DOCSLIB.ORG

Foundation Species: Consequences for the Structure and Dynamics of Forested Ecosystems Author(S): Aaron M

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Foundation Species: Consequences for the Structure and Dynamics of Forested Ecosystems Author(S): Aaron M Loss of Foundation Species: Consequences for the Structure and Dynamics of Forested Ecosystems Author(s): Aaron M. Ellison, Michael S. Bank, Barton D. Clinton, Elizabeth A. Colburn, Katherine Elliott, Chelcy R. Ford, David R. Foster, Brian D. Kloeppel, Jennifer D. Knoepp, Gary M. Lovett, Jacqueline Mohan, David A. Orwig, Nicholas L. Rodenhouse, William V. Sobczak, Kristina A. Stinson, Jeffrey K. Stone, Christopher M. Swan, Jill Thompson, Betsy Von Holle and Jackson R. Webster Source: Frontiers in Ecology and the Environment, Vol. 3, No. 9 (Nov., 2005), pp. 479-486 Published by: Ecological Society of America Stable URL: http://www.jstor.org/stable/3868635 . Accessed: 19/09/2014 10:31 Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at . http://www.jstor.org/page/info/about/policies/terms.jsp . JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact [email protected]. Ecological Society of America is collaborating with JSTOR to digitize, preserve and extend access to Frontiers in Ecology and the Environment. http://www.jstor.org This content downloaded from 158.135.136.72 on Fri, 19 Sep 2014 10:31:20 AM All use subject to JSTOR Terms and Conditions REVIEWS REVIEWS REVIEWS Loss of foundation species: consequences I for the structure and dynamics of forested ecosystems Aaron M Ellisonl*, Michael S Bank1, Barton D Clinton2, Elizabeth A Colburnm,Katherine Elliott2, Chelcy R Ford2, David R Foster1, Brian D Kloeppel3, Jennifer D Knoepp2, Gary M Lovett4, Jacqueline Mohan1, David A Orwig1, Nicholas L Rodenhouse5, William V Sobczak6, Kristina A Stinson', Jeffrey K Stone7, Christopher M Swan8, Jill Thompson9, Betsy Von Holle1, and Jackson R Webster10 In many forested ecosystems, the architecture and functional ecology of certain tree species define forest structure and their species-specific traits control ecosystem dynamics. Such foundation tree species are declining throughoutthe world due to introductionsand outbreaksof pests and pathogens,selective removal of individual taxa, and over-harvesting. Through a series of case studies, we show that the loss of foundation tree species changes the local environmenton which a varietyof other speciesdepend; how this disruptsfun- damental ecosystem processes,including rates of decomposition, nutrient fluxes, carbon sequestration,and energy flow; and dramatically alters the dynamics of associated aquatic ecosystems. Forests in which dynam- ics are controlled by one or a few foundation species appear to be dominated by a small number of strong interactions and may be highly susceptible to alternating between stable states following even small pertur- bations. The ongoing decline of many foundation species provides a set of important, albeit unfortunate, opportunities to develop the research tools, models, and metrics needed to identify foundation species, antic- ipate the cascade of immediate, short- and long-term changes in ecosystem structure and function that will follow from their loss, and provide options for remedial conservation and management. I Front Ecol Environ 2005; 3(9): 479-486 WV e are living in an era of unprecedented and rapid life on Earth (Eldridge 1998). The loss of a common or ecological change (Reid et al. 2005). Through abundant foundation species (sensu Dayton 1972; see habitat conversion, over-consumption of resources, and Panel 1), which by virtue of its structural or functional worldwide introductions of pests and pathogens, humans attributes creates and defines an entire ecological com- are causing species extinctions at a record rate: the sixth munity or ecosystem, can have dramatic effects on our extinction crisis in the billion-year history of eukaryotic perception of the landscape and broad consequences for associated biota, ecosystem function, and stability. In a nutshell: Foundation species differ from keystone predators (Paine * In manyecosystems, a singlefoundation species controls pop- 1966) in that the former usually occupy low trophic levels ulationand communitydynamics and modulatesecosystem whereas the latter are usually top predators.They are also processes distinct from core (Hanski 1982) in that foundation * species The lossof foundationspecies acutely and