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What's behind the biodiversity crisis?

An intro to the current threats to biodiversity which are fueling the crisis

Jennifer Dever

on 19 September 2016

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Transcript of What's behind the biodiversity crisis?

What's behind the biodiversity crisis?
1. Habitat Alteration
Habitat Loss
Habitat Fragmentation
Habitat Degradation
3. Overexploitation
overharvesting - the over use of wildlife and plant species by people for food, clothing, pets, medicine, sport and many other purposes.
Our Ecological Footprint is too BIG
Ecological Footprint = Influence a person has on both the surrounding environment and locations across the globe, "the area of productive land and water ecosystems required to produce the resources that the individual consumes and assimilate the wastes that the individual produces, wherever on Earth the land and water is located.
The U.S. comprises only 5% of the world population, yet we use >30% of the world’s resources.

How big is your footprint?


Over 1/2 of the world’s forest cover has been removed for croplands, pastures & settlements:
Shifting cultivation [subsistence farming] (60%)
Commercial logging (20%)
Cattle ranching (10%)
Cash-crop plantations (5-10%)
Fuelwood (90% of all African’s sole energy source)

Loss of Grasslands, Savanna & Shrublands
Between 1800 and 1950, as much as 97% of North America's tallgrass prairie was converted to farmland (White et al. 2000)
Loss of Wetlands
Wetlands = Lands transitional between terrestrial and aquatic systems where the water table is at or near the surface or the land is covered by shallow water
Many are ephemeral
Many endangered species dependent upon wetlands
>92% of all wetlands lost in California

Loss of Coral Reefs
Globally, >25% of all coral reefs gone (estimate from 2000)
overfishing + destructive fishing practices that degrade and destroy the habitat itself;
poor land use practices and runoff of pollutants, sediments and nutrients;
coral bleaching, associated with increasing seawater temperatures and global change; and
removal of coastal mangrove forests.

IUCN 2012 Red List Species
Background extinction rates compared to current levels:
Currently, organisms are disappearing at up to at least 1,000 times the "background levels" seen in the fossil record (Rockström et al., 2009 -Nature)
-estimates as high as 1 million times higher...
Rare species & Endemics
Narrow geographic range
Large home range
Seasonal migrants
Non-vagile species
Specialized niche requirements
Low fecundity and/or late maturation
Form permanent or temporary aggregations
Vulnerable to exploitation
Small population
Low genetic variation

Some species are more vulnerable than others
Habitat Fragmentation
Fragmentation = Formerly continuous natural habitats broken up in to smaller, less valuable patches.
The clearing of native vegetation divides habitats which were once continuous, turning them into separate fragments.
These fragments tend to become very small islands isolated from each other by crop land, pasture, logging, or development.

2 components of habitat fragmentation:
A reduction in the area covered by habitat type
A change in the habitat configuration, with the remaining habitat existing as smaller and more isolated patches

The Edge Effect
Abrupt edges alter the microclimate conditions - resulting in changes in plant community composition, mortality rates, regeneration processes
The intensity of edge microclimatic gradients depends on how sharply the two adjacent habitats differ
Temperature & humidity affected - inhospitable for native plants and animals, favorable to exotic plants and animals!

Habitat Degradation
Acid Precipitation
Climate Change
Pesticide Pollution & Biomagnification
Acid Precipitation
Smelting operations, Coal & Oil-fired power plants produce NOx & SOx emissions; these combine with moisture in atmosphere and create HCl and ClONO2
Acid precipitation lowers pH
Increases concentration of toxic metals

Climate Change
Significant increase in greenhouse gases (CO2, CH4):
Arctic & Antarctic Ice core data: Isotopes of oxygen 18O2 & 16O2 used to calculate atmospheric temp.
Record from past 740,000 years, significant correlation between GG & temp.
Increasing global temp. will push our current interglacial period to one that is warmer than any sustained period

Climate impacts on habitat:
Dramatic alterations in weather patterns
Dramatic alterations in ecosystems
Not local, or regional - GLOBAL
Scale, Duration & Probable Severity separates climate change from any other environmental issue!

Changes in precipitation, changes in ocean circulation systems, changes in ocean acidification…
Reproduction cycles shifting: birds, frogs
Loss of species in warming regions, movement of species to cooler regions
Alteration in vegetation composition
Exotic = Species living outside of its native range;
any species, including its seeds, eggs, spores, or other biological material capable of propagating that species, that is not native to that ecosystem…
2. Introduction of Exotic Species
Problem with invasive exotic species – they replace healthy, diverse ecosystems with biologically impoverished, homogeneous landscapes
Impacts of Exotic Species
A. Predators & Grazers – kill/eat native species
B. Parasites & Pathogens – tiny predators can have lethal consequences on native biota
E.g. Chestnut blight, sudden oak death, avian pox
C. Competitors (out-compete natives)
D. Hybridization (interbreed with natives, swamping out genetic diversity)
E. Ecosystem effects
Disturb productivity, nutrient cycling, soil structure

Why do some exotics become invasive?
Most imported species perish unless nurtured by humans, the “right” conditions often not met;
Increased # of introductions increases chance of success
Invasives tend to be abundant, tolerant of a wide range of conditions w/ high reproductive potential
Islands more sensitive to exotic species:
Fewer native species, greater # niches
Fewer predators, parasites, pathogens
Natives are “weaker” competitors
Disturbed ecosystems more susceptible
Makes resources available that can be exploited by invaders

Where do exotic species come from?
Unintentional Accidents
Intentional incidents
Characteristics of Invasive Plants
often possess characteristics which make them highly competitive, such as:
early maturation
profuse reproduction by seeds and/or vegetative structures
long life of seeds in the soil
adaptation for spread
production of biological toxins that suppress the growth of other plants

Some species are more vulnerable than others
Long life span & slow growth
Late age at maturity
Low reproductive capacity
Aggregate together
Subsistence Hunting
Bushmeat Crisis
N0n-timber forest products
Commercial Harvesting
currently >40% of fisheries are unsustainable (WWF study, 2009)

Collectors & the Pet Trade
Pet trade - Poorly regulated industry -
Highly profitable - $$$> $10 billion annually.
Pets sold represent depleted wild populations, While some pets (eg. Fish, reptiles, amphibians) are bred in captivity, most are taken from the wild or born of wild-caught parents.
Rare species are particularly sought after
Wild birds, reptiles, fish highly sought after

as known as:
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