet: An Introduction to Earth’s Major Ecosystems

About Your Professor/Introduction ...... 4

Lecture 1 Ecology and the Big Picture ...... 6

Lecture 2 Earth and the Goldilocks Effect ...... 10

Lecture 3 Distribution of Global Ecosystems ...... 15

Lecture 4 Climate and Ecology ...... 19

Lecture 5 Biogeography and Evolution ...... 23

Lecture 6 Polar Ecosystems and Tundra ...... 28

Lecture 7 Boreal Forest ...... 33

Lecture 8 Temperate Deciduous Forest ...... 39

Lecture 9 Grassland and Savanna ...... 44

Lecture 10 Desert ...... 50

Lecture 11 Tropical Rain Forest ...... 55

Lecture 12 Marine Ecosystems ...... 61

Lecture 13 Unique Coastal Ecosystems ...... 67

Lecture 14 Current Issues in Global Ecology ...... 75

Course Materials ...... 80

3 About Your Professor John Kricher

John Kricher is a professor of biology at Wheaton College, Norton, Massachusetts. His books include r

e Galapagos: A Natural History, A h c i r

K Neotropical Companion, three ecology n h o J f field guides (Eastern Forests; Rocky o y s e t Mountain and Southwestern Forests; r u o c

o and California and Pacific Northwest t o h P Forests), and First Guide to Dinosaurs . John is a fellow in the American Ornithologists Union and past-president of both the Association of Field Ornithologists and Wilson Ornithological Society. He resides with his wife Martha Vaughan on Cape Cod.

Introduction Earth is the only known ecological planet, a place with life. But life is diverse: plants, animals, microbes, millions of species, many interacting in complex ways and all of them influenced in myriad ways by the environments in which they are found. Ecology is the study of organisms as they relate to their envi - ronments, the scientific study of natural history. But what does that really mean? It means that because of the many physical, chemical, and atmos - pheric characteristics of Earth, diverse forms of life have evolved throughout the history of the planet, life that is shaped and reshaped by both physical and biotic forces. Life is forced to evolve because of Earth’s diverse condi - tions and the fact that, over time, conditions change. Ecology is the search for broad general patterns evident in the distribution and abundance of life. Further, ecology attempts to explain such patterns with empirical reasoning. Ecology, a word taken from the Greek oikos , meaning home, is the same root as the word economics. Like economics it studies complex systems, in this case ecosystems. Ecology is the broadest level of organization in biology, the discipline that deals with interactions among populations, ecological commu - nities, and ecosystems. Earth is a planet with a complex climate, one that varies dramatically from equator to poles. As a consequence, life-forms adapted to polar regions are not well suited to equatorial areas and thus climate alone forces a high diver - sity to evolve among Earth’s numerous and variable organisms. Polar bears, for all their magnificent adaptations, are not adapted to survive in tropical conditions and the diverse array of trees comprising equatorial tropical rain forests would not long survive at higher latitudes. This course explores exactly why Earth supports life. It examines the various reasons why a small planet of about eight thousand miles diameter orbiting an average-sized star is uniquely suited to have a biosphere, a thin layer of living

4 matter surrounding its surface. Life abounds on both land and oceans but takes many different forms, mostly because climate is so variable. Beginning at the polar regions, the cold wind- swept Arctic and Antarctic, Professor Kricher will devote lectures to each of the Earth’s major ecosys - tems, called biomes. These include the vari - ous major forest types, m o c .

the northern coniferous s o t o h

(or boreal) forests that P surround the higher lati - © tudes like a vast belt of spruce and fir trees, the immense temperate decidu - ous forests of North America, Europe, and Asia, and the tropical rain forest, the ecosystem with more species than any other. When moisture is insufficient to support forest, other kinds of biomes occur. These include grassland, called prairie in North America, as well as savanna, a combination of grassland and scattered trees that typifies much of East Africa. The driest of all biomes is desert, which is always water stressed but may be hot or cold depending on where it is located. The largest ecosystems on Earth are marine, the oceans and coastal areas where land meets sea. The ocean realm has ecosystems that differ by depth. The open ocean or pelagic zone is where the food webs of the sea begin, where billions of tiny plants, the phytoplankton, capture some of the Sun’s energy and thus support all of the other creatures of the seas. But most of the ocean below about six hundred feet is cold and dark, and the benthic zone, or sea bottom, is lit only by the bioluminescence of the life-forms that inhabit it. Coastal ecosystems such as salt marsh, mangrove swamp, and coral reefs are among the most ecologically valuable as they are highly productive. At the same time, they are among the most threatened. The final lecture in the course will focus on how ecology has matured into a pragmatic science that is as essential as economics for making sound judg - ments about how best to steward the ecological planet.

5 Lecture 1: Ecology and the Big Picture

The Suggested Reading for this lecture is John Kricher’s A Field Guide to Eastern Forests (chapters 1 and 2). m o c . s o t o h P © Wildflowers at the edge of a wooded field.

cology is the scientific study of how life-forms interact and coexist. It is concerned not only with how living things adapt to each other, but also how they interact with and adapt to the nonliving compo - nents of the environment. Ecology is often defined simply as the study of organisms as they relate to their environments. Another definition is that ecology is the study of how various factors in the environment affect the distribution and abundance of organisms. Those “fac - tors” are divided into two broad categories, abiotic and biotic. Abiotic factors are such things as temperature, precipitation, phosphorus, oxygen, salinity, and fire. Biotic factors are interactions such as predation, parasitism and pathogens, competition for resources, and mutually beneficial interactions. Ecology is taken from the Greek word oikos , meaning “home,” the same root from which the word “economics” is derived. Both disciplines, ecology and economics, study how things relate within complex systems. Economists study the flow of money through economic systems as well as how materials move in the form of goods and services. Ecologists focus on energy flow

E through ecosystems and study how atoms combine and recycle as life uses N

O energy and material to maintain itself. The word “ecology” was coined in 1866 E by Ernst Haeckel. He was attempting to form a word describing the “economy R

U of nature” that Charles Darwin described in his monumental book On the T

C Origin of Species (1859). E L

6 Nothing in ecology makes sense without environmental context. For instance, you can watch a kangaroo in a zoo cage but you will not be observ - ing ecology. Kangaroos live in Australia, in open grassland and savanna habitats. To really learn about the ecology of a kangaroo, it is necessary to study the creature in the wild, in the Australian outback where groups of kan - garoos eat, groom, defend their territories, mate, and reproduce. So it is with all other animals and plants as well. Ecology looks at living things in the con - text of the environment for which each is adapted. Ecology is often described simply as the scientific study of natural history, its roots reaching back to the early writings of the ancient Greek scholars who were curious about such questions as why fish look as they do, have scales, and swim in water, while birds look quite different, have feathers, and fly in air. But ecology is far more than descriptive natural history. It encompasses broader, more deeply penetrating questions. The living world does not yield its secrets easily. Ecology is the science that attempts to uncover patterns in nature and then to discover causal explanations for such patterns, explana - tions that account for the distribution and abundance of plants, animals, and microbes, and predict how various factors effect changes in such patterns. Ecologists study the “big picture” within the biological sciences: how an open field of grasses and wildflowers can, with time, develop into a closed, shadowy forest; why large predatory animals such as jaguars or great white sharks are so much rarer than their prey species; why the loss or gain of but a single species in a habitat can radically affect and alter that habitat while other species come or go with little, if any, discernible effects; why some species are abundant and broadly distributed and others are very local and rare; why some regions of the Earth are covered by rain forest while others are deserts; how essential minerals such as phosphorus and nitrogen move from the nonliving to the living components of what we call “the environ - ment.” Ecologists today are concerned with such major global questions as the potential for climate alteration, the complex effects caused by pollu - tants, the increasing prevalence of invasive species, and the decline of global biodiversity. At the base of ecological study is the organism. Ecologists study organisms in the context of both their present environment and their evolutionary histo - ries, meaning how they are adapted to survive within their environments. Organisms of the same species in nature are grouped into organizational units called populations; thus ecologists speak of the grizzly bear population at Denali National Park in Alaska or the right whale population in the Gulf of Maine in the Atlantic Ocean. When the focus is on questions pertaining to whole populations, the term “population biology” is often used. But no natural environment consists of but a single kind, a single species of organism. Thus various populations, called an ecological community, coexist within the same locality. Grizzly bears, along with caribou, Dall’s sheep, and arctic ground squirrels, are each part of the arctic tundra animal community in Denali. Right whales, along with various oceanic birds such as gannets and greater shear - waters, plus other whale species such as humpback and minke whales, along with numerous fish species, oceanic invertebrates, and tiny plants called phy - toplankton, are all part of the Atlantic pelagic (open sea) community.

7 Ecological communities, by necessity, interact with the nonliving, or abiotic environment, the air, water, and substrate. The combination of the living, the biotic, with the abiotic components of any habitat forms the most encompass - ing level of organization in the life sciences. The interactive association between a community of organisms and their physical and chemical environ - ment is called an ecosystem. When ecology was in its infancy it was described as physiology (already an established laboratory science) applied to the environment, an attempt to explain how organisms function in an adaptive manner that permits some to survive in freezing cold and others to thrive in blazing heat. The ecosys - tem concept, first clearly articulated in 1935, was formulated to show that the interactions of multiple organisms with the physical environment in any given region forms a dynamic system worthy of its own study as a level of organization. Ecosystem boundaries are often fuzzy: a decaying log in a woodlot is an ecosystem, but on a larger scale, so is the woodlot in which the log is found, and on a larger scale still, so too is the regional forest of which the woodlot forms but a part. The largest ecosystem known is called the biosphere or ecosphere (the terms mean the same thing), the thin layer (perhaps twenty- five kilometers) of living matter that inhabits the crust and atmosphere of the Earth, thus far the only known area in the Universe to have an ecology, which brings us to the next lecture. E N m o O c . s o t E o h R P © U T

C Grizzly bear near a streambed in the Denali National Park, Alaska. E L

8 FOR GR
EATER UNDERSTANDING

Questions

1. Is ecology the same thing as natural history study? How is ecology unique? 2. What are the differences among populations, communities, and ecosystems ?

Suggested Reading

Kricher, John. A Field Guide to Eastern Forests. Boston: Houghton Mifflin Company, 1998.

Other Books of Interest

Attenborough, David. The Living Planet. Boston: Little, Brown, 1984. Bates, Marston. The Nature of Natural History . Princeton: Princeton University Press, 1990. Wilson, Edward O. The Diversity of Life . New York: W.W. Norton, 1992.

9 LECTURE TWO 1 0 The Br for li qu ev an ch fo up ev ar of oc Ma r ma E E Evi rm o ar ol u c a a ow d ice y o und m id u rth’s rt h nt s d ac te rg a e Sug r co , ens en ti on nl ster d w in e p it an is n vid hysict at e e a in ce se em s o aq ri ta trua is ms , g lo th e oids. o nly st i ’s such e es in r, ng r fr ue ou E nt cs , nce om fo r l l th e art Rar abou ted fa ectu a th ir no natu cycl with on ar e mou liq The h to t p i an s ts d a ke y e up ca ar ti cu la rl y to Rea uid re i t e), ral s s be t he pl a var pe rs is te nc e Eart the mo st ly o o ol ut io n. o l s , ea u 4.5 cea n ma to co a nivers sa o is ne t po ab se n ding m iety ting cean, a Eart re “singu h ld on’s th e tellite, unu b rid ke n? tim . s ilon fr . of t co mp os ed p om A f h it ge W or ig in su of it s t e or oridg strob sour perh no w “just a itself l hi le su a al a the the years ag e th e of nd th wi th ou t rity,” lite rface. as ces is Goldicks. io aps of wa te r e. a Solar Moon the righ S L bega an d logist nd plane lectu e un , l I more girl if e. old, t ct su of salty, t” Go Ma r ha What li qu id ur te mp er at ur e gest ab o n ma System, to wa te r named It (the d tary re nea e ldio a s l po is su ike t y bout 2: ut o is b ap pe ar migh di ff ic ul t pulary ha ve wa te rly name Its por ena satellites b 93 cks an d to Petr e tha Go as charte 13.8 “ comp the mi ll io n ju t t r th t on ce Efec al l be ldi life. s be ca us e old st is , Jup caled to D. othe a to ma ke locks bilo derived bi oc he mi c r cra ig are go de fo rm as iter’s be Ward fl ow ed t ht,” mi le s ristc, wling r nse n and the Earth a p the E was ye lane sc en ar io s not ce ll s, li fe le ss ar th m from over Sun. a a ars its on “Big or on wa y. nd al ver to outlined ts, with su it ab le size swim ago toping wh ic h re ac ti on th e the Donald y Euro Earth comet Bang. hot de se rt . Th e selctiv the and pl an fo r with Greek and pa m in S ng ” fo r s, li fe ’s s laye ak e et un ’ this an s r

© Photos.com presence may contribute to why life exists on Earth. It is proportionally large relative to its planet, indeed, proportionally the second largest moon in the Solar System. Earth and the Moon are unusual in that astronomers character - ize them as virtually a biplanetary system, given the large proportional size of the Moon to the Earth. Thus, given Newton’s insights regarding gravity, the Moon has a strong effect on the Earth. What if Earth had no moon? Yes, there would be no moonlit nights, many romantic songs would not have been written, eclipses would not occur, and wolves would have nothing to howl at. But the consequences of moonless - ness could be more ecologically profound. The Moon, which today is on average 238,860 miles (384,400 km) from Earth, was considerably closer to Earth when it formed, though exactly how close is a matter of conjecture. Today the Moon is becoming more distant from Earth, receding at about three centimeters annually. But the proximity of the Moon to the Earth, and the proportionally large size of the Moon to the Earth, means that throughout its existence, the Moon has exerted a strong gravitational effect on its planet. Most of us realize that Earth’s tidal cycles are caused mostly by the influence of the Moon. Given that life may have originated in conditions prevalent in tide pools and other coastal environ - ments, the Moon may have indirectly contributed to the first appearance of life on the planet. What is generally less well known, and what may be more important, is that the Moon likely stabilized the tilt of the Earth in space, what astronomers call Earth’s obliquity. If the Earth’s obliquity had undergone numerous substantial changes, making the planet basically “wobble” unpredictably, Earth’s climate would have undergone far more frequent, severe alterations, possibly too severe to permit complex multicellular life to evolve. Our Moon’s gravitational “calming” effect on Earth may have been of utmost importance to its future inhabitants. The Moon, a lifeless place, may have helped make life more pos - sible on its larger neighbor. Earth has a strong magnetic field (the Van Allen belts) and that too is impor - tant for sustaining life. Earth is constantly being bombarded by potentially harmful radiation from space, most of it from the Sun, but also cosmic rays from space. The Sun emits what is called the “solar wind,” and radiation of this sort could certainly be harmful to life, particularly large multicellular life-forms. But we exist happily along with elephants and redwood trees, so how are we protected from cosmic rays and the solar wind? The answer is that Earth gen - erates a strong magnetic field, called the magnetosphere. Like flak jackets around the planet, the belts intercept cosmic rays from space and solar wind particles from the Sun, affording a magnetic blanket of protection to Earth. The huge planet Jupiter also helps protect Earth and thus helps Earth sup - port life. Jupiter is immense in comparison not only with Earth but with virtual - ly all other planets in the Solar System. Its huge mass means that Jupiter exerts a very strong gravitational attraction on things that pass reasonably close to it, things like asteroids, comets, and meteors. There are many objects in space that have trajectories that occasionally cross the orbital path of Earth. The last of the dinosaurs, as well as many other life-forms, were vic - tims of one of these objects at the close of the Mesozoic Era. There have

11 LECTURE TWO 1 2 we ab ab eco na pa t r o n n o s y a d 3 2 o s a e s y r a v r o i t i t e h t r a w o t t i b r o t r a E m o r f t u o s r a l o s e H o N th n o i t a u h w e h t on th rh gr te ven t r o n n o i t a u ma of po ev act th en be Se S Ea T l , e m t e us rn at ythms a he o o o n t e si d e p . 3 2 l h p s i m e l i h t r a c s si e n n i M g e d nted syte t nts a r ut ut ern t ed n eco ot i b r o u q e s n r e h n r e h h r e h y h w th’ it w a as so fa th n i of s t i t bl s u p e r a d n r e e h t d a r o ent o s ve e h u o s º 5 4 it ? s n o r p wa t t re s ir e , s i c o n h h th th e s e e r h nal o syte t h t n o . clima o t a t s e a h t l i t e e n eco of senc to fo of ia e er ver ms E t a i co co S r e h w S o d sn’t, the m u s t a l r u c r i e p a e r g h s S e H h t a l kind f o n i an am s ar E um E ly n u rm M r a e s ch e u o p nat lison conlu lison t i t n o i te u S e im , d u t i s e r o , e l i s i l o r a la ar a f o lo th e c a l s t i p s i m , s o c fu x a esozic nua m e s s te d most p d u . ation azing mp ang d d n m h t nd pa . t w gy h t th n s y a o ure nctio h W o s o ang a E h t r u e r o m a l a i a f an e r e . of r o er o r e s t n i t a e . s e f t I r o f re s era cts l s s s i h 2 e n S , e s mig . s n s l l is es cosm h b , n p r mig d de ave s i n e 7 a t d n a n u o r a t w o n h t a na h t er t e r a cas e r o t a u q e th . s t l i t i we of fa ro e h of a t eh ph str t r o N t r a p d e t l i re tu b a w a er no . n i m larg o fe of t ous , e rations l, a x e sA baly tc e r i d eh a h io E t t a l P n ration Ear c re re hat a s i h ysiolgca on em a s ual ben closey ,g n o l planet. r omplex h t ic cted div Ea la i x A winter, s l l a f Ear a. ev ,s e t u e h force y d o and to y l t c gly e n objects. th “va ti s f seaon r e planet fo u e But st i th , o s th, h rsity be nder st with of in - folwe n o seao of cum ave r preci ca e h t u r e v e prof a some it Th som far thou spring ecolgia caribo tuned n i M use standig p co pote Jupiter such es ality ater chang While n r mo . d e s nal. uld clean e sand undly p a e n it d latiudn ation, e t n i w major way : ntialy re u, b pate ns h e h as to y W M as ach ave es frequ wilde it .s i l o to the e o e r o influec sea of r,” by Jupite com of is . r , f b rns and th take than ca bo en th the i ben r u D true sweping evo bird s the at sonal ent, best, l h g i l e tasro th a are dife ar result k. p r na g n i th unites. lution an part existnc befor t la tha speci likey e, Th such worse e s l l a f tural at net. rencs g cyles. importa e e h t phic se in and h of ti the pr in de, l e ow of t ason the redu n o calmit o evious world our o n an su f so and sp n very th aro spe ew r e h t r in n e u B ch d ine M e of ace nt ces yea ma the Ea , sin ost und day pre cies sea e kn detr to life-or esn rth devasting es ny vents n r r. debris. ce s o the major ows the Solar ty ecolg . e t n i w length, son. the Even could others. adpt. the minat s e r i A much numbe ce ms, degr tha as glob r S d o Jup of ical som It et ne e h t yste pre fa if afe t Thin the is e na h ermi Think how fo l of r iter tha pat as - e ti s r o m ct - f k - - -

© James Kaler color changes in leaves and hibernation in animals. Each of these elegant ecological patterns, and many more, occurs because of a 23.5º axial tilt. It is indeed a significant tilt. The position of Earth’s continents and the fact that their positions have changed throughout history also has a strong effect on Earth’s ecology and the evolution of organisms. Look at a map showing the positions of the oceans and the various landmasses. Look at South America and notice how the East Coast of South America looks almost as though it could fit rather well against the West Coast of Africa. If the globe shows relief, notice how the Himalayan Mountains form a rugged boundary at the border of India and Asia. Australia sits by itself, alone, an immense island continent in the south - ern Pacific Ocean. The occurrence of cataclysmic events such as earthquakes and volcanic eruptions informs us that Earth’s geology is active. Unlike Earth’s Moon, or planets such as Venus and Mars, Earth is dynamic, continuously rearranging its surface because of processes occurring in its interior. One of the great scientific discoveries of the twentieth century was that the crust of Earth itself is changeable, and that as it changes the continents that rest atop it actually move in relation to one another. The term for this process of change is plate tectonics. Continental movement caused by plate tectonics has mighty consequences for Earth’s ecology. Without such constant movement, Earth’s climatic history would have been very different and less variable. As the continents move about the surface of the planet they effect changes in ocean currents, air cur - rents, and climate in general. As more coastline is exposed, coastal shallow- water species such as corals tend to proliferate. But when coastline is mini - mized, as when continents fuse, extinctions of such organisms seem common. Separation of the continents acts to geographically separate organisms, stimulating evolutionary change, allowing evolution to proceed along varied and different pathways from continent to continent, island to island. The isola - tion of Australia, for example, led to the diversification of marsupial mammals, making Australia unique as the “land of marsupials.” Likewise, eucalyptus trees of over six hundred species occur in Australia and nowhere else (except when transplanted). Part of the great biodiversity of mammals throughout the Cenozoic may be attributable to continental separation stimu - lating high levels of speciation among groups isolated from one another. The Earth has changed continuously and dramatically since its origin, an evolving planet in an evolving universe. The scale of change has varied both with time and in area, but any careful consideration of the history of life on Earth shows that change is the rule, not the exception. Life exists only because it has the potential to change as circumstances around it change. The tapestry through time that has been woven by life on Earth has generat - ed many millions of species, a temporal montage of fascinating ecosystems, most of which have forever been relegated to history.

13 FOR GR
EATER UNDERSTANDING

Questions

1. Why might life be rare in the solar system, confined essentially to Earth ? 2. What major characteristics of Earth are essential for supporting life ?

Suggested Reading

Ward, Peter D., and Donald Brownlee. Rare Earth . New York: Copernicus, 2000.

Other Books of Interest

Upgreen, Arthur. Many Skies: Alternative Histories of the Sun, Moon, Planets, and Stars. New Brunswick, NJ: Rutgers University Press, 2005. Ward, Peter D., and Donald Brownlee . The Life and Death of Planet Earth: How the New Science of Astrobiology Charts the Ultimate Fate of Our World. New York: Owl Books, 2004. O W T E R U T C E L

14 Lecture 3: Distribution of Global Ecosystems

The Suggested Reading for this lecture is Robert G. Bailey’s Ecoregions: The Ecosystem Geography of the Oceans and Continents .

uppose you want to see all ten thousand or so of the world’s extant bird species. What would you have to do? In a word, trav - el. You would look for parrots in the tropics and penguins in the Antarctic oceans. And those are simply two extremes. Earth’s distinct seasonality combined with ever-drifting continents over millions of years has resulted in widely separat - ed landmasses where unique organisms have evolved to survive in varying climates. The result of this reality is that ecosystems vary dramati - cally from one point in the world to another. The goal of this lecture will be to provide an overview of ecosystem distribu - tion and discuss how ecological processes vary from one region to another. We begin with the most obvious characteristic of ecosys - tem distribution, which is that Earth has two major kinds of ecosystems, aquatic and terrestrial. The seas are vast but they do not encompass the entire planet. This is no small point. Because continents and islands exist, the evolution of life on Earth evolved to be far more diverse than it would have been had life been confined entirely to the seas. Consider insects, for example. Though just under a million insect species have been described, it is estimated that between two and thirty million actually exist. Regarding beetles alone (order Coleoptera) there is thought to be over a million species. Insects have a strong influence on numerous terrestrial ecosystems, ranging from plague pro - portions in the case of outbreaks of locusts, to disease vec - tors, to essential plant pollinators. But there are no insects in the oceans. Insects are terrestrial. They evolved from early terrestrial arthropods and today, as in the past, repre - sent the most abundant kind of organism on our planet. Without land, there would be no insects, and thus the most diverse kind of animal ever evolved would not exist.

