Conservation Biology and Restoration Ecology Chapter 56 Conservation Biology and Restoration Ecology

Overview: The Biodiversity Crisis Conservation biology integrates the following fields to conserve biological diversity at all levels Ecology Evolutionary biology Physiology Molecular biology Genetics Behavioral ecology

Restoration ecology applies ecological principles In an effort to return degraded ecosystems to conditions as similar as possible to their natural state

Losing Tropical Forests Contain some of the greatest concentrations of species Are being destroyed at an alarming rate Figure 55.1

The HUMAN Impact Throughout the biosphere, human activities are altering ecosystem processes on which we and other species depend! Rates of species extinction are difficult to determine under natural conditions The current rate of species extinction is high and is largely a result of ecosystem degradation by humans Humans are threatening Earth’s biodiversity

The Three Levels of Biodiversity Biodiversity has three main components Genetic diversity Species diversity Ecosystem diversity Genetic diversity in a vole population Species diversity in a coastal redwood ecosystem Community and ecosystem diversity across the landscape of an entire region Figure 55.2

Levels of Biodiversity Genetic diversity comprises The genetic variation within a population The genetic variation between populations Species diversity Is the variety of species in an ecosystem or throughout the biosphere Ecosystem diversity Identifies the variety of ecosystems in the biosphere Is being affected by human activity

Conservation biologists are concerned about species loss Species Diversity An endangered species Is one that is in danger of becoming extinct throughout its range Threatened species Are those that are considered likely to become endangered in the foreseeable future Conservation biologists are concerned about species loss Because of a number of alarming statistics regarding extinction and biodiversity

Biodiversity and Human Welfare Human biophilia Allows us to recognize the value of biodiversity for its own sake Species diversity Brings humans many practical benefits

Benefits of Species and Genetic Diversity Many pharmaceuticals Contain substances originally derived from plants The loss of species Also means the loss of genes and genetic diversity The enormous genetic diversity of organisms on Earth Has the potential for great human benefit

Ecosystem services include Ecosystem services encompass all the processes through which natural ecosystems and the species they contain help sustain human life on Earth Ecosystem services include Purification of air and water Detoxification and decomposition of wastes Cycling of nutrients Moderation of weather extremes And many others

Four Major Threats to Biodiversity Most species loss can be traced to four major threats Habitat destruction Introduced species Overexploitation Disruption of “interaction networks”

Human alteration of habitat Habitat Destruction Human alteration of habitat Is the single greatest threat to biodiversity throughout the biosphere Massive destruction of habitat Has been brought about by many types of human activity In almost all cases Habitat fragmentation and destruction leads to loss of biodiversity

(b) Introduced kudzu thriving in South Carolina Introduced Species Introduced species Are those that humans move from the species’ native locations to new geographic regions Introduced species that gain a foothold in a new habitat Usually disrupt their adopted community (a) Brown tree snake, intro- duced to Guam in cargo (b) Introduced kudzu thriving in South Carolina Figure 55.6a, b

Overexploitation Overexploitation refers generally to the human harvesting of wild plants or animals At rates exceeding the ability of populations of those species to rebound The fishing industry Has caused significant reduction in populations of certain game fish

Disruption of Interaction Networks The extermination of keystone species by humans Can lead to major changes in the structure of communities Figure 55.8

Conservation biologists who adopt the small-population approach Conservation Effort Population conservation focuses on population size, genetic diversity, and critical habitat Biologists focusing on conservation at the population and species levels Follow two main approaches Conservation biologists who adopt the small-population approach Study the processes that can cause very small populations finally to become extinct

A small population is prone to positive-feedback loops The Extinction Vortex A small population is prone to positive-feedback loops That draw the population down an extinction vortex Small population Inbreeding Genetic drift Lower reproduction Higher mortality Loss of genetic variability Reduction in individual fitness and adaptability Smaller Figure 55.9

The key factor driving the extinction vortex Is the loss of the genetic variation necessary to enable evolutionary responses to environmental change

Minimum Viable Population Size The minimum viable population (MVP) Is the minimum population size at which a species is able to sustain its numbers and survive A population viability analysis (PVA) Predicts a population’s chances for survival over a particular time Factors in the MVP of a population A meaningful estimate of MVP Requires a researcher to determine the effective population size, which is based on the breeding size of a population

