Transcript The Loss of Biodiversity II (week 10)

LOSS OF BIODIVERSITY II
ESC 556 week 10
Nature’s Last Stand
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GDP vs. LPI
Overpopulation & development  habitat loss
Hawaii
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Polynesians 400 AD
Introductions
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Pre-human Hawaii
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Ants, snakes, thorny pants etc.
125-145 endemic species
Birds
Now 35 species/24 endangered
 Hard to find
 Many non-native species
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Plants
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902/1935 species alien
10,000 native animals & plants
Hawaii Introduced Species
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Human effects
Hunting
 Clearing forests for agriculture
 Introduction
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Disruption of natural immigration processes
Aerial plankton
 Natural rafts
 Adaptive radiation
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Polynesians increased the colonization rates
Pigs, rats, domestic plants
 Birds, mammals, plants
 Insects, spiders, mites
 35% of 8790 insect species alien, 4373/22070 species alien
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Introduced Species
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Many species, few really damaging
Big-headed ant
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Millions of workers
Destroy insects (pollinators)
Ripple up the food chain
vs. argentine ants
Not adapted to any such invader
Not adapted to ground-dwelling mammals
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Hoary bat & Hawaiian monk seal
42 mammal species
Common pig
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100,000
Destroy understory forest cover, affect soil ecosystems, alien plants
Rats, mongooses, feral house cats
Goats and cattle
HIPPO
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Population
HIPPO vs. OPPIH
Various combinations of causes
Vancouver Island marmot
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Decline in late 20th Century
< 70 indivs by 2000
Remote montane habitats
Clear-cutting
Hawaii Land Snails
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1900s Giant land snails from Africa
1950s predatory rosy wolfsnail
Rats, shell collectors, deforestation
50-75% of 800 native species
24/106 native species in Mauritus
Captive breeding and reintroductions
Frog Decline
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Gastric breeding frog, discovered & extinct in < one year
Golden toad of Costa Rica
2%/year since 1960
Habitat loss
Sierra Nevada – air pollution
Minnesota, chemical pollution
Oregon – increased UV light
Introduced trouts & bull frogs
Central America – fungus
Warning signal for environmental deterioration
Small Population size
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Inbreeding depression
 Double
dose of defective genes
 Fritillary butterflies vs. cheetah
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Vulnerable to stochastic events
 Hurricane
Andrew  Schaus’s swallowtail
Habitat Destruction
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Massive loss of species
Centineal Ridge in Ecuador  70 endemic plant species
Freshwater mussel fauna of United States
 damming
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& river pollution
Clearing of forests
 Maximum
@ 6000-8000 years ago
 Agriculture  50% remains
 30 % of conifer - 70% of tropical dry forests
Species – Area Relationship
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Species number proportional to area
 90% reduction in area – 50% species
Nature reserves
 Bigger reserves more robust
Island
Area
# of Species
Cuba
44,164
100
Puerto Rico
3435
40
Montserrat
33
25
Saba
5
10
Redonda
1
5
Tropical Rainforests
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7% area  50% species
Fragmentation
1% deforestation / year
15/25 hotspots: tropical rainforests
1.4 %  44% plants; 1/3 of terrestrial animals
<10% cover
Hotspots: two sides of a coin
Frontier forests
Amazon
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10 square km > Europe
Perception
 Timber
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resource, agricultural land
14% gone
3-5% in reserves in Brazil – 10% goal
Not resilient
Biomass aboveground
 Fast
decomposition – quickly converted
Synergism
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Dry periods smoke  limit rainfall
Cutdown trees  reduce rainfall  lose more trees
Forest  dry scrubland
Indonesia
 80%
committed
 < rainfall  forest fires
 Dipterocarp tree – El Nino relationship
El Nino Southern Oscillation (ENSO)
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El Nino, La Nina
Higher frequency & amplitude
Global warming
 Industrial
activity
 Cutting and burning of forests
 1.3oC - 5.7oC
 Storms, heat waves, forest fires, droughts, flooding
 Sea level rises
Global Warming & Biodiversity
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Northward movement velocity of climatic zones
Tundra
 Lichens,
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mosses, polar bears, rein deer
High mountain range species
Gondwana lands
 Entrapment
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– e.g. southern Africa
Alien species
 From
Red Sea into the Mediterranean
 4500/200,000 alien in the US – starling
 Removal of control mechanisms
Conserving Populations
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Various levels of conservation
Species  populations
 73%
of 2290 plants in NA, < five populations
 Informed action for conservation
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Factors controlling population density
Identification of threats
Predict the effects of management actions
What is a population?
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Fixed geographic area
Convenience to the investigator
Scale
Populations description
 Density
 BIDE
 Structure
Monitoring Demographic Structure
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States of development
 Plants:
juveniles, seedlings, reproductive, senescent
 Marsh gentian
 Invasive
(bare soils), regressive (high ground cover
percentage)
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Individual counts
Census data
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Census data vs. survey data
Spider orchid
80% decline in 50 years
Endangered in Britain
Chalk & limestone grassland
Cattle vs. sheep grazing
What is rarity?
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Some species naturally rare
Changes in population size
Classifying types of rarity
 Size
of geographic range
 Habitat specificity
 Local population size
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Barn owl
Osprey
Causes of Rarity
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Anthropogenic effects
Patterns in the ecology of rare species
Poor dispersal abilities (sedentary species)
 Plants,
invertebrates
 No migration to favorable habitats
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Deterministic vs. stochastic process
External and Internal Influences