Chapter 11 new(1).pptx

ENVIRONMENTAL SCIENCE A Study of Interrelationships, 16th Edition Chapter 11 Biodiversity Issues Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 11.1 Biodiversity Biodiversity 1 is a broad term used to descr...

ENVIRONMENTAL SCIENCE A Study of Interrelationships, 16th Edition Chapter 11 Biodiversity Issues Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 11.1 Biodiversity Biodiversity 1 is a broad term used to describe the variety of life. More formally: Biodiversity is the variability among living organisms from all sources, including terrestrial, marine and other aquatic ecosystems, and the ecological complexes of which they are a part. This includes variation in genetic, phenotypic, phylogenetic, and functional attributes, as well as changes in abundance and distribution over time and space within and among species, biological communities and ecosystems. 11.1 Biodiversity 2 We can look at biodiversity by counting up the number of different types (or variants) at various levels of a hierarchy: Genes within populations. Populations within species. Species within communities and ecosystems. Ecosystems within landscapes and the overall biosphere. It also recognizes that nature is dynamic, and that biodiversity changes over both time and space. 11.1 Biodiversity Species 4 Richness: In practice, the most common measure of biodiversity is the number of species, which is called species richness. Estimates of total diversity of all organisms range from the billions to trillions. The two most important factors that determine the number of species in an area are energy and water. In aquatic systems, other factors are more important. Salinity. The availability of nutrients. Water movement. 11.1 Biodiversity Species 8 Diversity: Several other factors influence species richness in an area. The geological and evolutionary history of the region. The size of the area. The degree of isolation of the area. 11.1 Biodiversity Genetic 9 Diversity: Refers to the number of different types or variants of DNA present within a population, species, or community. When genetic diversity is high, the chance is high of having beneficial genetic variants that could provide a major advantage in the face of a new challenge. Genetic Diversity Population size is an important factor: The smaller the population, the less genetic diversity it can contain. There are fewer variations for each characteristic. Random events can significantly alter the genetic diversity in small populations. Selective breeding can affect diversity because undesirable characteristics are eliminated. Many domesticated plants and animals could not survive without human help. 7 11.1 Biodiversity 11 Ecosystem diversity is a measure of the number of kinds of ecosystems present in an area. The number of ecosystems present depends on the scale at which you look at them. Major terrestrial biomes. Ecoregions within biomes. Variants within ecoregions. FIGURE 11.7 Ecoregion Diversity 11.1 Biodiversity 12 Beyond the Number of Variants: We must distinguish between species richness and species diversity. Species diversity takes into account the number and evenness of species. Communities with more even abundances among species are more diverse. FIGURE 11.9 Species Richness vs Diversity Access the text alternative for slide images. 11.2 The Value of Biodiversity Humans 1 depend on the biodiversity and functioning ecosystems. Nature’s Contributions to People (N CPs): Way to understand and recognize the contributions, both positive and negative, of living nature to people’s quality of life. Three Categories: Regulating. Material. Non-material. 11.2 The Value of Biodiversity Regulating Ps: NC Access the text alternative for slide images. 2 11.2 The Value of Biodiversity Material NCPs: Access the text alternative for slide images. 3 11.2 The Value of Biodiversity Non Material NCPs: Access the text alternative for slide images. 4 11.2 The Value of Biodiversity Variation 5 in Biodiversity Affects Ecosystem Functioning. As the number of species in a community decreases, so do measures of ecosystem function. For Example, in experimental grasslands, increasing plant diversity increases: Productivity. Efficiency of nutrient use. Efficiency of nutrient retention. 11.2 The Value of Biodiversity More 7 diverse communities are more: Resistant: Remain largely the same even when faced with a potentially damaging disturbance. Resilient: Return to their original state after being affected by a disturbance. 11.3 Threats to Biodiversity 1 The growth of the human population and how we consume resources drives biodiversity loss. Indirect factors drive more direct threats to biodiversity. Access the text alternative for slide images. 11.3 Threats to Biodiversity 2 Habitat Loss Natural or human activities damage and destroy habitat. Original habitat is no longer capable of supporting the species and communities that naturally occur there. Occurs on land, and in both freshwater and marine In water: systems. Onaquatic land, habitat loss removes 1. natural communities for: Agriculture. Dredging. Mining. Forestry. Siltation. Urbanization. Drainage and diversions. Disturbance of bottom (For Example, for certain forms of fishing). 