AP Environmental Science Mr. Grant Lesson 65 Forest Ecosystems And Forest Resources Forest Loss & Forest Management
Objectives: • Define the term maximum sustainable yield. • Summarize the ecological roles and economic contributions of forests. • Outline the history and current scale of deforestation. • Assess aspects of forest management and describe methods of harvesting timber.
Define the term maximum sustainable yield. • Maximum Sustainable Yield: The maximum usable production of a biological resource that can be obtained in a specific time period. The MSY level is the population size that results at maximum sustainable yield.
Summarize the ecological and economic contributions of forests. • Many kids of forests exist. • Forests are ecologically complex and support a wealth of biodiversity. • Forests contribute ecosystem services, including carbon storage. • Forests provide us timber and other economically important products and resources.
Many kinds of forests exist • Forest = any ecosystem with a high density of trees • Boreal forest = in Canada, Scandinavia, and Russia • Tropical rainforest = South and Central America, Africa, Indonesia, and southeast Asia • Temperate deciduous forests, temperate rainforests, and tropical dry forests also exist • Woodlands = ecosystems with lower density of trees • Plant communities differ due to soil and climate • Forest types = are defined by predominant tree species
Forest types • The Eastern U.S. has 10 forest types • Spruce-fir, oak-hickory, longleaf-slash pine • The Western U.S. holds 13 forest types • Douglas fir, ponderosa pine, pinyon-juniper woodlands
Forests are ecologically complex • Forests are some of the richest ecosystems for biodiversity • They are structurally complex, with many niches • They provide food and shelter for multitudes of species • Fungi and microbes have parasitic and mutualistic relationships with plants • Plant diversity leads to greater overall organism diversity • Succession changes species composition • Old-growth forest diversity exceeds that of young forests • They have higher structural diversity, habitats, and resources
A cross-section of a mature forest The scarlet tanager lives in the eastern U.S. temperate deciduous forest
Forests provide ecosystem services Forests provide cultural, aesthetic, health, and recreation values Forests also provide vital ecosystem services Stabilize soil and prevent erosion Slow runoff, prevent flooding, purify water Store carbon, release oxygen, influence weather patterns, and moderate climate Roots draw minerals to surface soil layers Plants return organic material to the topsoil as litter
Carbon storage helps limit climate change • Carbon storage by forests is of great international interest • Nations debate how to control climate change • Trees absorb carbon dioxide and store carbon • The world’s forests store 280 billion metric tons of C • Cutting forests worsens climate change • Dead plants decompose and release carbon dioxide • Fewer trees soak up less carbon dioxide • Preserving forests keeps carbon out of the atmosphere
Forests provide us valuable resources Benefits: medicines, food, fuel, shelter, ships, paper Help us achieve a high standard of living Logging locations: Boreal forests: Canada, Russia Rainforests: Brazil, Indonesia Conifer forests/pine plantations: U.S. In 2010, 30% of all forests were designated for timber production
Outline the history and current scale of deforestation. • We have loss forests to clearance for agriculture and over-harvesting for wood. • Developed nations deforested much of their land as settlement, farming and industrialization proceeded. • Today deforestation is taking place most rapidly in developing nations. • Carbon offsets are one new potential solution to deforestation.