Meet the Beetles m o c . s

Pictured at the right are five exotic members of the more than 30,000 species o t o h belonging to the family scarabaeidae (scarab beetles). These specimens, P found in Latin America, are from the subfamily rutelinae (shining leaf chafers). ©

15 LECTURE THREE Car 1 6 ma com tin Arct fo te ad re If th cul in an Ecol cip is fr o th e sha al th an So ag o shr at e, wa spe di ser som wa kno M Ph T We O i clud ve bo un ms e ou t g h sou y w a d d hat m n u a e it ters, ter, r i ve ion e mp. r ci w ysi , pte s u kin ine th ic atio a jo nt rse f mo e ply ogi d wi th sa a An th lo c ca du po l s es. n g 23 .5 d is ver r in the at te twe raze Tund on re cal e Po w d sh nd a d th it a t t n n st to ri eco n, g arct er so the sepa gro Bu nd es erin gion oth s of ng no t at ag ly shr T ar ea ru rn s le . ge in r nty re d º rest speci, con p l on Osteich eg he a t cold have bs to in sytem up e ti thu er e e ra er ic) A equ Flor ner th g rg ubs th W lt cosyte fo xper th ular rat re nt mit amo i t s pola po rial diton eq ua to r. e s plan ely , ey hou of biom an e h he n o s r alize arct o te ed and are iva Te r id w f Al th th e s ar such f long E d m ve ie are mp i ask sno a eco a, de at un ti on s sa fo re st r th ar th ’s ts. e le rm, ca b A nce uch ica inc ti ar s of e, , r rte ab fa ct ye ut wh egio te ms n in nd t w nt ar ct ic a era by th of wfal, syte n ct c This t underst of shore a as , luding e rmine bra out y olectivy s, s e t it tend Fo r a of use. er un of a spe know clim id vast te, recogniz tha pe ri od , th at be in g anu les ax is , wil ns m way the sag dr land entifyg te insect th e forty- is ms ost a. ex am th a it cia s, . and ate, to nd be char wil th e ecosytm bon ebru the some is en But t od al “te dr if te d co re a han tion, a speci-r mor meld gr ad u sp s best five re tropical. s hot it sp pr nt in it at par rest pl e co nt in en t dom y land f me if ecis. sh. is re su lt ed ar tha eciptaon wil op caled on si e cteris ten fish. it th and tha the , ticulary de h en ts , the tog ntioed co al ly to le as re to Ea rt h undr in T hig i of be a sert, s inches if b he ld ate describ region th at While ethr l,” fishe ich u Crustace inha le The you Of of car re pl ac ed broa nique, biomes. an dive cold ma ke s ed coldest m fo r in of moun in wo ul d sed g usaly course ib po si ti on d ost of bit temp , ab roup know ma vastn th e An ta rc ti ca t d wher ou rse i yo of d hat some ts de exp are ter ges esolat ove, f clima are resh the u tains. rainf the se as on al it y, wo rl d and sert, Ea r a, than be region Inside of by erinc of g es e an ratu t th and domin strial et he t marin tu are of he ab ou t climate t th ’s the vert tic m al hey gr as sl an d es water. l lemin exa ndra. domin a spe insect, of or e averg be co mi ng thes but e n lo re lichens is an . the des cl im at e the e the an bster a mple. o For r s ated e brate gions cies. di re c cosytem. egions nualy cur te mp er at e verla 36 with a an Tru d ten ated as Arcti gs. oce inh co mb in ed cold rt-yp exampl e pater m d by a s tl y with e : sub In , an d and p. Th temp il li on a thousand ther te abit Tund qu it e polar is ans crabs, wil tundra mo re by a various thrivng ov er m winter An e e predict re Circle the tropical. ns about arine sa va nn a. nu next cold- ecos fresh be ye ar s has in ra not examp are va ri ab le ratue , ( merous of grou th e A te mp er a wi th an ge ne r desrt. , is is r pr mo ys cti is or suc bird thir d not e p - th of st le - - ty e - -

© Photos.com The temperate zone begins beyond the Arctic and Antarctic circles. In the north it begins with the Boreal Forest biome that extends like a ring of spruce and fir trees around the globe, encompassing much of Canada, northern Europe, and Siberia. It is also found along mountain ranges, par - ticularly in the American West. This biome is dominated by cone-bearing coniferous trees, most of which are evergreen. It is often called the “spruce- moose” biome. The next major biome is Deciduous Forest, comprising broad-leaved trees that typically drop their leaves before the cold of winter sets in. The autumnal changing colors of the leaves makes this biome one of the most aesthetic of nature’s ecosystems. Much of eastern North America as well as Europe and parts of China are dominated by deciduous forests of oaks, maples, sycamores, and elms, as well as numerous other trees and shrubs. The third major forest biome is tropical and it consists of a range of forest types from dry woodlands such as typify much of the Australian outback, to rich Tropical Rain Forest such as is found throughout the Amazon Basin, as well as parts of central Africa, Asia, Indonesia, and northeastern Australia. The Tropical Rain Forest is characterized by having more species of plants and animals per square hectare than any other of the world’s terrestrial bio - mes. Tropical Rain Forest is equatorial, and occurs between the Tropic of Cancer and Tropic of Capricorn, encompassing about a 47º latitudinal band. There are also biomes of grassland, savanna, and desert. These occur in areas with less precipitation or much more seasonal precipitation than is typi - cal of forest biomes. Grassland once typified the American prairie, but much of the original prairie is now converted to agriculture. The steppes of Russia is another region dominated by mixed species of grasses. Savanna, which is well developed in much of Africa and Australia, consists of grassland with various amounts of trees scattered within. Deserts are found where moisture is least available and are usually dominated by shrubs. Hot deserts have suc - culents, such as cactuses in the Western Hemisphere and euphorbias (which closely resemble cactus) in places such as Africa. Fire-adapted shrubs and highly seasonal precipitation characterize a biome called Chaparral, which is found in much of central and southern California, Chile, and throughout the Mediterranean region. The biome concept is normally not applied to the world’s oceans. Rather, their life zones differ by depth and proximity to land. For example, the littoral zone is found near coasts, where water is shallow. The pelagic zone is the area of deep open ocean and the benthic zone is the life zone at the depths of the seas, on the bottom of the ocean floor. Why study biomes? Because they demonstrate how plants and animals are adapted for various kinds of climates. And because the amount of the Sun’s energy captured by vegetation differs remarkably from one biome to another. Since virtually all life on Earth depends on photosynthesis, such differences, and the reasons for them, are important. Climate and its effects on ecosys - tems will form the subject of the next lecture.

17 FOR GR
EATER UNDERSTANDING

Questions

1. Why is the fact that Earth has continents important in the biodiversity of life on the planet ? 2. What is a biome? Name the major terrestrial biomes .

Suggested Reading

Bailey, Robert G. Ecoregions: The Ecosystem Geography of the Oceans and Continents. New York: Springer, 1998.

Other Books of Interest

Aber, John D., and Jerry M. Melillo. Terrestrial Ecosystems. San Diego: Harcourt Academic Press, 2001. Barbour, Michael G., and William Dwight Billings. North American Terrestrial Vegetation. Cambridge: Cambridge University Press, 1988. Walter, Heinrich. Vegetation of the Earth: In Relation to Climate and the Eco-physiological Conditions. New York: Springer-Verlag, 1973. E E R H T E R U T C E L

18 Lecture 4: Climate and Ecology

The Suggested Reading for this lecture is Heinrich Walter’s Vegetation of the Earth: In Relation to Climate and the Eco-physiological Conditions .

hen I was a student in high school I was assigned The Grapes of Wrath , the classic novel authored by John Steinbeck. It is a poignant tale of the Joad family and their daunting trek across 1930s America, following Route 66 from dust-strickened Oklahoma to what they hoped would be the promised land of southern California. The Dust Bowl, a term describing the effects of a protracted and severe Midwestern drought, had a profound effect on the ecology of the region. But why did it happen? In 2004, a team of researchers using a complex atmospheric-land general circulation model determined that before the onset of the drought, sea-surface tempera - tures both in the Pacific and Atlantic oceans had deviated significantly from normal: the Atlantic warmer than it should have been, and the Pacific cooler. In particular, the colder-than-normal Pacific sea-surface temperature altered the air circulation in the upper troposphere of the atmosphere such that rainfall was suppressed throughout the Great Plains. The warmer-than-normal Atlantic sea-surface temperature created different conditions, but those resulted in blocking moisture from the Gulf of Mexico. The combination resulted in the severe and protracted drought. Records from tree-ring data suggest that the Great Plains has experienced similar droughts once or twice a century over the past four centuries. Such a frequency is sufficient to impose significant ecological stress on the ecosystems of the region. And that is why climate is the number one factor in determining ecosystem characteristics. m u b l A h s r a M . E e g r o e G , A A O N © Dust storm approaching Stratford, Texas, April 18, 1935.

19 LECTURE FOUR 2 0 l c spe scal ro ea ar Sta en spe br ou clo th th th er Ear mo Co an pl e r a g e r r a l s e D g e r u s e h w o m o c t a Ear an at be tr th ad che ext in th T A T B T T ast i icat e er e mosp us e n i o a c i t a m he he he e h e i l n v n d d, r ti s, d d cause a e g e h t ser r rem lo ve s i ment ed ad-l l s a o i o i tes, t t ci r r iol cks et a c , pte bro cou Orig e e r e h’ h e r y el sed , o g re o e r u t r e or be ofte i n s n es ed move l s s n a f h cean a c is s e inka h cl an k y s t s u jackr n o e lo rm it d g as h t n o e a re o co t a he nte a a su ockw ro to q a of i said e ef s aved e r a v o dest f by e n w d e r a s i w is re n co to , e u t r e w it in e v f sytem mixtur k ta h t se t ric n w ch ge n i a h ay w ith e c t a e h th h o st t r a E r- s. r ext plan c men mo lacks o m ab ing ld oth clima dust o i t a i pr th e her erb f hic ct. t c n o clo vera io ron o e y t a v i v e v i ise ga tha B Sp gr sen fr betw t e odu s i r or p o w rem o i speci n. re vin e r E in g n p ecau e v om h t n a l e its, ckw aceo A a o i r ts asl E t se, he gly n n e a c i art eci c g dro stor n ciru t l I d l r tic of s Da s i an art wa c n o c g c . e t a m i l e h f bo s, ce bo l e c an m o r f d ely o s o l s u hu e h i t h the th a wh a l ise f so in a con : . t en a n o se h’s ug rw shift u m s in d ter re u a e h th t a ve s a d ms b g whatevr s e l fr n s l fore penig t p flu e y l s s so, t e h T uth ose oth a e ation d om Ch e mospher in t i animls. ht, s e c a l t s a whic or eq ob , e r e h p rage ciru caled of Earth clim u t i t a l s l l e c o h c vect o t plants, rotain is t a r t n encs finer ters t a h e s, s t o b n e n ref m o i B , st, ar ua ject ned cosyt with those n r o f e kinds I scar an very to c n o c m Earth u s e r the u ate b les Mar io lation o tor p r a h c s e d p num d e eliv e r o n o c c u s red the f reso ha ca e c a l des eco n is biome e ab m o s org s e ce o rial le-av e very th Dar grase and t l it anto e. ce t n e s se cean r e p s But c cosytem of ems fro plane moving e r o r e v h ove o bers 2 t c a ey r a l mo west. e v n o o logica is an a f f i d anism lution. al wer ls u q i l b 3 in Clima a o t rts, f a t win m nd e t a r th res, to º 5 . reas thus ecol g esn e f f i d z i r e m s u s wh ves d a r h t t r e of as ey it n a , e are mies he t i n we cure ts ig t an of be s, im heat s e g r t a i d grasln n a e h d wro o n d at y l e This thes o r f de r e h t o ht e e h t wel a te ro ha nor st m n e r pers d So a mensly e r a For a sp defl on l n u s caled and gy the re h t r ca e c n g e r such nd v r T ce aths n o i cky, m ost be, comp e sp te, result ve t a r nts to o i r a y ecis. may uther eflct th ach l a i t a est caled use the c i p o fact, h as e n o . a ecis, various n a n o i o most t h g i ea . e h t as tre cted thing “Clim a a r t s q it wit e r e t a m i l C f in du s u ds, of as t uickly ctive e h d n ocea prai climat plane st, wil ositn. is s be es s n s e k i t lon can h atur th s s e for e h sty n a p biomes? 2 obvius orga hig Graslnd n a from t i t a l o t n i t a o suclen cha Hem s, savn east s e l o for efc e so 5 . 3 a ate m opr f and g be r e h t o ie d exam q e n a i t n e h t wil Nor a C phe su wildfoers. clima be ay l h t t b at d u e. a g exampl s. racteizd l º nism t c e winds q th en . plays u h defl r t a u ispher the selctio e rface. or tive o s uren s i e c n e t i u esiv. perio the . s e Earth e B b e thern r Desr quickly n at nome adito p s e y l l vergn p as, r o ple, h t u ad h t west te r o n a l inter u a c a m i r t can understo a p r of cted h t s equ h T e y l d n i l b ca d e r th red is an ts n a di d n a on , o t e It ’s d i o v e can ptaio f He c no al ts . . o at b e s e a m r o cal e s r cti n. complex is action reats h t y l i r be d as lacks Such ator, n, A r u a c e m ominatly impo reval be t s o m Jupiter. by to are mispher wer cheks.” In s e o c i r p a C h t furth and on, f o somewh b seaon landfor . h t u o a d know s l l e c e s u a c e b or ts e l o o c ns e the co s u s t c e l e s distnc the escribd n o i t o s i h t resu typic e s rtan and f d. inter a large- mposed deci r i d of er lon the to ta h t not in th east cli United In o P It fo t c e t at co ,t c a f lt envi g- he ms, co as mate n .n r aly - a l o as tive part gen ca The at On of a m u ro f of yl n nd o it - n r - - - in f - differing arrays of adaptations from one climatic region to another. Two vari - ables, temperature and precipitation, largely determine the type of biome. Amazingly, if one knows the average annual temperature and the average annual amount of precipitation, one can predict with great accuracy just what type of biome will be present. For example, if the mean annual precipitation is somewhere between 300 and 400 cm (118 to 157 inches) and the mean annual temperature is from about 20º to 30º C (68º to 86º F), the biome will be lush tropical rain forest. But if the mean annual precipitation is only, say, 100 cm, even if the mean annual temperature remains between 20º and 30º C, the biome will be savan - na. Deserts are uniformly arid, receiving less than 50 cm precipitation annual - ly, often much less. But some deserts are hot, as warm or warmer than rain forests while other deserts are cold, as cold as any place in the temperate zone. Arctic tundra, the realm of the caribou and snowy owl, is both dry and cold, so cold that permafrost (frozen soil) endures throughout the year. Tundra typically receives about 50 cm of precipitation per year and has a mean annual temperature of only –10º C. The importance of mean annual temperature and mean annual precipitation in determining which terrestrial biome will prevail in any one location was first revealed by Leslie R. Holdridge in 1947, who developed a system of ecologi - cal classification that he called “life zones.” The Holdridge system has passed the test of time and is still used today to classify ecosystems. Topological features such as mountains exert a strong influence on climate, creating what ecologists call rainshadows. Consider what happens in the Cascade Mountains of Oregon, for example, if you were to travel from west to east. You would begin in the cool, moist temperate rain forest of tall Douglas- firs and western redcedar trees, with a lush understory of bigleaf maple and various shrubs. In all likelihood, it would be raining. Ascending the mountain up its western slope, the trees would become shorter with increasing expo - sure to wind and cold. Spruces and firs would replace the temperate rain for - est, some stunted and twisted by exposure. Once on the eastern slope of the mountain the predominant forest would be composed of ponderosa pines, and would be decidedly drier than the temperate rain forest. What is impor - tant is that the ponderosa pine forest occurs at exactly the elevation where, on the western slope of the mountain, there had been temperate rain forest. Finally, you descend into desert, the sagebrush desert of the Great Basin. The marked difference between the west and east slopes of the mountain is due to the fact that prevailing winds come from the Pacific Ocean, carrying evaporated moisture. As these winds encounter the tall Cascades, they are forced upward. As the air rises, it cools, condensing the moisture held within and producing rainfall in generous amounts. This precipitation supports the lush temperate rain forest. By the time the wind has crossed over the peaks of the Cascades, it is largely depleted of its moisture. It is therefore not possi - ble to support temperate rain forest on the east slope, though there is suffi - cient moisture to support ponderosa pine forest. Finally, even this moisture is used and the air becomes so dry that only desert can occur. In our next lecture we’ll see how separation of the continents, biogeography, also plays an essential role in global ecology.

21 LECTURE FOUR 2 2 1. 2. Od Wal Ch Other Sugest Question Be Te Eco Wha Why a um, te pi re l mont r, n -ph , t Eu Bo d stri H F. ch oe einr ysio gen , a ar oks Stu d s C l E ich. clim lo A: Re e cter art colg gical P of Th ading , ate Ve ., istc Pame oms I a nter y. g Con nd F var e OR New taion of Gary y la est n, ditons. GR with E A. 205 a York: of rth
W. E M la AT t atson, he . afect tiude New Bar Sp E Ea R ret. ringe UNDE York: rth: ? an climate d Fun In , Har 2 Sp RSTANDIG Relation 02. damen ? old ringe A. tals -Verlag Mo to o Climate f ney. Ecolgy. , 1 973. Princples an d 5th the ed. of Lecture 5: Biogeography and Evolution

The Suggested Reading for this lecture is C. Barry Cox and Peter D. Moore’s Biogeography: An Ecological and Evolutionary Approach .

he famous ecologist G. Evelyn Hutchinson once authored a book with the intriguing title The Ecological Theatre and the Evolutionary Play. What he meant to convey was that an understanding of the principles of organic evolution is prerequisite to really comprehending the patterns evident in the world’s ecosys - tems. And it is essential to understanding that evolution results in different organisms inhabiting different continents. It is obvious that today’s world consists of several immense continents sepa - rated to various degrees by oceans. In addition to continents, there are numer - ous islands, ranging from large ones such as Madagascar and Borneo to extremely tiny islands whose names few would recognize. Some islands such as South Georgia (near the Antarctic Circle) are rather isolated, while others, termed archipelagos, are in close proximity, such as the Hawaiian and Galapagos islands. Each continent and each island contains unique species, some of which migrated and colonized, and some of which evolved there. The study of biogeography compares various regions of Earth that are geographi - cally distinct and examines the processes responsible for the differences. In some cases, such as the famous Darwin’s finches of the Galapagos Islands, organisms evolve and are unique to a single region. These sorts of species are termed endemic. In other cases, such as the cattle egret, which colo - nized the Americas from Africa, species are recognized as invasive. In either case, they become part of the ecology of the region. Consider a walk in a rain forest along the Napo River in eastern Ecuador compared with a similar walk in a rain forest in Queensland, Australia, half a world away. Initially, both rain forests would appear very similar. The climate would be hot and

Geospiza magnirostris (Large Ground Finch) An illustration of two large ground finches from the Charles and Chatham Islands, Galapagos Archipelago, as printed in John n

Gould’s (1804 –1881) The Zoology of the i a m

Voyage of H.M.S. Beagle, Part III: Birds o D c i (London: Smith, Elder & Co., 1841). l b u P

23 LECTURE FIVE 2 4 an cen pi flyi lo pi re ab con five re ma con in as Ant som hu Pan li La sou Me in fo hu ou Jur Tr la ap th ar ea th th wi nu tr an mu Bri fl Au T T ig A fe e a o a g it r re ei e ey su m e opi th sba he he ht d senc g u m r p ch m d S n styl ial l k ls a mal so a g e arct tal ti r ti th. st on e rasi ear tres, u ain st s pur si g out gae t t e a lt id sic ero gy, va ven d ne ne ha com ho gar are co n maj ly cal t su ra g sc ed zo tu reg s w sou ens squir e, 6 e the ty mole, eo ri Evo ed Au ica t o u a n l int w ate 6 s. us ch ie a p ic G i Quen ou po nce , a ose t. t uld sand s loks tine or ra in th io m p . pelingy ould ar o lo li Lone a ther m nce stra an o w Ma der la ma Er eriod B ha (o Thu f s d nd n. sibly , oug in had ep lution a u rels, gic asitzn t ilon stru ith tw he place rg ut ta s ch s, d w ma the a. in of s mar ny ( fo T ip n ma sl lia, t. P P G l o ely suga ide o bea r yea s h son milo w he an histo a be eta in a e hytes, a re T f alike. ctur spl co w M t rsup on r a nd of su ary re spe infa e ma voluti e th bio he yea d, sup ide n ra cli bu th st nta ur ar ab ntie mo fo Ko r rs like g it d ma e ls, pe n the Au r into us al an in m a lite rsu wan ry supial s geo h t Ea rest n cies l. ly fr ial sent al it. p a rs g spe cts l a lon ia stra in as placent le-ik r s ate But aterns with i o y fte b a charte l m contie go. pla nsect, of id p a se l re Me One’s rth g pials nt m ago, of n Sa bandico b gr a la “mice,” amls g l ers r vice ben cies like in ia few e pa Ear of parte of nt tha until n ce of the up can ap are the yea . isolate and soz The g at wid ctuary ma co s in rt ps m mar ntal marsu th Gon on hy Au wer a th ba tha such have mon opy beg ) othe arsupi rs impreso o Me mals both is e 2 at pres birds, huma ha in p ristc r ic strali 48 ma r r t s, closer d su la b in each ecogn t ho m dwan. d ts sp o sozic ve utres Era, an time e - and La r the ost - - milo f as t a cosytem ver withn rom ecis so nt dapt ns an b mals with urasi to inde ls such e en orch uther sole split of y some s inspecto the ize consite voled sin d take a n pro n the dif began ba rived t r Near those t he to s s o ainy ce the ye h hat doing d id tre ck f as lif f ma ernt ad n at th rom to rest a s bo ars e difer erat 15 day. th co at ven tro som colnized the th in kangr wid malin the throu th not with , e th d br with 0 n ntie of at t Pan ago Antarci pical e of so r he t o evo anches m ir espon im of e it The d the nor e f toda e colnize a nt what ilon b si would r evr on nd e ghout tach ecolgy o their t gae 4 ange ase. hes at lu m os n trajeco .5 th o r fungi e for ain tionar s y ilar o f Austra the ocup bilo a sup f the yea by ear was oth since. dogs est would nd hape and the bega of son the fores fores T to clim d (Australi begi flying are lier), er erconti he rs din y and Go n hab wo the th o M ies lia. ants grow year. histore. years, t nce a ates only n e han osaur, crown t esozic ts nig q ndwa uld be ned b go, itas biome, now-isla uite an to g fact e betw Placent to would enral of lea part coverd d be b ab o wil the but Au to reak n distnc the s and was but and tha of rned out t, complex a strali) be of the b hea of those Era, a to the be n tre e e for nd the apr both forty- alon thriv th ted ntire sim the tha t, tha by e in e - t, -

© Photos.com that resemble placental rabbits and hares. This evolutionary phenomenon of two distantly related kinds of organisms evolving similar phenotypes is termed convergence or convergent evolution. Convergences are common throughout the world’s ecosystems. Indeed, convergence is so common that it often presents evolutionary biologists with difficulty. Is apparent similarity among certain organisms a result of sharing a recent common ancestor, or is it a case of ecological convergence, a result of natural selection molding very different genotypes into similar phenotypes? Genetic analyses such as DNA sequencing help answer such questions. Ratites are a group of large flightless birds: the ostrich, the rheas, the cas - sowaries, the emu, and the kiwis. The term “ratite” refers to the absence of a bony carina or “keel” on the sternum (breastbone) for the attachment of flight muscles. For many years it was debated as to whether or not the ratites are all genetically closely related or are an example of convergence. They do not fly, yet are widely separated, occurring on different southern continents. The argument for convergence seemed strong. The argument weakens, however, when one realizes that cassowaries are forest dwellers, unlike ostriches, emus, and rheas that all live in open savannas, and kiwis are unique in being nocturnal. In other words, the various ratites do not occupy such similar habi - tats that one would expect selection pressures to result in similar body forms. Recent work on DNA hybridization as well as DNA sequencing has shown convincingly that the ratite birds are not convergent but all stem from a com - mon ancestor in ancient Gondwana. The ratite distributions offer convincing support for the reality of plate tectonics and resultant continental drift. A key issue in ecology is the question of what, exactly, is a species. If you travel throughout East and Central Africa you will surely see elephants. As large and unmistakable as these ponderous beasts are, it may surprise you to learn that, until quite recently, taxonomists were mistaken about exactly how many species of elephants currently inhabit Africa. It was assumed that there is but a single species, the African elephant, Loxodonta africana , when in fact there are two. Recent studies suggest strongly that there is a second species of African elephant, the African forest elephant, Loxodonta cyclotis . Compared with L. africana , now renamed the African savannah elephant, the forest ele - phant is smaller in body size, has rounded, not pointed ears, and straighter tusks. The results of the molecular analysis suggest that forest and savannah elephants are each as distinct from one another as lions are from tigers. Ecologists thus determine species by a combination of factors: anatomy, ecology, and genetics. The most widely used definition of a species is that it is a population that is reproductively isolated from other populations. Cichlids are a group of colorful freshwater fish commonly kept by fish enthusi - asts in freshwater aquariums. These diverse bass-like fish are found in tropical waters around the world. There are about three hundred species in the Americas, including one that occurs as far north as Texas. But, by far, most species of cichlids are found in East Africa, clustered in three lakes that formed in the Great Rift Valley: Lake Victoria (less than four hundred species), Lake Tanganyika (two hundred species), and Lake Malawi (three hundred to five hundred species). Why are there so many species of African cichlids?

