Biological Extinction
-a species can no longer be found anywhere on earth
Background Extinction Rate
-natural, low rate of species extinction
-before humans arrived, estimated to be 0.0001% species going extinct per year
-current rate is at least .1%, by end of century will be up to 1%
Mass Extinction
-extinction of 50-95% of species in a short period of time
Endangered Species
-so few individual survivors that the species could soon become extinct
Threatened/Vulnerable Species
-has enough remaining indiv's to survive in the short-term, but is likely to become endangered in the near future
Reasons to Avoid Premature Extinction
-world's species are vital to earth's life support syst--provide natural resources/services we need (i.e. pollination)
-most species contribute to econ services--ecotourism
-would take 5-10 mill yrs for natural speciation to rebuild lost biodiversity
-man
Underlying Causes of Extinction
-population growth
-rising resource use
-undervaluing natural capital
-poverty
HIPPCO
-acronym for most important direct causes of extinction
Habitat destruction/degradation/fragmentation
Invasive species
Population growth/increasing use of resources
Pollution
Climate change
Overexploitation
Habitat Fragmentation
-a large intact area of habitat is divided into smaller isolated patches
Major Effects of Habitat Fragmentation/Loss
-decrease tree cover
-block animal migration routes
-divide pop's of species into increasingly isolated groups that are more vulnerable
-creates barriers that limit abilities of species to disperse, colonize new areas, locate needed food, find mates
-leav
Island Species
-more vulnerable b/c they must now adapt and learn to work as a smaller group
-could mean less food and some w/o mates
Nonnative Species
Benefits: provide more food, help control pests, give shelter, medicinal, aesthetic enjoyment
Harmful Effects: lack of natural predators, can trigger ecological disruptions
-i.e. Kudzu vine
Bioaccumulation/Biomagnification
-fat-soluble chemicals in pesticides accumulate in fatty tissues of animals
-concentration is biologically magnified and gets higher as it goes up the food chain
-i.e. DDT
Colony Collapse Disorder
-most/all of a species in a population mysteriously disappear
-i.e. honeybees
-could be caused by parasites, fungus, viruses, bacteria, pesticides, or poor nutrition leading to stress
Poaching
-illegally killing an animal for valuable parts
Bush Meat
-indigenous people used to sustainably hunt for it before b/c they couldn't estab a farm or agr due to growing populations and political instability
-now is becoming more widespread, leading to local extinction
-also helped spread HIV/AIDS and Ebola to hu
Convention on Biological Diversity
-ratified by 191 countries
-focuses on ecosyst's, not individual species
Endangered Species Act of 1973
-designed to identify/protect endangered species
-most far-reaching enviro law adopted by a nation
-forbids fed agencies (except Defense) to carry out/fund/authorize projects that would jeopardize any of those species or their habitat
-includes 1370 speci
Wildlife Refuges
-National Wildlife Refuge System started 1903 w/ T Roos
-most serve as wetland sanctuaries
Gene and Seed Banks
-preserve genetic info/endangered plant species
-store seeds in refrigerated, low-humidity environments
Botanical Gardens/Arboreta
-contain many of world's known plant species
-but hold small fraction of world's rare/threatened plant species
-too little space and funding
Wildlife Farms
-raising individuals on farms for commercial sale takes some pressure of endangered/threatened species
-also can educate visitors
Zoos
-goal is to reintro species into protected wild habitats
-use egg pulling, captive breeding, artificial insemination, embryo transfer, incubators, and cross fostering
Precautionary Principle
-better safe than sorry
-take precautionary measure to prevent/reduce harm to human health or enviro
Green Belt Movement
-main goal is to plant and protect trees to combat deforestation and provide fuelwood
-women are paid a small amount for each surviving plant
-reduces soil erosion, gives shade and beauty, helps slow projected climate change
Old-Growth (Primary) Forest
-uncut or regenerated forest that hasn't been severely disturbed by human activities or natural disasters for a very long time
-reservoirs of biodiversity, provide niches for many wildlife species
Second-Growth Forest
-forest that went through secondary ecological succession
-devel after trees have been removed by human activities or natural forces
Tree Plantation
-grow 1 or 2 tree species, clear-cut when they're commercially valuable, then replant and start cycle over
-lack of diversity and sustainability, depletes topsoil
Ecological Services of Forests
-supply energy flow and chemical cycling
-reduce soil erosion