chronically impacts are not abundant and com- fluxesof andnutrients, foodwebs, and bio- species only locally regionally energy hydrology, mon but also create stable conditions diversity locally required by * Humanactivities, including logging and the introductionof many other species. They also serve to stabilizefundamental exoticpests and pathogens, often functionally remove founda- ecosystemprocesses such as productivityand water balance. tion treespecies from forests Trees are most to be foundation in * likely species Foundationspecies that are currentlybeing lost fromNorth forested as their architecture and functional Americanforests include eastern hemlock, Port-Orford cedar, ecosystems, andoaks and physiological characteristics define forest structure and alter microclimates, while their biomass and chemi- 'HarvardUniversity, Harvard Forest, 324 NorthMain Street, Petersham, MA 01366 *([email protected]);2USDA Forest Service SouthernResearch Station, Coweeta Hydrologic Lab, Otto, NC, 28763; 3Universityof Georgia,Institute of Ecology,Athens, GA 30602; 4Instituteof EcosystemStudies, Millbrook, NY 12545;5Wellesley College, Department of BiologicalSciences, Wellesley, MA 02481;6College of theHoly Cross, Department of Biology,Worcester, MA 01610;70regon State University, Department of Botanyand Plant Pathology, Corvallis, OR 97331;8University of Maryland,Baltimore County, Dept of Geography& EnvironmentalSystems, Baltimore, MD 21250;9University of PuertoRico, Institute for Tropical Ecosystem Studies, San Juan, PR 00931; 'VirginiaPolytechnic Institute and State University, Department of Biology,Blacksburg, VA 24061 www.frontiersinecology.org © The Ecological Society of America www.frontiersinecology.org This content downloaded from 158.135.136.72 on Fri, 19 Sep 2014 10:31:20 AM All use subject to JSTOR Terms and Conditions I Loss of foundation species AM Ellison et al. Figure 1. (a) An old-growtheastern hemlock (Tsuga canadensis) stand, (b and inset) a stand decliningfollowing 10 years of infestationby the introducedhemlock woolly adelgid (Adelges tsugae), and (c) denseregeneration of blackbirch (Betula lenta) saplingson a siteformerly dominated by easternhemlock in southernConnecticut. Nearly all hemlocktrees in this 150-hectareforest in southernConnecticut were killed in themid-1 990s by hemlockwoolly adelgid. cal makeup contribute substantially to ecosystem canadensis)resulting from an introduced insect and pre- processes. Foundation tree species are declining through- emptive salvage logging; the local extirpation of white- out the world due to a number of factors, including intro- bark pine (Pinus albicaulis)caused by interactions among ductions and outbreaks of nonindigenous pests and a nonnative pathogen, a native insect, and human alter- pathogens, irruptions of native pests, over-harvesting and ation of fire regimes; and the functional removal of high-intensity forestry,and deliberate removal of individ- American chestnut (Castanea dentata) by an introduced ual species from forests. We use three examples from pathogen. Our examples focus on trees in systems we North America to illustrate consequences for both terres- know best, but they are broadly representative of a wide trial and aquatic habitats of the loss of foundation tree range of foundation species and illustrative of their role in species: the ongoing decline of eastern hemlock (Tsuga forests throughout the world (Panel 2). Panel 1. The many definitions of foundation species * The rise and fall of eastern hemlock Followingnomenclatural priority, we adopt Dayton's(1972) ter- minology and general definitionof a foundationspecies: a single Majestic hemlock groves (Figure 1) evoke reverence, speciesthat definesmuch of the structureof a communityby creating affection, and poetry (Frost 1923). Eastern hemlock stableconditions other and and sta- locally for species, by modulating (Tsuga canadensis),one of the most long-lived, shade-tol- bilizingfundamental ecosystem processes. erant trees in North America, dominates about 1 x 106ha Subsequentauthors, working in differenthabitats and appar- to southern ently unaware of historical antecedents, have suggested terms of forest from the southern Appalachians with some or all of the attributesof foundationspecies, including: Canada and west to the central Lake states (McWilliams Core species (Hanski 1982) are locallyabundant and region- and Schmidt 2000). In the north, hemlock typically ally common;associated satellite species are sparse and rare. occurs in stands with species-poor understo- An associated model core-satellite nearly pure metapopulation (the ries. In the south, hemlock in mixed stands in nar- hypothesis) explains relationships between a species' local grows abundanceand its regionaldistribution. row riparian strips and moist coves, often with dense Dominant species (Grime 1984) competitively exclude understories of rhododendron (Rhododendronmaximum). subordinate species by garneringa disproportionate share of In hemlock-dominated stands, the combination of deep