Demand for wood leads to deforestation Deforestation = the clearing and loss of forests Changes landscapes and ecosystems Reduces biodiversity Worsens climate change Disrupts ecosystem services Ruins civilizations Although the rate of deforestation is slowing, we still lose 12.8 million acres/year
Deforestation fed the growth of the U.S. Deforestation propelled the expansion and growth of the U.S. and Canada Eastern deciduous forests were the first to be logged Timber companies moved south to the Ozarks, west to the Rockies 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 Secondary forest = contains second-growth trees Smaller trees, very different species and structure
Most primary forest is gone The entire eastern half of the continent used to be covered in primary forest Most primary forest was cut for agriculture and timber
Loggers lose their jobs with deforestation • As each region is deforested, the timber industry declines and timber companies move 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 • Most move to developing countries
Rapid deforestation in developing nations • Uncut tropical forests still remain in many developing countries (Brazil, Indonesia, and West Africa) • Technology allows for even faster exploitation • Developing countries are so desperate for economic development, they have few logging restrictions • Concession = corporations pay the government for the right to extract resources • Temporary jobs are soon lost, along with the resources • Wood is exported to North America and Europe
Deforestation affects people • In Malaysia, foreign corporations have deforested millions of acres of tropical rainforest • Affecting 22 tribes of hunter-gatherers • The government did not consult the tribes • Deforestation decreased game • Oil palm agriculture’s pesticides and fertilizers killed fish • The people peacefully protested • The government wants to convert tribes to farmers
Palm oil plantations • Palm oil is used in snack foods, soaps, cosmetics, biofuel • Borneo has lost most of its forest cover • Clearing encourages further development and illegal logging
Solutions to deforestation are emerging • Conservation concessions = organizations team up to reduce deforestation and illegal logging • Carbon offsets = curb deforestation and climate change • Forest loss causes 12–25% greenhouse gas emissions • The Kyoto Protocol does not address this • REDD = Reducing Emissions from Deforestation and Forest Degradation • From the 2009 Copenhagen climate conference • Wealthy nations would pay poor nations to conserve forests
REDD • The Copenhagen conference ended without a binding agreement • The REDD plan fell through • But some of the $100 billion/year going to poor nations may go to REDD • Guyana is taking a leading role in REDD • It is poor financially but rich in forests • Cutting forests would provide $580 million/year • Norway will pay $20 million in 2010 for conservation and up to $250 million in 2015
Assess aspects of forest management and describe methods of harvesting timber. • Forestry is one type of resource management. • Resource managers have long managed for maximum sustainable yield and are beginning to implement ecosystem-based management and adaptive management. • The U.S. National forests were established to conserve timber and allow its sustainable extraction. • Most U.S. timber today comes from private lands. • Plantation forestry, featuring single species, even-aged stands, is widespread and growing.
Assess aspects of forest management and describe methods of harvesting timber. • Harvesting methods include clear-cutting and other even-aged techniques, as well as selection strategies that maintain uneven-aged stands that more closely resemble natural forest. • Foresters are beginning to manage for recreation, wildlife habitat, and ecosystem integrity. • Fire policy has been politically controversial, but scientists agree that we need to address the impacts of a century of fire suppression. • Climate change is affecting forests. • Certification of sustainable forest products allows consumer choice in the marketplace to influence forestry practices.
Forest management Forestry (silviculture) = forest management Sustainable forest management is spreading Foresters = professional managers who must balance demand for forest products (short-term benefits) vs. the importance of forests as ecosystems (long term) Resource management =strategies to manage and regulate potentially renewable resources Sustainable management does not deplete resources Managers are influenced by social, political, and economic factors
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 fastest at an intermediate size Population size is at half its carrying capacity Harvesting to keep the population at this size results in maximum harvest While sustaining the population
Maximum sustainable yield has problems • Managed populations are much smaller than they would naturally be • Reducing populations so drastically affects other species • Changing the entire ecosystem • Trees are cut long before they grow to maximum size • Changing forest ecology • Eliminating habitats
Ecosystem-based management Ecosystem-based management = managing resource harvesting to minimize impacts on ecosystems and ecological processes Sustainably certified forestry plans protect areas Restore ecologically important habitats Consider patterns at the landscape level Preserve the forest’s functional integrity It is challenging to implement this type of management Ecosystems are complex Our understanding of how they operate is limited
Adaptive management Adaptive management = testing different approaches and aiming to improve methods through time Monitoring results and adjusting methods as needed Time-consuming and complicated, but effective The 1994 Northwest Forest Plan resolved disputes between loggers and preservationists over the last U.S. old-growth temperate rainforests The plan let science guide management It allowed limited logging while protecting species and ecosystems
