the key; every ecosystem service re- quired by humans (and most other animals as well) is created either di- rectly or indirectly by plants. We have degraded ecosystem function by re- moving plants from local ecosystems, or by assuming that all plants function equally well in every environment. It follows that we can repair the damage Features we have inflicted on the typically built landscape simply by putting the right plants back. And who better to lead the way in this most noble endeavor than landscape architects and designers. Unfortunately, most professionals Creating Living Landscapes: Why We Need to in these two careers have not been trained in the fundamentals of ‘‘eco- Increase Plant/Insect Linkages in Designed logical landscaping.’’ Instead, programs in landscape architecture and design Landscapes have followed a centuries-old tradition of treating plants as tools of creativity: Douglas W. Tallamy1 decorations that can be combined with artistic hardscape to create beauty in our surrounds. Plants are indeed in- ADDITIONAL INDEX WORDS. host plant specialization, ecosystem services, herently beautiful but they are far biodiversity, landscape design, environmental landscape more than that; plants are essential SUMMARY. Specialized relationships between animals and plants are the norm in to sustaining life, both on earth and nature rather than the exception and landscape designs that destroy them also inourgardens.Weneedtoexpand degrade local ecosystem function. Plants that evolved in concert with local animals our expectations of what plants must provide for their needs better than plants that evolved elsewhere. The most common do in designed landscapes to include and arguably most important specialized relationships are those that have developed their critical ecological roles and between insect herbivores and their host plants. Here, I explain why this is so, why encourage new cross-discipline col- specialized food relationships determine the stability and complexity of the local food webs that support animal diversity, and why our yards and gardens are laborations among entomologists, essential parts of the ecosystems that sustain us. I also discuss how we can use our restoration ecologists, and the hor- residential and corporate landscapes to connect the isolated habitat fragments ticultural community to accomplish around us and produce valuable ecosystem services, and what we can do to make our this. This article will discuss features landscapes living ecosystems once again. common to all living landscapes and suggests simple strategies for incor- s the human footprint con- To believe there will always be suffi- porating them into our designed tinues to expand at the ex- cient oxygen, clean air and water, spaces. A pense of the natural capital carbon sequestration, pollinators, Nature equals specialized that sustains us, there is a growing and the biodiversity that produces need and increasing demand for these resources, regardless of how relationships residential, corporate, urban, and we treat local landscapes, or to sug- A pattern is emerging from con- suburban landscapes that generate gest that technology can effectively servation efforts around the world; if natural resources rather than de- replace them is folly in its most mis- you want to save a particular species, stroy them. At our current popula- guided form. you have to save the specialized re- tion levels, a culture that segregates Fortunately, we already have the lationships that support that species. humans from nature is not a sustain- knowledge required to integrate hu- If, for example, you want to save the able option and by whittling away at man habitats with the natural world. resplendent quetzal (Table 1), a gor- functional ecosystems, such a culture Indeed, the concept itself is ironic geous but endangered bird in Central has led to a reduction in the earth’s because humans are products of the America, you have to restore popula- ability to produce essential renewable natural world—one of millions of life tions of wild avocado trees because resources (also known as ecosystem forms that natural systems sustain the fruits of that species are an essen- services) by more than 60% (Millen- every day—and we have never been tial component of the resplendent nium Ecosystem Assessment, 2005). even partially independent of earth’s quetzal diet. If you want to save bounty. What types of landscapes are jaguars, you need to protect large Department of Entomology and Wildlife Ecology, capable of sustaining humans and populations of palm species that make University of Delaware, Newark, DE 19716. nature simultaneously? Ones that small palm nuts (as opposed to co- 1Corresponding author. E-mail: [email protected]. feature plants that interact with the conuts). Why these palms? Because doi: 10.21273/HORTTECH03699-17 species around them. Such plants are palm nuts are a critical and
