Forest Ecology Chapter 12

Forests Temperate: cm even precip throughout year, temperatures -30 to 30 C, oak, hickory, beech, hemlock, maple, elm are plants; animals: squirrels, rabbits, birds, deer, bobcats, foxes Tropical: >200 cm/yr precip even throughout year, C, plants: trees like mahogany, orchids, bromeliads, vines, palms, buttressed trunks shallow roots; animals: birds, bats, sm. Mammals, insects Taiga: cm precip mostly as snow, very cold temperatures, plants: Evergreen conifers, pine, fir, and spruce, animals: woodpeckers, hawks, moose, bear, weasel, lynx, fox wolf, hares, shrews

FORCING FUNCTIONS Factor that determines the structure/function of an ecosystem Hydrology: water topography light fire Nutrient cycling or availability

Range of tolerance each pop has range of tolerance in physical and chem env individuals may have slight differences range is usually average conditions genetics, age, health total range and optimum range

law of tolerance The existence, abundance, and distribution of species in an ecosystem are determined by whether the levels or one or more physical or chemical factors fall within the range tolerated by that species. Shelford’s law-presence and success of an organism depend upon the extent to which a complex of conditions are satisfied-excess or too little of these conditions are the limits of tolerance

limiting factor principle too much or too little of any abiotic factor can limit or prevent growth of a population, even if all other factors are at or near the optimum range of tolerance. 1) hydrology 2)soil 3)nutrients 4)sunlight 5) temperature 6) dissolved oxygen in aquatic systems 7) salinity

Natural resources are vital to us We need resources Soils: agriculture, natural communities Water: drinking, agriculture, wildlife Wildlife and fisheries: game, nongame, and marine species Rangeland: livestock Minerals: mined nonrenewable resources

Maximum sustainable yield Maximum sustainable yield = aims to achieve the maximum amount of resource extraction Without depleting the resource from one harvest to the next Populations grow most rapidly at an intermediate size Population size is about half its carrying capacity Managed populations are well below what they would naturally be Reducing populations so drastically affects other species and can change the entire ecosystem

Ecosystem-based management Ecosystem-based management = managing the harvesting of resources to minimize impact on the ecosystems and ecological processes Carefully managing ecologically important areas Considering patterns at the landscape level Protecting some forested areas It is challenging for managers to determine how to implement this type of management Ecosystems are complex, and our understanding of how they operate is limited

Adaptive management evolves and improves Adaptive management = systematically testing different management approaches and aiming to improve methods Monitoring results and adjusting methods as needed A fusion of science and management Time-consuming and complicated The 1994 Northwest Forest Plan resolved disputes between loggers and preservationists over the remaining old-growth temperate rainforests in the continental U.S. Allowed limited logging Protected species and ecosystems Science-guided management in Oregon, Washington, and California

Forest Management Forests cover over 30% of Earth’s land surface Provide habitat, maintain soil, air, and water quality, and play key roles in biogeochemical cycles Provide wood for fuel, construction, paper production Foresters, professionals who manage forests through the practice of forestry, must balance ecosystem services with demand for wood products

Ecological value of forests One of the richest ecosystems for biodiversity Structural complexity houses great biodiversity A forest provides many ecosystem services Stabilizes soil and prevents erosion Slows runoff, lessens flooding, purifies water Stores carbon, releases oxygen, moderates climate

Economic value of forests Benefits: fuel, shelter, transportation (boats), paper Helped society achieve a high standard of living Logging Locations: Boreal Forests: Canada, Russia Rainforests: Brazil, Indonesia Conifer Forests/Pine Plantations: U.S. In 2005, over 1/3 all forests were designated for timber production

Demand for wood leads to deforestation Deforestation = the clearing and loss of forests Alters landscapes and ecosystems Degrades soil Causes species decline and extinction Ruins civilizations Adds carbon dioxide to the air Developing countries boost their economies and get land for their growing populations by logging forests

Deforestation in America and Canada Deforestation propelled the westward expansion and growth of America and Canada Eastern deciduous forests were the first to be logged for farms and to build cities (i.e., Chicago) Timber companies moved south to the Ozarks and west to the Rockies

Loggers moved westward, searching for large trees Primary forest = natural forest uncut by people Little remained by the 20th century Second-growth trees = grown to partial maturity after old-growth timber has been cut

Loggers lose their jobs with deforestation As each region is deforested, the timber industry declines and moves on Local loggers lose their jobs Once the remaining ancient trees of North America are gone, loggers will once again lose jobs Companies will simply move to another area The scarcity of remaining old-growth trees fuels scientific concerns and empassions environmentalists

