3.3 Human Impact on Biodiversity

Transcription

1 3.3 Human Impact on Biodiversity Learning Goals: 1. Explain how human activities are reducing 2. Explain how logging and fires are reducing forest 3. Explain how human activities are reducing aquatic I. Human Activities A. Why biodiversity is important to humans 1. Ecological services: oxygen, recycling nutrients, etc. 2. Economic services: food, lumber, paper, medicines, etc. B. Major causes of biodiversity depletion 1. Habitat Loss conversation of habitable area for urbanization and agricultural fields. 2. Habitat Fragmentation large adjacent ecosystems are divided into smaller, more isolated areas by developments, cities, roadways, agricultural fields, and logging 3. Invasive Species out-compete native species for resources and do not have any known predators in their new habitat. I. Human Activities C. Extinction 1. Biological Extinction when a species is no longer found in any ecosystem on earth. 2. Endangered Species at extreme risk of becoming extinct over most or all of their natural habitats. 3. Threatened Species could potentially become endangered in the near future. D. Legislation and Treaties 1. U.S. Endangered Species Act of 1973: identifies and protects endangered organisms; prohibits destruction of essential habitat 2. Convention on International Trade in Endangered Species (CITES): bans the selling, hunting, capturing of threatened and endangered species. 1

2 1. Importance: high biodiversity, release oxygen, store CO 2, reduce soil erosion, nutrient cycling, influencing climate, lumber, paper 2. Old-Growth Forest has not been modified by human activity or natural disasters in 200+ years 3. Secondary-Growth Forest form from secondary succession once land has been cleared due to disturbance. 4. Threats: a. Deforestation via logging practices i. Clear-cutting removing all trees in area at one time; most damage. ii. Tree Plantation commercially maintained for timber resources; low biodiversity, poor soil nutrients iii. Selective cutting only remove mature trees iv. Strip cutting removing strip of trees along contour of land; quick regrowth of trees 4. Threats: b. Forest Fires i. Surface fires only burn leaf litter; promoted growth and replenishes nutrients ii. Crown fires burn tops of trees and spread easily; decrease biodiversity, increase erosion iii. Prescribed fires ( control burns ) help to prevent crown fires. iv. Forests Restoration Act: allows timber companies to thin forests at risk of fires c. Climate Change: increased risk from insects and diseases 2

3 5. Solutions: a. Use strip cutting b. Protect old-growth forests c. Certify timber grown sustainably d. Subsidize sustainable logging practices e. Rehabilitate clear-cut forests B. Grassland Ecosystems 1. Importance: valuable cropland due to fertile soils and abundant grasses for grazing livestock. 2. Rangelands - wide-open, non-restricted areas for grazing 3. Pastures fenced areas that are maintained by ranchers 4. Threats: overgrazing occurs when the number of livestock animals exceed the carrying capacity; causes erosion and decreases soil s ability to hold water. 5. Solutions: a. Prescribed fires to eliminate competing plants and replenish nutrients b. Rotational grazing livestock are rotated among fields to prevent over grazing in one area III. Sustaining Aquatic Diversity A. Threats 1. Overharvesting a. Many commercial fish stocks are overfished and declining b. Bycatch unintentional killing of non-target species 2. Pollution: most ocean pollution comes from land runoff of sediments, fertilizers, pesticides, industrial solvents, plastics, excessive nutrients 3. Climate Change a. Rising sea levels destroy reef habitat and mangrove forests b. Melting ice impacts polar bear habitats 4. Invasive Species: introduced through ballast water on ships 3

4 III. Sustaining Aquatic Diversity B. Solutions: 1. Practice sustainable fishing that reduces bycatch 2. Set catch limits 3. Filter ballast water 4. Establish marine sanctuaries 5. Reduce carbon emissions to reduce climate change 6. Marine Mammal Protection Act of 1972: prohibits harassing, hunting, or killing any marine mammals; includes bycatch regulations and stock assessments. 1. Explain how human activities are reducing I can summarize the Endangered Species Act and CITES. I can explain how human activities are reducing I can contrast endangered and threatened species. I can define habitat loss, habitat fragmentation, and invasive species. 2. Explain how logging and fires are reducing forest I can propose ways to sustain forest I can explain how logging and fires are reducing forest I can describe different logging practices. I can contrast old-growth and secondary-growth forests. 4

5 3. Explain how human activities are reducing aquatic I can propose ways to sustain aquatic I can explain how human activities are reducing aquatic I can identify sources of pollution in the ocean. I can define bycatch. 5