446 • August 2017 27(4) Table 1. Taxonomic identification of organisms discussed in this article. tropics that they are the rule rather Common name Taxonomic nomenclature than the exception. What surprises many, however, Birds is that specialized relationships, par- Bluebirds Sialia species ticularly involving food webs, are Buntings Passerina species also the rule in the temperate zone, Carolina chickadee Poecile carolinensis and we cannot create living land- Crossbills Loxia species scapes if we exclude them. If you Doves Zenaida species want may apples to spread by seed, Finches Fringillidae you need a population of box tur- Flyctachers Tyranni tles. May apple seeds germinate best Great green macaw Ara ambiguus after passing through the gut of Gray catbird Dumetella carolinensis a box turtle that has eaten the may Hummingbirds Trochilidae apple fruit. If you want pileated Northern cardinal Cardinalis cardinalis woodpeckers in your neighborhood Orioles Icterus species you need trees that harbor large Red bellied woodpecker Melanerpes carolinus colonies of carpenter ants because Resplendent quetzal Pharomachrus mocinno carpenterantsarewhatthesebirds Tufted titmouse Baeolophus bicolor feed their young. If you want your Tree swallow Tachycineta bicolor wild blue phlox to produce viable Wood thrush Hylocichla mustelina seed, you need the plants that sup- Mammals port the larval development of Black bear Ursus americanus day-flying sphinx moths (native vi- Foxes Vulpes species burnums for the hummingbird Jaguar Panthera onca moth or native coral honeysuckle Peccaries Pecari species for the snowberry clearwing or virginia Raccoon Procyon lotor creeper for the nessus sphinx), for Reptiles thesemothsaretheprimarypollina- Eastern box turtle Terrapene carolina tors of phlox. Amphibians Even species that do not seem to Frogs Anura species depend on any specialized relationships Toads Anura species often do, especially during repro- Arthropods duction. Chickadees provide an ex- Spiders Araneae cellent example. As anyone with Insects a bird feeder knows, chickadees are Lepidoptera seed-eaters during the fall, winter, Hummingbird sphinx Hemaris thysbe and early spring. When the time Nessus sphinx Amphion floridensis comes to feed the young, however, Snowberry clearwing Hemaris diffinis chickadees join 96% of the terrestrial Coleoptera birds in North America and rear Ladybird beetles hymenoptera Coccinellidae their young on insects (data from Ants Formicidae Dickinson, 1999) and not just any Bees Apoidea insect; they feed nestling caterpillars, Digger wasps Crabronidae the larvae of moths, butterflies, and Hemiptera sawflies. Chickadee parents could Assassin bugs Reduviidae feed their young other abundant Damsel bugs Nabidae insects, but the overwhelming ma- Stinkbugs Pentatomidae jority of their prey during reproduc- Neuroptera tion is caterpillars. Those are not Lacewings Chrysopidae just any caterpillar, but those that Plants are not covered in hairs or spines. Black-eyed susan Rudbeckia hirta Because chickadees rear their young Mayapple Podophyllum peltatum on caterpillars, there will be no Palms Arecaceae chickadees where there are not Virginia creeper Parthenocissus quinquefolia enough caterpillars to bring a clutch Wild almond Dipteryx panamensis of eggs to independence from pa- Wild avacado Persea americana rental care. How many caterpillars are re- quired to produce a clutch of chick- substantial part of the diet of pec- populations of wild almond trees adees? Carolina chickadees bring caries, the wild pigs that are jaguar because they are the only trees those somewhere between 390 and 570 prey. If you want great green macaws birds will nest in. Such specialized caterpillars to their nest each day, in the future, you need to restore relationships are so common in the depending on the number of chicks
• August 2017 27(4) 447 FEATURES in the nest (Brewer, 1961). Parents live, work, farm, and play seems come by these adaptations through feed nestlings in the nest for 16– counter-productive at best. thousands of generations of exposure 18 d before the young fledge and How, then, can we design land- to the plant lineage in question, al- then for 30 d or more after fledging. scapes that support a diversity of in- though occasionally they coinciden- If we focus only on the caterpillars sect species that stay in a balanced tally possess enzymes that are able to required to reach fledging, it takes equilibrium with the natural enemies disarm an evolutionarily novel plant 6240–10,260 caterpillars to fledge that control them? Before we answer (Rosenthal and Berenbaum, 2012). a single clutch of chickadees, an this question, we have to consider the In short, by becoming host plant astounding number, even to those most important and abundant spe- specialists, insect herbivores can cir- who study bird behavior. No one cialized relationship on the planet: cumvent plant defenses of a few plant knows how many more caterpillars the relationship between the insects species well enough to make a living, are required during the 30 d after that eat plants and the plants they eat. while ignoring the rest