1) human activities (such as clear-cutting for timber or conversion to cropland) or
2) natural forces (such as fire, hurricanes, or volcanic eruption)
2) reduce soil erosion
3) absorb and release water
4) purify water
5) purify air
6) influence local and regional climate
7) store atmospheric carbon
8) provide numerous wildlife habitats
•pulp to make paper
•Emergent (ex. birds)
•Canopy (ex. reptiles)
•Understory (ex. squirrels)
•Floor (ex. worms)
•Subsoil (ex. nematodes)
1) biological diversity,
2) long-term sustainable production of high-quality timber,
3) selective cutting of individual mature or intermediate-aged trees, and
4) multiple use of the forest for timber, wildlife, watershed protection, and recreation.
1) taking inventory of the site,
2) developing a forest management plan,
3) building roads into the site for access and timber removal,
4) preparing the site for harvest,
5) harvesting timber, and
6) regenerating and managing the site until the next harvest.
(Before 1960s, it was 2-3%; trees grew at about as fast as the money invested, so owners could afford to wait decades before harvesting them, normally using uneven-management)
1) clear-cutting diverse, uneven-aged forests,
2) investing the profits in something else,
3) growing new even-aged stands of trees as quickly as possible,
4) cutting them down,
5) reinvesting their money, and
6) repeating this process until the soul is exhausted.
2) habitat fragmentation and biodiversity loss,
3) exposure of forests to invasion by nonnative species, and
4) opening of once-inaccessible forests to farmers/miners/ranchers/hunters/ and off-road vehicle users (and in U.S, it disqualified the land for protection as wilderness)
•permits reforesting with genetically improved stocks of fast-growing trees
•shortens time needed to establish a new stand of trees
•takes less skill and planning that other harvesting
•usually provides the maximum economic return in the shortest time
•if done carefully and responsibly, often is the best way to harvest tree plantations and stands of some tree species that need full or moderate sunlight for growth
•eliminates most recreational value for several decades
•reduces biodiversity, disrupts ecosystem processes, and destroys and fragments some wildlife habitats
•makes nearby trees more vulnerable to being blown down by windstorms
•leads to severe soil erosion , sediment water pollution, and flooding when done on steep slopes
2) reduce the stock of nutrients once stored in trees and leaf littler,
3) diminish biodiversity,
4) make soil more prone to erosion and drying,
5) increase the rate of runoff of water and soil nutrients from the land,
6) reduce the uptake of greenhouse gas CO2 from the atmosphere, and
7) adds CO2 to the atmosphere if cleared trees are burned or allowed to decay.
2) emphasize selective cutting of individual trees or small groups of most tree species, strip cutting instead of conventional clear-cutting, not clear-cutting (including shelterwood and seed tree and shelterwood cutting) on land that slopes more than 15 degrees.
3) minimize fragmentation of remaining large blocks of forest
4) stop or sharply reduce road building into uncut forest areas
5) use road-building and logging methods that minimize soil erosion and compaction
6) leave most standing dead trees (snags) and fallen timber (boles) to maintain diverse wildlife habitats and to be recycled as nutrients
7) have timber grown by sustainable methods certified and labeled by outside certifying groups
8) includes the estimated ecological services provided by trees and a forest in estimates of their economic value
2) phasing out the harvesting of second-growth forests over a 10-20 yr period as tree plantations are phased in
3) establishing tree plantations only on truly degraded land, not on any newly cleared land or existing cropland
4) phasing out governement subsidies and tax breaks for harvesting timber from old-growth and second-growth forests and phasing in governemnt subsidies and tax breaks for establishing tree plantations on truly degraded areas
>3 deadly diseases caused by parasitic fungi that were accidentally introduced to the U.S from other countries are chestnut blight (from China), Dutch elm disease (from Asia via Europe), and white pine blister rust (from Europe)
2) spruce bud-worm and gypsy moth larvae that was accidentally introduced to the U.S from Europe in 1869, and are now established in 16 states. They can kill trees by eliminating their foliage that the trees need to carry out photosynthesis and produce food.
3) hemlock woolly adelgid, which was accidentally introduced in the U.S from Asia in 1924. During the 1990s, these insect pests have destroyed large areas of hemlock forest throughout the eastern U.S. In 1996, scientists began trying to control this invader by introducing a tiny beetle from Japan that is the natural enemy of the woolly adelgid
2) ban imported timber that might introduce harmful new pathogens or insect pests
3) remove infected and infested trees or clear-cutting infected/infested areas and burning all debris
4) treat diseased trees w/ antibiotics
5) develop disease-resistant trees
6) apply pesticides
7) use integrated pest management
2) release valuable mineral nutrients tied up in slowly decomposing litter and undergrowth
3) increase the activity of underground nitrogen-fixing bacteria
4) stimulate the germination of certain tree seeds (ex. giant sequoia, lodge-pole pine, and jack pine)
5) help control pathogens and insects
6) some wildlife species (ex. deer, elk, woodcock, quail) depend on occasional surface fires to maintain their habitats and provide food in the form of vegetation that sprouts AFTER fires.
