Disturbance and plant succession in the Mojave and Sonoran ...
Terrestrial Biodiversity Chapters 11 & 12. Biodiversity Increase Factors Middle stages of succession...
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Transcript of Terrestrial Biodiversity Chapters 11 & 12. Biodiversity Increase Factors Middle stages of succession...
Terrestrial BiodiversityChapters 11& 12
Biodiversity
Increase Factors
•Middle stages of succession
•Moderate environmental disturbance
•Small changes in environmental conditions
•Physically diverse habitat
•Evolution
Decrease Factors
•Extreme environ- mental conditions
•Large environmental disturbance
•Intense environ- mental stress
•Severe shortages of key resources
•Nonnative species introduction
•Geographic isolation
Figure 11-2Page 195
Value Intrinsic (existence)- value regardless of
usefulness to us Instrumental- value based on usefulness
to us Existence- value whether we see it or get
direct use from it (nonuse) Aesthetic- appreciation of beauty (nonuse) Bequest- willingness to pay to protect
natural capita for future use
Conservation Biology Uses rapid response strategies to stem
loss & degradation of biodiversity Bioinformatics- applied science of
managing, analyzing, & communicating biological information Importance- to understand & sustain
biodiversity
Public Lands 35% of U.S. land 73% (of the 35%) is in Alaska
National parks and preserves National forests(and Xs) National wildlife refuges
National parks and preserves National forests(and Xs) National wildlife refuges
Use of Public Land1. Protecting biodiversity, wildlife
habitats, & ecological functioning of public land ecosystems
2. No government subsidies or tax breaks for using or extracting resources on public lands – user-pays approach
3. American people deserve fair compensation for extraction of any resources from their property
4. All users or extractors of resources on public lands should be responsible for any environmental damage they cause
Economist, developers, & resource extractors view public lands for their usefulness in providing timber, mineral, and other resources & ability to increase economic growth
Figure 11-7 8 important ecological services provided
by forests 7 important economic benefits of forests
Forest Growth Old-growth forest- uncut forest or
regenerated forest that has not been seriously disturbed by human activities or natural disasters for at least several hundred years
Second-growth forest- a stand of trees resulting from secondary ecological succession
Tree plantation- tree farm- managed tract with uniformly aged trees of 1 species that are harvested by clear-cutting as soon as they are commercially valuable; replanted & recut
Years of growth30
2515
10
5
Clear cut
Weak treesremoved
Seedlingsplanted
Tree Harvesting Even-aged- tree farm that consists of 1
or 2 fast-growing & economically desirable species (6-10 yr harvest)
Uneven-aged- variety of tree species at many ages & sizes
Figure 11-11Page 203
Trade-Offs
Clear-Cutting Forests
Advantages Disadvantages
Higher timber yields
Maximum economic return in shortest time
Can reforest with genetically improved fast-growing trees
Short time to establish new stand of trees
Needs less skill and planning
Best way to harvest tree plantations
Good for tree species needing full or moderate sunlight for growth
Reduces biodiversity
Disrupts ecosystem processes
Destroys and fragments some wildlife habitats
Leaves moderate to large openings
Increases soil erosion
Increases sediment water pollution and flooding when done on steep slopes
Eliminates most recreational value for several decades
Deforestation Temporary or permanent removal of
large expanses of forest for agricultural use
Natural Capital Degradation
Deforestation
•Decreased soil fertility from erosion
•Runoff of eroded soil into aquatic systems
•Premature extinction of species with specialized niches
•Loss of habitat for migratory species such as birds and butterflies