25 The oldest of the three African lakes is Lake Tanganyika, which formed 9 to 12 million years ago, and the youngest is Lake Victoria, whose origin is between two hundred fifty thousand and seven hundred fifty thousand years ago. Considering only Lake Tanganyika, if one assumes it to be 12 million years old, the highest estimate of its age, and it has two hundred cichlid species, that is a speciation rate of about one species every sixty thousand years. However, researchers are in agreement that the amazing diversity of cichlids in the African rift lakes arose recently, within the past few million years, demonstrating that speciation can occur with impressive rapidity. m o c . s o t o h P ©

Two of the many varieties of cichlids found in Africa. At the left is a male Malawi cichlid found in Lake Malawi. At the right is a male “Zaire Blue” found in the waters of Lake Tanganyika in the Democratic Republic of the Congo (formerly Zaire), about 100 miles north.

Studies of DNA of the cichlids from Lake Victoria demonstrated that this cluster of species is genetically very closely related, showing that they all recently evolved from a common ancestor. What is stunning is that the total genetic variation among these four hundred species is less than that found throughout Homo sapiens , humans. In other words, the genetic distance between you and a stranger you might meet is greater than that between two separate species of cichlids from Lake Victoria. Given the estimated rates at which mutations occur, researchers believe the entire assemblage of cichlid species in Lake Victoria to have arisen within two hundred thousand years. That’s equivalent to about one species every five hundred years. The evolutionary process whereby one kind of organism, in this case an ancestral cichlid, evolves into numerous species, each adapted in such a way as to be uniquely specialized, is called adaptive radiation. There are numer - ous examples of adaptive radiation both in the fossil record and among extant animals and plants. Evolution is the process by which biodiversity is generated. Now it is time to see how it varies from one biome to another. E V I F E R U T C E L

26 FOR GR
EATER UNDERSTANDING

Questions

1. What is convergent evolution, and how does the Earth’s current continental distribution affect convergent evolution ? 2. What criteria are used to distinguish a species ?

Suggested Reading

Cox, C. Barry, and Peter D. Moore. Biogeography: An Ecological and Evolutionary Approach. Oxford: Blackwell, 1993.

Other Books of Interest

Adams, Douglas, and Mark Carwardine. Last Chance to See. New York: Harmony Books, 1990. Few, Roger. The Atlas of Wild Places. Washington, DC: Smithsonian Institution and Press, 1994. Kingdon, Jonathan. Island Africa. Princeton: Princeton University Press, 1989. Weiner, Jonathan. The Beak of the Finch. New York: Alfred A. Knopf, 1994.

27 LECTURE SIX 2 8 in An T Gu id e pu in gr th th wo po to me Arct po tin Two O T he clud e e synt 20 e t ho e f l l ar cea r ar ar l at ds, ti nt in sun oce 06 ic ct Su g s ng ug s ic atel reg co . w in he o n Oce to h t a conti hale n an g hey at nt shine cu li si. t ge st ions te bite E va t n in ic an, he its r ar net; ort a com s ent riou ent e fod re B south N th a u th, ed m rly fea ach s h her A not po ut a ort po e ave on s ar for rc ti c a is s lo se t si fact cold st n Re ad h n brin her gin we ri pe se te also cap cate eith , a gh a a P la o in i i s n . mag b con s. n t ole of fe tiudes g you t , time guin a hat tu com th a d dur in g the w nd ret u Antarci, r Po ice re fa e e tin p a yo d s mon l a se-co th s ing oes d lar in of esn you a bou fo r sp e re u t ife it e ating. hat nt, the re also the are ecis is standi f th Ec n ths lor ir th th is nty renc spectab are Ea An Earth’s st e t becau at ed is hat osy tial dark stand rth o part su loca tarci. o L the view ter once n stan le ct ur e at ’ f e s mer ch they t inve bet ct g Po restia he ake polar tem so or se tion south ing le emical o ur o ding la f we uther n pa twilgh surface r the rteb am o are e s of Re regions th on f gro is Th rt en is 6: l glo a A ern e g ly. ount on t rct 90 nd of he io ecol n e ice ates E. C. wi nutrie No them? ns bal ic Th la No the º G pole. n for seaon ar Tu Ocean wate rth nort an tiudes g of ondwa e e rth clima gicaly and Pi el ou ’s se ndra South sho much d ke the Po ts h The Ice ason. rs. a Pole . y wn t and Both le. fish. to te Sun’s to the and In l above. tha a, pr of a the Po bo And cha pola is nsw im bot the oductive. is Man South A th unty. le? ages mu located surond surface nge en the e Na tu ra list’ s h r supoe At er secon res year, productivy y What, polar left wer is rgy colde seabird, is Pole is tha e and curently on d In genr by wh the both regions s besid 90º st you other at the this a en ph t con ated the o is - -

© Dave Pape/NASA On land it is a different story. The growing season is short and in extreme situations, as are found in interior Antarctica, virtually no plants exist. But there is one kind of ecosystem found not only in the high Arctic but also at high elevations on mountains that is permanent and diverse, adapted to the climatic extremes of wind and cold. This ecosystem is called tundra. Suppose you are standing in New Hampshire at an elevation of about fifty- three hundred feet on Mt. Washington. Or suppose you are visiting Rocky Mountain National Park in Colorado, on Trail Ridge Road at about the eleven thousand foot elevation. Or perhaps you are wandering along the gravel road in Deadhorse, Alaska, well inside the Arctic Circle. Or maybe you are just lost in northern Siberia. Regardless, in each case you would be on tundra. Tundra is the biome that is found in the coldest, driest places on the planet, where conditions are sufficiently severe so as to prevent the existence of trees, except in extreme dwarf form. Vegetation consists of lichens and moss - es, grasses and wildflowers, scattered shrubs, and little else. Tundra is open and wind swept, in a climate so dry that even the protective blanket of winter snow, so common in the boreal forest, appears sparingly, if at all, on tundra. Organisms of this biome endure the worst weather conditions and enjoy the briefest growing season of anywhere on Earth. Latitudinally, the tundra biome, named “Arctic tundra,” occurs generally north of the Arctic Circle (at about 66º north latitude), though “low tundra,” where tundra mixes with boreal forest, begins at about 72 to 73º north lati - tude. Tundra exists as a band around the northernmost of the world’s conti - nents and is generally similar in North America and Eurasia. Tundra can also be found above treeline at the summits of tall mountains. Montane tundra is usually called “Alpine tundra,” to distinguish it from latitudinally based tundra, though the two are much alike in appearance. Tundra is highly limited in Antarctica. Obviously tundra regions are cold much of the year, with a markedly short growing season. In the case of Arctic tundra, temperature is affected by the low angle of solar radiation. Even during the warmest time of the year, mid- summer, temperatures reach only about 15º C. In the case of alpine tundra, exposure from elevation tends to keep the temperature low even though the angle of solar radiation may be much more direct than in the Arctic. Winds are a constant component of tundra climate. Wind speed is frequently high, especially in the Arctic, where it can routinely reach 65 km/hr. Snow is the usual form of precipitation for much of the year, but, perhaps surprisingly, in the Arctic snowfall amounts tend to be small. Precipitation is sufficiently sparse as to be within the range of that of a desert. Alpine tundra areas expe - rience considerably more precipitation than Arctic areas. The most notable characteristic of Arctic soils is permafrost. This means that part of the soil is permanently frozen, preventing its use by plants. Roots can - not penetrate into permafrost. In summer, the upper levels of the soil thaw, providing sufficient moisture for the rapidly growing plants. Because of the thawing and refreezing of the upper layers of soil, there is an intrinsic instabili - ty in Arctic soils that results in the formation of hummocks, which are elevated areas, and polygons, geometric patterning that often spans wide areas. Polygons form from constant thawing and freezing of water in the upper layers

29 LECTURE SIX 3 0 gr spe wo ge de ro pe r dw a sh ar e to (o n pe r th an Re da pr th e r a d n a s l i o s y l whi c of sm N An In I Ge A or n at an o d e y ap l e cl d r mi n so th lves, d e n i p all en ly mi t. o wi ent k vail Ar ge , g n u o ci i se. al s c rf in uced mals me w su a h k i p e, il, fo t m m o er es y t ng si xt y estrn ct ic ni al hat ni e n bi rc he im i i s tr o ced tse l r c i p a er in gr ow s a H ma M ical a rub n u t ar ca o most seao g ze pro cess er nd, al, an y fou f a tu nd r biod tu . wi en er a h y l l a o cti f ly le ls. to bou sho Te bl ds d n may n ld ev ap or at iv e shaped s th a r g n i v nd , e, d am o dra along ri on . N in pe r fl ow of i n a r a of e fox, al l ve reb t S n, nd a, lemin or o s one dep o e in th ed ge s biod e be t y d ie car en ni al re rsity he a ng th e b s l i hu nd re d tha t er s ird dur e s, y k c o r o tr ue lon hu f n e e g g the with m r o th sev eral h rizly ib Ca io sit ing s, w o d th e iver mo pr arsh in fo u g er ou m ns. eve ntua lly inter, gs les, na sandpier g of te n of es en ce r c with wi ld fl ow er s, ay t o n Arcti a e r a sity da bio re in de er wa te r w cks nd t (caled a e exprin he al In bea h t i . climate. the da ys ) re mes, p t a u s u d e t m in cond he lon of th s in e re do mi na te sume sult o l ete rs r, lar ger e th e ha o l clear both s t os s of y l l a region h t i w f snowy h tu nd ra reind s, se le ct s it s, res, sor ts wit fr a t i b a h li ch en i f o h io g ce A om ly ig h gr as h in a p x e rc ti c ns h so me alpine a r g r visble h t fra gmen ts nd ebs, r Arct serv th dia g epat we ll the e the is we wi nd s . er t o rowing n e i r e n o i t hat . l e v e ( plovers It wl, r al so fo r Cl ad on ia met er. i g n i s i ic, n in t e in is ca ll ed sevrity lar g habite an ar ea s. xception as are and ed an as pr os tr at e r o f a L t Euro no ta bl e it his e c an d oc cu r d to er is d e g r seao f o import cyle im s on Arct gen r e p var nest r h c u pr gr ow “c us hi on fra g pe) d. ough- age h t a Th es e sp p o r ofund th of r f a m ious eraly e ic L in co n s of th at e k c of n men ts ife-or graze e r c dur ant m physica pl an ts , tund .) , al pi of ra pi dl y bor ders in the certa leg t n u o tr ac te d , s d l e i f . t s o sp e r u t a ing abu dw ar f nu me ro us ve ge ta ti on the fo uns ne ly arcti pl an t ra eci ms od on of n i a in cold, y e h T th nda d tu nd ra . li te ra ll y Arcti. is l s wh en e roc ks s h have itable d e l l a c co hawk. tundra th s of wi ll ow gr ow in g s” s a m ources . e g n a r ot short nce e of nditos arkedly the win fo r e r a desrt. tundra st o m r a m ducks sp ec ie s co nd it io ns pa tt er Smal are evol fro m ly in g for and th ei r s, dy, Many - l l e f pol ygon , Arc e g es e h T for an se as on plants in a r e n and ,s d l e i f tic les ed the tha with ns a d lo w the nd of l -

© Photos.com shaggy musk oxen. Many insects occur on tundra and any visitor to the Arctic tundra in summer soon becomes familiar with just how abundant mosquitoes can become. Tundra is fragile. This is because the growing season is so short that it requires many years for vegetation to recolonize and grow in areas subjected to disturbance. Unlike in the temperate zone or in the tropics, where vegeta - tion development following disturbance is generally quite rapid, the opposite is true on tundra. The fragility of the tundra as an ecosystem was cause for concern when a pipeline was built to transport oil from the North Slope of Alaska, Prudhoe Bay, several hundred miles south to the port city of Valdez. The pipeline was carefully engineered to prevent damage to the landscape and, in various areas, it was either raised or buried to permit caribou herds to pass unimped - ed during their annual migration. In general, the pipeline has been successful in not damaging delicate tundra ecology. Proposals to drill for oil within the Arctic Wildlife Refuge, an area entirely on tundra supported by permafrost, have met with skepticism because of the potential damage that could be inflicted on the ecosystem. In Russia and the Ukraine, where environ - mental protec - tion laws are far less than those of North America, tun - dra areas have been subject - ed to damage

far in excess m o c . s o than any expe - t o h P

rienced in © North America. The Alaska oil pipeline is shown snaking through Atigun Pass (elevation Direct damage 4,643 feet) in the Brooks mountain range. The Dawson Road is at the right from human of the photo. use has been augmented by air and water pollution from numerous factories that deal with mining and oil production. Alpine tundra areas have been negatively affected by human use for activi - ties such as skiing and hiking. One of the worst threats to alpine tundra is the increased use of off-road vehicles, which do significant damage to the fragile plants. Polar ecosystems illustrate how organisms evolve diverse adaptations to cope with extreme climate. Deserts, as will be clear in another lecture, are similar in that regard.

31 LECTURE SIX 3 2 Pi Sh M 2. Sa 1. Other Sugest Question il el Pr Pr U gr is Why Why ir g e ou, n i e, s, o ha i e t nce ive und win s, Hu Br i, Bo E a d rsi to Ha yan re oes .C g ra 1 gh, ty n 94 oks se ? d p dor . U A olar o and t ason Re T und f niver . Natu am he T of ading exas ar ra Mike . ? Ar sit I eas The ra nter e cti F y list’ xist OR Pres, Pre Sa e C est a colgia omplet p lisb nd GR s, Guid rimaly Its ury.
19 E 20 AT e 85. Wildfe. 02. ly to K E Gu in in R th pro gdom id t UNDE e he e ductive Arcti. New t A o r of cti Anta RSTANDIG the Yor Chica evn an rcti k: Ice d F n go: with Wildfe ot acts Bear. in Un the o Antar iversty n Austin, . shor F Prince ile, ctia? t 1986. of TX: ton: Chicago What Lecture 7: Boreal Forest

The Suggested Reading for this lecture is E.C. Pielou’s The World of Northern Evergreens .

he Boreal, or Northern Coniferous Forest, is a vast biome that encircles the far northern latitudes, covering just over 10 per - cent of Earth’s terrestrial area. It is strongly identified with the wild, yodeling call of the common loon, which nests on the seeming - ly innumerable lakes that dot the boreal forest (thanks in large part to recent glaciation). It is a land of relatively low tree species rich - ness, with millions upon millions of spruces, firs, and pines, intermingled with larches (which are deciduous conifers) and a few broad-leaved tree species such as aspens, birches, and willows. Often termed the “spruce-moose” biome, the largest of the world’s deer does, indeed, thrive throughout the biome, feeding on aquatic vegetation within the numerous bogs that interrupt the unbroken vastness of the forest of “Christmas trees.” Species such as moose, wolverine, lynx, goshawk, boreal owl, hawk owl, and red crossbill are among those found not only in the boreal forests of North America but also in Old World boreal forests as well. Plant species are not the same but are closely similar, with, for example, Norway spruce replacing m

white spruce in Europe. o c . s o t o

The northern third of the h P boreal forest, where trees © are stunted and shrub-like One of the many moose residents browsing in the woods at due to the severity of cli - the Algonquin Provincial Park in central Ontario, Canada. mate, is traditionally called “taiga” (from a Russian word), but the word “taiga” is now often used to name the entire biome, thus “boreal forest” and “taiga” are commonly considered interchangeable. Much of the region of the northern coniferous forest has been subject to recent glaciation, resulting in poor soils and an abundance of lakes and bogs, created by the scraping action of the immense, heavy glaciers. A bog is dif - ferent from a lake in that it has no inflow and outflow of water but is, instead, an isolated basin that eventually fills with peat, becoming increasingly acidic. In North America, the Boreal Forest begins roughly at the Canadian border, though it is also found in northern New England and northern Michigan,

33 LECTURE SEVEN 3 4 te Becau we Bor ne do de fr a Th to exp te in wi am cal var cal un No wi tr th in ven fr sta te cip be Win br th to to re Th in te Eng ab fo Ameri th Ap Mi So om e ozen Th g g r, mpe e r. e mpe un e b i g th nt n l e sol scri ng d i u d a – e es l led r it at , nt ng o i u ion eal proc es thern neso eri ts i up dle ergo nda el soi col rct 5º Grea te s maki In sta er atio el al ls e e ng d rde b co it t i na from must a rs ma achi elo he can ude be in ca pla g a ra s, ra ic w se ar w w C d so l, d moistu ni gr tw nd so ncig row l bo sp n hig n eav orm es i bling i i . tur te ar te thin e r t ta, nter tun of ng nter cal to t w t n oun a we mew nts hus bo o ec tre t In ils a of ecis) ut he th Sm West the e thr typ h mo r ver es p tisu ing the speci n w ent as a rea an dr a the ig ro e sp a (t hysiol snow a sh a , – te d f t in s, int nt ou ncy. E ha g rom he ica dam t lm hat re oky the re ht a 15 ha th nth w age u spe subze fe he d sh er mp ru row xte ape p se surfa l . er gho f w , ye gh itho es. gro e rde ost orest r w soil Wisco o from º ly w t In ce Ro th e m ort hic into ason f , era nsio cie to M s C ars. ag ra - e ta ing p e t th whic ge un ut n typica a g l ut to he , a ckies, lac b th a ou k n ce. as ro - m e cid, i bore s e re with etwn lways tur leachd - - ge was n rou d the of ten n sea ntais onth, Spods nsi. es, b snow. eral, becoms 90 soft so e The o oreal the as ghout ds cur al l co bore of, most son Ca “ te of thin, days gent podz lo for m uld u A mean thou to mper Pacif upe say, spruce abo , o scade, ng nder s uch forest is al uniqe est f th ad at the pre an ls poten Nor or e and short, ica gh fo ut incre l, ature r 30º fot. ar hig as d in m ” an rest, ciptaon l so hig e hyd th ly 4 , Nor faling b terming e n in s 0 ra cold, 1 ut utrien tialy il and and ext asingly a C, erals Ca simlar ual 0º a the ngi Bo el Bogs rogen cid hor extr thwes. at is t nd elva hat a rolina re temp vations ic re r nsio nd tre Siera firs C izo the as acu al eplacd ems 50 les depo . word po faling du l is elin, are a fro win n In tha ion r shorte tions ndsca acts aver ain cm or. e, with a and For is mulate m oth of ratu s sited ter par Neva signfca from in usa has south the in a The a to pe age to borea wher as of er exa nualy by sou bout the ned pa a ticulary sum e the y i aid n the words, lo snow. in ben da, rt, closey ly the form until ra oca mple, n daily th ward conife w o as a l 120 mer up nges rth the to a Ro the for to a of, hea t lowe e and er s grayish on siona the bra bu re rn Georgia. est, cky acid lo er In tre from wel days sumer white say, and forest r place word e re F t w ildup ou from nches r gen i soil of br n is moves lated Mounta l “B” ic tempr the s s an ly eakdown as sno fairly sum – Ma in in forest d. due spru co d layers 70º used ab of hybri g ral, ho with shed southern ives by ine w lor. bre In could out leaf mer riz north bo C con ce, ature in ins. pre spo the dize. ak to . to on . the th way 4º win lit to - ing of - - - to C -

