ENVR SCIENCE EXAM

Human use of Bioproductive Lands

Half (51%) of all bioproductive lands are used for agriculture

• 33% Grazing/Pasture

• 18% Cropland

46% of all bioproductive lands are used JUST FOR MEAT PRODUCTION

Grasslands

Majority of grasslands have been converted to cropland/pastureland

Rangeland- ¼ of US land area

Overgrazing- occurs when animals exceed the land’s carrying capacity, leading to soil erosion

Deforestation

• Globally, 1/2 of all forests have been lost.

• By 2050, 2/3 of forest biomes will be gone

Forest Cover Changes

Most Deforestation is now happening in the most biodiverse habitats, containing 50% of the animals on 2% of the land.

Cause of deforestation

85% of deforestation is due to Agriculture.

Cause of forest degradation

85% of forest degradation is due to chopping for wood.

Old Growth Forests

Dominated by enormous trees that are centuries old and more ecologically complex than second growth forests

• majority of old growth forests in US are gone

Wetlands land use

More than half of wetlands are gone.

Have been shrinking 24,300 acres per year since 1985.

Coastal mangroves/salt marshes are disappearing due to human development

Habitat Fragmentation

• creates smaller parcels of land that can only support small populations

• Causes Inbreeding Depression (decreasing genetic diversity in species due to small population)

Edge Effects

• the habitat on the edges of forest is not good for animals as it’s less bio diverse and dominated by weed species

• When habitat is fragmented, it decreases the amount of interior habitat and increases edge effects.

How do we combat the destruction?

1. Create and expand protected areas

2. Restore degraded habitats and reconnect fragmented habitats

3. Reduce the direct and indirect causes of destruction

(Indirect- Human Population Groth

Direct- Deforestation)

Protected Areas

Only 15% of global land area (12% of US) is currently protected.Much is severely degraded or not strictly protected.

Only about 20% of biodiversity hotspots are included in protected areas.

• 30 by 30 plan seeks to triple US protected lands by 2030

Restoration Ecology

The study of the historical condition of a damaged ecosystem, with the goal of returning it to its former state.