11.3 Threats to Biodiversity 1. Habitat Loss Agriculture: Leading cause of terrestrial habitat loss. 50% of habitable land. ~3/4 of available freshwater resources. FIGURE 4 Agriculture: Rangelands now occupy 70% of arid and semiarid lands. Overgrazing may lead to desertification. 11.15 Extent of Agriculture FIGURE 11.16 Desertificat 11.3 Threats to Biodiversity 1. 6 Habitat Loss Agriculture: Strategies to reduce impacts: Increase productivity of existing agricultural land. For Example, new methods of irrigation, crop rotation, and harvesting. For Example, new crop varieties. Deforestation: Process of clearing land of trees. Strategies to reduce impacts: Reforestation. Forests are being lost rapidly in some regions. Use of alternate products. 11.3 Threats to Biodiversity 2. 9 Habitat Degradation A decline in the quality of habitats. Degraded habitats no longer support the same species and/or number of individuals. Goes hand-in-hand with habitat loss. 11.3 Threats to Biodiversity 2. 10 Habitat Degradation Habitat fragmentation: Change in the shape and configuration of remaining habitat after habitat loss. FIGURE 11.18 Habitat Fragmentation Access the text alternative for slide images. 11.3 Threats to Biodiversity 2. 11 Habitat Degradation Habitat fragmentation: Effects: Initial crowding. Loss of species requiring large areas of habitat. Isolation of fragments. Small populations prone to extinction. Edge effects. Loss of specialists. Increase in proportion of generalists. 11.3 Threats to Biodiversity Habitat 12 Degradation: Strategies to reduce impacts: Maintain larger areas of habitat. Provide corridors to connect fragments. Proper planning. FIGURE 11.19 Habitat Corridors Access the text alternative for slide images. (a) Treat, Inc; (b) Frans Lemmens/Getty Images 11.3 Threats to Biodiversity 3. 13 Overexploitation Humans use or extract a resource to the point of exhaustion or extinction. Often results from unregulated and/or illegal harvesting. Over 30% of endangered species of animals and ~ 8% of plants are threatened by overexploitation. 11.3 Threats to Biodiversity 3. 14 Overexploitation Aquatic systems: In many areas, protein from fish and invertebrates is the primary source of protein in people’s diets. Also harvest aquatic organisms for: Ornaments. Aquarium trade. Medicine. dyes and other products. May lead to bycatch: Capture of non-target species. 11.3 Threats to Biodiversity 3. Overexploitation Terrestrial systems: Hunting for food. Animal parts. For Example, ivory, rhinoceros horn. Pet and aquarium trade. Horticulture and ornamental plant trade. Traditional medicine. 15 11.3 Threats to Biodiversity 3. 16 Overexploitation Strategies to reduce impacts: Monitor and regulate harvests. Pursue alternate sources. Ingenuity (technological ’fixes’ for specific issues). For Example, beacons and weak links in nets to avoid marine mammal bycatch. Aquaculture 28 11.3 Threats to Biodiversity 4. 17 Species Introductions Transport of species outside of their native range. May be intentional. For Example, crops, sport fish, ornamental plants. May also be unintentional. 11.3 Threats to Biodiversity 4. Species Introductions Many different pathways of species introductions that differ in the degree of intentionality. FIGURE 18 11.21 Pathways of Species Introductions Access the text alternative for slide images. Introduction of Exotic Species Some introductions of exotic species are purposeful, while others are accidental. Globalization is responsible for spreading thousands of invasive alien species around the world. The IUCN estimates about 30% of birds and 15% of plants are threatened because they are unable to successfully compete against invasive exotic 31 Introduction of Exotic Species Introduction of disease has had considerable impact on American forests. Chestnut blight Dutch elm disease Various insects have had an effect on ecosystem structure. Asian long horned beetle Freshwater Zebra ecosystems have been greatly affected. mussel 32 11.3 Threats to Biodiversity 4. 19 Species Introductions Not all species introductions are successful. Species may be introduced but later go extinct. Species may become invasive. Spread and cause harm to native species. May have major economic consequences for humans. Invasive Species 34 11.3 Threats to Biodiversity 5. Climate Change Discussed Results 23 in detail in Chapter 17. in: Increased and more variable temperatures on land and in the ocean. Altered patterns of precipitation. More extreme weather events. Changes in ocean levels and acidity. Climate Change Affects Arctic Animals 36 11.3 Threats to Biodiversity 5. Climate Change Effects: Individuals. Growth and survival. Heat and water stress. Populations: Distribution. Increased susceptibility to other threats. Timing of important events. 24 11.3 Threats to Biodiversity 26 Multiple drivers act together. Many drivers act simultaneously in any given ecosystem or region. For Example, tropical deforestation. For Example, chytridiomycosis in amphibians. Various drivers may be synergistic. The total impact of two or more threats is greater than what you would expect from the impact of each threat on its own. 11.3 Threats to Biodiversity 27 Broad 1. Outcomes Extinctions Global extinction: No member of a species remains alive anywhere in the world. Local extinction: Species is no longer found in an area it once inhabited but still occurs elsewhere. 