Rangeland

How Should We Manage and Sustain Grasslands? Important ecological services of grasslands: Soil formation Erosion control Nutrient cycling Storage of atmospheric carbon dioxide in biomass Maintenance of diversity

How Should We Manage and Sustain Grasslands? Almost half of the world’s livestock graze on natural grasslands (Rangelands) and managed grasslands (Pastures). We can sustain rangeland productivity by controlling the number and distribution of livestock and by restoring degraded rangeland.

Some Rangelands Are Overgrazed Overgrazing occurs when too many animals graze for too long and exceed carrying capacity of a grassland area. Grass/shrubs are damaged beyond repair Reduces grass cover Leads to erosion of soil by water and wind

Some Rangelands Are Overgrazed Desertification - The degradation of land that results in a desert Caused by overgrazing, deforestation, or overuse The worlds deserts are getting bigger Prevention of overgrazing: Rotational grazing Replant barren areas Apply fertilizer Reduce soil erosion

FORESTS

Forests Vary in Their Make-up, Age, and Origins Old-growth forest: Original forests that have not been disturbed for logging, road building, or development Sometimes called primary, ancient, virgin, or primeval forests 36% of world’s forest High biodiversity because of many specialized niches

Remaining Old-Growth Forests in the U.S.

Forests Vary in Their Make-up, Age, and Origins Second-growth forest: Area which has re-grown after a major disturbance such as fire, insect, or timber harvest 60% of world’s forest The area is reclaimed by the natural process of secondary succession Small shrubs and trees followed by the larger trees

Tree plantation (tree farm): Planted stands of a particular tree species that are maintained, harvested, and replanted Typically used for paper or particle board

Economic and Ecological Services Estimated annual value: Economic services $1.8 trillion Ecological services $4.7 trillion

Deforestation

Unsustainable Logging is a Major Threat to Forest Ecosystems Building roads into previously inaccessible forests paves the way for increased erosion, habitat fragmentation, loss of biodiversity, and invasion by non-native species. For this reason, many federal wilderness areas do not allow the construction of roads.

Three major tree harvesting methods: Selective cutting Clear-cutting Strip cutting

Mature trees are harvested individually from diverse forests Selective Cutting: Mature trees are harvested individually from diverse forests Younger trees left to harvest later Reduces crowding Removes diseased trees Encourages growth of younger trees

Clear-cutting: Removing all trees in a single pass.

Clear-cutting

Strip-cutting: A type of clear cutting that involves clear trees along the contours of the land. Less erosion

Deforestation in the tropical rainforest Amazon and the Congo

Tropical Forests Are Disappearing Rapidly Large areas of tropical forest are burned to make way for cattle ranches and crops. Soil in the rainforest is very poor Farmers burn the trees down to provide nutrients for the soil Heavy rain leaches away the nutrients so they move to another area and burn again

Not limited to the tropics

USA Swift River Valley below

Tropical Forests Are Disappearing Rapidly

Tropical Forests Are Disappearing Rapidly At least half of the world’s terrestrial plants and animals live in tropical rain forests. About 2,100 of the 3,000 plants identified by the National Cancer Institute as sources of cancer-fighting chemicals come from tropical rain forests.

The Congo

The Congo

Logging roads give access to once isolated ecosystems

The Congo

The Amazon

The Amazon

The reason Why!!!!

Forest Fires

We Can Improve the Management of Forest Fires Fire prevention programs have been very effective…too effective. Large amounts of highly flammable underbrush have accumulated Leads to larger, more destructive crown fires To reduce fire damage: Set controlled surface fires (Prescribed Fires). Allow fires to burn on public lands if they don’t threaten life and property. Clear small areas around property subject to fire.

Threats Logging interests cut down rain forest trees for timber used in flooring, furniture, and other items. Power plants and other industries cut and burn trees to generate electricity. The paper industry turns huge tracts of rain forest trees into pulp. The cattle industry uses slash-and-burn techniques to clear ranch land. Agricultural interests, particularly the soy industry, clear forests for cropland. Subsistence farmers slash-and-burn rain forest for firewood and to make room for crops and grazing lands. Mining operations clear forest to build roads and dig mines. Governments and industry clear-cut forests to make way for service and transit roads. Hydroelectric projects flood acres of rain forest.

Solutions Sustainable-logging regimes that selectively cull trees rather than clear-cut them would save millions of acres of rain forest every year. Campaigns that educate people about the destruction caused by rain forest timber and encourage purchasing of sustainable rain forest products could drive demand down enough to slow deforestation. Encouraging people who live near rain forests to harvest its bounty (nuts, fruits, medicines) rather than clear-cutting it for farmland would save million of acres. Government moratoriums on road building and large infrastructure projects in the rain forest would save many acres. From National geographic