of the plants in fledging. What’s more, chickadees Most insect herbivores, some 90%, in their ecosystem. are tiny birds; a carolina chickadee fact, are diet specialists (Bernays and Does this mean specialists have weighs a third of an ounce, the Graham, 1988; Forister et al., 2015). won the evolutionary arms race with equivalent of four pennies. In com- Just like breeding chickadees, they are plants? Somewhat, but only in rela- parison, a red-bellied woodpecker, restricted to eating just a few lineages tion to the plant lineage on which whichalsorearsitsyoungoninsect of plants. Plants, of course, do not they have specialized. When viewed larvae, weighs eight times more than want to be eaten. They want to cap- across all lineages, plant defenses are a chickadee. How much insect bio- ture the energy from the sun and use very effective at deterring most in- mass is required to create a red- it for their own growth and repro- sects. The monarch butterfly provides bellied woodpecker? How many duction, so they manufacture nasty an excellent example. This species is insects are required to sustain an tasting chemicals specifically to deter a specialist on milkweeds that use entire population of chickadees and plant eaters. These chemicals are sec- various forms of toxic cardiac glyco- woodpeckers . . . and titmice, and ondary metabolic compounds that sides to protect their tissues. They orioles, bluebirds, wood thrushes, do not contribute to the primary also defend their tissues with a milky catbirds, cardinals, buntings, fly- metabolism of the plant. Their job latex sap that jells on exposure to air. catchers, and all of the other birds is to make various plant parts dis- Insects that eat the sap soon find their that signal healthy temperate zone tasteful or downright toxic to insect mouthparts glued permanently shut. ecosystems? The numbers are mind- herbivores. Some well-known plant Because of their specialized physio- boggling. defenses include toxic compounds like logical adaptations to detoxify cardiac cyanide, nicotine, cucurbitacins, and glycosides and behavioral adaptations Consequences of pyrethrins; heart-stoppers like cardiac to avoid the sticky latex sap, monarch specialization glycosides; and digestibility inhibitors caterpillars can eat milkweeds that Suggesting that designed land- like tannins. are not viable host plants for most scapes should produce rather than If plants are so well defended, other insect herbivores (Dussourd and destroy insects would have been ludi- how can insects eat them without Eisner, 1987). crous if not heretical in the past. After dying? This question dominated The advantage of this relation- plant–insect interaction studies for ship is obvious for the monarch, but all, if plants are simply decorations, we three decades, but at this point, the there are disadvantages to specializ- would want them to be forever flaw- answer has been thoroughly delin- ing, especially in today’s world. Un- less and untouched by natural pro- eated. Caterpillars and other imma- fortunately for the monarch, the cesses. In fact, if flawless plantings are ture insects are eating machines; some ability to detoxify cardiac glycosides really the goal, using silk or plastic species increase their mass 72,000- in milkweeds does not confer the plants seems like the more logical fold by the time they reach their full ability to disarm the chemical de- option. If our goal, however, is to size (Imms et al., 1977). Because fenses found in other plant lineages. create landscapes that contribute to caterpillars necessarily ingest chemical This means that of the 2137 native rather than detract from local ecosys- deterrents with every bite, there is plant genera in the United States, the tem function, then we must include enormous selection pressure to re- monarch can develop on only one, ‘‘the little things that run the world’’ strict feeding to plant species they the milkweed genus. The evolution- (Wilson, 1987). Decades of research can eat without serious ill effects. ary history of this butterfly has locked have shown that insects are essential Thus, a gravid female moth will lay it into a dependent relationship with for pollination, nutrient recycling, eggs only on plants with chemical milkweeds and if milkweeds should pest control, and for feeding many defenses their hatchling caterpillars disappear from a landscape, so would are able to disarm. the monarch. And this is exactly what other animals. A world without in- There are many physiological has happened across the United sects is a world without biological mechanisms by which caterpillars can States in recent years. A growing diversity; and a world without bio- temper plant defenses, but they all culture that favors neat, manicured logical diversity is a world without involve some combination of seques- agricultural fields combined with an humans. If insects were to disappear, tering, excreting, and detoxifying unwillingness to share designed land- humans would not last more than defensive phytochemicals contained scapes with milkweeds has reduced a few months (Wilson, 1987). In this before they interfere with the cater- monarch populations 96% from their light, waging war insects where we pillar’s health. Caterpillars typically numbers in the 1970s. Can monarchs