© Photos.com the influx of decomposing litter as well as the prevalence of sphagnum moss, which enhances the acidic nature of bogs. Some boreal soils have per - mafrost, where the soil remains frozen throughout the year. Throughout much of North America, two species of trees, white spruce and balsam fir, are the dominant upland species of the boreal forest. In wet areas, black spruce abounds along with various willows and tamarack (American larch). Areas subjected to recent fire support stands of aspens, birches, and/or jack pine. In the Eurasian boreal forest these species are replaced by others, but the appearance of the forest is essentially the same. Bogs, most created by glacial retreat, are generally abundant throughout much of the boreal forest. Bogs provide habitat for species of insectivorous plants such as sundews and pitcher plants, as well as many other specialized plant species, including sphagnum moss, the dominant bog species through - out most of the biome. In the most northern regions of boreal forest the trees are much reduced in stature due to the severity of the winter weather. It is here that trees such as spruces and firs take on a shrub-like appearance called krummholz , a word that means “twisted wood.” The spreading, shrubby growth form is caused by the fact that the tree branches beneath the snow survive, but those that pro - trude above it are killed by wind chill. Thus the tree grows mostly horizontally, producing a shrubby, often prostrate form. Beyond the zone of krummholz , trees cannot exist due to the severity of winter weather, and it is there that the boreal forest yields to arctic tundra. Characteristic mammal species include red squirrel, ermine, varying hare, lynx, wolverine, grizzly and black bears, woodland caribou, and moose. Some of these, such as the ermine and the hare, change pellage seasonally, being white in winter and mottled tan in summer. In winter, bears locate dens where they enter into a deep sleep, though not a true hibernation. Mammals such as hare and lynx remain active throughout winter months, the former trying to avoid predation by the latter. Beavers are particularly abundant in many bore - al forest regions. Porcupines are common rodents in boreal forests through - out North America, but are absent from Eurasia. Many bird species, such as common loon, wood warblers, thrushes, and fly - catchers, are strongly migratory, but others, such as the pine grosbeak, bore - al chickadee, three-toed woodpecker, spruce grouse, and great gray owl are resident, even during the cold, snowy winter months. Reptiles and amphibians experience a reduced biodiversity in the boreal for - est compared with more southern latitudes. This is most likely because these animals are ectothermic and cannot survive easily in an ecosystem where cold temperatures predominate for most of the year. There is a major insect flush in the spring, as many insect species emerge from over-wintering eggs and pupae. Mosquitoes and black flies, a significant nuisance to humans as well as other animals, are often dramatically abundant. Timber harvesting is widespread in boreal forests in North America and much of Eurasia. The wood is used for construction as well as for paper pulp. Clearcutting, a lumbering practice where a large section of forest is complete - ly cut, is a common practice in many regions. Clearcutting is controversial

35 LECTURE SEVEN 3 6 gr ev be spa tr an fo asemb Co coa an spe ou fo im gr a Te do th an po str re fo r mi tt e in ex bi vest Th ne ha act ma at ma yea of ha th am I T Bo Bo T e n o re re e ou co o a cr r he pa p N cause d es n s m d p w b r th tr e mpe e lumbi ee logica ual ture ke o wt nd vest. ma r n osi st ci r r r ual ula it fur s s st eat st es, o in ly f ast , esti s. ng g e e may Wash e sh d ns io n at orest t es, rt h Paci h s o , s, h al al b t g ly h is o la c fir ng n to ly s. ti f Cl e j i ion t a r s t a tem ust fting le co i b rad ca y l cate on hem th n an fo on at nd a, l , e age . s cu rr en A l rv es ti ng C ive w e is or on it B r ar h n nha an ways red T for fic , e nse rest eg ro al me ri so d e arcu in n we lea h i ave e scape ecau pr of eal is e. he declin m la per a com cut, ive fe ich te gto R d d be sp f est mo me pu th Nor ovides of rge rom w als su l land le a rcut nce ba rr O r ain s mpe com in rsity. co vation ca , ate ousa w, n od ts fo ecis tl y a t rpo n, can ne aco t ita th d pose saic in run se e re s of r re thwe , old rest, Eu such mb col th en on e re su lt in g by be an F an bio in a are ble th th at Nort o ra se gio s ra , b ta th ks us s or ro te nd f -g a then e inato o speci, twe th in d mplished R te d con in d gr o ax l es a such diversty t n as g biolgst real mp st ns e pe. al n h rowth t ea hig . us si a, fu e go ot ed as f t re sit h ist of is some large st: years. ar fo r abits he Actives Douglas-f ain or of ly un d necsary cep are ch America tres it er ka s rest ge ne ra ll y be n habits the b n thro mo ma Can A as sem t North sa ate eav cal in eight p 40 hat ab ov e, of fo clear t spru fore recipta harvest typical tu nd ra are wh er e Uniq re w. ar most is an coletivy m rest. ugh co This b coast in and for adin rain su often eas. y akes devlo beca lush. to r mon st, T ce, ov er al l fet cut such America such a pr ch he ir ar ue speci scale to chan a l, 70 nd In , forest staue th e sh ou ld hig fore o ovidng moistu fa r in to e ed th proce a we i io a ne suce use complex 0 n pro l exc i wide Conif Tre Californ, resd t rguab a lyn e fog n, a ping for as ca se . dife ye a mo re ge fectd lon st stern in , in lo ss ca a rainf vin wa ar x particul dife it est sque t ars, re as is , is as eds s ermd p s alo re with whic id ea ll y ribou tha ha at eas in de erous ower ce rent a y ly , into a ro d ecolg ed al, of fo whic of shor Th to a lso hem ve ng as their rent the “patch stroy the thoug utinely in physical 30 o tr ad by re st of “ req time of fo re st ecol su f e shiftng to fro a or up b to this the alowing u boatin the Britsh th stae t en lock, al en rly mo st mo cle increa stae m nique port Fo prom uire i base. m a fet ica ti on al ly enh “re e is has , to h work odel s large Californ North time in fore arcuts o tre st res gical te u th exc cu t s th at ly in ne historca 35 s re ome ance brush mper we e struc g Washingto se ri ou s in ma es der,” of mosaic” exp an of Colum sed in t simlar st 0 te for sm ma su st ai na bl e an nu al ly q a for as heig stern It is tracs rego su uilt” jestic rea oc cu pi ed Califo h cm m American also un d ra with is ave may al ate how y re su lt in g presvatio h y any sutainble rie cesion forty 20 pid uman exrt no has (138 ares. maturing, ly bia, and e of sualy staure, lo ss n t. wth, red in 0 to rain in not o of rnia, of ced of rmal atin ares timbe reg This exploitd difernt f cludes fet to otherwis th an the b habits. forest, is th Oregon a ced inches of en signfcat and u recn by can fore rowth sixty n e signfcat tre yi el d the sage Loking tal Orego in for in tha con boreal bo re al old r Earth’s a ar, fo re st . is mor n an har st. B one heigt t l the s t - ife of pe r he tly, ritsh ifer ) ite an d, fo for e - n r - , - if of rapidly growing spruce-fir forests that typify most of the boreal region. Because of the old - growth nature of much of the temper - ate rain forest, there has been significant controversy surround - m o c . s

ing logging practices. o t o h Tracts of forest have P © been clearcut in many areas and the The giant redwood tree named “General Sherman” dwarfs tourists at the Sequoia National Forest near Visalia, California. The tree has a forest that is regrown maximum diameter of 36.5 feet, is 274.9 feet tall, and is believed to either from seed or be about 2,200 years old. by planting seedling trees will itself be har - vested in as short a time as sixty years, thus preventing the eventual reestab - lishment of old-growth forest. Clearcutting also has the potential to increase erosion of soil, polluting streams that provide essential habitat for salmon and other species. The intrinsic beauty as well as ecological significance of old - growth forests have made many urge that they be conserved. Because of the logging issue, old-growth temperate rain forests have been subjects of much ecological study. The northern populations of spotted owl have been at the center of intense debate (the owl made the cover of Time magazine’s June 25, 1990, issue) because the species, which is considered threatened, apparently is restricted to old-growth forests for nesting sites. In addition, a small, robin-sized seabird called the marbled murrelet, common on the offshore waters from British Columbia through northern California, flies from the sea to nest atop the tall trees of the temperate rain forest. This bird’s nesting site was utterly unknown until a nest was discovered atop a Douglas-fir in northern California in 1974. The red tree vole, sometimes called the red phenacomys, seems to live its life in a single Douglas-fir, feeding on the needle leaves and nesting within the boughs m o c . s

o of the huge tree. Whole t o h P populations and numer - © ous generations of red Moss-covered trees in the Olympic National Park near Port Angeles, Washington. The park boasts ocean shoreline and tall phenacomys reside with - mountain peaks, including Mount Olympus at 7,965 feet. The in a single tree. annual rainfall in the park is 56.5 inches.

37 LECTURE SEVEN 3 8 Sto M Kr He Pi 2 1 Other Sugest Question . . at el iche Be Ed I Fo al W ev W n nst r hews, ou, er, ry, so ha hy re r i ti kel it rg r, o st u t J. a Tr Bo E is ns, ti Joh d s. ey: en .C for on a if Da much Da cy oks fer B d 1 est n. Un vid T ost a 98 niel. tre enc Re I., nd h A e ivers . o of es? of and . Can Field ading f n: Pr Wo Ca ne s t I es, he Ho nter sepa ty rld F ed Rob scad OR da ugh Guide b of le o ore 2 est ’s ert - f rate 02. Californ e le GR ton No Bo al aved O L. to rthe
l E fo th real ym Mifln, Usinger. AT rest e Californ pic tre ia b n E For oreal R Pre Ever domina Nat s 19 est. UNDE ? s, i Siera ural a fore gre 8. an W 19 ted a RSTANDIG st Hist d ns. shingto 63. Pacif Nevad fr by om ory. Itha nedl the ca, Po a Coast , Natu DC: rtland, tempra NY: -leavd Smithson ral Nor C omstck, OR: History. thwes rain Raven ian for 198 est, 8. Lecture 8: Temperate Deciduous Forest

The Suggested Reading for this lecture is John Kricher’s A Field Guide to Eastern Forests .

astern North America, as well as much of Europe and temperate Asia, has forest characterized by broad-leaved deciduous trees. The similarity among these forests can be striking. Sycamores in China are scarcely distinct from those in North America. This is not a coincidence but rather the historic result of continental drift, the trees having evolved before the division of ancient Laurasia, the northern supercontinent. Oaks, maples, sycamores, beeches, and hickories all typically lose their leaves in synchrony as summer turns to autumn. Leaf drop is an adaptation to the impending winter, when the air temperature will become sufficiently cold to freeze the soil, making uptake of water impossible for the trees. Leaf drop is a precursor to physiological dormancy, permitting the trees to endure the prolonged cold of winter without catastrophic water loss. A temperate deciduous forest typically contains a mixed assemblage of deciduous trees along with some evergreens such as hemlocks and pines. Such a forest is annually cyclic, leaves gradually opening and unfolding in spring, with summer, the growing season, the time of maximum photosynthe - sis. As autumn arrives, chlorophyll, the pigment that reflects green (thus mak - ing the leaf look green to us) and is of crucial importance in photosynthesis, deteriorates, and other pigments, masked until then, make leaf colors turn various shades of red, yellow, and brown. The array of fall colors, from the blazing oranges of sugar maple to the subtle browns of oaks, makes this for - est one of the most splendid to behold. In winter, aside from the scattered conifers that mostly retain their needle-like leaves, the forest has a stark look, the branches barren of their leaves. Deciduous forests are typically stratified into fairly clear layers determined by the heights of the resident plants. There is a canopy layer defined by the crowns of the tallest trees, typi - cally sixty to eighty feet above

Colorful leaves

enhance a beautiful m o c . s

autumn day in o t o h

New England. P ©

39 LECTURE EIGHT 4 0 eas etati pre inte ca whe mos the Be from dep typ as the thro itse istr tio of sa gr o me bac co th e th le a te Pre well mo Ca th of sou be ar son Aust al ea and dog the als num D T T so e r, e e he hi tion nd mm u n comes stern ec re th ca o r y ic ve w a st c un lf, ci rac il k ol , th . os woo d s s g gro sume ug it favor s re on. t ipi s n oth e d cy ral y ally ell o a fo , id u oil o de Thi ee ro us the pi s, i into , ke con imp d ra o th b na, , f its s il t h an p D tati tion fer u cl m b o t un fte i u iom cal ilt, t ni e pe pe er ation a, as enetr l e in re l has an d ds ou s y he nd, Tree lu ep s i N th nd ing acid tt er in n nu top able the ty ” ce or n/h erb of ed, d. on, n so the to 17 ebe rr o sh is ndig r ort le T e a pla ea eral the e or o vegeta rth ta r . a nd hori asm ntrated. fa t with d l il soil U its m fo re ha f su bs eq i the 5 ort und eachi So th at l Soi m h. ic. is l ate si s s nt is nts ayers typi roots a ls ve cl sas safr as. sua hori t for s da ng che Am emp ac ti ve nd clay ont in w are er ies , ow r im zons F uth s le var ani epr getation, ls a st s erst nu a upo lay s. into very or ys ca col lect ivel y i d re it s lly suta s s ate, z mi ne ra ls i hs veg ng, tio erica, n m n are eeper . ons, mber Tem ia er leaches esn lly (M hu er th en sno of ex ue nt ly dr o in pattern and A - n , th th n var ble to atures, in s - and difern ckl eber ries , ample, isp whe re m soil ere e locaity, usually New ined p w, water iable, pera often mu lc hi ng due ing ixtures northe ted Eur wo rk ed of Ben ea of le layers. the wil l Ne whic and be av es th at clim days th York, minerals of ope, gro in te to cal led from var ious w essence pi, t below e the ta ke n moves b be fairly stratifi r the rn spe forest the ut, th ate wt ange of wi ll Ze T in Thus Ge on is wh emp much a hemisp gro th e h. and the m alnd. ab rho dode nd becau cies, nort fa sub cano py una is en te gr orgia, by en fre As - s l out win wil dflo we l is oun d-co ver. tem an d only fro hern rate de co mp vailbe condit of wil l f you r in zin ound g se 3º m pera China Lo er se sou th u g 140 Deciduo C b a o hem might uisan), ason e bout f ron s, f or to s ture, thern thr as rs th a or os er to th er e da , e ispher s 18º much shr ub ough gro wn you an und 150 plant of co ys exp is or whic us d Arge or g C. ld a tem in ers tory oth er is move Ja abo bout a cm of Fo lay er air ct, an is ms . Me amo ng rots Ontario a pan. thr fairly pera ntia, th rest ut su bs ta nt ia l varie to temp the an 250 oug e shr u in 2 of of 25 ture w A until 0 a w is growin l s inter atiude hout var ious southern nual the , eratus 0 tre es days bs. ide simlar Th is g Cand. from days cm. rowing and it fer n The re rang month most melts “l it te r in suc h bu il du p p h mo in from recipta fo seaon vib ur igh sp much e of rest No se isture o The is of eci es s. la ye r and as in f win a rth - - of is - -

© USDA Forest Service The biodiversity of temperate deciduous forests is impressive, though it never rivals that of equatorial rain forests. Permanent residents include many nut consumers, such as squirrels, chipmunks, raccoons, wild turkeys, and blue jays. Deer, skunks, and foxes are abundant and wide ranging, and bears are common in certain areas. In most regions, however, large predators such as bears, bobcats, and wolves have been eliminated. Vegetation diversity is complex in deciduous forests. In Eastern North America, for example, different regions are dominated by different tree species. In the Southeast, for example, is the Southern Hardwood Forest, a rich forest of species such as various magnolias, Virginia live oak, common persimmon, pecan, redbay, and pawpaw. This species assemblage is in strong contrast to that of the Northern Hardwood Forest comprising mostly yellow birch, sugar maple, American beech, eastern hemlock, and eastern white pine. The most species-rich area of deciduous forest is in the Appalachians, the Cove Forests of the Great Smoky Mountains of eastern Tennessee. Over thirty tree species may occur in close proximity, including such species as white basswood, Carolina silverbell, tulip tree, yellow buck - eye, and sugar maple. Ecologists have struggled to understand what factors determine species composition in various regions within the overall deciduous forest biome. One prevalent view was that such forest associations were interdependent and thus strong interactions among, say, American beech and sugar maple forced both species to associate. A school of study called “phytosociology,” largely started by European ecologists, struggled to find order among plant associa - tions and reveal predictive “rules of assembly.” But other ecologists objected, suggesting that the co-occurrence of such species was largely coincidental, a result of each species having similar physiological requirements and similar distributions. If anything, many species likely competed among themselves and with other species to reach adult size and successfully reproduce. This view of the plant community was termed “individualistic,” meaning that no two plant communities are more than superficially similar. Studies of pollen profiles in bogs and lakes, as well as carefully done statisti - cal studies on plant distributions, have confirmed the individualistic model. Plant pollen accumulates (without decomposing) through thousands of years in the layers of mud found in bogs and lakes. Such accumulations allow a look back through time, reaching back to the time of glaciation, some 20,000 years ago. What is seen is that today’s plant associations did not move as a unit when glaciation forced northern species to the south and, when glaciers eventually melted, plants did not migrate north in the same associations as now exist. Forests throughout much of eastern North America were extensively cut during the years of European colonization, but these areas, used for agricul - ture and pasture, were largely abandoned when the West opened to colo - nization in the mid-1800s. After abandonment, vegetation strongly tended to follow a generally predictable series of changes as weedy invader species were progressively replaced by various grasses and shrubs, then colonizing trees, and then so-called climax tree species typical of the mature forest. This process is called ecological succession and has been the subject of

41 LECTURE EIGHT 4 2 da ta fr re sma og fu do me po such con th th th an ar at cen as dr veh com an to ra th of in cha th po an ove be th fe n i v i s s a m e r o f e i c e p s h c u m R L As M Bi om se s n e t ts nct e us e io ei e e rn m e a n a m i r r d d r d l e m m a o st ow a n ” t a mat ge . n tri ns r tury i nges r sto emr pro wi ani ain s s t s n cle cts, diver me l i su gric aged ta w ake ig h w a an P dsc is l, ng io isol trop “sou is y t bu e ousin s nte in hin on at y t i rant ti t s o fr ha gr s n ch to ra ma vi l icaly s im ce , e o n on eft bein do a i f t agm ultr fro er te d u n ag ape at e f er a h as ou den d ti ro tion s w gen ica tem sity ve gs a r in th al s rce” specialy th h one as , d l su rma or in d n ith ch a . y m o poluti p in bird om m o n i v in nd g co e the e t b g nima l to speci t a g ob as hou ent e t ch of tac h ecol cut ce fra pe fr il. io win de c E lan e is em d mo a int m d on sub as o w h c g p nt g o po ag p d y colgy yet s, for ser diver e c n a b r u t s i ch opu biodve rat gm stro e ed w do ushe uri vel o l o B o e erna gh dsca be ly iso ter and p st u o e n e pula ls arlie men co re th f o e v l o v ird unity op dive up ved n com e rma gy n a a s op in en wo come g e ver ca la su in . ind s k r n ng t g n sity. d he de p s i tha a b Acid speci l d othe ti ns g th lots. clea p t s men ted fo t ing the ter ch e io odlts. ranch a combustin ecting s t ly , ed ons nt ted . umer ustr t e. mercial rsity. westard. ciduos d rushe, g he te o cuse s th a ns t Som and o pilar rounds se f e v a h With ctu e f i l or as typical Ecolgist a t habit “for e wo re r win f for ts, m . rain, .s t c a r a v This back ialzed ne o in ason indu gro T sizeab Ea d se pts al n f s For of some g n i y r e c y c s i h rogs est the al st ter. shop s, ofer large But d dlots. sm the mi-dor on stern wi mon a a e l sp ve uring ecolgy for is strial warble forest fa t ts. rea flies, into al of e l o to w e i v n exam isla two ecis, al The nture ho ilu n r are be in g Much and s open le requ ping m s i d in en exam w th ma ths, nest for e is re f t a h t w for Deciduo nds,” im sp cause h fore ie use tr e mant the d p deciu gines. frag and . b r u t ich mo s a h act est mu lants ple, ld s land s toa of ic it m As ire est t s, in mals, thoug t a h e such caled in mals of ple, of or st a ost Euro ca the g na st ment birds r e c n a ch o o ds o e r be and la eprs such, s e r the stage “island.” i the scape rioles, cove and what o f f ho they f le pr ture’s c u s ous rge as f d fo re etls. la two us t p o is ter lie h as d pean d e t l u onu may lea ram using industr rge. rest broa peat ea land plan such we a h t n o i s s e c atem r m d F hey r l a m i are dor move . forest estora the r o t s i m was ves wodl bypro ch nt orest t In fo patch and oday. proce l “ any It hiberna nced into tic fragm scape d-leav et as. mant n i setl sect rest as As relativy as survie forest d m as Th is s e i t a ia in pt pastur are n i w e i v exa s, ay n tan as tion l autom duct in of But then we a evr- es is spr est o i r a v wo se e r to pa lots, ts Howevr, nothe seaonlity with e h t a r sect entaio ment in be sur North mple surpl re in ecolgy, s t l u s l te in rks, ne ar ing is gers, e if failu th as alizto e d o tha as the tera g colgy. smale to s u forest. e vie o a in subject st a f obile wildfoers e pe an r thrus r r d nd c industra i of and s g wodlan solated of rot a h t r f mud e re, in omes exampl, su o u d i c e entr n” s l e v e l America s ub rmanet latiudn olf ct d sm re m fect m o the in thus indvua seaon “sink” s farml to jectd turn n any m to n thru a r course, mals, al and sytem e nd uch s a parcels, throu is e m u n has from to d contie, afect g de they a esc f o to resto she found speci lizaton, from by has cuting flush ha oth case nd of wa i l sup a a l l al t p “cori eco ed ghout ribe o h g frag lter nd su o r ls bi tor tha er a s a e t - - to ir l of in - - - - - t FOR GR
EATER UNDERSTANDING

Questions

1. In what ways does length of growing season influence the adaptations of temperate forest trees? 2. What was phytosociology and what was it attempting to do? Why is it no longer used in ecology ?

Suggested Reading

Kricher, John. A Field Guide to Eastern Forests. Boston: Houghton Mifflin Company, 1998.

Other Books of Interest

Braun, E. Lucy. Deciduous Forests of Eastern North America. New York: Hafner, 1972. Brooks, Maurice. The Appalachians. Boston: Houghton Mifflin, 1965. Robichaud, Beryl, and Murray F. Buell. Vegetation of New Jersey. New Brunswick, NJ: Rutgers University Press, 1973. Sutton, Ann, and Myron Sutton. Eastern Forests. New York: Alfred A. Knopf, 1985.