-absorb/release water
-purify water/air
-influence local/regional climate
-store atmospheric carbon
-provide numerous wildlife habitats
Economic Services of Forests
-fuelwood
-lumber
-pulp to make paper
-mining
-livestock grazing
-recreation
-jobs
Harm From Building Roads into Forests
-have to do this to harvest timber
-but paves the way to fragmentation, destruction, and degradation
-increases erosion/sediment runoff into waterways
-loss of biodiversity
-exposes forests to invasion by nonnative pests, diseases, and wildlife species
Selective Cutting
-cutting intermediate-aged or mature trees in a forest singly or in small groups
Clear-Cutting
-most common harvesting method
-remove all trees in an area
-most efficient
Advantages: high timber yields, max profits in shortest time, reforest w/ fast-growing trees, good for tree species that need full/moderate sunlight
Disadvantages: reduces biodive
Strip Cutting
-more sustainable version of clear-cutting
-clear-cut a strip of trees within a corridor narrow enough to allow natural forest regeneration
Surface Fires
-burns undergrowth/leaf litter on forest floor
-allows wild animals to escape
-prevents more dangerous fires from occurring, gives nutrients back to soil
Crown Fire
-dangerous fire that burns whole tree
-occurs if forest hasn't had a fire in a while
-destroys most vegetation, kills wildlife, increases soil erosion, and burns/damages human structures
Ways to Manage Forest Fires
-Smokey Bear education campaign
-prescribed fires
-allow fires on public land to burn
-protect structures in fire-prone areas
-thin forests in fire-prone areas
Major Harmful Effects of Deforestation
-decreased soil fertility from erosion
-runoff of eroded soil into aquatic systems
-premature extinction of species with specialized niches
-loss of habitat for native and migratory species
-regional climate change from extensive clearing
-release of CO2
Certified Timber
-use a logo to assure buyers that the product has come from a forest that was managed in an environmentally and socially responsible manner
Reduce Need to Harvest Trees
-improve efficiency of wood use
-make paper using other fibers
-decrease use of wood as fuel
Reduce Severity of Fuelwood Crisis
-estab small plantations of fast-growing fuelwood trees/shrubs
-burn wood more efficiently
-solar/wind-generated electricity
-burn garden waste
Rangelands
-unfenced grasslands in temperate/tropical climates that supply forage
-vegetation for grazing/browsing animals
Pastures
-managed grasslands or fenced meadows
-usually planted with domesticated grasses or other forage crops
Overgrazing
-when too many animals graze for too long
-damages grasses/roots
-exceeds carrying capacity of rangeland
-reduces grass cover
-compacts soil and exposes it to erosion
-encourages invasion of once-productive rangeland species that cattle don't eat
Ways to Reduce Overgrazing
-rotational grazing (confine cattle to certain areas at different times and keep them moving)
-suppress growth of unwanted invader plants
-controlled short-term trampling by large livestock
-replant severely degraded areas and apply fertilizer
Problems with US National Parks
-extremely popular
-causes noise, congestion, pollution, damage/destruction to vegetation/wildlife
Buffer Zone
-area around a park in which there are still restrictions to protect animals
Habitat Corridors
-connections between isolated reserves to allow species to move and migrate more
Wilderness Act 1964
-allowed gov't to protect undeveloped tracts of public land from development
-most areas are threatened habitat islands surrounded by developed land
-buffer zones/habitat corridors would improve this system
Biodiversity Hotspot
-areas especially rich in plant species found nowhere else that are in great danger of extinction
Ecological Restoration
-repairing the damage caused by humans to biodiversity and dynamics of natural ecosystems
-i.e. replanting forests, restoring grasslands/coral reefs/wetlands/stream banks, reintroducing native species, removing invasive species, freeing river flows by rem
Four-Point Strategy
-identify causes for degradation
-stop abuse by eliminating or sharply reducing these factors
-reintro key species to help restore natural ecological processes
-protect area from further degradation and allow secondary ecological succession to occur
Reconciliation Ecology
-form of conservation biology
-focuses on inventing, establishing, and maintaining new habitats to conserve species diversity in places where people live, work, and play
Ways to Sustain Earth's Terrestrial Biodiversity
-adopt a forest
-plant/take care of trees
-recycle paper/buy recycled paper products
-buy sustainably produced wood and wood prod's
-choose wood substitutes
-help restore nearby degraded forest/grassland
-landscape yard w/ diversity of native plants