448 • August 2017 27(4) adapt to other plant species? In theory no insect herbivores, all of the crea- It was not until 1981 that Mac- yes, but in reality no. Monarchs have tures that depend on insect herbi- Arthur’s Law was challenged by an been genetically locked into a relation- vores for their nutrition, that is, the analogy between species populating ship with milkweeds for millions of insectivores of the world, would also an ecosystem and the rivets that once years. Adaptation could conceivably disappear. A world without insecti- held airplanes together (Ehrlich and modify this relationship very slowly vores would be a world without spi- Ehrlich, 1981). In their rivet hypoth- over enormously long periods, but ders; insect predators and parasitoids; esis, Paul and Anne Erhlich suggested asking monarchs to suddenly (within frogs, toads, and other amphibians; that ecosystem productivity was in- 30 years!) switch their dependence to lizards; bats, rodents, skunks, opos- deed tied to the number of species an entirely different plant lineage, say, sums, raccoons, as well as mammals in an ecosystem, but only to a point. for example crape myrtle, is like asking we do not think of as insect-eaters, Their hypothesis introduced the humans to develop wings. The num- such as foxes and black bears, both of concept of species redundancy; the ber of genetic changes required to which get a quarter of their nutrition Erhlichs reasoned that there was re- make such a switch reduces the prob- from insects (Wilson, 1987). Studies dundancy in the species performing ability of it happening before mon- have shown that even some freshwa- particular roles within ecosystems just archs disappear to near zero. ter fish get more than 50% of their as there was redundancy in aircraft Please note that monarchs are protein from terrestrial insects that rivets. An airplane could lose some not exceptions, either in their special- fall into the water (Sullivan et al., rivets before a wing fell off the plane, ized relationship with milkweeds or in 2012). And let us not forget that and an ecosystem could lose some their current plight. They are typical a world without insect herbivores species before it suffered a measurable of 90% of the insects that eat plants; would also be a world without most loss in productivity. their evolutionary history has re- terrestrial bird species; with the ex- Generalist pollinators provide an stricted their development and repro- ception of doves, finches, crossbills, example of species redundancy. A duction to only the plant lineage on and our largest birds of prey, terres- black-eyed susan needs to be polli- which they have specialized, and as we trial birds rear their young on insects nated before it can produce seeds, but have homogenized plant diversity and the spiders that ate insects to many species of bees, moths, butter- around the world by replacing diverse become spiders. To reiterate, a world flies, beetles, and even ants are capa- native plant communities with a small without all of these creatures would ble of doing the job (although not all palate of ornamental favorites from not only be a world without biolog- do it equally well). The redundancy in other lands, the insects that depend ical diversity, it would be a world black-eyed susan pollinators implies on native species have declined. Data in ecological collapse that is incapa- that one or even several of these from Europe paint an alarming pic- bleofsupportinghumans(Wilson, pollinator species could disappear ture; insects in Germany have declined 1987). from the system without a reduction in abundance and diversity 5.3-fold in seed set in black-eyed susan. Sim- since 1989. This includes the extinc- Biodiversity and ecosystem ilarly, landscapes that produce dozens tion of 46 species of butterflies and function of species of caterpillars are far more moths. Globally, invertebrate abun- Research over the decades has stable in the eyes of reproducing birds dance has been reduced 45% since tied the number of interacting species than landscapes that produce just 1974 (Schwageral, 2016). We have in an ecosystem to both ecosystem a few (Tallamy, 2004). In years with caused these declines by the way we function and ecosystem stability. Let weather unfavorable to caterpillars, have designed landscapes in the past. us first consider ecosystem function. there would not be enough food to But we can reverse them by the way we We can define ecosystem function in rear young in landscapes with only design landscapes in the future. several ways: the ability to hold en- a few caterpillar species. In those with ergy captured from the sun within many species, however, several cater- Making insects pillar species in combination would biological systems