Load more

Recommended publications
  • 19 | Population and Community Ecology 515
    CHAPTER 19 | POPULATION AND COMMUNITY ECOLOGY 515 19 | POPULATION AND COMMUNITY ECOLOGY Figure 19.1 Asian carp jump out of the water in response to electrofishing. The Asian carp in the inset photograph were harvested from the Little Calumet River in Illinois in May, 2010, using rotenone, a toxin often used as an insecticide, in an effort to learn more about the population of the species. (credit main image: modification of work by USGS; credit inset: modification of work by Lt. David French, USCG) Chapter Outline 19.1: Population Demographics and Dynamics 19.2: Population Growth and Regulation 19.3: The Human Population 19.4: Community Ecology Introduction Imagine sailing down a river in a small motorboat on a weekend afternoon; the water is smooth, and you are enjoying the sunshine and cool breeze when suddenly you are hit in the head by a 20-pound silver carp. This is a risk now on many rivers and canal systems in Illinois and Missouri because of the presence of Asian carp. This fish—actually a group of species including the silver, black, grass, and big head carp—has been farmed and eaten in China for over 1,000 years. It is one of the most important aquaculture food resources worldwide. In the United States, however, Asian carp is considered a dangerous invasive species that disrupts ecological community structure to the point of threatening native species. The effects of invasive species (such as the Asian carp, kudzu vine, predatory snakehead fish, and zebra mussel) are just one aspect of what ecologists study to understand how populations interact within ecological communities, and what impact natural and human-induced disturbances have on the characteristics of communities.
    [Show full text]
  • Modeling Foundation Species in Food Webs 1,3, 2 1 BENJAMIN BAISER, NATHANIEL WHITAKER, and AARON M
    Modeling foundation species in food webs 1,3, 2 1 BENJAMIN BAISER, NATHANIEL WHITAKER, AND AARON M. ELLISON 1Harvard University, Harvard Forest, 324 N. Main Street, Petersham, Massachusetts 01366 USA 2Department of Mathematics and Statistics, University of Massachusetts at Amherst, 1424 Lederle Graduate Research Center, Amherst, Massachusetts 01003-9305 USA Citation: Baiser, B., N. Whitaker, and A. M. Ellison. 2013. Modeling foundation species in food webs. Ecosphere 4(12):146. http://dx.doi.org/10.1890/ES13-00265.1 Abstract. Foundation species are basal species that play an important role in determining community composition by physically structuring ecosystems and modulating ecosystem processes. Foundation species largely operate via non-trophic interactions, presenting a challenge to incorporating them into food web models. Here, we used non-linear, bioenergetic predator-prey models to explore the role of foundation species and their non-trophic effects. We explored four types of models in which the foundation species reduced the metabolic rates of species in a specific trophic position. We examined the outcomes of each of these models for six metabolic rate ‘‘treatments’’ in which the foundation species altered the metabolic rates of associated species by one-tenth to ten times their allometric baseline metabolic rates. For each model simulation, we looked at how foundation species influenced food web structure during community assembly and the subsequent change in food web structure when the foundation species was removed. When a foundation species lowered the metabolic rate of only basal species, the resultant webs were complex, species-rich, and robust to foundation species removals. On the other hand, when a foundation species lowered the metabolic rate of only consumer species, all species, or no species, the resultant webs were species-poor and the subsequent removal of the foundation species resulted in the further loss of species and complexity.