•Regional climate change from extensive clearing
•Releases CO2 into atmosphere from burning and tree decay
•Accelerates flooding Figure 11-12Page 203
Forest Cover Difficult to estimate due to lack of
satellite & radar data, unmonitored land-use change, & different definitions of what constitutes a forest
Bad News1. Human activities have reduced original
forest cover by 20-50%2. 40% of remaining forests will be
converted to other uses within 10-20 years
Good News Total temperate forests increase slightly
due to reforestation Cut areas of tropical forests have
increased tree cover from regrowth & tree farms
Forest Value Estimated economical value - $36
trillion/yr Economic savings provided by
conserving nature vs. immediate profits by exploiting nature
Government subsidies & tax incentives support destruction & degradation
Figure 11-13Page 205
Solutions
Sustainable Forestry
•Grow more timber on long rotations
•Rely more on selective cutting and strip cutting
•No clear-cutting, seed-tree, or shelterwood cuttingon steeply sloped land
•No fragmentation of remaining large blocks of forest
•Sharply reduce road building into uncut forest areas
•Leave most standing dead trees and fallen timber for wildlife habitat and nutrient recycling
•Certify timber grown by sustainable methods
•Include ecological services of trees and forests inestimating economic value
Good News Forest cover more now than in 1920 Many diverse second-growth forests
from cleared or partially cleared between 1620-1920
Every year, more wood is grown than cut
Bad News Remaining old-growth & diverse second-
growth forests have been cut & replaced with tree farms
Disrupts ecosystem processes (energy flows & chemical cycling)
Reduces biodiversity
Figure 11-14Page 207
Sudden oak death White pine blister rust Pine shoot beetle Beech bark disease Hemlock wooly adelgid
Reduce Harmful Impacts Ban imported timber Selectively remove or clear-cut infected
or infested trees Develop tree species that are
genetically resistant to common tree diseases
Conventional pesticides & biological controls
Forest Fires Surface fire- burns undergrowth & leaf
litter Crown fire- extremely hot fire; burns
whole trees & leaps from treetop to treetop
Ground fire- surface fire that goes underground & burns partially decayed leaves & peat
Protection From Fire Prevention Prescribed burning (setting controlled
ground fires to prevent buildup of flammable material)
Benefits of fires To plants & animals:
Stimulate germination of certain tree seeds
Helps control pathogens & insects
Crown Fires Advantages- clears out flammable small
trees & underbrush in high-risk areas
Disadvantages-???
Healthy Forest Initiative Law Advantages
Medium & large trees are cut down
Reduces ground-level fuel & vegetation in dry forests
Clears flammable vegetation around homes & buildings
Disadvantages Removal of tress
encourages dense growths of highly flammable young trees & rapidly growing underbrush
Leaves behind highly flammable slash (debris)
Timber Harvesting1. Pressure on Congress by timber
companies2. Forestry Service keeps money from
timber harvest3. Government subsidies
Revenue from timber sales does not cover the cost of road building, timber sale preparation, administration & other overhead costs
Trade-Offs
Advantages Disadvantages
Logging in U.S. National Forests
Helps meet country’s timber needs
Cut areas grow back
Keeps lumber and paper pricesdown
Provides jobs in nearby communities
Promotes economic growth in nearby communities
Provides only 4% of timber needs
Ample private forest land to meet timber needs
Has little effect on timber and paper prices
Damages nearby rivers and fisheries
Recreation in national forestsprovides more localjobs and incomefor local communities thanlogging
Decreasesrecreationalopportunities Figu
re 11-16Page 210
Tree-free paper Advantages- faster growth; less
pesticides; nitrogen-fixing
Disadvantages- ???
Tropical Forests Being cleared – FAST!