43 LECTURE NINE 4 4 Indi abun pra the T Ca Mo Me cen th do th th ho Co of wh go of sho be typ wi re ocurs, Ro er som Gr Bot Inse Top I G G he n e e an te g s th m r o comes ir vast asln ra ra an ro l u ich cky la if n xi izon ion Nort t tra r n d sho con open da e : om nt y t e r ta ina t, Su g : sl sl desr gra co. ge Th any in A cal re nt, t ry.” g na l s. an Cu s : i he st s Mou e ss t be tes o Tal and and C rt. ra ti a h he gives i co S F s ne led pe A most t , d ge st . son an gr gr ract e o sla ocea li d A m l p S ta In ntr the Th gr pr U t. nt mo hm an the a ev the red nt, ase as.” ub n mer , s n nit o ass n tes ib “ Hil ne whe g ta d of is da st do Big dominant w ey ed ute ed nds oa re ly g rasl r t D he a f omin ls ntu n. in he rema centra rom hy s. rase pr ica, pate p ea su akot s s Sta g chin into not of swe s, to lace airie pid ’s rev Gr Re ad Sky , ra sig aly and im co ster ch Mo K a th Th t gr i er es. A ni aslnd sla an g an south e n as, al pre rn g ht nt e viso is e ng s rasl aslnd gr take as r d, nta, er l d e sa Fi e pin n astern mixes tly dominated ain the wildfoe in g iv asses wa part it xcep o is t l s nd, sion al o er the f g co ld ok advantage n l - sity is evidn ving gr m p fo r Gr nt nd of as of redo is ilo Gu a t a ap alike. ain of nd asl t th is he in th pears id e ns by f o rs, minatly e t rbs t three pr he in grasln and of o L Be t with le ct ur e air f o ect (no the North biso gentl mon cause ie. th main n-w an f u lowering e lite re n oo d tal otn No rt h d Amer grasses g dy is 9: S bre of razing b in av , grase, io St ep no g difer t ez, us, me an ras he n-g ica, Am er ic an : B s ras he n es ig wa on poula in a po wh Bl s nces d Nor , y u othe end uestem, rtays, flowering er ring R. of th ted les tres Jo ne in the rs the Pr ai ri e America, an Little mixed, pollination fo with plants) praie, tales nual s r and the B an d . lues various , mo t sh and m hough grase a tem, cy Ru th the ind’s rubs. istu “sea cle. oth and les r e, - s of

All images: © Teresa M. Woods/Konza Prairie Long Term Ecological Research (LTER) Program Kansas, Nebraska, and Oklahoma are historically grassland dominated, and natural prairie occurs as far east as Ohio. Grassland is also the natural vege - tation of the Central Valley of California. The biome occurs in many other places in the world: in South America, where, in Chile and Argentina, the grassland is called pampas. Throughout central Europe grassland is called steppe. In central and southern regions in Africa it is veld. In North America, it is called prairie. In general, mean annual precipitation is less in grassland than in forest, but there is a wide range. In the short grass prairie of Colorado, for example, the mean annual precipitation is a meager 10 inches (25 cm), but it ranges from 25 to 40 inches (65 to 100 cm) in the most eastern regions. In some prairie regions, mean annual precipitation is as low as 6 inches (15 cm). There is a gradient in precipitation from west to east, with increasing precipitation mov - ing eastward. Thus tallgrass prairie is found in eastern regions, and much of the central prairie is mixed grassland. Because North American grasslands are confined to the interior of the conti - nent, there are no mitigating climatic effects by the oceans, such as occur along the eastern and western seaboards. Extremes of temperature, indeed, extremes of weather, are common. Prairie experiences severe winter bliz - zards with drifting snow blown by incessant high winds. One of the character - istics of prairie most recorded in the journals of settlers and pioneer travelers during the nineteenth century was the constancy of wind. Tornadoes are commonplace throughout the summer months. In spring, one day may be mild while the next features a major snowfall. Natural fire, set by lightning (many thunderstorms occur throughout the sum - mer months), is a major factor influencing prairie ecology. Without regular fires, in many areas prairie would eventually be replaced by forest. This pat - tern is evident in places such as Wind Cave National Park in South Dakota. The area where the park is located is called “the Black Hills,” named for the dark foliage of ponderosa pine forests that occur there. Without prescribed burning by the National Park Service, Wind Cave National Park, one of the last vestiges of natural grassland in the region, would be invaded by pon - derosa pine and associated species. There is anthropological evidence that suggests that Native Americans regularly set fire to the grasslands, apparent - ly understanding that doing so would maintain the area as grassland, which was desirable for hunting game and for moving from one place to another. Soils are typically rich in nutrients, with abundance of such elements as cal - cium, potassium, and phosphorus. The dense roots of the grasses effective - ly tap into this abundance of nutrients, allowing continual growth through the 120- to 200-day growing season. Because of the natural richness of the grassland soils, it is hardly surprising that agricultural activities dominate regions of grassland. Many species of grasses occur throughout the biome, but they differ from one region to another depending on how much precipitation the region receives. Tallgrass prairie in North America is dominated by species such as big bluestem ( Andropogon gerard i), which is a bunch grass. Bunch grasses, as the name implies, have stems that radiate from a central cluster. Big bluestem, under ideal growing conditions, can reach a height of just over three meters,

45 LECTURE NINE 4 6 pra man may othe was pra nu gr ar gra they no gr th of Nor gro ne on two fir en of th it til as in rea ea Gr to te abo by up wh Ba bra in as M Sca T I M G M n i in e e em m o e a ty h the a ase m n a ce t sy mic th cut ra ttl e os a a ich vari u b , l ir ir s un lly v und zing Nort er to th n awns, ut -gra rly cen kin l n n t nd l sl r es y ero ie, ie, ake an con e of on se t ha ue ar ha t y y te f e a op w d e an a e or A a u tal ten t o gr na o o d t mo er e he d ssenti s wi g ce t . s re ith t t li v sa a o tr b d f meri s us cur h he s kin us s o gra s by tain en en rase eat d e l T re ar ut im qu gr both for al gro tural g the are l d e A g dflower ble of he an att ack ng a fe la razin na gro mamm w se e xtinco he spe d a ras s soil. clover ini b mer irr the re th re m two land speci s wn et. can ond se und man pleasu w d ison mo tural ab of Li emed al w bl rou a t els ron shin gio fo as w he keys s prai ad ildfowe cie m ttl e in ack tota Whe g ica, ( in und ground crops. rm in prairie s N ar st erfu tha t Bou mammal, arsh ns wh gho d-p a s the y stem m also es g th m s, als s. he umero to g ri grassland spe e pte su . Big horn o -footed a d tone uch l e a at ost re an endless. er se the The o b whic n u in n “ ol ly Thu lpe of teloua ar r s ut Cus ter’ s me sol dier s. sod e f esp vious include in d d ck s e cie co s tly are rs Gen e vera eas s inated, a th Thus the grasse dog colrfu a of m sh d fo or squirr biodiversity wind North caled species s us caled speci mb e bunda abun d e s rout in uch r to f or en r—a exp nco ormin common it more pr ferr niet ta are l closely ra of in are gracils sp spe short ine ral ebirds. is a conse it se aire ke are The pid el, coyotes, no nimals the Mon tan after dance loring of unter s cav alry ecies, et, l Am is whic the rhizom mixed Cus ter’ s lawn pra cie flower the in m and n rmaly g,” tisue t a the in difficult se g gras re now itroge su a at erica o and rowth de s nth rve m comb ire associates ) f maintaining ed fire member rathe America are ch throug places mower that of rea and covering wildflowers ember Nor centr the termin are of is a, s, es, fields am rod the centu many p ther badgers, a com preva n as or prai has an legum l scattered othle Sit ting in s th g tro op to wo afte b r pra bu closey fr ong e row son al lack-tailed gra ation can t grasln hout the om ef Ame han find in posite, thr ou ar uld falo of is been . of i ry. n re ire r e of ils. ecol g zing ectiv e s gra , vasbck the es fir a e s. b the gions with abo the wheat, if a Bul l’s the mong otherwise Bison gene sentialy i carpe wer e gr bunch natu rican pr of e so is (“ and re gh, T gras asocited gra f se, assland, r air urthe soil. wee preserves o hes rodent ve-gro (conside atmo n low gist eplaced to p weasel d, r sim ral daisy-lke means ie sland rairie a mak ing rally of g pronghorns. and enjoy e ting b ma nd prevn the wer razing. r ds”) asi ly gr p rav es ecology. ye, ila ( and r North in prairie spher are Buchlo recipta be en ase. und p cluding r family, small. the e a an pr prevai dog raie liev corn, to have as family r hanc by the red imp def eate d for wil aire of esntial als, it ho with that ting wer e a gra sho white-tailed, Amer They are rea. agriculture. where m eas y plants, pole c e head, w myriad and ortan persv olonies. tha Prairie ion, Specis In l d es sorghum, invaded se and wer grase. dactyloi of ots, le sustain in invaso ogs. pra often and many tot ally addition gumes Th ican the n o “grazin these incorpate for perio regula ire, ften other at once disperal a making e nestig many g tha the hunted Bison, s o hig dogs razes the one rot the re. prai species f Other n wel such na natural but h sp dic difer rarest areas. es and What h On by idd en such and , make it tural r has ”). fer of sy ), e ie are th as e it a in - - e d - The spread of cattle and sheep ranching in North America has made a major impact on grasslands. In areas that are particularly sensitive, such as the short grass regions found in the southwest, natural grassland has become desert as a result of selective grazing by cattle. Cattle eat the grass - es but ignore such noxious species as cacti and creosote bush, allowing these species to eventually replace the grasses. Savanna Savanna is an open habitat with scattered trees among various grasses. Trees, particularly acacias, may be scattered rather evenly among the grass - es or be more restricted to certain areas within the expanse of grasses. Wind is often a major factor and periodic fire, set by lightning, is common through - out savannas. In Africa, large animal herds are an obvious feature of savan - na, but an abundance of large animals is not a universal characteristic of savannas elsewhere. The vast herds of antelope, gazelles, wildebeest, zebra, and elephants that serve as food for lions, cheetahs, leopards, and hyenas are unique to Africa. Most of us associate savanna with east and southern Africa. But savanna occurs elsewhere. In North America, the Everglades of Florida is a type of wet savanna. There is much savanna throughout parts of South America, particularly the llanos of Venezuela, the cerrados of northern Brazil, and the pantanal of southern Brazil. Savanna can also be found in parts of Central America such as Nicaragua and Belize. Savannas are also found in parts of India and southeast Asia, and Australia. Savannas occur in regions with a strongly developed dry season. The severity of the dry season varies among savannas, but in East Africa, the dry season is sufficiently severe to require annual migrations of the large animals, as they move in search of water and fodder. Savannas generally receive between 50 and 150 cm of precipitation annually. During wet months, the grasses and trees are green and lush, but during dry season, the landscape turns brown. Tropical savannas experience a mean annual temperature from about 18º to 30º C, the same temperature range as is found with rain forests. The lack of rainfall during dry season and overall high temperature result in significant physiological stress on both plants and animals. It is unclear to ecologists exactly what factors determine the existence of savannas. Not all savannas occur in areas with a protracted dry season. As a result, some ecologists believe that savannas are also caused by nutrient- poor soils that, for various reasons, are insufficient to support lush forest. Prolonged human agricultural activities have been blamed for causing savan - na formation. The argument is that human use has depleted nutrients in the soil, thus preventing regrowth of rain or seasonal forest. Savanna vegetation claims such depleted soils by “default.” Fire is another strong factor in savanna ecology. Periodic natural fires, just as they do with grasslands, aid in promoting regrowth of savanna grasses and sedges, at the expense of woody species that, in the absence of fire, might eventually come to dominate the region. Because most savannas are also areas of strong human influence, fire frequency may have increased due to human activity.

47 LECTURE NINE 4 8 sav a l s l a m i n a de fo evo savn in cal te t a c i t g n i e b a as gi an wi fe in ma in of thi s Savn ca th the s e s a e y b l f s a s a t s i s e r i t e v a h s a d n a u t a n Ele S H T El T Wi H e v ) y n o se r g te s e t nd ri ed e sa ld ho he us a n n a v a af e d ist o u h ly e e l t b m v t t ze mal ph th r l or n y e h e h d n a ply o Ce ma Afri eb cl ut ct pha t c e t van ao fe, est n h t i w l a r g t na ing ug t a h u q s o min most u h ex ants o t n a l d n a e a h s azels ima ti ri arge ion na d n a sa b a gr na spe n u c bo s n a n durin cal ca h r o in i per e est s m m i , ozo i ng t nts n a na a m the azing. s. van id a l e l le b s gr h t a qu on vert e r s biom o t e r e v i t d n is f s o t i ly s a ly, eing a l a cies s, c s or r pha s , o elsw e v e ie I e g t ained rich d o f he o t e g d sav f exr o the u s estion h t h t c re n u cone o n sp shi o s i ) s e as a v e c o s t nce an on sav anna ebr a p he r la r a t as n no rbivo Er p s r e e o m a i ly hro p as nt, s, p o l rea d .y t i e s i d r a t h t mo ar wn ft Br ce o l o p e leav in w . Af h t p a. t a i y l r a e n t a t s te e ate most n ( he w e n e as S po e tha t e v g n t a el ve t c e v rica fam ug str owser ha s e i c n e g o e an sto rs s, t a n - n o s a tre t r rn o h c u d e a the Glo bal c s e s a th d a e re n e g o h e t ou s p r al o s e s a h ong b m n a ed a d colg o r a ldwie. fo o v e es at ulation ar s f on f o ilarty ou ita l com s was s de r o savn spr p s y in a c en s wart g i h r sav anna ta h t larg , from e si d g sa of prev h Af s, , d n u on g a v a s t to ma it ul i . s e i c e n i the ,e l t t h c u s tioned ef e v i the ng ave the ra desrv African h rica s ma i hum an cli mate - is - like caly lik ely e o . a c i r f A grase mals sy hog. e v i d o i b ne nas. with shrub a world herd sav erupt cts a n n an nd o t bee n nt n s l a m i n a g of h T ar r s im ab irafes import g i m whe re t on th ainfore most heir a s savn na. e l s e b eas a bei ngs, io m ha e s e als s. e s ove, lack of savn y t i s r of in s to sav e t a r ns, ostly an maj or g n i p e s T cr m e w reg a African ho m wit be her aten ant, bec ome u m e r d It eas in and a t n i a onc e st likey to na this , ost l l o na t has h h t i w na-like res, g f caled a r g fed a t s nerat fro t sel ecti on raslnd u ermits, as rang sca k c i s s d tion T are a a d e n i e u q i n g o e b the r m d e z homps sociated o ecolg evn mazing owe savn (ung wel e h t in r e h t n terd s s e n io while Eas t dri er nu ing ot a p e s on “na e hab a n, s a s a a e s rea mero ulate) the su was p s as be a Af from . tural” thus whose y. t c n a s a e r pre ssur e i and h t a e v ( port t a r as . s e i c e t n’s tr graze rican ma ir at. . s n o s ze nd sin ce T e es, n unb roke n with us ve d e , s hey e r o t c fe bra, e v i t a n ma locust, evntualy g sug Sou ther n mor e as e i r a u ry ed azel e r a spe nea m o r f sa tal ste s, n I the t I sav d alin gestd exi far wilde d e van, amge mals in s i cies like d n e p e d o i t i d d a ither rly ms mo t s y b s l a m i n a stenc emp erat e, mid dle as , s a e r a the t r o f na s u h whic for rai nfor est. the unds dive best, e h t zeb from Afr ica. of our tha by convertig th eme rg e h t exam n tres , n ecolg r e p m i same a at t n e ra rsity es t e s t ume e h w brows ntelops to speci’ par t char a period inh es e h t n a c ug n u our and no ple, . enc e r a er su a o It of b It y. tc a - u - c it ch - is s is - -

© Photos.com FOR GR
EATER UNDERSTANDING

Questions

1. How do variables such as precipitation, fire, and grazing combine to affect grassland? 2. What is the essential difference between grassland and savanna ?

Suggested Reading

Jones, Stephen R., and Ruth Carol Cushman. A Field Guide to the North American Prairie. Boston: Houghton Mifflin, 2004.

Other Books of Interest

Brown, Lauren. Grasslands. New York: Alfred A. Knopf, 1985. Gleason, Henry A., and Authur Cronquist. The Natural Geography of Plants. New York: Columbia University Press, 1964. Reichman, O.J. Konza Prairie. Lawrence: University of Kansas Press, 1987.

Websites to Visit

1. The TIEE ( Teaching Issues and Experiments in Ecology ) journal website provides an excellent abstract of an article by professors Harmony J. Dalgleish (Kansas State University) and Teresa M. Woods (Utah State University) entitled “The Effects of Bison Grazing on Plant Diversity in a Tallgrass Prairie” — http://tiee.ecoed.net/vol/v5/practice/dalgleish/abstract.html 2. Konza Prairie Biological Station (LETR) Long-Term Ecological Research at Kansas State University, Manhattan, KS, provides a comprehensive website about prairie ecology — http://climate.konza.ksu.edu/konza

49 Lecture 10: Desert

The Suggested Reading for this lecture is James A. MacMahon’s Deserts .

eserts look dry. The very word “desert” seems to convey a sense of aridity, of a land where water is at a premium. Indeed that is true. But there is much variety evident in the world’s deserts, which can range in appearance from undulating sand dunes with little apparent life, to colorful landscapes awash with the color of myriad blooming flowers. Some deserts, like the Atacama along the coast of Peru and Chile, resemble what we imagine the surface of a planet such as Mars to be, seemingly devoid of any life. Others, like the Great Basin Desert of western North America, are populated by a monotonous-looking assemblage of shrubs, such as Big Sagebrush. Still others, like the Sonoran Desert of Mexico, Arizona, and southern California abound with succulents, various cacti, and other species, some the size of trees. Deserts contain many unique species of plants and animals because inhabi - tants of deserts are subjected to strong selection pressures resulting in remarkable adaptations to the constant aridity. Some adaptations of desert organisms, like the water-holding barrel-shape of spiny cactuses, are readily evident while others, like the subtle behaviors of lizards to control their body temperatures or the ability of kangaroo rats to subsist without drinking liquid water, are much more subtle. Desert biomes occur in many places on Earth. Deserts found in the temper - ate zone are called cold deserts because they experience snow and cold temperatures in the winter months. Deserts closer to the equator are called hot deserts because they rarely experience snow. Shrubs tend to be the N E T m o c . E s o t R o h P U © T C

E The vast Atacama Desert, near San Pedro de Atacama, Chile. L

50 dominant form of plants in cold deserts, but succulents join shrubs in hot deserts. In general, biodiversity is highest in hot deserts. Globally, many deserts occur around 30º north or 30º south latitude. This is because of major convection cells in the atmosphere that converged at those latitudes and that are previously depleted of moisture. Thus dry air is forced down, but precipitation does not occur, so deserts result. There are four deserts in North America: the Great Basin, the Chihuahuan, the Sonoran, and the Mojave. Of these, only the Great Basin is cold desert. It ranges from the Canadian border and Washington south to Nevada and parts of Arizona and eastern California. It is called the Great Basin as it is bordered to the east by the Rocky Mountains and to the west by the Cascade and Sierra Nevada mountain ranges. The Chihuahuan Desert is found throughout much of northern and central Mexico, crossing the U.S. border in Texas and eastern New Mexico. The Sonoran Desert, perhaps the most picturesque of any of the four North American deserts, contains many cactus species includ - ing the giant saguaro cactus and organpipe cactus. It is found from north - western Mexico and the Baja Peninsula through southern Arizona and parts of southern California. The Mojave Desert is the smallest of the North American deserts, confined to southeastern California, including Death Valley and the Salton Sea. It is famous for its joshua trees, which belong to a group of desert-dwelling plants called yuccas. In South America, one finds the Atacama Desert along the coast of Peru and Chile, blocked from obtaining moisture from the huge Amazon Basin by the high Andes Mountains. There is desert in Africa both in the northern part of the continent, where the great Sahara Desert extends from Morocco through Egypt, as well as in the south, where the Karroo Desert is found. Much of interior Australia is desert, a huge area. The largest desert on Earth is the vast Gobi desert found throughout most of central Asia, throughout much of China and Mongolia. Deserts typically experience below 10 inches (25 cm) of annual precipitation. What moisture they do receive is seasonal, falling during a brief wet season. In the Sonoran Desert in southern Arizona, for example, rain falls briefly in the spring, often resulting in a flush of annuals, many species of colorful flow - ers that bloom in synchrony. Rain also occurs again sparingly in mid to late summer, when late afternoon thunderstorms are typical. The temperature range of deserts is wide, with annual mean temperatures from 23º F to 86º F (–5º C to 30º C). The warmest temperatures of any place in the United States are typically recorded for Death Valley, California, in the Mojave Desert, where a temperature of 134.5º F (57º C) was once recorded, ranking as the second highest temperature recorded on Earth. Desert soils tend to be fertile, with an abundance of essential minerals. The sparse plant growth that typifies deserts is thus the result of a continual short - age of water. Some desert plants, such as honey mesquite, have long tap - roots that grow sufficiently deep to reach ground water. Others, like the many species of succulents, absorb large quantities of water during the brief times when it is available and then utilize it as needed during the long dry spells. In areas of high temperature, evaporative water loss from desert soils can result in the deposition of minerals on the soil surface. Minerals, dissolved in the

