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Colin Townsend obtained his DPhil at Sussex before taking up teaching positions at Oxford University and the University of East Anglia. In 1989 he moved from the UK to New Zealand, where he was appointed Chair of Zoology at the University of Otago; he is now Director of the Ecology, Conservation and Biodiversity Research Group at Otago.

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Ecological Applications offers a progressive examination of the way ecological theory can be applied to remedy the many problems confronting us. The text moves through the levels of individual organisms, populations, communities, and ecosystems, culminating with the macroecological scale of landscape, regional, and global issues. The book is designed to grab the reader’s interest with real-life problems but also to instil an understanding of the fundamentals of ecology.

Applications including species conservation, pest control, harvest management, biosecurity, restoration, and reserve design are explored in both terrestrial and aquatic settings. The focus is on ecological sustainability, but economic and sociopolitical dimensions related to the sustainable use of natural resources are also examined.

Ecological Applications is a current and comprehensive guide to the theory and practice of ecology for students and practitioners alike.

Aus dem Klappentext

Ecological Applications offers a progressive examination of the way ecological theory can be applied to remedy the many problems confronting us. The text moves through the levels of individual organisms, populations, communities, and ecosystems, culminating with the macroecological scale of landscape, regional, and global issues. The book is designed to grab the reader’s interest with real-life problems but also to instil an understanding of the fundamentals of ecology.

Applications including species conservation, pest control, harvest management, biosecurity, restoration, and reserve design are explored in both terrestrial and aquatic settings. The focus is on ecological sustainability, but economic and sociopolitical dimensions related to the sustainable use of natural resources are also examined.

Ecological Applications is a current and comprehensive guide to the theory and practice of ecology for students and practitioners alike.

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Ecological Applications

John Wiley & Sons

Chapter One

The history of the human species as global caretaker has not been good. As Homo sapiens subspecies exploitabilis we have polluted air, land and water, destroyed large areas of almost all kinds of natural habitat, overexploited living resources, transported organisms around the world with negative consequences for native ecosystems, and driven a multitude of species close to extinction. Our 'evolution' to subspecies sustainabilis needs to involve some significant behavior changes underpinned by ecological knowledge.

Chapter contents

1.1 Homo not-so-sapiens? 2 1.1.1 Homo sapiens - just another species? 3 1.1.2 Human population density and technology underlie environmental impact 3

1.2 A biodiversity crisis 4 1.2.1 The scale of the biodiversity problem 6 1.2.2 Biodiversity, ecosystem function and ecosystem services 7 1.2.3 Drivers of biodiversity loss - the extinction vortex 11 1.2.4 Habitat loss - driven from house and home 12 1.2.5 Invaders - unwanted biodiversity 13 1.2.6 Overexploitation - too much of a good thing 14 1.2.7 Habitat degradation - laying waste 17 1.2.8 Global climate change - life in the greenhouse 18

1.3 Toward a sustainable future? 20 1.3.1 Ecological applications - to conserve, restore and sustain biodiversity 22 1.3.2 From an economic perspective - putting a value on nature 28 1.3.3 The sociopolitical dimension 29

Homo not-so-sapiens?

Homo sapiens, the name of the most recent in a line of hominids, might well be considered a misnomer. Just how sapient (wise) has Homo sapiens been? We have certainly been clever - inventing an amazing array of tools and technologies from the wheel to the nuclear power station. But how much of the natural world has been disrupted or destroyed during this technological 'progress'? And is our way of life actually sustainable? A crunch question is whether your descendants will be able to enjoy the same opportunities as you. If not, perhaps they will judge their ancestors to have been far from wise.

Humans destroy natural ecosystems to make way for urban and industrial development and to establish production ecosystems such as forestry and agriculture. We also exploit the natural world for nonrenewable resources (mining) as well as renewable ones (fisheries and forests). Mining destroys habitat directly, and fishery techniques such as bottom trawling can physically disrupt habitat. The natural ecosystems that remain are also affected by human activities. Our harvesting of species from the wild (whether trees, antelopes or fish) has often led to their decline through overexploitation. Our transport systems allow species from one part of the world to hitch a ride to another where, as 'invaders', their impacts on native biota can be profound. And every human activity, including defecation, transport, industry and agriculture, produces 'pollutants' that can adversely affect the biota locally or globally.

You might imagine there would be consensus about what constitutes reasonable behavior in our interactions with the natural world. But people take a variety of standpoints and there are a host of contradictions. Farmers usually consider weeds that reduce the productivity of their crops to be a very bad thing. But conservationists bemoan the farmers' attack on weeds because these species often help fuel the activities of butterflies and birds. The Nile perch (Lates nilotica) was introduced to Africa's Lake Victoria to provide a fishery in an economically depressed region, but it has driven most of the lake's 350 endemic fish species towards extinction (Kaufman, 1992). So gains at our dinner tables can equate to a loss of biological diversity.

Then again, our knowledge of plant physiology allows agricultural ecosystems to be managed intensively for maximum food production. But heavy use of fertilizers means that excess plant nutrients, particularly nitrate and phosphate, end up in rivers and lakes. Here ecosystem processes can be severely disrupted, with blooms of microscopic algae shading out waterweeds and, when the algae die and decompose, reducing oxygen and killing animals. And even in the oceans, large areas around river mouths can be so badly impacted that fisheries are lost. The farmers' gain is the fishers' loss.

Pesticides, too, are applied to land but find their way to places they were not intended to be. Some pass up food chains and adversely affect local birds of prey. Others move via ocean currents and through marine food chains, damaging predators at the ends of the earth (such as polar bears and the Inuit people of the Arctic). And hundreds of kilometers downwind of large population centers, acid rain (caused by emission of oxides of nitrogen and sulfur from power generation) kills trees and drives lake fish to extinction. Ironically, in other parts of the world a new ecology is imposed in previously fishless lakes because of the introduction of fish favored by anglers.

So Homo sapiens has a diversity of views and a wide variety of impacts. But are we really so different from other species?

1.1.1 Homo sapiens - just another species?

Feces, urine and dead bodies of animals are sometimes sources of pollution in their environments. Thus, cattle avoid grass near their waste for several weeks, burrow-dwelling animals defecate outside their burrows, sometimes in special latrine sites, and many birds carry away the fecal sacs of their nestlings. Humans are not unique, either, in regarding corpses as pollutants to be removed. The 'undertaker' caste of honeybee, for example, recognizes dead bodies and removes them from the hive.

And just like humans, many species make profound physical changes to their habitats. These 'ecological engineers' include beavers that build dams (changing a stream into a pond), prairie dogs that build underground towns and freshwater crayfish that clear sediment from the bed. In each case other species in the community are affected. The impact may be positive (for pond dwellers in the beaver ponds, for species that share the prairie dog town, for insects whose gills are sensitive to clogging by sediment) or negative (stream species, plants displaced by burrowing, insects that feed on sediment).

Overexploitation, where individuals of a population are consumed faster than they can replenish themselves, is also a common feature in natural ecosystems. Sometimes overexploitation is subtle, with preferred prey species less common in the presence of their consumers - as compared to their less tasty or harder-to-catch counterparts. But overexploitation may be more dramatically demonstrated when the disappearance of top predators (such as wolves) allows herbivores (such as...