11.3 Threats to Biodiversity 28 Certain species are more likely than others to become extinct. Table 11.1 Probability of Becoming Extinct Most Likely to Become Extinct Least Likely to Become Extinct small populations everywhere at least one large population Found in small area Found over large area Specialized niche Generalized niche Low reproductive rates High reproductive rates Biodiversity Loss and Organisms Extinction in small, restricted areas, such as islands. Specialized organisms Organisms at higher trophic levels. 11.4 What is Being Done to Preserve Biodiversity 1 Species-level 1. Approaches: Listings and legal protections. IUCN Red List: The World Conservation Union (IUCN) lists over 21,000 species as threatened with extinction. Carries out species assessments. Categorizes threat status: Critically endangered. Endangered. Vulnerable. Legal Protection Awareness and concern about loss of biodiversity are high in many developed countries. Most vulnerable species in these areas have already been eliminated. Loss of biodiversity is not a high priority for the general public in developing countries. They are more concerned with immediate needs of food and shelter than long-range issues such as species extinction. In the U.S., the primary action related to the preservation of biodiversity involved the passage of the Endangered Species Act (1973). 43 Legal Protection Endangered species are those that have such small numbers that they are in immediate danger of becoming extinct. Threatened species could become extinct if a critical environmental factor is changed. The preservation question ultimately becomes one of assigning value to the species. Amendments to ESA have weakened ability of U.S. government to add new species to the list. 44 Endangered Species 45 From Endangered to Vulnerable In 2016, the giant panda bear — long the symbol of wildlife conservation, via the World Wildlife Fund — was officially bumped off the endangered list, as the population of giant pandas living in the wild jumped to just over 1,800 Technically, the Arabian oryx was once extinct: the last remaining Arabian oryx in the wild was reportedly shot in Oman in 1972. So, in a move that was at the time unprecedented, an effort to save the species from the brink began — by breeding the animals that remained alive in captivity, and eventually reintroducing them to 46 there their natural habitats. Today, are more than 1,000 Arabian oryx Sustainable Management of Wildlife Populations Habitat Analysis and Management Managing a particular species requires an understanding of the habitat needs of that species. An animal’s habitat must provide food, water, and cover. Cover conceals or protects animals from the elements or enemies. Modifications made to enhance the success of a species are known as habitat management. Game species are often managed so they do not exceed carrying capacity of their habitat. Wildlife managers use population censuses to check if populations are within appropriate levels. With suitable habitat and protection, most wild animals can maintain a sizeable population. High reproductive capacities and heavy protection have caused very large populations to arise from once-rare animals. 47 Population Assessment and Management Wildlife management often involves harvesting for sport and meat. Regulating hunting activity is an important population management technique. Seasons usually occur in the fall so surplus animals are taken before the challenges of winter. When populations get too small, artificial introductions can be implemented. Native species can be reintroduced to areas where they had been extinct. Non-native species are introduced for empty niches. 48 Managing a Wildlife Population 49 Special Issues with Migratory Animals Migratory They birds can travel thousands of kilometers. travel north in spring to reproduce. They travel south in fall to escape cold temperatures. International agreements may be necessary to maintain appropriate habitat. 50 Sustainable Management of Fish Populations Coastal oceans. regions are most productive regions of the Sunlight penetration of shallow water makes it warm. Nutrient deposition from land makes this region fertile. Wind/wave action stirs nutrients. Fishing pressure is concentrated here. One of the major problems associated with the management of marine fisheries is achieving agreement on harvest limits. 51 Sustainable Management of Fish Populations Humans have easy access to freshwater ecosystems, so management of these systems is much more intense. They are typically easier to regulate because of containment within a smaller political region. Many North American freshwater fisheries are primarily managed for sport fishery. Fisheries’ biologists pay special attention to water quality. 52 End of Main Content Because learning changes everything. www.mheducation.com Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. ®