51 LECTURE TEN 5 2 in mo th ver fr an sag wi ca ers ing ba act are are la on ste ed at br de pr Th th mi be ad fr co ra ti in v in ca ma te th in an co wat e me D om om M Gi v D Th Be r e ta or rs e a o th cti s n nc ze s cavit th ly d r n a d e e ol , ions ms. ve , n d n n t b w es k. nches duce any t uc uaro che se pte sert early he case ns imp the out o a c e cause bu e, y ta is g y the , ve p r, en is ca idel en to a a on wa ug T ro u a h wa te r re d ry t wo re com tho rt t he d s w as gr in cr ea i h n re ne l tra ted ctus The d i ortan es a se usua w d ar e e a ve no h th e other al s P te oug y gen hic mai i r catu to r esert ou xper re rld mp o in t h d ocks ge ar po et ha div o rn is we har b an sp r rt sa b ave in evlop as mo ther y t nd, los by rifed m esn eacon na palo a gian s and hrive h t l ll a n in is rsh l a t ima os s a urs l sa se su in s, bo h od ienc rt in in any pol ced as pasing desert it r re n de se s beh tu ra l pl a ed as th ro the eq ui t a e ated the d gua hat ch l r s is ors b wi in a ike t l, physica ants, f Old e g l a ck verd a ca us ed sur is rom ina odi es Fo a me ev en , cat in toxic se tia i nd l i of e lea l n o nd Go d a for shad ch with mea re r j hig re ro ventu fe rt il it y contai g honey o cations, o of t e n re by prisng d tors, rved l to nt gr e soil. Wor po r in e in to sert. ot early fles lat e t e to bi heat as e use in pollinato st ca he h mica shrub an plant. sert. t section ve mo re chemials of anim t ns llinators, of shalow, e cluding ively germina at re l De ecosyt can bio ctu in the by ld aly ima condit visiting evapor as n pr od uc ti ve Leavs of t sta ndin g he de al of me of f and ly m Arizona. sert ls. or emr diversty mo re eup Su se, an o hi gh als. a in a ro wat er l Th amls in Shr lite dispe dro ma ny h f catus. sq such such much cluding Speci shrub ch rs. “ ig th abun nurse hobias, ho t wind. of e in cr t caled te uite So h ative for ps as e gin ext ubs the te m a wa e eosote b In are p wa te r in Chin b s Son nd rsal. rosin est unles mp er at ur e. eva p me, lant de wat er, d as iodversty. are o as str , examp dance One te r the typ of of t ag or es large f nsive as become heir s Some have typica from tre se grow. w Dinosau uctre place oran a creos a joints. o the such animls. er ri cu lt ur a if pho tr th an cover, so like a Thes ora tes. case r we rt a e,” y der a e ter b t of nd is some leavs me nd a it ir ri ga ti on u de so white le of the year, r l be tosynh re sh creosote l furn ot the Desr is picked such Many plants ly los . th ey as for . th us as il s, sert, Mong A fosil. of te hum en M or , amazingly com mo F on ero smal Th us r plan low Man me l times Sal t or sytem rich ish joint any chola large Nat the a bush it Up la nd . flowers pe it t to excavtd a w hat as te nd s sion t sagur is examp min sq des stil ing esiz have crown ts cary. ou many of is est slo y be ca us e io discour giant to lak es, desrt cr op s li li tt le and can a ui bush, In a nal spe expos n would ha so catus ld gbird and Do in g e pe catus te, by can , th by pa fosil rt in sential No to wher ve in at irty an mo tha colorful n easily le, waxy, o cies su rp ri se M lo pla sagua intrg the a palo of wind som e T ame big be su ch whe a rth night. pho nd age se onumet lo anim produce he . species. ver abund stly a com b a nts, co so of s e ng huntig speci absor ed c ird c actuly of America sed sagebruh has sh uing d joint, a reatu. verde, re tosynheiz os tl y. the de. ol er , and th e , herbivo be trais ro nciet as throug des ert sha als ho we ve r, p e for to rub when speci chain-lk most Many min eral s lants th at come cactus, with some remains It co rn hi gh germin lo ca ti on . nce biotc flodwa are de o its small transp in or is Th e moisture f grounds tha te and use ir ri ga ti on a h , particu sedi gren flower during reg i Utah com leav Once have insects nd palo ac such of ra ev ap o their shad s. e nest hi gh are inter min flow is ed bats tive e ate ort to their are ons . - - of - s. - - is - e - - - - only at night when the air temperature is much cooler, minimizing evaporative water loss. Numerous rodent species inhabit deserts, some elegantly adapted anatomically and physiologically to the harsh desert conditions. The kangaroo rat subsists on water obtained from the seeds it digests. Jackrabbits have large ears that obviously serve to increase evaporation and cool the animal during the heat of the day. Wood rats, sometimes called pack rats, assemble large middens containing mostly seeds as well as other objects unrelated to nutrition. Reptiles adapt well to deserts, and numerous species of lizards and snakes can be found throughout the world’s deserts. One of the more spe - cialized species is the sidewinder, a rattlesnake that moves in a sideways manner rather than forward, an adaptation to unstable, shifting desert sands. People have adapted throughout history to living in deserts and continue to do so. Many of the major oil-supplying nations of the world are located in the Middle East, now a region that is primarily desert. Thanks to sophisticated though costly irrigation techniques, countries such as Israel are able to grow many crops in some of the world’s most arid lands. Human use of deserts in North America is potentially stressful to regional water supplies. The only way to bring water to deserts is to tap what is deeply below ground or transport the water, via pipelines, from other areas. Thus as human populations grow in desert regions, as agricultural activities in such areas increase through irrigation, water is depleted from some other location. Because of increasing human populations in desert regions, encroachment by housing developments, malls, and industrial parks is threatening many deserts with fragmentation and species loss. Immigrants to desert regions fre - quently attempt to replace natural vegetation with lawns and other water-costly landscaping. Such luxuries as swimming pools, which tend to be common - place among residents of desert regions, require significant amounts of water. Another threat to deserts is the increasing use of off-road vehicles. Like the Arctic tundra, desert plants are not able to recover easily from disturbance. It requires about eighty years for a saguaro cactus to attain a height of 6 to 8 feet, at which point it will produce its first blossoms. Full maturity of the plant is not reached until it is well over a century in age, and it can survive for up to 250 years. Nonetheless, the root system is very shallow, and a minor impact from an SUV or pickup truck can topple the tree in seconds. Unfortunately, many desert plant species are in demand as ornamentals. The illegal collection of various cactuses has become an increasing problem, requiring legal pro - tection for species such as organpipe cac - tus and giant saguaros. Deserts, once thought of as “wastelands,” must be recog - nized for their unique ecological character - istics and afforded reasonable conserva - tion protection. m o c . s o t o

A saguaro cactus emerged from the scant shade h P

provided by a palo verde plant. © 53 FOR GR
EATER UNDERSTANDING

Questions

1. What are the primary adaptations of desert plants? 2. Why are deserts fairly different in different places ?

Suggested Reading

MacMahon, James A. Deserts. New York: Alfred A. Knopf, 1985.

Other Books of Interest

Jaeger, Edmund C. Desert Wildlife. Stanford, CA: Stanford University Press, 1961. Kirk, Ruth. Desert: The American Southwest. Boston: Houghton Mifflin, 1973. Phillips, Steven J., and Patricia Wentworth Comus, eds. A Natural History of the Sonoran Desert. Tucson: Arizona Sonoran Desert Museum Press, 2000. N E T E R U T C E L

54 Lecture 11: Tropical Rain Forest

The Suggested Reading for this lecture is John Kricher’s A Neotropical Companion: An Introduction to the Animals, Plants, and Ecosystems of the New World Tropics .

ropical rain forest is the most lush and diverse of the world’s terrestrial bio - mes. The word “jungle” is closely associated with tropical rain forest, but rain forest and jungle, though related, are really different habitats within the same biome. Jungles are dis - turbed areas where rain forest has been temporarily destroyed, either by cutting, windthrow, or some other factor, to be replaced by a thick tangle of vegetation that often grows so densely that a machete is necessary to cut a path through it. Jungles, if left m o c . s alone, will eventually transform o t o h back into rain forest, a process P © called ecological succession. Tropical rain forest in southern Venezuela. Tropical rain forests are much more open inside and deeply shaded than jungles, composed of many species of trees, some of which grow to great stature, often in excess of 100 feet. Trees, which are broad-leaved and usually evergreen, are often rather slender, accentuating their apparent height. Branches radiate out high above ground level, like spokes on an umbrella, and roots emerge in large buttress - es at the bases of the trees. At ground level rain forests are well shaded, as up to 99 percent of the light striking the canopy fails to reach the forest floor. Rain forest trees are often abundantly laden with an impressive assemblage of epiphytes, plants that live on other plants. These include orchids, various cacti, and bromeliads (with a pitcher-like array of spiky leaves resembling those of a pineapple). Vines also typify rain forests, including various figs (such as strangler fig), philodendrons, and looping, twisting lianas. The com - bination of numerous tree species plus diverse epiphytes and vines makes the physiognomy, or physical structure, of the rain forest perhaps the most structurally complex of any terrestrial ecosystem. Animals are generally hard to see well within rain forest, as the complex physical structure of the forest shelters its animal inhabitants very well. Mammals, ranging from canopy-dwelling monkeys to tapirs and tigers, can be

55 LECTURE ELEVEN 5 6 l i o s t s o M i t aw acum at ra ev fr soi tr le th Th Equ pl sea (n ra da op up le ot wi (2 C) No is Sou fo Basi exp th th bo mo Mo str ar wh pr str ver I C T R n o om op f n So a a ve op e he re ou e p e i 2 e e th he u , n ong ikes ys p u o a e a l r ine chi ces, i vi y t id arl º senc t r e su n thea st so anse some resi nde nst in con o sou i st best ato t in t r a p y l, il cal f o n. r g fore o he cold ng C). di so t s pe o b t s. h a y 4 he creasin p w n in hum al na f e l i f o r of o f nl an efo or nd sea Ra o r i 60 p g r, a ar bl me or stan th. 60 t l i l soil rest icu no r ste e l c i T y he a c i p st t osite ated er . st Th y ve. l, est dev o lit o r t cia e time r o t ye ds, he by w n rains A in ainy re of year ef cm act idty m osin r f sona he or inche lt A rn is o in s th er of E ming n a s, t p ar. ra h t ost Al fo sia ften l m t is to icen the g ter ver wa pr l a c i gly at are te das he ual tem s leachin mo o s A o p in lo the ro ( ( d t a take rest -r any 180 leav se fo can mp ecipta r re In subtan det ust , hig p lity s pe a . oun ter win o u l a glad s l i s) fore T so che T ist acid r m und he nd r fl vails ge aso f per s l i o s t an ecipta an Ea th ro ain hailn d ower era rali. n it s e k a in a to b uth an s l a u n i m in p g avily re fo e e o ct. d. p d lso ird d in s, micals st r ocuring es to rth ature ase g. ic. r, n logicay ches) elat ic r in s 30 ach r t d fo Amazon tion ain ho o other ure est, T south gethr eason, p e r a twigs, i Buterflis from is and s, ’s n It sp of re are in o ypical e roximty Ading ia 0 e v a h tion d, m e h t t er ively cu quat the usaly may st most atr forest ly e sum as cm sou washing Can is ran t f o it In ode o cies throu or h n caled , stridula in , s e d i x the o s rs is basic during donesia ave of ightly , acting hig world a n e rots, orial (1 th a ge anciet, consta more the can cer da se nd the du l i Basin, us in infert t s to h g i h a he equa ers, F e f to gh p e e d of em il 8 prevails ring from a nd an Centr ther are lorida y time as to tropical the l e Unite region al be h c lo inch ch th the ly the E is ting th de hig soil the d pr ile in as w ironc , q nt t o c p m o c e fo tor, 9 s l a c i m e he ance e the f con m precita fo eciptaon uator Ma consta sect ad low ound ir late r 5 an e r tem in mine al h s i d d e es) t n e t n soil. h “ is it ost colr d i und ran quato dry n min p r igh north tem s it d fore laysi, ain spicuo animl “ra whic is sect. Africa durin ercn Sta lo moist soil e t c a sum thr pera tha ads sound th anu to . k o ts in erals rals in seaon” in withn humidty pera ful f nt to eir st o as Howevr, ough entr es o f r, y th o th tion f fe So an n i g , d mer lush ture in t, , f f inse r c sea e p wh aly. al great e subt N rtily from fore hydr be a Sout it, is bodie , y a l an d tures o c h c i h w lants uth m e p p i l s in ra m l e te l out rang about er includ th in an come on fals aking w nualy. son,” r o l month th thro inerals in cts. is r mpera are st. ropical. ain Some as ogen e America a hern e char places Guin the ywher is ag u fo the the s) can e u d are true Tr o r c i m es soil recyling , y r ugh sualy a l p a wel. the Birdso rest, fo e Ra s e by opic a s thoug, th more soil, s acter world Haw ea, be rest te of ha India, atom Rain d n a aro s t n the rain a 47º are e o t in ar rain and of fact early the ctively The wher c i p o c s twen s zone. rain air N , e from of f e h t a und a a the not ng orest a h as in almost ai . orth also ares, ize rapidly latiudn subject g round s . s, veg forest be is In proces tha fel Capricon y m m u a Rain of la e v the wel in for Jan e rev exprinc al u m u c c a nd making year. seaon n typical al 8 an 1 rgest wash At ad of etaion sunlight 15 minerals r many d n i k 30 est Island, e l t t i l esultd many very Amazon º y uary and rain 72º as du the consta als ground 0 fore p puled F are to to ne h w revails. ti In s c e ed (31º c ly fo sue, it .e s u m b al, . the F aled 25 the st to elt, to - o 0 in is f wet. Not all tropical soils are infertile. In areas where there is recent geologi - cal activity, such as mountain raising or volcanism, tropical soils are young and mineral rich. More species of organisms comprise tropical rain forests than do any other ecosystem on Earth. One of the unique characteristics of rain forest is the high species richness that typifies it. Indeed, more than 50 percent of the world’s total species are thought to inhabit rain forests. Nearly 300 different species of trees have been identified within a single hectare (approximately 2.5 acres, not a large area) of some Amazonian rain forests. In contrast, in the most species-rich forests in the temperate zone, such as one finds in the Great Smoky Mountains in Tennessee, at most thirty species of trees will be encountered within a hectare. Typically, the number is lower than that. Added to the diversity of trees is the diversity of such groups as epiphytes and vari - ous vines, all adding to the profligate diversity of plant life in the forest. Animal life is also stunningly diverse. There are more bird species, more insect species, more frog species, more snake species in rain forest than in other kinds of ecosystems. In one area in southwestern Amazonia, 1,234 species of butterflies have been identified from within a two kilometer area. The total species richness of insects and other arthropods is unknown, but one estimate, based on carefully collected samples from single trees, sug - gests that as many as 20 to 30 million arthropod species may reside within the world’s rain forests. Vertebrate diversity is high as well. Within a single reserve in Amazonian Ecuador, eighty-one species of frogs have been documented, the same number of frog species found in the entire United States. Bats are highly diverse in rain forests around the world. In African, Asian, and Australian rain forests there are large bats often called “flying foxes,” for their dog-like faces. These impressive creatures dine mostly on fruit and are essential in dispersing the seeds of many fruit trees. In South and Central American rain forests, bats are found that consume insects, fruit, nectar, fish, frogs, birds, other bats, and even blood. The infamous vampire bat, which makes small, painless incisions in sleeping mammals and then laps the flowing blood, is found throughout the American tropics. In the tiny country of Belize, in Central America, a land with approximately the area of the state of Massachusetts, there are eighty-four bat species, compared with a total of forty m o c . found within the entire United States. s o t o h P

Birds are among the most species rich of © vertebrate groups in rain forests. Roughly twice as many species of birds, 1,695, are One of many species of Poison-Arrow Frog ( Dendrobates ventrimaculatus ) found in Colombia, in northern South found in the Amazonian rain forests of America, than in all of North America. There Brazil, Colombia, Ecuador, French are far too many species of rain forest birds Guiana, and Peru. Adults reach a length of a little more than a half inch. It feeds to even attempt a summary but, like bats, mainly on ants. This photo was taken in they demonstrate many modes of feeding. the Parque Nacional Yasuní in Ecuador.

57 LECTURE ELEVEN 5 8 am two cir re cen sna in tig ta ma an fe of ra to spe kin str bi th an th pa Gu Ne swi on Sn M T A r pi ed ro ey a i he cumfe e r n uct ds d d r g se ch a d w inea o mal a t ches ft adi tra ke r r ci a ray re ugh n s i ng s s in fore Bo co e nches ke mi on f Gu es y st h io in li o s, (Ind roa l se ar nut-madi gh ti f i ki f rneo n s, cl x n Af ore th an out slo nga fe i t st, o pit re par s five ne nd py he ud their an t. inh the e m rica, f includ ia d such nce, ths st an d a s T in lea e the vipe d , s, rot ea th b m abit . an r h fe to m of de an ang row sp tbird pe Th leng e es an such veg gle a f s t bled ostly d he Ame weig nd howler prim in rs, nse d liter eci fo as t rfom live e y Ne Asia n. ing in g su re s o th ar a lu d t m t ou d tar f co rue So w rth ar in a st le s rica g ates, ro hing sh er e on wit Sout of a on fr s ca r ). osa ngth e nstr ian wher Guinea nd en om elabo intero, simla ropd me the n undig mon hin rain keys, the vipers, large , fo n ( pigs Ra ur as ver h die und ictors tro virt lowand antb foliage. Guian but ra -like rain mph Am keys forest rate r s much pics. y t males ualy in fr whic e (or with at an in to ecosyt pre is asto uits ir erica, agles an fo for such ds f xic cour empting Sout d l in ve ig pe rest, d Bot yed n a is est gor Austr as Not ocasin htles ta a the ry l co swaino cone veno caries it co ctualy t tship ken to the h of he h as eight p ilas bras t f on ck-oft hick, lo al lucks fe Amer Ame ms, most the them ali, python haunt or. m. large ed from to by casowry ntrae r “dance in ain are harp acomp ) al in and It en rica, fle so largey ja ica wh he-ro pho fr Af higly ar is st sm th om guars forest metis the of fou rica, pound s borea n ile to y e magn in the many o most an al gr s” the t f in ck, Ame the nd ropics. ra are eq ap th d on colr t orang ma anim Africa, i o (Ame ny bird he n e ualy Gab l, with s. bo a ifcently nas forest of en of speci d rican for fruit wor re dwel raudin over a Th as, in s ful Au tice als. the rmy in est Va on wid utan the rican o are b ld’s e and tr f strali rilant a tho r m canopy riou tropics), sn ain twelv opical th ely withn re s Hondur fl femal Colrfu a g viper, c s or, gaudy: eagls, eir nt subtle ake of ugh amouflged ants. comn tropics) bo in s forest. sprea swarm po hofed own and th ma Sumat thoug an has Asia, ofte the inch isonu s. whic during l groups a rain nakis shade birds-of many d nd Many fed New co n wor fangs a es In h for ra with nd and n hard and - e ld’s s in its st of - .

© Photos.com Most people are aware that rain forests are being cut down around the world, often for wood to be used as fuel or for building, often for such activi - ties as agriculture or cattle ranching. Loss of rain forest is of major concern to those who value biodiversity and believe it to be essential for ecosystem functioning. As rain forest is lost, so are species. Many rain forest species are rare, their distributions limited, and thus they are quite vulnerable to loss of habitat. Most remaining rain forest is in the vast Amazon Basin, an area where increasing human encroachment is ongoing, but one that is so immense that the majority of the overall forest remains, at least for now, intact. In contrast, rain forests of Central America, central Africa, and Asia are being lost very rapidly. Less than 5 percent of remaining rain forests on Earth are protected as national parks or reserves, so rain forests remain vulnerable to the chainsaw and bulldozer. When rain forest is cut, it is typically burned, releasing carbon dioxide into the atmosphere and contributing to global warming through Greenhouse Effect. Beyond that, rain forest is often replaced with ecosystems that take in far less carbon dioxide. Indeed, rain forest is often called a “sink” for carbon dioxide, as it takes in so much of it in the process of photosynthesis. Thus rain forest removal is a “double-edged sword” in the steady accumulation of carbon dioxide in the atmosphere. Rain forest loss is unlikely to be lessened, as the most rapidly growing human populations on Earth are in tropical regions. The conflict between humanity’s perceived needs and the utility of preserving natural ecosystems is nowhere more challenging than in tropical regions. Rainfall is distributed quite unevenly over the course of a year in some tropi - cal areas. In such places, the dry season is so severe that tropical rain forest cannot exist on the site. In its place is a type of ecosystem called either Tropical Dry Forest, Thorn Scrub Woodland, or Tropical Seasonal Forest. In marked contrast to lush rain forest, Tropical Seasonal Forest typically has a decidedly arid look to it. Trees are far smaller in stature than those that typify rain forest and the species richness, not only of trees, but of other life-forms as well, is less, often far less, than in rain forest. Woodlands consist of rela - tively few tree species, typically those with thorns, such as acacias, for exam - ple. Mean annual temperature ranges from about 20º to 30º C, the normal range for tropical ecosystems, but mean annual precipitation can range from as low as 50 to about 250 cm. What this means is that there is a moisture gradient from moderate (250 cm) to low (50 cm) and thus there is a range of ecosystem types within the overall biome itself. At the wettest end of the gra - dient, forests exist, ranging from broad-leaved evergreen to seasonally decid - uous. The canopy is always low, typically no higher than 10 to 12 m (roughly 30 or 40 feet) and epiphytes and vines, so common within rain forests, are far less abundant, if present at all. The ground is often covered with grasses and small shrubs, many of which have leathery leaves. On the driest end of the moisture gradient, bordering that of a typical desert, the ecosystem consists of low stature trees often referred to as thorn scrub. Many animal inhabitants of Tropical Seasonal Forest, from insects to large mammals, are migratory, their perambulations determined by their need to find water.

59 LECTURE ELEVEN 6 0 2 1 Pri Jan Fo Kri Other Sugest Question . . a C Fo Pr Pl W al W rsyt mack cher, n ze h l a i ha ha d re nce ica t nt n, h h, Bi st t t e s, Bo go , Jo a fa D to og A wo of R re an anie dr ctor n hn oks ichar Pr eog d C rld’s ian, d t U he . es, en Re s niver E l A ra H co of com d, tra m and N ading te phical . ajor sytem 1 eo a Co l r sit I 983 nter n an bine estr F tro d Ke y s OR d th ta Rich Pre . pica Comp n ial South re est to Rican Miyat GR ats s, ecosyt of ard ma l Comp
E arison. the to 19 ke AT America a. Corlet Natur 9. r ain New Tr t E ropical anio: R opical ms? Oxford al forest UNDE . W . T Histor NY: ropica o An rain rld Na biod : RSTANDIG Touch Blackwe, Introd ture: Trop y. fore l ive Chicago: Rain ics. st Life rsity uction stone, For th 2nd ? and e 205 est: Universty mo to 198 ed. Death th st . 7. e An Princeto speci Animals, Ecolgia in o the f n: rich Rain of Lecture 12: Marine Ecosystems

The Suggested Reading for this lecture is Sean Connell ’s Marine Ecology .

he world’s oceans are the largest and most voluminous of Earth’s ecosystems. The major variables of importance in deter - mining ocean ecology are the amount of solar radiation received and the abundance of available elemental nutrients such as phos - phorus and nitrogen. The topic of oceanic productivity will be dis - cussed in the next chapter. What is important here is to understand the basic organization of oceanic ecosystems. Oceans do not exhibit life zones that are comparable to those found terrestrially. It is helpful in under - standing the great diversity of oceanic life to recognize patterns in zonation as determined by depth. Consider that the oceans’ average depth is about 2.33 miles (3.7 km), and that the deepest trenches in the oceans exceed 7 miles (11.2 km), substan - tially deeper than Mt. Everest is tall. Physical conditions change radically from surface waters to deep waters. In addition, conditions near shore and over the continental shelf are different from those far from shore, in open ocean. Pelagic Zone When you are on a ship on the open ocean, far from shore, and you look at the rolling waves of the sea, you are looking at the Pelagic Zone. Suppose you had access to a submersible, such as a diving bell, a device that could y v a N e h t f o . t p e D . S . U © The Major Zones in the Marine Ecosystem

