LOSS OF BIODIVERSITY II

ESC 556 week 10

Nature’s Last Stand

GDP vs. LPI Overpopulation & development

habitat loss

Hawaii

Polynesians 400 AD Introductions

Ants, snakes, thorny pants etc. Pre-human Hawaii

125-145 endemic species Birds

Now 35 species/24 endangered Hard to find Many non-native species

Plants 902/1935 species alien

10,000 native animals & plants

Hawaii Introduced Species

Human effects Hunting Clearing forests for agriculture Introduction

Disruption of natural immigration processes Aerial plankton Natural rafts Adaptive radiation

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

Introduced Species

Many species, few really damaging Big-headed ant

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

Hoary bat & Hawaiian monk seal 42 mammal species Common pig

100,000 Destroy understory forest cover, affect soil ecosystems, alien

plants Rats, mongooses, feral house cats Goats and cattle

HIPPO

Population HIPPO vs. OPPIH Various combinations of causes

Vancouver Island marmot

Decline in late 20th Century < 70 indivs by 2000 Remote montane habitats Clear-cutting

Hawaii Land Snails

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

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

Inbreeding depression Double dose of defective genes Fritillary butterflies vs. cheetah

Vulnerable to stochastic events Hurricane Andrew Schaus’s swallowtail

Habitat Destruction

Massive loss of species Centineal Ridge in Ecuador 70 endemic

plant species Freshwater mussel fauna of United States

damming & river pollution Clearing of forests

Maximum @ 6000-8000 years ago Agriculture 50% remains 30 % of conifer - 70% of tropical dry forests

Species – Area Relationship

Island Area # of Species

Cuba 44,164 100

Puerto Rico 3435 40

Montserrat 33 25

Saba 5 10

Redonda 1 5

Species number proportional to area 90% reduction in area – 50% species

Nature reserves Bigger reserves more robust

Tropical Rainforests

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

10 square km > Europe Perception

Timber resource, agricultural land 14% gone 3-5% in reserves in Brazil – 10% goal Not resilient Biomass aboveground

Fast decomposition – quickly converted

Synergism

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) 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 Northward movement velocity of climatic

zones Tundra

Lichens, mosses, polar bears, rein deer High mountain range species Gondwana lands

Entrapment – 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

Various levels of conservation Species populations

73% of 2290 plants in NA, < five populations

Informed action for conservation1. Factors controlling population density2. Identification of threats3. Predict the effects of management actions

What is a population?

Fixed geographic area Convenience to the investigator Scale Populations description

Density BIDE Structure

Monitoring Demographic Structure States of development

Plants: juveniles, seedlings, reproductive, senescent

Marsh gentian Invasive (bare soils), regressive (high ground

cover percentage) Individual counts

Census data

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?

Some species naturally rare Changes in population size Classifying types of rarity

Size of geographic range Habitat specificity Local population size

Barn owl Osprey

Causes of Rarity

Anthropogenic effects Patterns in the ecology of rare species Poor dispersal abilities (sedentary

species) Plants, invertebrates No migration to favorable habitats

Deterministic vs. stochastic process External and Internal Influences