before it escapes What type of landscape is capable yield enough food so that birds could back into space; the ability to produce of producing insects in the numbers reproduce every year, regardless of products or perform services useful to required to support viable food webs? the weather. Thus, caterpillar diver- A landscape created from the plants humans and other species; the ability sity in the landscape creates food web that have each developed specialized to create living and dead biomass; and stability. relationships with a diversity of insect so on. In 1955, famed ecologist Robert The rivet hypothesis was some- species. A landscape occupied by or- MacArthur predicted that ecosystem what comforting to ecologists be- ganisms that have interacted with function would increase linearly as the cause it predicted that the local or each other over evolutionary rather number of species within an ecosys- global extinction of some species than ecological time spans. A land- tem increased (MacArthur, 1955). would not send ecosystems spiraling scape that showcases specialized re- Diverse ecosystems with many equally into collapse, at least not right away. lationships rather than ignores them. abundant species would be more pro- Replicated studies of entire ecosys- As we have seen, diet specialization is ductive than species-poor ecosystems tems in which distracting variables are the rule among insect herbivores, not dominated by one or a few species. controlled are extremely difficult to the exception. Without the plant lin- Although no one had tested this pre- conduct, and so the compelling logic eages that support insect herbivores, diction, it was logically appealing and of both MacArthur’s Law of Nature there would be no insect herbivores soon came to be known as the Law of and the Ehrlich’s rivet hypothesis (Narango et al., 2017). If there were Nature. remained untested for many years
• August 2017 27(4) 449 FEATURES after it was proposed. In 2012, how- Which plants should we use? Federation website under ‘‘Native ever, three studies were published If non-native ornamentals do Plant Finder’’ (National Wildlife Fed- that support MacArthur’s predictions not support the relationships re- eration, 2017). Enter your zip code over those of the rivet hypothesis quired to restore ecosystem function and a list of plant genera found in (Maestre et al., 2012; Naeem et al., to our landscapes, which plants do? your county, ranked from most to 2012; Reich et al., 2012). As the Simple logic tells us that using a pal- least productive, will appear. number of species in an ecosystem ette biased toward native species Creating trophic balance goes up, so does ecosystem function should be sufficient to support robust and stability. Redundancy in the roles food webs in our landscapes. How- Because our past goal in con- species play within ecosystems surely ever, comparisons among plant gen- structing built landscapes has been exists, yet studies now show that it era of host records for moths and to create beauty using plants rather does not buffer ecosystems from a loss butterflies, the backbone of most than to restore ecological integrity, of productivity every time a species terrestrial food webs, reveal two strik- a primary concern has been the aes- disappears from the system. Not good ing patterns that suggest this conclu- thetic appeal of the plants themselves. news. If this relationship is borne out sion needs to be refined (Tallamy and A specimen unmarred by insect dam- by additional research, we can no age has been the ideal. As we have Shropshire, 2009). First, there are longer be complacent about the loss seen, though, an unmarred plant is huge differences among plant genera of species from local ecosystems. one that has not interacted with other in their ability to make caterpillars and New evidence suggests there is species in our landscapes, and a land- thus support creatures in higher tro- an important caveat to MacArthur’s scape full of unmarred plants is an phic levels. Oaks in the mid-Atlantic prediction. Lee Dyer and colleagues ecologically depauperate space devoid states, for example, serve as host are showing that it is not actually the of animal life. Is it possible to choose plants for 557 species of caterpillars, number of species in an ecosystem plants that are simultaneously beauti- that controls ecosystem function, but tulip poplars only feed 21 species, and ful and productive? Plants that can rather, it is the number of interactions yellowwoods are not used by any pass some of their energy on to the among species (Dyer et al., 2010; caterpillars. These are order of mag- insect herbivores that can then sup- Scherrer et al., 2016). This explains nitude differences among plant gen- port a vibrant community of other why invasive plants are decreasing era that are all native to eastern North species? Indeed, it is but to do so we rather than increasing ecosystem America. Second, a mere 5% of the must attract even more species to our function around the world. When