>convinced most members of public that all forest fires are bad and should be prevented or put out
2) allow many fires in national parks, national forests, and wilderness areas to burn as long as they don’t threaten human structures and life
ex. spring of 2000- a poorly planned prescribed fire got out of hand in an area managed by the Park Service near Los Alamos, New Mexico. result was a 33-day fire that burned 19,000 hectares (47,000 acres), destroyed or damaged 280 homes, damaged 40 structures at the Los Alamos National Laboratory, and caused an estimated $1 billion in damages.
>allowing the logging companies to selectively cut or thin larger trees will not reduce the fire hazard because larger trees are difficult to ignite. smaller trees, shrub, slash fuel most fires
> solution is to reduce emissions of the offending pollutants from the coal-burning power plants, industrial plants, and motor vehicles
>in the coming decades, regional climate change due to global warming threatens forests, especially temperate and boreal forests)
> this can increase the threat of forest fires in areas that may get less precipitation and cause some types of tree species to die out in some areas
>can also reduce the pressure to clear-cut more diverse old-growth and second-growth forests
>serve as grazing lands for more than 3 million cattle and sheep each year
>provide about $4 billion worth of minerals, oil, and natural gas per year
>contain a network of more than 612,000 kilometers (380,000 miles) of roads, equal in an area to the country’s entire interstate highway system. Taxpayers pay for building and maintaining these these mostly narrow dirt roads that give private logging companies access to timber stands
>are the principal habitats for thousands of pollinator species that contribute $4 – 7 billion per year in the U.S agriculture
>provide some of the country’s cleanest drinking water (worth about $3.7 billion per year) for more than 60 million Americans in more than 3,400 communities. This single ecological service is worth more than the annual value of the timber harvested from these lands
> contain about one-third of the country’s protected wilderness area
2) using more sustainable forest management practices for timber cutting in national forests
3) having timber companies pay more for trees they harvest from national forests
4) managing national forests primarily to provide recreation and to sustain their biodiversity, water resources, and other ecological services
2) provides cheap timber–> lumber and paper prices cheap
3) improves forest health by removes diseased trees and helps prevent forest fires
4) provides jobs –> economic growth
2) ample private forestland is available to meet the country’s demand for wood
3) below-cost timber prices in national forests increases pressure for timber cutting in national & state forests and have little effect on consumer costs of lumber and paper
4) after timber companies deplete the timber and move to other areas, communities relying heavily on 25% of the proceeds from national forest timber sales experience severe economic slumps
5) recreation in national forests provide many more jobs and more income for local communities than logging does.
>ex. (2002 study) recreation, hunting, and fishing in national forests generates about 2.9 million jobs and add about $234 billion to the economy each year; logging, mining, grazing, and other extractive uses in the national forests add about 407,000 jobs and $23 billion to the economy per year
6) eliminating losses from timber sales in the national forest would save taxpayers $1.6 billion over the next 10 years
> moved to reverse decisions by the Clinton administration to block road construction in road-less areas of national forests (which makes them ineligible for protection in the National Wilderness System)
> called for eliminating long-standing requirement that the Forest Service manage national forests to protect the viability of wildlife
> dropped a requirement imposed by the Clinton administration that “ecological sustainability of resources be the overall goal of forest management”
>timber companies’ goal is to reduce management costs such as preparing complex environmental assessment documents (goal isn’t to increase activities like logging)
conservationists and elected officials worry because:
> this is a way to evade environmental regulations governing use of national forests and make increased timber cutting the primary focus
> local officials are more easily influenced by timber company interests….