Declining-Population Approach The declining-population approach Focuses on threatened and endangered populations that show a downward trend, regardless of population size Emphasizes the environmental factors that caused a population to decline in the first place The declining-population approach requires that population declines be evaluated on a case-by-case basis Involves a step-by-step proactive conservation strategy

Case Study: Decline of the Red-Cockaded Woodpecker Red-cockaded woodpeckers Require specific habitat factors for survival Had been forced into decline by habitat destruction (a) A red-cockaded woodpecker perches at the entrance to its nest site in a longleaf pine. (b) Forest that can sustain red-cockaded woodpeckers has low undergrowth. (c) Forest that cannot sustain red-cockaded woodpeckers has high, dense undergrowth that impacts the woodpeckers’ access to feeding grounds. Figure 55.13a–c

Case Study: Decline of the Red-Cockaded Woodpecker In a study where breeding cavities were constructed New breeding groups formed only in these sites On the basis of this experiment A combination of habitat maintenance and excavation of new breeding cavities has enabled a once-endangered species to rebound

Weighing Conflicting Demands Conserving species often requires resolving conflicts Between the habitat needs of endangered species and human demands

Regional Conservation Landscape and regional conservation aim to sustain entire areas of biodiversity In recent years, conservation biology has attempted to sustain the biodiversity of entire communities, ecosystems, and landscapes One goal of landscape ecology, of which ecosystem management is part Is to understand past, present, and future patterns of landscape use and to make biodiversity conservation part of land-use planning

Fragmentation and Edges The structure of a landscape can strongly influence biodiversity The boundaries, or edges, between ecosystems are defining features of landscapes As habitat fragmentation increases and edges become more extensive, biodiversity tends to decrease (a) Natural edges. Grasslands give way to forest ecosystems in Yellowstone National Park. (b) Edges created by human activity. Pronounced edges (roads) surround clear-cuts in this photograph of a heavily logged rain forest in Malaysia. Figure 55.14a, b

Much of the focus on establishing protected areas Biological Hot Spots Much of the focus on establishing protected areas Has been on hot spots of biological diversity Biodiversity hot spots are obviously good choices for nature reserves But identifying them is not always easy

Finding Biodiversity Hot Spots A biodiversity hot spot is a relatively small area With an exceptional concentration of endemic species and a large number of endangered and threatened species Terrestrial biodiversity hot spots Equator Figure 55.17

Philosophy of Nature Reserves Nature reserves are biodiversity islands In a sea of habitat degraded to varying degrees by human activity One argument for extensive reserves Is that large, far-ranging animals with low-density populations require extensive habitats

Restoration Ecology Restoration ecology attempts to restore degraded ecosystems to a more natural state The larger the area disturbed The longer the time that is required for recovery One of the basic assumptions of restoration ecology Is that most environmental damage is reversible Two key strategies in restoration ecology Are bioremediation and augmentation of ecosystem processes

Bioremediation & Biological Augmentation Is the use of living organisms to detoxify ecosystems Biological augmentation Uses organisms to add essential materials to a degraded ecosystem

Exploring Restoration The newness and complexity of restoration ecology Require scientists to consider alternative solutions and adjust approaches based on experience

Facing increasing loss and fragmentation of habitats Sustainable Use Sustainable development seeks to improve the human condition while conserving biodiversity Facing increasing loss and fragmentation of habitats How can we best manage Earth’s resources?

Sustainable Biosphere Initiative The goal of this initiative is to define and acquire the basic ecological information necessary For the intelligent and responsible development, management, and conservation of Earth’s resources

Biophilia and the Future of the Biosphere Our modern lives Are very different from those of early humans who hunted and gathered and painted on cave walls (a) Detail of animals in a Paleolithic mural, Lascaux, France Figure 55.24a

Biophilia and the Future of the Biosphere But our behavior Reflects remnants of our ancestral attachment to nature and the diversity of life, the concept of biophilia (b) Biologist Carlos Rivera Gonzales examining a tiny tree frog in Peru Figure 55.24b

Biophilia and the Future of the Biosphere Our innate sense of connection to nature May eventually motivate a realignment of our environmental priorities