native plant genera in any North landscapes. a plant from outside of a local food American ecosystem support 73% to When species interact over long web moves into a new ecosystem, it 75% of the caterpillar species. Stated periods of time, a balance among either displaces native plants species, in reverse, 95% of the native plant plants, herbivores, and natural ene- reducing the total number of species genera support only 25% to 27% of mies (predators, parasites, parasitoids, in the area, or it joins them without the caterpillars that drive local food and diseases) emerges that typically significantly reducing species rich- webs (D.W. Tallamy, D.L. Narango, keeps any one species from eliminat- ness. In either case, the number of and K.J. Shropshire, unpublished). ing the others. This is the ideal we interactions among species declines. We cannot build ecologically rich should strive for in our built land- Non-native plants are just meeting landscapes if we do not include the scapes. If we use native plants that the plants and animals in the ‘‘novel’’ core genera, those top 5% that create support dozens of species of insect ecosystem for the first time in evolu- most food driving local food webs. herbivores, we will create a food re- tionary history (Hobbs et al., 2006), We do not yet understand why source for the natural enemies of which means they have not had the some plant genera are responsible for those insects, so they too will become time to develop the adaptations re- so much of the life around us while residents in the landscape and will quired to interact with many of the most pass on minimal energy and keep insect populations below the other species in that ecosystem. That some none at all to local wildlife, but aesthetic injury level. The spiders, is, species dependent on specialized we do not need to understand the assassin bugs, damsel bugs, ladybird relationships with particular plant basis of the relationship to use it beetles, lacewings, predatory stink lineages either become less abun- effectively in landscape design. This bugs, digger wasps, parasitic Hyme- dant or disappear altogether if their pattern is consistent across all bio- noptera, bluebirds, tree swallows, car- native plant lineage is competitively regions of North America and is not dinals, hummingbirds, catbirds, and excluded by the invasive plant. When changed by latitude, longitude, or many other insectivores all kill tens of bush honeysuckle from Asia, for plant diversity levels. Wherever we thousands of insect herbivores before example, displaces native spicebush are in the United States, we can create plants suffer noticeable damage. But in the understory of eastern forests plantings that sustain birds, reptiles, natural enemies will not be in our or in our designed landscapes, the amphibians, and mammals by gener- landscapes if there is not enough food spicebush swallowtail loses some or ating tens of thousands of insects. to support them. Fortunately, we all of its host plants and the number Landscape designers and architects, have some wiggle room here, for of interactions in that space de- land managers, restoration biologists, studies have shown that people do creases. Such losses are multiplied and homeowners can learn which not even notice insect damage until every time a native plant is pushed native plant genera contain core spe- about 10% of the leaves have been from a landscape (van Hengstum cies, as well as where to obtain these eaten (Sadof and Raupp, 1996). Most et al., 2013). species, at the National Wildlife plants are viewed at a distance; even
450 • August 2017 27(4) the oak tree that supports hundreds remaining degraded and fragmented biological corridors that reconnect of caterpillars looks untouched from ‘‘natural’’ spaces to produce them. If habitat fragments are recon- 20 feet away. enough. We must now design beau- nected, they will support populations tiful landscapes that also support that are large enough to withstand Using more plants complex food webs that in turn sup- normal stochastic fluctuations with- Creating vibrant landscapes that port the biodiversity that runs our out disappearing. Our new park will become functional extensions of local ecosystems. We need landscapes that not perfectly replicate the plant and ecosystems can only happen if we use sequester carbon; lawn sequesters 27 animal communities that once existed the plants that drive those ecosys- times less carbon than a meadow and on these sites, but it will reassemble tems. Choosing the right plants is 32 times less than a forest (Schwartz, the local relationships between plants a necessary first step, but we must 2014). We also need landscapes that and animals that coevolved over the also put enough of those plants into clean and manage water. A lawn-dom- eons and that are necessary for eco- the landscape to achieve the ecosys- inated landscape impedes infiltration, system function. Its design and main- tem integrity we desire (Aronson creates disastrous storm water runoff, tenance