61 LECTURE TWELVE 6 2 pa pr sea lu Joi pr size Bio th up you wo you be gy som such wi (a te r an i br a wa th e wh ic an y of sma con “w a ki n “p l in c ba r oce fo we kin ot Th th be ta D O F M Yo ck, ose re he e ke e o b l e an r . n l e th e m is nce u ds lu n u ter l d ma ow i te s na t sure tei l out ed s nd r . ce anic u umi eat m ep at Nu zon , st ch in ld s e l at ha ch r h of di n o l i Even kt o you th at t a fo s as b n er c s cl e ho mi of g f t o in g nt l e f to o er z e a s, ha no t mer a ou ve eg s h you 2 o t h f hu a w un re r n o of an f e g m nua re he t ra n” uc h ll n ug 0 f sm al hem e rea phyto in s, escn op l y con w the h so me stil, , t tice qua ma nd in o per olecu ute tu na re on th ge d. te e d its .” er cr us ta ce a ag ai the hic sur of i ous r f in h cr o som s nter te fe rs met e an kt on lm. your th light. d Pl e cean as P cent ny in o eup th th ab s, ta princ sper rte th e l the fa pla ivn squa life in y face your n e , hyto a plan an kt on p fi ns t e ce ey ke sp the ed m si r t m e sq ers) hot elu sh , S fa r. fir gr to th nt hotic a ph yt op la n s. fe rate g ng le -c el le d, cu rr jour ome ac ke re l, da n in igra , tro ecis m tho If efli ui d Th an d is ase are . e pla s. th e th re kton p d th ei r pr m wer divng be sur fr om co mm un it y, wh ic h Mo Wha , yo t rkn al e synt water pi whale ns a e he e ore ofund whe m Y ne en ts . te inch nkto l t an d or se cal capture ecolgiay s u hem face zone. cu rr en ts , f p prey, perman je ll yf is h. ou st s s , orm es kinds p re la te d y a hy oce ga n ab il it y to ( wer t hesi much ase th e ( shalow whic of re of include re a a would sea bel wou in sh ar ks , t sh r as column the Al l t kt on oplankt might waters fath yo pr for an is ms o th bio ligh ly (or th the tu rn sa me f of s, bu t im p yo aires. e u to o is e ld dar ent “ in to surface is of is lu micros to cold f om Zo o thro are an t b bu t ho r ligh wou u pl ac in f o giant you withsa dr th e ne minesc ish pe ocurin plankt iolumnesc mo su pp or t ar e scho d con mo cean it dive k lo b ar e e y se a darkn epth ag would equiva Gr beca de s ed nter is single- pl ugh netra no an t n, , ot he rs oth ligh ld ve They fi sh , st st e find? wil fined b a so ee k a co ll ec ti ve ly a g squid t ols d coletivy ut nk to n past tu rt le s, a se fr mu lt ic el lu la r. surfa on er ef fe ct iv el y r ar e nau ndig and t” rs p the th em , the use ve es ealy pic om sm al l m tes. p wh g, e la ce ta ce an s, la rg er be le ro ot o creat plants) entr celd are nets icrospe an d ry t, to ar e nkto f so nt you tical va ri ou s . , so last o ba at dep ce, lan tha’s o ilum fo rm vario if bservat co If nt abou me flies f wh man in th at th fo r as thypelag yo la rv al phyto it cr ab s, th p ate tern and ld. fish fi as wh twilg e d te hytoplan wha is diatoms, al e u e sh in net of th e can re fe al us th e ca ag ai ns t p rm b t at y r wher As th ey wo m er it ated caled more l rimay y ki nd s th s, wate must t an d a fish So hun plankto l in io he t st ag es esopla sq plum to tu rt le s, al, not you ht wo rd the re rr ed e tha e fo od ar e uld is the an d t n. d sunligh en ts me , ic uid se first ha ve o fish tin dre by a the ot he r b na rs kton p f de oxida y zon of most se would nd be pe rm an en t the bs ut mean to th e dino hotsyneiz the y, prod po rp oi se s. ba se “p la ne t, ” a do tin o , li ke thes an d e 60 zo op la nk to n, of nd cas an d b nop as n s becaus gic hatc centr th ply. no e, li m euphotic is y etl cu rr en ts . would is t euphotic to or ga ni sm s flage o a an im al s tion e ucers avilbe str shrim co pe po ds , lights the “n ek to n, ” s f e in i more co lankto fo r pu rp os es a zone. fe nightly te d depths la rg er the pounds Animals, six bundat, with ifuged ikes tin et etfish. low lect s). of lates, dep nu me ro us me an i mo bi li ty , astound y tre or p. fet) me m of sim certain Th e than they plants the density, You the zone, su c in v many zon W , so b the in s enr from ar ilar asi, a of ti ny , ith st ng and er te be rs te rm of h se at e light the lig e as to so a i - ht f - . mesopelagic zone, the permanent inhabitants of this zone must rely on organic matter from the euphotic zone to eventually drift downward. A fish that dies in the surface waters is consumed well before it strikes the bottom several miles below. You might see the skeleton of a tuna or swordfish drift - ing past your diving bell but little more of the deceased creature. Energy is at a premium at such a great depth. Some amazing fish inhabit the deepest depths of the oceans. Many are small, their color predominantly black, though with bioluminescent pattern - ing, particularly in the head region. Some, popularly called swallowers and gulpers and viperfish, have immense jaws with needle-like teeth. A swallow - er has an abdomen that can expand to hold a fish longer than it is. There are also species of deepwater sharks and rays as well as deepwater squid and octopus. Deep-sea anglerfish are chunky, with huge mouths that snap up prey attract - ed to the bioluminescent lure that they wiggle to entice prey to within capture distance. Some species of deep-sea anglerfish have a curious life cycle such that males trans - form into parasitic worm-like animals that attach to the body of a female anglerfish. This odd characteristic is adaptive and points to an interesting ecological char - acteristic of the bathypelagic zone. It is adaptive because these animals, like most of the bathypelagic creatures, are relatively rare, existing in small popula - in a m tions within an immense volume of o D c li b habitat. In an environment with so little u P organic matter, most populations will be limited. When a male angler attaches to a female and Illustration of a humpback anglerfish (Melanocetus johnsonii ) becomes an ectoparasite, at least Source: Brauer, A. Die Tiefsee-Fische: Tiefsee-Expedition the female has a source of sperm Valdivia, 1898 –99 . Jena: Berlin, 1906. accompanying her. When she sheds eggs, she need not search the vastness of the ocean depths for a mate. He’s already attached to her. Benthic Zone The R.M.S. Titanic , subject of several popular motion pictures, many books, and an ambitious and successful underwater search, rests on the benthic zone of the North Atlantic Ocean. The term “benthic” refers to bottom. It can be applied widely, to lakes, shallow bays, or the ocean depths. Once it was believed that no life could exist on the ocean bottom. It seemed incredulous that an environment so deep, so permanently cold, with no light, and under thousands of pounds per square inch of water pressure, could support living things. Such a view was, to say the least, naïve. Another fanci - ful idea was that the ocean bottom was uniformly covered by a curious organ - ic “jelly” called “Bathybius,” a living organic slime of sorts. Though such a suggestion may sound like the plot of an old episode of Star Trek , it required

63 LECTURE TWELVE 6 4 cet av ma in no di of Th in pl th of an sup Lit th fin as ma clo ib th som fir ja op de on po be ma ver Pal ed chi bo ab com itse th to a M L T C I Wh n tr ti g a le wl st esi at ey at se i he d t d p a e d r t o o th wat d es to t a o u o ace nt shark o ki s y y t s, eoz ad oral , l i port . solar om ortu d ut ast al o isp es f, n la ns ds pod e p en of ri du e e co co fro fi ng s cap s be ap E exu ra y l ris l ou sh a stua wh se b ma it d , a er, o or N ven po su rove al mp ver ced t i l m ki t il l a th i t o nclud l f pea you he cu nistc ora ti ns in s, them , ort f s i virtu i a comp Z zone re de ale ty f roa car c ish nd w on, pr ny ch sib e ar ra w w g its o ble oce th et re ries st clam hic fr Er , h the ve at hic a l he otr w of ne r co ra s ea diaton pa es o case it a tr e ars ming of a zone nd o aly divn A cau at per n a, e . m of le rte anspo nce s th s o scave ndu re anic r nutr mo udin le d s, zo with ts, tlan rt a ocea er th f the kelp o e ar -like in kel e befo se x th s consu fish and br su hap tyi ne, of wher lig da the nse cove a re ha yo e s g g p cive eco w rou the ie of s ate ab t m . g p p ng ic, e rea ht ha ro th l of el eco ma be nt rted n r n u p o b “fo xped re s an fro cr (tail) bu ca multicear sa irds. th baly m e ge ort g rodu f it ca s. sytem. g pen e s r a oce flo might themslv t you ming l tes eaturs as hout to ed dea he rest,” y fish e d the n uco t m nd nd p fresh lo an th rs. rcas s T h or, proximty erman from b countles in gro gicaly iton biodver as heir et e an fin, to th itself with ctive The wor e d d e would dept vertb dinosa Amon for is rates pres e olars, ven the se th am s an se ocea w reach org flo wa , making adp se ld e rive closet thr prime on diments ace litora . a in th tha ong on hs The abu ’s water ca anism ctive ter. Cur diments. tropica divers nt r. ough e crinod g rates al abun se sity. ns, th nce anim urs oce t rcas. o s to in two whose “ Pe tive zoplan t e nda wer tiny s Chaleng d f he rents the litor Hagfish to l t fishng he knots th sh is se b b zon rhaps ans it evold. elong of relativ colum Not dance to skin ritle otm sp the e odest tha inha e l in lo ore the s, shel only a ls and wa cora and al co ce o fa what e in ok You and discou b ance supor pla t ceans, in on sea ntie zo otm, r y kton. y (and is pore bit ate shalow mea ar o star gr you n. like the m , are rema , the l f ext pr l to nt-like, s ne, y a e r you ound evr re join tide diso of might ore lito , of For Or stry oductive ar fish Expe is prime f the fe s. ensio ns efs. ar ragin thick migh un a also fosil The p t ts e a the or you t rtilzng s ing it ral elagic waving ob her T m divers tripod. this younge s tying lam th orga t a g bo ca lve ma mix are hey erm would bizar any diton,” stalked lso se re serv such at de wa p t cale muco led are tom, can d recod hytoplan se kes preys, a reason oth lineag a light n ep nic the are beca re ters, tha o of thems re kin forms utrien at such th Should xygen e-lok ser d g aches as r study and er be se the the the its of ma orga renadi e ds the water, mak tha from slim extr thr ech s ca . use co a a shalow the also sw re p , T tha nely ter thin s of s sea soft abund o n ought s of kton fish, n ectoral macros ed mpetiors he . productin nism aordinly lves). ing ing e inoderms d-loking wel of arming ecolgy. ba the are e Gran aply 1 yo physical amoe ge els gs they cosytem. jawles, 872 en so ocean som sh in sedimn ck u s sea photsyn h in ocean r as suring of ant metis as agfish alow, or waters, find the egul Hagfish d to moving captur fins b to to e can bas a m cum with ec B ratfish bra t in pic of slo such 1 he body anks flor ost, lakes arly a relat con ause 876, and flex for tri the - ts the are w - - - - if - - - many forms of life in the sea, and shallow waters can serve as ideal “nurs - eries” for juvenile fish. Offshore currents help distribute larval forms of fish and invertebrates, including many that inhabit the intertidal zone. Intertidal Zone The place where sea meets land is the intertidal zone. The definition refers to the area exposed between low and high tide. Intertidal zones are com - posed primarily of marine organisms, including some of the hardiest exam - ples. Like the littoral zone, it is an area of diverse habitats. It may be rocky, sandy, or composed mostly of mud, exposed at high tides. Intertidal zones may be associated with such coastal ecosystems as salt marshes and tropi - cal mangrove swamps. Rocky intertidal zones have many kinds of algae, often called seaweeds, among which are various barnacles, mussels, crabs, snails, and other life- forms. There is usually a fairly clear zonation from low to high water, with only the hardiest creatures able to tol - erate prolonged exposure to air. Just look at a dock piling exposed at low tide, for example, and you will likely see brown and red algae still partly submerged and partly mixed with mus - sels, above which, totally exposed, will m o c . s be a zone primarily of barnacles. o t o h P

Sandy and muddy intertidal zones are © frequently too unstable to support A rock on a beach near Kalaloch, Washington. many organisms on their surfaces, but The rock, seen at low tide, exhibits typical inter - tidal zonation. they both have a diverse infauna of burrowing worms and mollusks as well as others. In some areas, however, there are impressive forests of kelps among which there are many kinds of fish and invertebrates. Shallower waters support plants such as eelgrass, one of the only vascular plants (thus not an alga) that thrives in salt water. Eelgrass flats are often associated with salt marshes and support many kinds of marine organisms, including such odd fish as seahorses. Intertidal zones have many of the same ecological advantages as littoral zone habitats: an abundance of oxygen, light, and elemental nutrients well mixed by the tides. But intertidal zones are also subject to intense natural dis - turbances, as tides fluctuate and as storms batter coastal areas. Thus there are always areas of disturbance and recolonization within intertidal zones. The life cycles of organisms have evolved to adapt to such realities.

65 FOR GR
EATER UNDERSTANDING

Questions

1. What are the major zones of the sea and how does zonation by depth compare with factors that determine terrestrial biomes? 2. What areas of the oceans are most productive and support the highest bio - mass, and why ?

Suggested Reading

Connell, Sean. Marine Ecology . Oxford: University of Oxford Press, 2007.

Other Books of Interest

Bertness, Mark D., Steven D. Gaines, and Mark E. Hay, eds. Marine Community Ecology. Sunderland, MA: Sinaur, 2000. Hardy, Sir Alister. The Open Sea: Its Natural History. Boston: Houghton Mifflin, 1970. Russell, F.S., and C.M. Yonge. The Seas. London: Frederick Warne, 1975. E V L E W T E R U T C E L

66 Lecture 13: Unique Coastal Ecosystems

The Suggested Reading for this lecture is Mark D. Bertness ’s Atlantic Shorelines: Natural History and Ecology .

here are a number of marine ecological systems that appear only in specialized places on the Earth. Their uniqueness is due to such forces as the latitude, landform, wind, and ocean cur - rents. Other factors may be the nearness of freshwater estuaries, extreme tidal variations, and human intervention. Salt Marsh A marsh is defined as a wetland where grasses and sedges predominate. Freshwater marshes are often characterized by such species as cattails (Typha spp.). A salt marsh, as the name implies, is a coastal marsh where tidal influence is strong. Consequently the marsh is regularly inundated by salt water. However, a salt marsh is also affected by fresh water carried by rivers as they flow to the sea. Thus a salt marsh has brackish water, its waters carrying variable concentrations of salts, depending upon the degree to which fresh and salt water have mixed in the marsh and depending upon the tidal cycle. Salt marshes are usually in close proximity to estuaries. The combination of marsh and estuary is the ideal habitat for many kinds of marine organisms, particularly juvenile life-cycle stages of fish and inverte - brates that will later join the fauna of the open sea. Thus salt marshes have a valuable role in the conservation of marine fisheries. The ecological worth of salt marshes has not been appreciated until relative - ly recently. Both on the East and West coasts, salt marshes were historically regarded merely as havens for mosquitoes. Consequently, they were exten - sively drained and converted to various human uses. The so-called Back Bay region of Boston, Massachusetts, now home to many thousands of people, is well named. It was once a bay, extensively bordered by salt marsh. Those m o c . s o t o h P © Bride Brook and Coastal Salt Marsh, near East Lyme, Connecticut

67 LECTURE THIRTEEN 6 8 agi tage pre den bri mar hav pu lar io an sho ra (cr en te coa ad to ma ( ed de pa pa ( pa fo str ot cal ta sal ma sal do mo es. col Fr wa bo eco Ju S F T Sa A Sa u ms, un he ti co anci al id he ng ge r at d h d g n t te te m th th a t t. lect s tate s on close r n r st s ple abil e r t syte l l On s ern ances it e, t s bs, she sh dl ic t t expo enc ebi e cu ina n n d r . b at o dra Sa e io ing r th h for sp h ma ma d on , ph ornia s s it A er sal nce a sco, is bu gr than iv n e ig s emon s , in e thu c ma cor se i t rd te com ecis. is shr ty lt of edi visto e he ordgr ely s, go ysiolgca th the ow cr h g ge to aera rsh rsh not speci t m t y ms sure o s. ma sp of are s us, to m rtin dgr th abs bay zo p a the f nflies f ud n r imp, ment C ra mud lies, the ing sp th e caled ro nd es, es sa Ma ar the e cra ikegr str the ano rshe ad w in natio late a plish r tion ass. s as e as . like ductivy p di w sh lifo sp Be lt er overa to are a N ated a n a ny .) salt ( t bs. other s, th , ith ) snail, he Pa P also nd m r stand um t e xic, of d pt e o (called a making yond e rnia s gra fol as Bo rog to oug ing hig g n S cies Oth i nd arsh T ly inse h lo s spe o comm cif a in ch Without ro hig East to sa pa marsh ero he alo as th ston that the n l th , s cordga g her ne . a ws har b h ar wed m ea g ( er lt e ext giving marsh rtina olden hly cie bound e D ct irds of is th phytes, extensive o us t m r cord low uch coast a spe oleranc mar , istchl roots stern peat), subi f case speci dy salt fiddler we e go cteriz elvation, on remly usel, sp S. it thou toda s, cordgrass t s bird he b gra salt d such alty altern cie ecis, the in l of sh. S. y gras p folisa eith in ifficult s shen. the marsh prod hotsyn und in salt ). a gh a y as with North se plant s any pa salt which spe lso as hay water cordg T is crabs wou zone d er salt un spicat group lo as he the well wor grow iflora levs tens bu er b uctivy. m easily they is particu w cies file ar . for der of th m y a zone be arsh rrow tre ld biod virtualy acts It pla same Th m America ab e ms) e nd oxyg gr arshes. speci , rass, limits thesi of the a , have , is the d yond arshe a ne whe e int in ch contr s eir ase caled its le nt su are ca ) to mar relatd o ive fo o swalo slowing to ver network sup and ertidal arcte the zones la as mar r to en ch utcomp ca le crabs general combine lo saline stor re the d rly the rsity, tole sta a a oled sh s, throu rained d n pe re we anoxic wed a supect le Males lternifo sh tidal are m consit var and salt orts sa s su su y whe bilize tid vels. rsit growth rant e is l utualistic rized pla he hige zone to is lder g lt ch rvie are io down al as water ghout etd. som condit typical by of rase mead sedg name in ma ( many rons, us true re have nts, d T or currents of n have b condit fluenc Whe the animls th achyinet a higly p ( uisance y , by a mostly they tha rsh g Iva r ewhat som hotsynei under e hig sa o . simla virtu laswort the in of m varies ow f the M crab mud, egr Sp a s. “fiddler t kinds lt relatio n the and any one ns, fru co elvation, ixed much much e stable a a mar in The accumulation artin e con ha prod growin re ns rdgas, tescn is co zo would r difer of such such co ts, colony wh o co minu thus claw y, a z among f fed g she m a as ne of se and centraios nship onati rdgrass. Spartin a mpetion its reats. huge mong rails, uctive spe er of crab.” b of is bin colony. invertba icolr a ent. mosq speci of o as upon te tend usa San physiolg t “th continu that with xygen ation cies ) the beyond show the aids seaon. black . furthe is diatoms with mink a e adva the Salt th Studies ecosy nd ) s the pa uit is cit ly sub water The S by hi e an gras o to i of n alt with y” salt much oes tern resi gh a f ally S. s, lim are n rush o d var - - f - In s - ’s - - - - Salt marshes export much of their productivity to neighboring estuaries. Grasses that are products of the growing season die back in winter, surviving the cold and ice of winter as roots in the mud. The above-ground shoots, often sheared off by ice or tidal forces, are moved by tidal action, eventually reaching estuaries where they are colonized by a host of microbial organisms that form a food resource for larval invertebrates and fish. Thus the marsh grasses are also an important energy resource for the estuary. Salt marshes act as natural sponges, absorbing nutrients, which are recy - cled to the growing marsh plants. Some organisms such as the ribbed mus - sel ( Geukensia demissa ) are keystone species in concentrating nutrients. These filter-feeding mollusks, which grow abundantly among the salt marsh cord grasses, feed by filtering suspended particles such as plankton from water during periods of immersion. In doing so, they remove and concentrate nutrients such as nitrates and phosphates. These are deposited on the marsh mud in the form of compact “pseudofeces” that serve as small pellets of fertil - izer. Many marsh species, including various clams and oysters, also filter water to remove suspended food particles. Pollutants, ranging from pesticides such as DDT to heavy metals such as mercury, are also removed by organ - isms and concentrated in the marsh. This is the mode by which these eso - teric and often highly dangerous compounds begin to bioconcentrate as they enter natural food webs. Natural “pollution products” such as the toxins pro - duced by minute algae (dinoflagellates) responsible for red tide also can bio - concentrate in marshes due to activities of filter feeders. Mangrove Forest Mangroves are a diverse assemblage of coastal tropical tree species, all tolerant of high salt concentration. There are thirty-four species worldwide, mostly distributed throughout the vast tropical Pacific. A few species occur abundantly in tropical America. Mangroves are not a taxonomic group any more than all salt marsh plants are, instead representing numerous plant families. Mangroves are all defined by their physiological tolerance to immer - sion in salt water and thus are the tropical equivalent of salt marsh grasses, sedges, and associated plant species. Like salt marsh plant species, man - groves are halophytes. Mangrove forests typify tropical coastlines and may line rivers where there is tidal influence. Like salt marsh grasses, they thrive in high saline environ - ments, but are outcompeted by plants in low salinity areas, where otherwise mangroves could survive. In general, mangrove species are excellent colo - nizers and quickly invade and grow in areas subjected to the effects of tropi - cal storms such as hurricanes. Most mangroves are small trees, rarely exceeding 10 to 20 meters (33 to 66 feet) in height. Some grow as dense shrubs. Mangrove root systems grow well in soft coral sands as well as thick, anoxic mud. The forest itself provides a complex coastal habitat for many species of animals. Red mangrove ( Rhizophora mangle ) is an abundant species in tropical regions throughout the world. It typically has extensive prop roots anchoring it firmly in the shifting sands. The roots are abundantly equipped with lenticels, openings that admit air needed for the roots to survive when immersed. A superb colonizing species, red mangrove seeds actually germinate while still

69 LECTURE THIRTEEN 7 0 to in am Th var th la wa er ad th ma me Sim we ma am cha am ro mu ma gr me fo str so a ha at i T Bl n Ab g r ro is rm ta l s o o he B o val ikes d n b us ter l a i o n n r o o d l n ts ve o an ous s. se n seag ng che gin (b e she . i ugh ck en lary, unts, gro t ng unts . t u ve- den Ma p gladesh fl o se I d t p va acte sea V i t he is s e o a ro g p r ep ma l d and ariou th ve m to and org la rgy ats mo nd rio er ny i in so ra ve p ts se a o o e ositn an en nd, m in ria, to iod, eigh ngr anim nd s. f n us r is on bel ng rtica anism alime up sp m ots , ve . an to utilze air sta th s t w h ges ang rgy ow- he ove or dif ecis e fung rtica r It gro igh su t spo he e tra vert t eco he nds stua to als. ly gr is wa caye p of sea nta stain by er r rove nsp of s ly ve d? to are e e am ( ng r fr i i, l te e l Avice ca ly o nte m o on ries, o A om it pro sential th o cor ry r n va , se n lea e n Once orte an nt s vie f , rath l t ts. im ing s. ized w e fish s, r it cor shot is canl. rious kin cure e dr ductive, al her w gro the , plant. t m ves, mediatly xposed In nia he providn ane Nu formed. d and y er o the re angrove al ds can f and this orga by ves leavs ma tr ro merou su th s, re t mones, prot the th of e. fs. o marine ger In spit ot ngr an the Th ficent in ick caled r man ser provide ecosyt nic f ecogniz its y eithr As sand sytem. gest oves g e minas Once fish horizn zoans) pr out cur s and s ves dro n gro se ra m othe ovide ursei is fish tun te er, ater fo edlings spe pn a the oxygen p, ents. and ws moved case, ye waxy, od dro of particle exc icates, r euma ) mang and t ms taly, nd t hey on tha m a leaf of ho an p Man we ped per ag mu s hotsyn angro rot ten As th part w le a t, for the cra ain , lok b e esntia evn act g re, dflats, toph be rove pa b squ in in the ro nt Y a o molusk, grows obing of ap bs to juve in ve f cause rticle lea as of tur smal sed in ves habit a th like are mang tualy fo Isl s “ water, anch swamp f kne thesi their res, r n, f e in a eality, a nile site taking fr nd co d d co l fo lin metr o lon serv dens agmen and en with s” s its r she web or rove lonize, wh ral g drop m juven o for a d ( g, and they f p for so low a sha it. arine n Mi rgy ich clo b lter ad re bsor con e the s p ma functio ase ly as cro per u Red leaf, encil- hi microbal t on ma of vant sely worms low, ile a can f source. it n in gh n and a tinuos ny a curent low bs and ow e to animls. wha to day. for to life sia new thick, ph fod ma dige tha marine like linked. survie seawtr pas horiz ge the o back fod i microb n adequ t sur re cyle like ngroves find How the aper man s) st of it pods base Red colniz sedi anoxic until round at can as Pacif the salt i s ntal n pur an low ed - ate es. is for - the it for i ic. i it - - tide - - -

Left: © US National Oceanic and Atmospheric Administration Right: © Photograph courtesy of Eric Guinther Mangroves, like salt marshes, have high ecological value. It is thus regret - table that throughout the world mangrove forests are being cleared by such activities as dredging, channeling, or cutting as a source of wood. Huge tracts of Southeast Asian mangrove forest were destroyed by herbicide spraying during the Vietnam War, over three decades ago. In addition to serving as essential nurseries for many marine species, and in buffering the land against the forces of tropical storms, mangrove forests form important nesting areas for tropical waterbirds such as pelicans, boobies, herons and egrets, spoon - bills, and frigatebirds. In addition, long distance migrant landbirds often over - winter in the food-rich mangrove forests. Mangrove forests persist in North America in southern Florida and along the Florida Keys. The endangered American crocodile ( Crocodylus acutus ) is one of many species dependent on the mangrove ecosystem. Coral Reef Coral reefs are found throughout the clear marine waters of the world’s trop - ics. Among the oldest ecosystems on Earth, coral reefs, though not with the same assemblages of species found today, have existed virtually since the Cambrian Period, over 500 million years ago. Reef organisms are among the most abundant in the marine fossil record. Today, coral reefs support the high - est species richness of any marine ecosystem. Like their terrestrial counter - parts, tropical rainforests, corals reefs support myriad species and accomplish high rates of photosynthesis. Reefs are both diverse and productive. All coral reefs are confined to clear, warm tropi - cal seas. Cool water or sedi - ment deposition will kill coral reefs. Coral reefs require a temperature of at least 18º C (64.4º F). Most coral species are in Indo-Pacific waters, where over 700 species can be found. In comparison, Atlantic reefs are much less species rich, with only about sixty species. This difference in species richness between the older and larger Indo-Pacific n a g tropical oceans and the i r r a Atlantic/Caribbean is true of H m a i l l i

fish as well. There are about W r e d n

500 fish species in the a m m

Bahamas, compared with o C / s p r

2,000 in the Philippines and o C A

1,500 in Australia’s Great A O N

Barrier Reef. The difference © in richness between the two A pillar coral at the Florida Keys National Marine Sanctuary.