> up to 60% of the wood consumed in the U.S is wasted unnecessarily through inefficient use of construction materials, excess packaging, overuse of junk mail, inadequate paper recycling, and failure to reuse wooden shipping containers
2) switch to non-wood home-building & remodeling materials such as steel framing & floor joists, aluminum framing, concrete slabs instead of wooden floor joists, and carpet instead of finished wood floors
> involves shifting from a potentially renewable resource (wood) to nonrenewable resources (ex. limestone, iron & other minerals, and crude oil) used to make these products
> uses more energy for transportation & manufacture & produces more pollution than using wood and wood products (ex. steel framing uses 13 times more energy than wood framing, aluminum for walls takes 20 times more energy than wood framing…)
3) make paper by using fiber that doesn’t come from trees
>tree-free fibers come from 2 sources: agricultural residues left over from crops such as wheat, rice, & sugar and fast-growing crops such as kenaf and industrial hemp
price will probably go down if demand increases; greater demand allows lower production costs
1) difficulties interpreting satellite images,
2) different ways of defining forest, deforestation, and forest degradation
3) political and economic factors that cause countries to hide or exaggerate deforestation
1) the important ecological and economic services they provide
2) instrumental values (usefulness to us)
3) intrinsic values (right to exist regardless of their usefulness to people)
> timber and other building materials, fuel wood, medicinal plants, edible wild fruits and plants, and fiber
indirect use values:
> soil fertility, flood control, water purification, pollution control, recreation and tourism, education, ecological services (ex. pest control, pollination), and genetic information
> future products, medicine, genetic resources, biological insights, food sources, building supplies, and future ecological services
> protection of biological diversity, maintaining cultures of local people, and continuing ecological and evolutionary processes
> humans arrived to Madagascar 1,500 years ago —> 84% tropical seasonal forests and 66%+ of its rain forests have been cut for cropland, fuel, and lumber; what is left is being cleared or burned rapidly——-> erosion from fields and hillsides ——> Madagascar = world’s most eroded country (evidence from huge quantities of eroded sediment flowing in its rivers and emptying into coastal areas)
> since 1984, the government conservation organizations, and scientists worldwide have united to slow the island’s ecological degradation; for such efforts to succeed, the population growth will have to slow dramatically (projected to almost double from 17 million to 31 million between 2002 and 2025); even with this full implementation of this internationally funded effort, Madagascar will probably still lose have its remaining plant and animal species.
> exploitive government policies
> exports to developed countries
>failure to include ecological services in evaluating forest resources
> unsustainable peasant farming
> cash crops
> cattle ranching
> tree plantations
> flooding from dams
> oil drilling
2) cattle ranching. ranchers, sometimes supported by government subsidies, often establish cattle ranches on exhausted or abandoned cropland. heavy rain and overgrazing turn the usually thin and nutrient poor tropical rain forest soils into eroded wastelands. ranchers often sell their land to new settlers, move to another area, and repeat this destructive grazing process.
3) unsustainable forms of small-scale farming that deplete soils and destroy large tracts of forests
4) clearing large areas of tropical forest for raising cash crops. Large plantations grow crops such as sugarcane, bananas, pineapples, peppers, strawberries, cotton, tea, and coffee, mostly for export to developed countries.
5) Increasing forest fires. Between 1997 and 1999, huge areas of forest burned in Indonesia, Malaysia, Brazil, Guatemala, Nicaragua, and Mexico. Farmers using fires to prepare fields for planting or cattle grazing and corporations (clearing forests and burning the remaining plant residues to establish pulp, palm oil, and rubber plantations) started most of these fires. —>highly polluted air that: sickened tens of millions of people, killed hundreds, caused billions of dollars in damage, and released large amounts of CO2 into the atmosphere.
6) mining and oil drilling
7) building dams on rivers that flood large areas of tropical forests
> accelerates flooding and reduces the recharging of aquifers by removing the tree cover (that normally slows rainfall runoff and lets it percolate downward into aquifers). for example, China’s Yangtze River basin lost about 85% of its original tree cover. In 1998, this area experienced some of the worst flooding in its history, mostly because of its lack of water-absorbing tree cover
> affects patterns of precipitation. as forest area shrinks, the flow of moisture to downwind areas can drop. for example, deforestation in the eastern and southern provinces of China as an important factor in the decline of rainfall in the northwestern China
2) using debt-for-nature swaps, conservation easements, and conservation concessions to make it financially profitable for countries to protect tropical forests. in a debt-for-nature swap, participating countries act as custodians for protected forest reserves in return for foreign aid or debt relief. More than 20 such agreements, totaling $110 million, have been established in 10 countries. In conservation easement, a private organization, country, or group of countries compensates other countries for protecting selected forest areas. With conservation concession, a nongovernmental conservation organization protects land from logging by renting it from a government. In 2000, Conservation International (CI) purchased the world’s first conservation concession from Guyana. Guyana makes at least as much money as it would from renting the forest area to a logging company and ends up protecting part of its forests. In 2001, CI was negotiating similar renting agreements with six other countries.