will be so different from et al., 2017). Today many of our built and adds nutrient and pesticides pol- traditional practices that it could landscapes are dominated by turf- lutants to aquatic ecosystems. Finally, spawn a new ecological landscaping grass. For example, 92% of the area we need to design landscapes that industry, one that can balance aes- that could be landscaped in residen- support diverse pollinator popula- thetic and artful design with ecolog- tial neighborhoods in northeast tions. Pollinators across the United ical function and reverse the declining Maryland, southeast Pennsylvania, States are in steep decline due to large interest in horticulture we have seen and Delaware is lawn. Moreover, part in the loss of nesting sites and since 2008. To be sure this is an 90% of the trees are gone from seasonally abundant forage (Kremen optimistic view of our future but it is these landscapes and 79% of the plants et al., 2007). Manicured lawns provide entirely or largely obtainable and will that are there are from Asia (D.W. neither resource. Pollinators, includ- have enormous ecological payoffs Tallamy,J.Bruck,S.Walker,K.Pippins, ing the 4000 species of native bees that both for humans and our fellow S. Shpak, and A. Lucey, unpub- did all of the pollination in North earthlings. lished). We have favored large lawns America before the introduction of bearing few plants for two reasons: the honeybee, are not optional. They first, we prefer savanna-like land- pollinate 80% of all plants and 90% of Literature cited scapes, presumably because we feel all flowering plants. If we were to lose Millennium Ecosystem Assessment. safer in such environments (Falk and pollinators, we would lose 80% to 90% 2005. 2005 Millenium ecosystem assess- < Balling, 2010). Large flawless lawns of all plants including one-third of our ment. 30 Apr. 2017. http://www. millenniumassessment.org/en/index. have also been a status symbol of the crop species. > rich for centuries. Such landscapes html/ . may have met our physical and social Homegrown national park Aronson, M.F.J., C.A. Lepczyk, K.L. needs when we were hunter-gathers, We have it in our power to create Evans, M.A. Goddard, S.B. Lerman, J.S. but they are an environmental disaster a new national park of sorts simply by MacIvor, C.H. Nilon, and T. Vargo. in today’s world of 7.5 billion people. redesigning the landscapes in which 2017. Biodiversity in the city: Key chal- We are converting all built land- we live, work, and play. If we were to lenges for urban green space manage- scapes into lawn dominated spaces replace half of the area now in lawn ment. Front. Ecol. Environ. 15:189–196. that do not support ecosystem func- with three-dimensional plantings of Bernays, E.M. and M. Graham. 1988. On tion. To be sure, expanses of lawn powerful native plant communities, the evolution of host specificity in phy- are necessary for games and picnics, we could create over 20 million acres tophagous arthropods. Ecology 69:886– but there are few people who use of spaces that generate rather than 892. all of their lawn for these activities. destroy ecosystem services. Our Brewer, R. 1961. Comparative notes on We now have over 40 million acres ‘‘Homegrown National Park’’ will be the life history of the carolina chickadee. (16.2 million hectares) of lawn in enormous—bigger than all of the Wilson Bull. 73:348–373. the United States, an area roughly the major national parks combined—and size of New England, and we are add- it will provide us with many of the Dickinson, M.B. 1999. Field guild to the 2 2 birds of North America. 3rd ed. Natl. ing 500 mile (1295.0 km )more benefits we derive from visiting our Geographic Soc., Washington, DC. lawn each year (Kolbert, 2008; Milesi official national parks. Just 15 min in et al., 2005). the solitude of a well-planted garden Dussourd, D.E. and T. Eisner. 1987. can lower blood pressure, reduce Vein-cutting behavior: Insect counter- Raising the bar stress (cortisol), improve attention ploy to the latex defense of plants. Science To achieve a sustainable relation- span, raise immune responses, and 237:898–901. ship with the earth we must raise the provide unlimited entertainment as Dyer, L.A., T.R. Walla, H.F. Greeney, J.O. bar for what we ask of our built we observe the life around us (Louv, Stireman, III, and R.F. Hazen. 2010. Di- landscapes. In the past, we have asked 2005, 2012, 2016; Wolf, 2014). We versity of interactions: A metric for that they be attractive and well- will no longer lament over our dis- studies of biodiversity. Biotropica 42:281– tended spaces. We have achieved this connection with nature because we 289. in a grand style. But our need for will live in its midst. Our new Falk, J.H. and J.D. Balling. 2010. Evo- ecosystem services is now so great that plantings will fill the gaps between lutionary influence on human landscape we can no longer rely on the fragmented natural areas, creating preference. Environ. Behav. 42:479–493.
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