    [Show full text]
  • A Comparison of Marsh and Mangrove Foundation Species Erik S
    RESEARCH ARTICLE Jump-starting coastal wetland restoration: a comparison of marsh and mangrove foundation species Erik S. Yando1,2,3 , Michael J. Osland4, Scott F. Jones1,5, Mark W. Hester1 During coastal wetland restoration, foundation plant species are critical in creating habitat, modulating ecosystem functions, and supporting ecological communities. Following initial hydrologic restoration, foundation plant species can help stabilize sediments and jump-start ecosystem development. Different foundation species, however, have different traits and environmen- tal tolerances. To understand how these traits and tolerances impact restoration trajectories, there is a need for comparative studies among foundation species. In subtropical and tropical climates, coastal wetland restoration practitioners can some- times choose between salt marsh and/or mangrove foundation species. Here, we compared the early life history traits and environmental tolerances of two foundation species: (1) a salt marsh grass (Spartina alterniflora) and (2) a mangrove tree (Avicennia germinans). In an 18-month study of a recently restored coastal wetland in southeastern Louisiana (USA), we examined growth and survival along an elevation gradient and compared expansion and recruitment rates. We found that the rapid growth, expansion, and recruitment rates of the salt marsh grass make it a better species for quickly establishing eco- logical structure at suitable elevations. The slower growth, limited expansion, and lower recruitment of the mangrove species show its restricted capacity for immediate structural restoration, especially in areas where it co-occurs with perennial salt marsh species. Our findings suggest that the structural attributes needed in recently restored areas can be achieved sooner using fast-growing foundation species. Following salt marsh grass establishment, mangroves can then be used to further assist ecosystem development.
    [Show full text]
  • Energy Flow in the Coral Reef Ecosystem
    ENERGY FLOW IN THE CORAL REEF ECOSYSTEM Video Summary In this video segment, adapted from NOVA, learn how energy from sunlight is transferred through the inhabitants of the reef ecosystem. Photosynthesizing plants and algae convert light energy into chemical energy, which then gets passed through the food web to plant eaters, flesh eaters, and ultimately to scavengers and decomposers. www.teachersdomain.org/resources/hew06/sci/life/reg/foodweb Topics Covered: Recommended for Grades 3-12 – Life Science: Ecology Media Type: QuickTime Video – Life Science: Organisms and Their Environments Video Length: 3m 48s – Life Science: Regulation and Behavior Permitted use: Download, Share, Remix This media resource can be used only for non-commercial, educational purposes. For more information about Terms of Use see: www.teachersdomain.org/terms_of_use.html Discussion Questions Why do you think the polyps only feed on plankton at night? What do you think would happen to reef dwellers (e.g., coral, parrot fish, sea cucumbers) if the algae were not able to photosynthesize? What is a double diet? What do you think the advantages are, if any, of having a double diet? How does energy flow through the reef ecosystem? Background Essay All living things require energy to carry out life functions such as growth, movement, and reproduction. For nearly all ecosystems—diverse collections of species that interact with each other and their physical environment—the major source of energy is the sun. The flow of energy tends to follow the same basic pattern whether the ecosystem is a tropical rainforest or a coral reef. To portray the transfer of energy through an ecosystem, ecologists use simple models called food chains.
    [Show full text]
  • Are Foundation Species Effects Different Than Those of Dominant Species? a Case Study of Ant
    bioRxiv preprint doi: https://doi.org/10.1101/062265; this version posted July 6, 2016. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license. 1 Are foundation species effects different than those of dominant species? A case study of ant 2 assemblages in northeastern North American forests 3 Authors: Sydne Record1, Tempest McCabe1, Benjamin Baiser2, and Aaron M. Ellison3 4 1Bryn Mawr College, Department of Biology ([email protected], [email protected]) 5 2University of Florida, Department of Wildlife Ecology and Conservation ([email protected]) 6 3Harvard University, Harvard Forest ([email protected]) 7 Running title: Loss of foundation versus dominant species 8 Keywords (10): Adelges tsugae; Formicidae; foundation species; functional diversity; Quercus; 9 Tsuga canadensis 10 Article type: Letter 11 Number of words: abstract 149, main text 4,915, 0 text boxes 12 Number of references: 50 13 Number of figures 5, tables 1, and text boxes 0 14 Corresponding author: Sydne Record, 101 North Merion Ave., Bryn Mawr, PA 19010; 01-610- 15 526-5094 (phone); 610-526-5086 (fax); [email protected] 16 17 Statement of authorship: A.M. Ellison and S. Record conceived the study. A.M. Ellison, T. 18 McCabe, and S. Record collected field data. T. McCabe and S. Record did the taxonomic 19 diversity analyses. B. Baiser and S. Record did the functional diversity analyses. All authors 20 contributed to drafts of the manuscript.