3) establishing an international system for evaluating and labeling timber produced by sustainable methods
4) using gentler methods for harvesting trees. for example, cutting canopy vines (lianas) before felling a tree can reduce damage to neighboring trees by 20 – 40% and using the least obstructed paths to remove the logs can halve the damage to other trees
5) supporting national and global efforts to reforest and rehabilitate degraded tropical forests and watersheds. In 1998, China’s government established a 10-yr plan to reduce timber harvests in natural forests, restore natural forests in ecologically sensitive areas, convert marginal (land on edge of cultivated areas/ easily erodible) farmland to forestland, regenerate natural forests in degraded forest areas, and increase timber production in tree plantations
6) reducing the waste and over-consumption of industrial timber, paper, and other resources by consumers, especially in developed countries.
> educate settlers about sustainable agriculture and forestry
> phase out subsidies that encourage unsustainable forest use
> add subsidies that encourage sustainable forest use
> protect forests with debt-for-nature swaps, conservation easement, and conservation concessions
> certify sustainably grown timber
> reduce illegal cutting
> reduce poverty
> slow population growth
> rehabilitation of degraded areas
> concentrate farming and ranching on already-cleared areas
> buying fuel wood or charcoal can take 40% of poor family’s income
> waterborne infectious diseases and deaths can occur as prices rise and burning wood or charcoal to boil water becomes an unaffordable luxury (aka too expensive to boil water)
> an estimated 800 million poor people who cannot get enough fuel wood burn dried animal dung and crop residues for cooking and heating. Not returning these natural fertilizers to the soil reduces cropland productivity and can increase hunger and malnutrition
2) burning wood more efficiently
3) switching to other fuels
In Australia, these trees thrive in areas with good rainfall. However, when planted in arid areas, these trees suck up so much of the scarce soil water that most other plants cannot grow—-> reduces the amount of animal food (fodder) that farmers can give to their livestock and hinders (prevents/stops/delays) replenishment of groundwater
Eucalyptus trees also deplete the soil of nutrients, produce toxic compounds that accumulate in the soil (because low rainfall), and inhibit (prevents) nitrogen uptake.
2) give village farmers incentives (motivation), such as ownership of the land or ownership of any of trees that grow on village land
3) grow the trees on community woodlots, which are easy to tend and harvest (rather than fuel wood plantations located far from where the wood is needed)
>ex. Brazilian pepper tree has invaded Florida’s Everglades National Park
>ex. Mountain goats in Washington’s Olympic National Park trample native vegetation and accelerate soil erosion
ex. polluted air kills trees in California’s Sequoia National Park, blots views at Arizona’s Grand Canyon, and car smog damages many plant species in Great Smoky Mountains National Park
Death Valley National Monument- Las Vegas wd it
Sequoia and National Park and Kentucky’s Mammoth Cave – wp in parking lot
Florida’s Everglades National Park- wd for urban areas and agriculture–> may dry up
2) to make nature more available to the public
> increase the budget for 1) adding new parkland near the most threatened parks and 2) buying private lands inside parks
> locate all new and some existing commercial facilities and visitor parking areas outside parks and provide shuttle buses for entering and touring most parks, as was done in 2000 in Zion National Park, Utah. Shuttle bus systems are also available to Yosemite, Grand Canyon, and Denali National Parks
> require private concessionaires who provide campgrounds, restaurants, hotels, and other services for park visitors to 1)compete for contracts and 2) pay franchise fees equal to 22% of their gross (not net) receipts. private concessionaires in national parks pay the government only about 6-7% of their gross receipts in franchise fees; many large concessionaires with long-term contracts pay as little as 0.75% of their gross receipts.
> allow concessionaires to rent but not OWN facilities inside parks
> provide more funds for park system maintenance and repairs. currently, there is a $4.9 billion accumulation of maintenance, repairs, and high-priority construction projects at a time when the park usage and external threats to the parks are increasing
> survey the condition and types of wildlife species in parks
> raise entry fees for park visitors and pour receipts back into parks
>Limit the number of visitors to crowded park areas
>increase the number and pay of park rangers
>encourage individuals and corporations to donate money for park and maintenance and repair
currently, 17,000+ nature reserves, parks, wildlife refugees, wilderness, and other areas provide strict or partial protection for about 10% of the world’s land area; but many are too small to protect their native wild species and receive too little protection to prevent illegal and unsustainable exploitation of their plant and animal resources
2) intermediate disturbance hypothesis: ecosystems and communities that experience fairly frequent but moderate disturbances have the greatest diversity of species
3) we should view most reserves as “habitat islands” surrounded by a “sea” of developed and fragmented land.