Fear of a “timber famine” spurred forest protection • Depletion of eastern U.S. forests caused alarm • National forest system = public lands set aside to grow trees, produce timber, protect watersheds, and ensure future timber supplies • 77 million ha (191 million acres)—8% of U.S. land area • The U.S. Forest Service was established in 1905 • Manages forests for the greatest good of the greatest number in the long run • Management includes logging and replanting trees
Timber is extracted from public and private land • Private companies extract timber from public land • The Forest Service plans and manages timber salesand builds roads • Companies log and sell the timber for profit Taxpayers subsidize private timber harvesting on public land
Logging on private vs. public land • Most U.S. logging occurs on private land owned by timber companies or small landowners • Companies use the maximum sustained yield approach • Management on public lands reflects social and political factors that change over time • Public concern, changing management philosophies, and economics have caused harvests to decrease • But the secondary forests that replace primary forests are less ecologically valuable
Plantation forestry • The timber industry focuses on timber plantations • Fast-growing, single-species monocultures • Even-aged stands= all trees are the same age • Rotation time = trees are cut after a certain time • The land is replanted • Uneven-aged stands = mixed ages of trees and species Tree plantations are crops, not ecologically functional forests
Harvesting timber: clear-cutting • All trees in the area are cut • Most cost-efficient • Greatest ecological impact • May mimic some natural disturbance (e.g., storms) • Leads to soil erosion • Public outrage caused companies to use other harvesting methods • Clear-cutting destroys entire communities
Harvesting: other methods • Seed-tree approach = a few seed-producing trees are left standing to reseed the logged area • Shelterwood approach = some trees are left to provide shelter for the seedlings as they grow • 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 and affect species • Change forest structure and composition • Increased runoff, flooding, erosion, siltation, landslides
Harvesting forests Clear-cut logging Selection logging Seed-tree and shelterwood logging
Managing public forests • Increased public awareness caused people to urge that forests be managed for recreation, wildlife, and ecosystem integrity, instead of only for logging • Critics protest federal subsidies of logging companies • Multiple use policy = national forests are to be managed for recreation, habitat, minerals, and other uses • In reality, timber production is the primary use The Forest Service loses $100 million/year of taxpayer money and increased harvest by selling timber below cost
The National Forest Management Act (1976) • Every national forest must formulate plans for renewable resource management that: • Consider both economic and environmental factors • Provide for and protect regional diversity • Ensure research and monitoring of management • Permit only sustainable harvest levels • Ensure that profit alone does not guide harvest method • Protect soils and wetlands • Assess all impacts before logging to protect resources
New forestry • U.S. Forest Service programs: • Manage wildlife, non-game animals, endangered species • Push for ecosystem-based management • Run programs for ecological restoration • New forestry = timber cuts that mimic natural events • Sloppy clear-cuts mimic windstorms
Politics influences forestry management • The Bush administration rolled back regulations in 2004 • Freed managers from requirements of the National Forest Management Act • Loosened environmental protections • Restricted public oversight • Repealed President Clinton’s roadless rule, which protected 31% of national forests from logging • State governors had to petition the federal government to protect areas • Court rulings reinstated the roadless rule in 2009
Fire policy also stirs controversy • For over 100 years, the Forest Service suppressed all fires • But many ecosystems depend on fires • Excess vegetation produces kindling for future fires • In the wildland-urban interface, housing developments that are near forests are vulnerable to forest fires Catastrophic fires have become more numerous recently
Prescribed fires are misunderstood • Prescribed (controlled) burns = burning areas of forests under carefully controlled conditions • Clear away fuel loads, nourish soil, encourage growth of new vegetation • Are time-intensive • Are 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 • It seems logical, but is really destructive • Snags (standing dead trees) provide nesting and roosting cavities for countless animals • Removing timber from recently burned areas increases erosion and soil damage • Impedes forest regeneration and promotes future fires
Climate change is altering forests • The U.S. is warming and getting drier and will get worse • Pests kill huge areas of trees, particularly plantations • Dead trees do not remove carbon dioxide • Intensifying climate change • Woodlands, shrublands. or grasslands may replace forests Increased fires and pests destroy large areas of the U.S.
Progress toward sustainable forestry is mixed • The world is still losing forested land • But advances are being made toward sustainable forestry
Sustainable forestry is gaining ground • Sustainable forest certification = products produced sustainably can be certified by organizations • The Forest Stewardship Council (FSC) has the strictest standards • Companies such as Home Depot sell sustainable wood, encouraging better logging practices • Consumers look for logos to buy sustainably produced timber Strong certification standards drive sustainability