    [Show full text]
  • Species Diversity and Foundation Species: Potential Indicators of Fisheries Yields and Marine Ecosystem Functioning Matthew E
    BRACKEN ET AL.: BIODIVERSITY, FOUNDATION SPECIES, AND MARINE ECOSYSTEM MANAGEMENT CalCOFI Rep., Vol. 48, 2007 SPECIES DIVERSITY AND FOUNDATION SPECIES: POTENTIAL INDICATORS OF FISHERIES YIELDS AND MARINE ECOSYSTEM FUNCTIONING MATTHEW E. S. BRACKEN BARRY E. BRACKEN LAURA ROGERS-BENNETT Marine Science Center P.O. Box 1201 California Department of Fish and Game Northeastern University Petersburg, Alaska 99833 Bodega Marine Laboratory, University of California at Davis 430 Nahant Road P.O. Box 247 Nahant, Massachusetts 01908 Bodega Bay, California 94923 Email: [email protected] ABSTRACT United States to be managed using an ecosystem-based Recent calls to incorporate ecosystem-based ap- approach which considers the whole functioning system proaches, which consider multiple physical and biolog- instead of individual fishery stocks (Ecosystem Principles ical aspects of a system instead of a single stock, into Advisory Panel 1999). Furthermore, in response to fisheries management have proven challenging to im- demonstrated declines in fisheries stocks in the United plement. Here, we suggest that managers can use the States (Rosenberg et al. 2006), the Pew Oceans Com- diversity of species in an area and the presence of foun- mission (2003) and the U.S. Commission on Ocean dation species as two indicators of marine ecosystem Policy (2004) both indicated that ecosystem-based functioning. We used data from the 2006 sablefish approaches are necessary to curb these declines. Despite (Anoplopoma fimbria) test fishery in the inside waters of this need, scientists and managers still grapple with what southeastern Alaska to evaluate the relationship between ecosystem-based management is and how it can be mean- the diversity of fish species present in an area and the ingfully applied.
    [Show full text]
  • Loss of Foundation Species Increases Population Growth of Exotic Forbs in Sagebrush Steppe
    Ecological Applications, 20(7), 2010, pp. 1890–1902 Ó 2010 by the Ecological Society of America Loss of foundation species increases population growth of exotic forbs in sagebrush steppe 1 2 JANET S. PREVE´Y,MATTHEW J. GERMINO, AND NANCY J. HUNTLY Department of Biological Sciences, Mail Stop 8007, Idaho State University, Pocatello, Idaho 83209 USA Abstract. The invasion and spread of exotic plants following land disturbance threatens semiarid ecosystems. In sagebrush steppe, soil water is scarce and is partitioned between deep- rooted perennial shrubs and shallower-rooted native forbs and grasses. Disturbances commonly remove shrubs, leaving grass-dominated communities, and may allow for the exploitation of water resources by the many species of invasive, tap-rooted forbs that are increasingly successful in this habitat. We hypothesized that exotic forb populations would benefit from increased soil water made available by removal of sagebrush, a foundation species capable of deep-rooting, in semiarid shrub-steppe ecosystems. To test this hypothesis, we used periodic matrix models to examine effects of experimental manipulations of soil water on population growth of two exotic forb species, Tragopogon dubius and Lactuca serriola,in sagebrush steppe of southern Idaho, USA. We used elasticity analyses to examine which stages in the life cycle of T. dubius and L. serriola had the largest relative influence on population growth. We studied the demography of T. dubius and L. serriola in three treatments: (1) control, in which vegetation was not disturbed, (2) shrubs removed, or (3) shrubs removed but winter–spring recharge of deep-soil water blocked by rainout shelters. The short-term population growth rate (k)ofT.