71 LECTURE THIRTEEN 7 2 Ver th s u o l p e v a h o C zon wi wa mi i h an n I c u d o r p h w y e h t in gi car com sel at gr me cle di Co lu sea an ha d fi nd on e t s o h n e m g u a p t u o c n u f co wo u wit hi Bo in How e Pa oc s u a c e b C R C g a stanl m s t n a h g e e o th ra ea n the i d o o f e e , w o l l a h s th ci ter ves. s e s l a r c i mal nt b n wi t ut tal cel ra ra in secrt ld ica le p m s n i n o i t Cn an l fic y n i t onat te al r re t u n h h sti tha ns m i r p e r of ng re e e os te cl g u h ydr ve l l n . an e r a P co d a ef o c fi r a s a em ea dy n t re is l p s f o s. y, te i a is e r a e A or nsity nd e v i aci fi dar T the se li ed , nd r, zona gin b t g ca ms. e lumn tog y f e a r as. ke to efs ra he pose o a h t e r a r i gan y a A ive n h t to o l c c g ed on in w m o k e n , an , e ap p r a le s l ia l ta) m vert ly y e n a c kind alg m a muc h a e y - l l e w c, f o n hil eth h p a t u cr r en th e e T e s a no th e r C o o b th e ostly e - d tion cels. b t f h ism d, p l l a ( r g ef , is , s d e l l e c hey fa e re a u th eat f som n w a c i g o l o i s y e r r a or y r e e v a ro xi ma te ly u o o r using er co ica kno eef po s w n t w o f e and b o o l sca cto in the e of Ca ri bb ea n the t i l d e al t s i l u d stru sa me s st e ave n ure a un te re d. cor e d i x o i d is th l i old er u l num b s a yps n cnid s are th r, o t c a s t e , l l su r wn e t a w a k rs in d e s n e s n a e zona h t c le c i , uc at f tot al tim a nima a m an e yo u ctur als s a l p n i h t i w somewhat t a m i n a o th calium e h , y t i v i spend f o eit her re wou ld action e v i o n i rel ated re ture atrixes se Indo-Pacif, t x e f for part tha such oblast i es eir sp ec ie s m oc er , s r e h t y t a m r t n a l p s t n e h t sult tion cup-like, are r i e h t aly y l l cre spe cies wo ul d l als h p d r o a r n o eq ua their ean caled ten relat of n i x i f is y e h t captur of y b . s l e h t an d s a d e l l a c r p r te r o c y s o t o a sug gest of colnia, f egi on p comple d a the fis h also rom s tacles m o i b wit h c i p carb tha n i , the n e s e atern n i k o o l calium e h T or in a l p l g dep r a n i e e r wit h ten l a jelyfish o c r e t fi n yo u nu mb er s P mo d m r t u o b a m e s e the spe ci ric hnes s a r o c sting e s e h t n tiny ac if ic , y n o l o c phy the . s t n l a r d aug - t on are ta o i t c a f reg a o o z . s s a o th yl i e c is n a re n i by con side rabl y s. ne w x - g - mor e ab a m a - t a c i d windar r e w s , s l - eco f o - t n a x Hor h T e t a e l b nd rd n . s r e z i a t u B out s bu t x i r t s e h t s e r a y e a t e h t of to sytem, tha t d r a w o p lig izontal d n e of e h t m . e a l l e h sp ec ie s. o t the e h w in fi sh bot h e k a t ht , e r h c u t o z fis h t a h eci atio n a h s M r o f p p u s y h w ca s l a e v th e r b pent t n a x o u s a e sam e. e r to sp h c n a n r a c o s e p r o c l l a is gre ater tim e n i zonati In e n Pa ci fi c, T be the ec i y l e r a t i char l e s e h m owe r e t n i n o b s l a An th e e m e r h t ration. e a l l e h s i m f o t o n a g n i es in fou nd, e r o and In e a le t h c u a h t to e h s t n h t i w h t the Ca ri bb ea n, e s e r p s a pe r n oth er my are a cterizd t t a p a l p ward in s t n b r a c e . r e h as t are a is n a l p . r a c d n a Refs o c a r o Ind o-Pa cifi c. o c the s t n 10 per h t n a x o o z f de s n r e yo u f o n i a e c n l a r tha n n o s l a r Z et a r d y h o b wor ds, 0 s t . side co termind Car ibbe an e h t n a x o o e h t o p r u p d n a s t s e r o f The uni t me te rs ra e r mo ve d o i d n o b ma o s f o h t l y the s f e p yo u e k a t n i of e d i x .s e v l e s m e o t are a, both e h t Ind o- u n r i e h y c i p y t l you s e s ,e a l l e yp the Atl form e r a re m ta h t . w of e r f b ea l l na h t ro m , ant ic. ou ld a r o c ho l a y ref. n a ?f e tha n os - as ri fo d - l

© US National Oceanic and Atmospheric Administration fringing reefs, barrier reefs, or atolls. Fringing reefs typically surround islands, built by the corals in the shallow sediments where the island rises. Barrier reefs run parallel to coastlines, and atolls are circular reefs that remain where an island, now subsided, once existed. In one of his first major scientific works, Charles Darwin correctly surmised that the various kinds of coral reefs all form from the same basic process of coral growth. In other words, an atoll was once a fringing reef but, as the island subsided, the activity of the mil - lions of coral animals maintained the reef at the water’s surface, even as the island disappeared beneath the sea. Ecologists have learned that corals are highly competitive with one another. Like plants, some corals overtop and shade out other species. Still others poison their competitors when in direct contact with them. Given the clear competition among coral species, it may seem surprising that reefs can main - tain a high species richness of corals, but they do. The reason is that distur - bance is a relatively constant feature of coral reefs. Disturbance by wave action or storms (such as hurricanes) can quickly change the dynamics of competitive interactions on reefs. In this way, coral reefs are similar to ecosystems such as rainforests, where periodic distur - bances of varying magnitudes are a key component to the persistence of high species richness. Some disturbance agents can reek havoc on coral reefs. One in particular is the sea star (starfish) Acanthaster planci , the so- called crown-of-thorns. Population outbreaks of this species can result in the destruction of whole reefs. It is unclear what causes such outbreaks. Like rainforests, coral reefs are being lost due to various human activities. In many areas, over-fishing is a major problem, but other activities such as dredging and mining can cloud the water to the degree that corals can no longer endure. Chemical pollution is also of major concern. In recent years it has been learned that meteorological events such as El Niño negatively affect coral reefs. El Niño is a periodic and generally unpredictable change in global climate caused by the migration of a high-pressure system in the cen - tral Pacific. Patterns of current flow change, precipitation patterns change, and the result is that some ecosystems suffer serious negative impact. Unfortunately, coral reefs do badly in El Niño years. Globally, many scientists believe coral reefs are gener - ally in decline. n o i t a r t s i n i m d A c

Colorful reef fish— i r e h

Pennantfish, p s o m

Pyramid butterflyfish, t A d and Milletseed but - n a c i

terflyfish—school in n a e great numbers at c O l a

Rapture Reef, off n o i t a

the northwestern N S

Hawaiian islands. U ©

73 FOR GR
EATER UNDERSTANDING

Questions

1. What are the most essential ecological functions of salt marsh and how are these functions similar to mangrove forest processes? 2. Why is the coral reef so species rich and so highly productive? What are the current threats to coral reef ecosystems ?

Suggested Reading

Bertness, Mark D. Atlantic Shorelines: Natural History and Ecology. Princeton, NJ: Princeton University Press, 2006.

Other Books of Interest

Kaplan, Eugene H., and Susan L. Kaplan. A Field Guide to Coral Reefs: Caribbean and Florida. Boston: Houghton Mifflin, 1999. ———. A Field Guide to Southeastern & Caribbean Seashores. Boston: Houghton Mifflin, 1999. Shumway, Scott. The Naturalist’s Guide to the Atlantic Seashore: Beach Ecology from the Gulf of Maine to Cape Hatteras. Helena, MT: Falcon, 2008. Teal, John, and Mildred Teal. Life and Death of the Salt Marsh. New York: Ballantine, 1991. N E E T R I H T E R U T C E L

74 Lecture 14: Current Issues in Global Ecology

The Suggested Reading for this lecture is Edward O. Wilson ’s The Future of Life .

cology is sometimes called a “We must find new ways “subversive science” because it seems to commonly espouse to provide for a human views antithetical to well- society that presently has established disciplines such outstripped the limits of as economics. Conservation can historically be viewed as a sociopoliti - global sustainability.” cal movement that places intrinsic value on ~Peter Raven, President nature. Ecological science was not found - American Association for the ed to promote conservation, though ecolo - Advancement of Science, 2002 gists typically have sympathies toward the natural environment. As ecology has matured as a predictive discipline, approaches to conservation have become increasingly based on science and thus ecology has been at the forefront of such approaches. The field of con - servation biology is now recognized as one of the sub-disciplines of ecology. Ecologists have also developed applied and restoration ecology as sub-disci - plines of ecology, so ecological principles are being widely applied in ways that were not imagined a few decades ago. Conflicts arise about how best to utilize, value, and preserve what are per - ceived as natural environments. Humans, at least in Western culture, often consider themselves as somehow apart from nature, rather than part of the m o c . s o t o h P ©

75 LECTURE FOURTEEN 7 6 wa in in to no spe Ano al an cur is act am og col ra in an lo ga bi to to ly est do an ab di in Co ag as th Th tio f o r a p v e d n a T Bi En T Ea T N clud g ized fa n o f g e ti he he ech l a n u l o t d y. d i n d i e th e e is e h t o s lect n o ual ernt g-t ns sphe ed li soi r o o at y l t ci ncy vi r diver maj evo nsu nj oz ent t ty. sin cern diver com g ng na th e co va the a o a n he n re ha Bio ure es ron maj n o i t o row er gr f in n ot l, ly de p p x e po iv e W f nta y lu l g can E Th u t r ol ishe o e l s re ar ne a p g m r e air a r ve. e diver co th i ’ ate r s art me sity ma r e rived e the re nh opu ap s speci in og e r sity s or th a ea re fo ties h e . go mina t s lose a l tha at, eco m , ar ons- y r t t ncep la ser um a . h’s h r E sulted be ries abit man y w T w nta jor ly have en e n i of ent of e e yer od diver la roa pa h con d he n r sity los p ate drive or t by a e vice n o anity, iscp fr fo vir tions, n o r vie drivng r E ne type l extin tion, ca re d omic ter w ld s ecog s. se om , t atu o E o y e i v ches, abo e arth cuse r, vario c on ad of per f b ’s of ca ar t thics use se exr wed ap su mic caus s e s, is i n h y ns. a n p e lin ral w th men fis h d a u n ction n b u re and rima xo pl bj ’s de by s e h t ar at n th a or ecosytm be uman iton ma e d iodversty. d t f o us fre ized b heris for source, tod ied ect ted anlysi them but e r f ions , e gu a tic h ecosyt globa es pends, h e w on st ecosyt sci nvir m o e s ow ta u t a n as nity. t n over mean ildfe ably exp nvir d a r ay, bio y far speci a at con to to for l inter st sto enc com h until prob pro onme o emrg devlo best ural glob h c i h w rong ow to diversty str th t i r e r onme resd excd are bu -exploita cks biod lo servatio a n o i the t ther est e ar ductivy s, extinco. he are ong o s b r a t recn le ms and al ecosytm a f ser e m to ons est Humans in it ar ant con m iversty tmosph e na single ed declin ofte l o pment e t of a n e d is the e d man J d f r regu vice a h colgia ive tal f h s emain hrop tural as ive t econ e d u ram acing so nd top o t s i and r u t e o tinue from clea tly. los as n tion, n the nteri com rse e m cie rsity. and num b age s e o soil lation i thics h C - o grea b t a c i r io ange Ran ut-com er de s r lo ecosyt omics es repla Glob r tic of en cur dem ty genic is the u s e and logy to th such citzens mon com suta s, monstr fu bers ren g fisher an y l l grea to the at de It tes rent of gin declin. com t s i r a nctios e pr rega ntial . s t l inade and al ce d inclu is temp num pr cosytem biodversty d clin pone ought gre glo pet coupled resou efct agmt as incre wable i n a i p e e a climat t of n not esrv prob it i rat griculta h T from e ap able m ates e rding a bal in to is s. ding erous, with speci, quate nhouse e e h t ts b e ns, uniq e know f or a asing upon th unctio sen t th s rces to It Difer le ecaus, o d n ic r p e p to spe fresh such pur esour is f on tha e o l o m is pred o l i h opula o be habit whe deg natu with cha ne specia ne rigo fu centu a m nec study, in ely but ifcaton in cies. l a c i g o globa is l in ent whi num nctio practied p o s f it ho re ga nge ate land, ge d re in co tha water. y ral w ces rou human hum in compare tions modern is l their arge t to as ch hic w e b se, sary netic natio whic nservatio ry resouc l a c i h tion, ber los, Stil declin. w e i v ecosyt often native of sly is re many r we for ing ecosytm. fundamet al an is ecogniz depltion t a exploita of gulation, in also imp they per and of provide ns ho ity. in so diversty sutain life, a e l contiue o r poula to of polu to Africa. f o air a in industr in d w its l s t o cent speci ortance take sp Ea abn the t s afect the vasie ong na m w the di The inter and be ms. ecis su ith tion rth b tion. - iol st - - o a ch - - f - - - l - - water, cycling and movement of nutrients, generation and preservation of soils, and renewal of soil fertility, to seed dispersal, pollination of crops and other vegetation, to maintenance of biodiversity, it is clear that the functioning of natural ecosystems is essential to human welfare. But how essential? If put in the light of economic analysis, just how much, in dollar value, are nature’s services worth? A team of researchers led by Robert Costanza (Costanza, et al., 1997) used numerous databases to estimate that nature’s services, presuming that humans had to somehow “pay” for them, would be worth about 33 trillion dol - lars annually. It is noteworthy that this estimate is about double the gross world product, the total of all gross national products, which, at that time, was about $18 trillion. In 2002, updated estimates suggested a rough average of $38 trillion, with a range of between $18 and $61 trillion. The wide range reflects the extraordinary difficulty of attempting to measure the macroeco - nomic worth of all ecosystem goods and services. Some economists have criticized the effort by Costanza et al. for a number of reasons, including the assertion that the extrapolations made were incon - sistent with principles of microeconomic theory (Balmford, et al., 2002). In response, a team of nineteen researchers, including economists and ecolo - gists, examined over three hundred specific case studies in an attempt to compare what they termed “marginal values of goods and services delivered by a biome when relatively intact, and when converted to typical forms of human use.” Robert Costanza, who authored the previous study, was part of the research team. Their results were consistent in showing that natural ecosystems have the potential for greater societal economic gain than do ecosystems converted for narrow economic objectives. In one example it was clear that reduced impact logging in Malaysian tropi - cal forests did not provide the immediate economic benefits to individuals that would be obtained by high-intensity unsustainable logging, which is what is normally done there. However, unsustainable logging reduced social and global benefits through loss of forest products (other than timber), flood pro - tection, carbon stocks, and endangered species. The total economic value of the forest was about 14 percent greater when managed to be sustainable, using reduced impact logging techniques. In a second example, a mangrove ecosystem in Thailand was converted to aquaculture (shrimp farming), something that is occurring in many places in the world’s tropics. There was no question that short-term economic interests were well served by such a conversion. However, when social benefits of leav - ing the mangrove ecosystem intact were included in the economic analysis, the result changed. Benefits such as the sequestration of carbon, storm pro - tection, and protection for fish added much more value to the intact mangrove forest than to the aquaculture ponds. The estimate showed that the intact mangrove forest was worth about 70 percent more than the aquaculture. Most ecologists agree that climate change is the most significant factor now influencing Earth’s ecology. Climate change has always occurred throughout Earth’s history for many reasons that have nothing whatsoever to do with humans. But today’s climate change is unique in that human activities do, in

77 LECTURE FOURTEEN 7 8 col eco ma me in iso on Arct spe wa on com twe wi tio th by to Such con pr cor car th con an fo com mi no ga ly ga esn wi th to ph Ga gr fa T Al R I t g e is un an ct, o e th th he t ti n g d m se, se e e r b i lect lat r th he se vol n a r b w ces enh ai s gat nti l min ci ce ve th oin , ric cal onset lo ectab ic, in ogy re b e h y sure on eno d th o hic s se i a wel ed es re in ei as n ck i e u nt rted ti ug e ri o ali to s be iv t e ing l th g g may o qu he th a me su g e r a g f su the d t r e ase the ap use i l as betw ty hat d g h l h w m er nd ht a in a re th be nt io nef and le , po ick, wa ch t cen kno row eat lt tion an nd of ould o atm ra cre to t xid to e em era th pr can ( he t d case it of s comp o in an b are tem ter it hu Ear pid d ist y a e t ef as odu re e in w ulation e he is tur wn ing e, ased have ea en clim be re, of ctions osph t pa clima to o d po neg en r me nt an h hat solube le serio “ru ntly etn cean cha pe w ot th y, te su ich sy th ct. t I ctive rticu ase of ma w forcing th he nd use the ce are se a rg ate in d n mp , e ativ rat b i with ch erf ter at s e tra stea a le in th y ca la te u e is als “ tion s a us king at re p from n the s g d a strial ure m la era wa a ul nd fro e g of r cha a ng overm or nsit e, turn, rbon lobay. poten altering vapor, n mosph ch esnc can an ly with re carbon r, s ore for signfca incre case and dily influe m e y” f of ed grenh thoug ture ecolg br much a from osil en en of the car alo ngi. xa the nge from a Revolu eding pa an he a this would dioxe, house dange 31 to the and mple give gous nd bon ased ia re Ea with er flucta meth sin d phasized at Sun Som 5 volcan re fuel l. the lativey of wil ce of te, e ica th do Earth plane ouse rth p enrg Everywh spond not tod fect dioxe, t birth would ocean pm e g of the tion, s o th efct red trap globa a col atmo l ane, be for taken e and, absor n a a e mount ay pr ad e by the al. sp moun asily io ic t h in t ef . climate oces, his, to of p to water beca y mit lo ns abit nies b . mo it Pen atmosp la ecis, a em to spher s nitro l 1 pa by In contiu eyond Withou ng “Goldicks to space trap alter b is net def out er 960). seri ct.” of can o the re th ligh th iso t rticulay ca a of tha n guins a use cert period a of rough e liqud us oresta bout to se and Venus. nd le of Ear rbon on It e carb cha ecosyt t ing such rea e be t he heric , ain exist tha an nse, ns, Th is colgia t to o pla aly of of chan cirulato th of coastl the th xid th at lit in mor ab nge, heat 385 d trem is . on e th its water the t dioxe net. e th tion. pure a f ie T and as or e, whic t incre t th in e h sorbed tmosph this incre carbo rap plane rape ef in e ges o he s dep dioxe, eat e em e ceans, de p gla and endou exampl, t atm of much th is he liqu h ly Antar T it m fed ct,” heat. is gre is e eat. ase m n. plane se end ma is hes s ase hum p has physi , ore t n life la d ospher. id po ropetis carbon an tha it ( whe Th em “tra eric into dio ter par situ in wo nifest. sly ing is of fo in lar Ev cti an has an th a could gr e contribue excitng Some t. a two ped,” rm. xide cal uld cle to ts cy grenhou re carbon whic at ated entualy, pro enhous y gase, impor par th importa wo bea ares, gre cultre are buildp per be e corelatd ar ecolg Earth of dioxe reaction be One factors ces This uld t cone oceans, Rather en r and of atmos at tha she ocurin nhouse. becoming of tance milo is r suf tim dure. etaind not dio the has precis re nt pro phe d the d is an tha lf ist this se sin duc e ue icent in ntra in xide in act ice have s b - d n) - for - of e ce an to its is - g, - - FOR GR
EATER UNDERSTANDING

Questions

1. Why was ecology once described as the subversive science? What should be the relationship between ecology and economics? 2. What are the major factors that are today altering ecosystems on Earth? Which of these is likely to have the greatest influence ?

Suggested Reading

Wilson, Edward O. The Future of Life . New York: Alfred A. Knopf, 2002.

Other Books of Interest

Botkin, Daniel B. Discordant Harmonies: A New Ecology for the Twenty-First Century. Oxford: Oxford University Press, 1992. Levin, Simon A. Fragile Dominion: Complexity and the Commons. NY: Basic Books, 2000.

Articles of Interest

Balmford, A., et al. “Economic Reasons for Conserving Wild Nature.” Science . Vol. 297, pp. 950–953, 2002. Costanza, Robert, et al. “The Economic Value of the World’s Ecosystems.” Nature. Vol. 387, pp. 253–260, 1997.

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