50,000 to 170,000 km2 / year
Problem- important ecological & economic services provided by forests
•Oil drilling•Mining•Flooding from dams•Tree plantations•Cattle ranching•Cash crops•Settler farming•Fires•Logging•Roads
•Not valuing ecological services•Exports•Government policies•Poverty•Population growth•Roads
Secondary Causes
Basic Causes
Figure 11-19Page 213
Protect most diverse andendangered areas
Educate settlers about sustainableagriculture and forestry
Phase out subsidies that encourageunsustainable forest use
Add subsidies that encouragesustainable forest use
Protect forests with debt-for-natureswaps, conservation easements,and conservation concessions
Certify sustainably grown timber
Reduce illegal cutting
Reduce poverty
Slow population growth
Reforestation
Rehabilitation of degradedareas
Concentrate farming andranching on already-clearedareas
RestorationPrevention
Solutions
Sustaining Tropical Forests
Debt-for-nature Swap Goal is to make it profitable for
countries to protect tropical forests countries act as custodians of protected forest reserves in return for foreign aid or debt relief
Sustainable farming & logging
Tropical forests- help new settlers learn how to practice small-scale sustainable agriculture & forestry; multi-layered system of agroforestry – cultivate as many as 75 species on 2.5 acres
Kenya’s Green Belt Movement- women’s self-help group establish tree nurseries raise seedlings & plant/protect a trees for each of Kenya’s people
Threats to National Parks Loggers Miners Poachers Too little money Too few employees Too small to sustain many large animal
species Invasion by nonnative species
Figure 11-20Page 215
Solutions
National Parks
•Integrate plans for managing parks and nearby federal lands
•Add new parkland near threatened parks
•Buy private land inside parks
•Locate visitor paring outside parks and use shuttle buses for entering and touring heavily used parks
•Increase funds for park maintenance and repairs
•Survey wildlife in parks
•Raise entry fees for visitors and use funds for park management and maintenance
•Limit number of visitors to crowded park rangers
•Increase number and pay of park rangers
•Encourage volunteers to give visitor lectures and tours
•Seek private donations for park maitenance and repairs
Protected Land SHOULD protect at least 20% Only 7%is strictly protected
Costa Rica By mid-1970s had established parks &
reserves for ¼ of land (6% for indigenous people)
Parks & reserves are consolidated into 8 mega-reserves designed to sustain 80% of biodiversity
Eco-tourism is now the country’s largest source of income
Large Reserves Advantages- sustain more species &
provide greater habitat diversity; minimize area of outside edges exposed to natural disturbances, invading species, & human disturbances
Disadvantages- ??
Corridors between Reserves Advantages- help support more species
& allow migration of vertebrates; seasonal migrations; allow for shifts in rage to accommodate global climate change
Disadvantages- ???
Biosphere Reserve
Core areaCore area
Buffer zone 1Buffer zone 1
Buffer zone 2Buffer zone 2
Human settlements
Tourism andeducation center
Research station
Biosphere Reserve Core area- important ecosystem hat the
government legally protects from all human activities except non-destructive research & monitoring
Buffer zone- surrounds & protects core area; emphasis on non-destructive research, education, & recreation
Transition zone (2nd buffer)- surrounds inner buffer zone; local people can engage in more intensive sustainable forestry, grazing, hunting, fishing, agriculture & recreation
Adaptive Ecosystem Management1. Maintain & restore sustainability &
biological diversity2. Seek government consensus on how to
achieve common conservation objectives
3. Use failures as opportunities for learning & improvement
4. Continual information gathering
Wilderness Undeveloped lands protected from
human exploitation (1.8% of land in lower U.S.)
Importance- to protect areas as centers for evolution
Advantages- ??
Disadvantages- keeps areas of the planet from being economically useful to humans
Fixes Restoration- return habitat to natural state Rehabilitation- return habitat to functional
or useful state without restoring original condition
Remediation- cleaning up chemical contaminants to project human health
Replacement- replace degraded ecosystem with another type of ecosystem
5 Principles for Restoration1. Mimic nature & natural processes &
ideally let nature do most of the work, usually through secondary ecological succession
2. Recreate important ecological niches that have been lost
3. Rely on pioneer species, keystone species, foundation species, & natural ecological succession to facilitate restoration
4. Control or remove harmful nonnative species
5. Reconnect small patches to create larger ones & create corridors
Concerns- encourage environmental destruction & degradation by suggesting all harm can be undone
Tropical Dry Forest In Costa Rica
Biocultural restoration- making nearby residents an essential part of restoration of degraded forest
Protecting Remaining Ecosystems & Species1. Take immediate action to preserve hot
spots2. Keep old-growth forests intact3. Complete mapping of terrestrial &
aquatic biodiversity4. Find marine hot spots5. Protect & restore lakes & rivers6. Ensure all terrestrial & aquatic
ecosystems are being conserved
7. Make conservation profitable8. Initiate ecological restoration products
worldwide