Deforestation is proceeding rapidly worldwide Uncut tropical forests still remain in many developing countries Technology allows for even faster exploitation Deforestation is rapid in places such as Brazil and Indonesia Developing countries are so desperate for economic development, they have few logging restrictions Short-term economic benefits go to foreign multinational corporations Governments often help companies, at the expense of native people

“Timber famine” fears spurred forest protection National forest system = a system of forest reserves and public lands To grow trees, produce timber, protect watersheds, and ensure future timber supplies Resulted from depletion of U.S. forests and fear of a “timber famine” 77 million ha (191 million acres); 8% of the U.S. land area The U.S. Forest Service was established in 1905 Manage forests for the greatest good of the greatest number in the long run, including logging

Federal agencies own land in the U.S.

Timber is extracted from public and private land Timber is extracted by private companies, even on public land Forest Service employees plan and manage timber sales and build roads The companies log and sell the timber for profit

Most logging occurs on private land But, millions of cubic feet per year are still logged from national forests Timber harvesting remains stable in developed countries Timber companies manage forests according to the maximum sustained yield approach Management on public lands reflects economic forces, along with social and political ones These change over time Public concern, changing management philosophies and economics caused harvests to decrease

Plantation forestry The timber industry focuses on timber plantations Fast-growing species Monocultures Even-aged trees = all trees are the same age Trees are cut at the end of the rotation time and replanted Plantations are crops, not functional forests Some harvesting methods maintain uneven-aged (mixed ages of trees and species) tree stands

Harvesting timber: clear-cutting All trees in the area are cut Most cost-efficient Greatest impact on forest ecosystems May mimic some natural forms of disturbance Destroy entire communities Soil erosion Public is outraged over this type of harvesting

Harvesting: other methods Seed-tree cutting = a small number of seed-producing trees are left standing to reseed the area Shelterwood cutting = a small number of trees are left to provide shelter for the seedlings Selection systems = only select trees are cut Single tree selection = widely spaced trees are cut Group tree selection = small patches of trees are cut All methods disturb habitat Change forest structure and composition Increase erosion, siltation, runoff, flooding, landslides

Public forests can be managed for many things Increased public awareness caused people to urge changed forest management For recreation, wildlife and ecosystem integrity, instead of logging Critics protested federal subsidies of logging companies Multiple use policy = national forests were to be managed for recreation, habitat, minerals and other uses In reality, timber production is the primary use The Forest Service loses $100 million/yr by selling timber below cost

Harvesting forests

The National Forest Management Act (1976) Mandated that plans for renewable resource management had to be drawn up for every national forest Guidelines included: Consideration of both economic and environmental factors Provision for species diversity Ensuring research and monitoring Permitting only sustainable harvests Protection of soils and wetlands Assessing all impacts before logging to protect resources

New forestry management is under attack Calls for timber cuts that mimic natural disturbances Harvesting methods are based on ecosystem approaches The Bush administration has rolled back these regulations Freed managers from requirements of the Act Loosened environmental protections Repealed President Clinton’s roadless rule, which protected 31% of national forests from road building California, Oregon, and New Mexico have sued the government to reinstate the roadless rule

Fire policy also stirs controversy For over 100 years, the Forest Service suppressed all fires But many ecosystems depend on fires Fire suppression allows woody accumulation, which produces kindling for future fires Which are much worse Housing development near forests and climate change will increase fire risk

Prescribed fires are misunderstood Prescribed (controlled) burns = burning areas of forests under carefully controlled conditions Effective May get out of control Impeded by public misunderstanding and political interference Healthy Forests Restoration Act (2003) = promotes removal of small trees, underbrush and dead trees Passed in response to forest fires

Salvage logging Removal of dead trees following a natural disturbance Seems logical, but is really destructive Snags (standing dead trees) provide nesting cavities for countless animals Removing timber from recently burned areas increases erosion and soil damage Promotes future fires Increases commercial logging in national forests Decreases oversight and public participation

Sustainable forestry is gaining ground Sustainable forestry certification = only products produced sustainably can be certified International Organization for Standardization (ISO), Forest Stewardship Council (FSC) have different standards Consumers look for logos to buy sustainably produced timber Companies such as Home Depot sell sustainable wood Encourages better logging practices

Agricultural land use Agriculture covers 38% of the Earths’ terrestrial surface 26% supports pasture, 12% supports crops The most widespread type of land use Causes tremendous environmental impacts Governments spend billions of dollars on subsidies Proponents say farmers need this insurance against bad years Critics say farmers should buy their own insurance