    [Show full text]
  • Ecosystem Engineering Across Environmental Gradients: Implications for Conservation and Management
    Articles Ecosystem Engineering across Environmental Gradients: Implications for Conservation and Management CAITLIN MULLAN CRAIN AND MARK D. BERTNESS Ecosystem engineers are organisms whose presence or activity alters their physical surroundings or changes the flow of resources, thereby creating or modifying habitats. Because ecosystem engineers affect communities through environmentally mediated interactions, their impact and importance are likely to shift across environmental stress gradients. We hypothesize that in extreme physical environments, ecosystem engineers that ameliorate physical stress are essential for ecosystem function, whereas in physically benign environments where competitor and consumer pressure is typically high, engineers support ecosystem processes by providing competitor- or predator-free space. Important ecosystem engineers alleviate limiting abiotic and biotic stresses, expanding distributional limits for numerous species, and often form the foundation for community development. Because managing important engineers can protect numerous associated species and functions, we advocate using these organisms as conservation targets, harnessing the benefits of ecosystem engineers in various environments. Developing a predictive understanding of engineering across environmental gradients is important for furthering our conceptual understanding of ecosystem structure and function, and could aid in directing limited management resources to critical ecosystem engineers. Keywords: stress gradients, ecosystem engineers,
    [Show full text]
  • A Framework for Community and Ecosystem Genetics: from Genes to Ecosystems
    REVIEWS A framework for community and ecosystem genetics: from genes to ecosystems Thomas G. Whitham*‡, Joseph K. Bailey*‡§, Jennifer A. Schweitzer ‡§||, Stephen M. Shuster*‡, Randy K. Bangert*‡, Carri J. LeRoy*‡¶, Eric V. Lonsdorf*‡#, Gery J. Allan*‡, Stephen P. DiFazio**, Brad M. Potts‡‡, Dylan G. Fischer¶, Catherine A. Gehring*‡, Richard L. Lindroth§§, Jane C. Marks*‡, Stephen C. Hart‡||, Gina M. Wimp|||| and Stuart C. Wooley §§ Abstract | Can heritable traits in a single species affect an entire ecosystem? Recent studies show that such traits in a common tree have predictable effects on community structure and ecosystem processes. Because these ‘community and ecosystem phenotypes’ have a genetic basis and are heritable, we can begin to apply the principles of population and quantitative genetics to place the study of complex communities and ecosystems within an evolutionary framework. This framework could allow us to understand, for the first time, the genetic basis of ecosystem processes, and the effect of such phenomena as climate change and introduced transgenic organisms on entire communities. 1 community energy flow Community and ecosystem Jeffry Mitton asserted that the elaboration of fundamental processes such as or nutrient genetics and ecosystem genetics could “herald a new era in evolu­ cycling. Examination of the role of genetic interactions The study of the genetic tionary biology” and that “if this comes about, evolution­ at the ecosystem level begins a new era of evaluating interactions that occur ary biology and ecology will be more tightly linked than ecosystems within an evolutionary framework. between species and their ever before.” Although great strides have been made in Although the genetic analysis of a complex commu­ abiotic environment in complex communities.
    [Show full text]
  • 45 | Population and Community Ecology 1317 45 | POPULATION and COMMUNITY ECOLOGY
    Chapter 45 | Population and Community Ecology 1317 45 | POPULATION AND COMMUNITY ECOLOGY Figure 45.1 Asian carp jump out of the water in response to electrofishing. The Asian carp in the inset photograph were harvested from the Little Calumet River in Illinois in May, 2010, using rotenone, a toxin often used as an insecticide, in an effort to learn more about the population of the species. (credit main image: modification of work by USGS; credit inset: modification of work by Lt. David French, USCG) Chapter Outline 45.1: Population Demography 45.2: Life Histories and Natural Selection 45.3: Environmental Limits to Population Growth 45.4: Population Dynamics and Regulation 45.5: Human Population Growth 45.6: Community Ecology 45.7: Behavioral Biology: Proximate and Ultimate Causes of Behavior Introduction Imagine sailing down a river in a small motorboat on a weekend afternoon; the water is smooth and you are enjoying the warm sunshine and cool breeze when suddenly you are hit in the head by a 20-pound silver carp. This is a risk now on many rivers and canal systems in Illinois and Missouri because of the presence of Asian carp. This fish—actually a group of species including the silver, black, grass, and big head carp—has been farmed and eaten in China for over 1000 years. It is one of the most important aquaculture food resources worldwide. In the United States, however, Asian carp is considered a dangerous invasive species that disrupts community structure and composition to the point of threatening native species. 1318 Chapter 45 | Population and Community Ecology 45.1 | Population Demography By the end of this section, you will be able to: • Describe how ecologists measure population size and density • Describe three different patterns of population distribution • Use life tables to calculate mortality rates • Describe the three types of survivorship curves and relate them to specific populations Populations are dynamic entities.
    [Show full text]
  • Accounting for Multiple Foundation Species in Oyster Reef Restoration Benefits Keryn B
    RESEARCH ARTICLE Accounting for Multiple Foundation Species in Oyster Reef Restoration Benefits Keryn B. Gedan,1,2,3 Lisa Kellogg,4 and Denise L. Breitburg2 Abstract without hooked mussels, for monitored oyster reefs and Many coastal habitat restoration projects are focused on restoration scenarios in the eastern Chesapeake Bay. The restoring the population of a single foundation species to inclusion of filtration by hooked mussels increased the fil- recover an entire ecological community. Estimates of the tration capacity of the habitat greater than 2-fold. Hooked ecosystem services provided by the restoration project are mussels were also twice as effective as oysters at filtering used to justify, prioritize, and evaluate such projects. How- picoplankton (1.5–3 m), indicating that they fill a distinct ever, estimates of ecosystem services provided by a sin- ecological niche by controlling phytoplankton in this size gle species may vastly under-represent true provisioning, class, which makes up a significant proportion of the phyto- as we demonstrate here with an example of oyster reefs, plankton load in summer. When mussel and oyster filtration often restored to improve estuarine water quality. In the are accounted for in this, albeit simplistic, model, restoration brackish Chesapeake Bay, the hooked mussel Ischadium of oyster reefs in a tributary scale restoration is predicted to recurvum can have greater abundance and biomass than control 100% of phytoplankton during the summer months. the focal restoration species, the eastern oyster Crassostrea virginica. We measured the temperature-dependent phyto- plankton clearance rates of both bivalves and their filtration Key words: clearance rate, Crassostrea virginica, ecosys- efficiency on three size classes of phytoplankton to param- tem services, Ischadium recurvum, phytoplankton, top-down eterize an annual model of oyster reef filtration, with and control, water quality.
    [Show full text]
  • A Facilitation Cascade Enhances Local Biodiversity in Seagrass Beds
    diversity Article A Facilitation Cascade Enhances Local Biodiversity in Seagrass Beds Y. Stacy Zhang * and Brian R. Silliman Division of Marine Science and Conservation, Nicholas School of the Environment, Duke University, Beaufort, NC 28516, USA; [email protected] * Correspondence: [email protected]; Tel.: +1-252-504-7582 Received: 17 December 2018; Accepted: 16 February 2019; Published: 26 February 2019 Abstract: Invertebrate diversity can be a key driver of ecosystem functioning, yet understanding what factors influence local biodiversity remains uncertain. In many marine and terrestrial systems, facilitation cascades where primary foundation and/or autogenic ecosystem engineering species promote the settlement and survival of a secondary foundation/engineering species have been shown to enhance local biodiversity and ecosystem functioning. We experimentally tested if a facilitation cascade occurs among eelgrass (Zostera marina), pen clams (Atrina rigida), and community diversity in temperate seagrass beds in North Carolina, U.S.A., and if this sequence of direct positive interactions created feedbacks that affected various metrics of seagrass ecosystem function and structure. Using a combination of surveys and transplant experiments, we found that pen clam density and survivorship was significantly greater in seagrass beds, indicating that eelgrass facilitates pen clams. Pen clams in turn enhanced local diversity and increased both the abundance and species richness of organisms (specifically, macroalgae and fouling invertebrate fauna)—the effect of which scaled with increasing clam density. However, we failed to detect an impact of pen clams on other seagrass functions and hypothesize that functioning may more likely be enhanced in scenarios where secondary foundation species specifically increase the diversity of key functional groups such as epiphyte grazers and/or when bivalves are infaunal rather than epifaunal.
    [Show full text]