Wetlands have been drained for farming Many crop lands grow on former wetlands Governments have encouraged wetland draining Promote settlement and farming Transferred land to states Stimulated draining Less than half the wetlands remain

Perspectives on wetlands are changing Many people have a new view of wetlands Not worthless swamps, but valuable ecosystems Demanded regulations to safeguard remaining wetlands But, because of loopholes, wetlands are still being lost Conservation Reserve Program (1985) subsidized farmers to take highly erodable land out of production Turn it into wildlife habitat

Livestock graze one-fourth of Earth’s land Grazing can be sustainable if done carefully and at low intensity Bureau of Land Management (BLM) = owns and manages most U.S. rangeland Nation’s single largest landowner: 106 million ha (261 million acres) across 12 western states Ranchers can graze cattle on BLM lands for low fees Low fees encourage overgrazing Ranchers and environmentalists have joined to preserve ranchland against development and urban sprawl

Management of the American West Overexploitation of resources caused great damage to the American West Poor farming practices, overgrazing, farming arid lands John Wesley Powell in the late 1800s called for agencies to base management on science Farming Western lands had to account for arid conditions His ideas were ignored, contributing to failures such as the Dust Bowl of the 1930s

Parks and reserves Reasons for establishing parks and reserves include: Monumentalism = preserving areas with enormous, beautiful or unusual features, such as the Grand Canyon Offer recreational value to tourists, hikers, fishers, hunters and others Protect areas with utilitarian benefits, such as clean drinking water Use sites that are otherwise economically not valuable and are therefore easy to protect Preservation of biodiversity

Federal parks and reserves began in the U.S. National parks = public lands protected from resource extraction and development Open to nature appreciation and recreation Yellowstone National Park was established in 1872 The Antiquities Act of 1906 The president can declare selected public lands as national monuments

The National Park Service (NPS) Created in 1916 to administer parks and monuments 388 sites totaling 32 million ha (72 million acres) Includes national historic sites, national recreation areas, national wild and scenic rivers 273 million visitors in 2006

National Wildlife Refuges Begun in 1903 by President Theodore Roosevelt 37 million ha (91 million acres) in 541 sites U.S. Fish and Wildlife Service administers refuges Management ranges from preservation to manipulation Wildlife havens Allows hunting, fishing, wildlife observation, photography, education

Wilderness areas Wilderness areas = area is off-limits to development of any kind Open to the public for hiking, nature study, etc. Must have minimal impact on the land Necessary to ensure that humans don’t occupy and modify all natural areas Established within federal lands Overseen by the agencies that administer those areas

Not everyone supports land set- asides Restriction of activities in wilderness areas generated opposition to U.S. land protection policies Some western states want resource extraction and development The wise-use movement = a coalition of individuals and industries that oppose environmental protection Protecting private property, transferring federal lands to state or private hands, promoting motorized recreation on public lands Farmers, ranchers, loggers, mineral and fossil fuel industries

Wilderness protection has been weakened President George W. Bush has weakened wilderness protection Federal agencies have shifted policies and enforcement Away from preservation and conservation Toward recreation and resource extraction

Nonfederal entities also protect land Each U.S. state and Canadian province has agencies that manage resources So do counties and municipalities Land trusts = local or regional organizations that purchase land to protect it The Nature Conservancy is the world’s largest land trust Trusts protect 4.1 million ha (10.2 million acres) Jackson Hole, Wyoming is protected by a land trust

Parks and reserves are increasing internationally Many nations have established national parks Benefit from ecotourism Protected areas now cover 9.6% of the world’s land area Parks do not always receive necessary funding Paper parks = Areas protected on paper but not in reality World heritage sites = protected areas that fall under national sovereignty but are designated or managed by the United Nations 830 sites across 184 countries

Transboundary and peace parks Transboundary park = an area of protected land overlapping national borders For example, Waterton-Glacier National Parks in the U.S. and Canada Peace parks = transboundary reserves that help ease tensions by acting as buffers between nations Biosphere reserves = land with exceptional biodiversity Couple preservation with sustainable development

Biosphere reserves have several zones This can be a win-win situation for everyone

Habitat fragmentation threatens species Contiguous habitat is chopped into small pieces Species suffer

The SLOSS dilemma Which is better to protect species? A S ingle L arge O r S everal S mall reserves? Depends on the species: tigers vs. insects Corridors = protected land that allows animals to travel between islands of protected habitat Animals get more resources Enables gene flow between populations