2) create user-friendly reserves that allow local people to use parts of a reserve or a buffer zone surrounding a reserve for sustainable timber cutting, livestock grazing, growing crops, hunting, and fishing. Also train local people as guides and local wildlife experts and hire them to help restore degraded areas.–> local people = partners in protecting a reserve from unsustainable uses, not destroyers
however, in some locales, several well-placed, medium sized, isolated reserves 1) may have a wider variety of habitats and thus preserve more biodiversity than a single large reserve of the same area, 2) may better protect more populations of endemic species with small ranges than a single large reserve, and 3) are less likely to be simultaneously devastated by a single event such as a flood, fire, disease, or invasion by a non-native species than a single large reserve
a mixture of both large and small reserves may be the best way to protect a variety of species and communities against a number of different threats
BUT! corridors can 1) threaten one-isolated populations by allowing the movement of pest species, disease, fire, and exotic species between reserves, 2) increase exposure of migrating species to natural predators, human hunters, and pollution, and 3) be costly to acquire, protect, and manage.
2) use bioinformatics (databases of biological information) and other sources of data to show the known or estimated geographic distribution of the region’s plant and animal species
3) place (superimpose) the species distribution maps onto the GIS maps of existing vegetation and protected areas to determine 1. unprotected areas, 2. gaps w/ very high species diversity, or 3. unprotected pockets of rare species.
4) use this information to close the gaps by 1. establishing new nature reserves, 2. expanding the size and shape of existing reserves, 3. adding corridors, or 4. persuading private landowners or developers to modify their existing or proposed patterns of land use
2) a emergency action strategy that identifies and quickly protects biodiversity hot spots. they are areas especially rich in plant and animal species that are found no where else and are in great danger of extinction or serious ecological disruption.
> sustain viable populations of its major native species and prevent or control populations of invasive species
> sustain its essential ecological processes such as energy flow, nutrient cycling, and succession
> maintain the evolutionary potential of its species and ecosystems
> allow sustainable human use of all or part of its area in ways that don’t harm its functioning and long-term sustainability
these goals are difficult to achieve b/c 1) nature reserves are affected by mostly unpredictable biological, cultural, economic, and political changes, and 2) their size, shape, and biological makeup often are determined by political, legal, and economic factors that depend on land ownership and conflicting public demands rather than by ecological principles and considerations
> seeks ways to get government agencies, private conservation organizations, scientists, business interests, and private landowners to reach a consensus on how to achieve common conservation objectives
> views all decisions and strategies as scientific and social experiments and uses failures as opportunities for learning and improvement
> emphasizes continual information gathering, monitoring, reassessment, flexibility, adaptation, and innovation in the face of uncertainty and usually unpredictable change
to get conflicting interests to cooperate in achieving ecological and economic sustainability is not easy and takes time, effort, and patience; but human and ecological rewards are worth the effort.
-The U.S Wilderness Act of 1964 states that a wilderness consists of areas “of undeveloped land affected primarily by the forces of nature, where man is a visitor who does not remain.”
-U.S president Theodore Roosevelt summarized what should be done w/ wilderness: “Leave it as it is. You cannot improve it.”
-U.S Wilderness Society estimates that a wilderness area should contain at least 4,000 square kilometers (1,500 square miles); otherwise it can be affected by air, water, and noise pollution from nearby human activities.
> (most important reasons:) 1) to preserve the biodiversity they contribute as a vital part of earth’s natural capital and 2) to protect them as centers for evolution in response to mostly unpredictable changes in environmental conditions
> 1) provide mostly undisturbed habitats for wild plants and animals, especially those that need a large range, 2) help protect diverse biomes from damage, and 3) provide a natural laboratory in which we can discover more about how nature works in the few remaining areas not seriously disturbed by human activities (aka, wilderness= biodiversity and wilderness bank and an eco-insurance policy)
> some analysts believe that wildernesses should be preserved because the wild species it contains has an ethical right to 1) exist (or struggle to exist) and 2) play their roles in the earth’s ongoing biological evolution and ecological processes, without human interference; aka species have intrinsic value, regardless of their usefulness to us
> 1) emphasis on wilderness protection of grasslands lowland forests, and wetland that are largely absent from the current system and 2) allowing some degraded areas to return to a more wild state
2) large, remote wilderness areas used only by people who get a permit by demonstrating their wilderness skills
3) undisturbed biologically unique areas with no human entry allowed
> rehabilitation, which involves any attempt to restore at least some of a degraded system’s natural species and ecosystem functions. ex. removing pollutants and replanting areas such as mining sites, landfills, and clear-cut forests to reduce soil erosion (basically to make it functional again, not to its original state)
> replacement, which involves replacing a degraded ecosystem with another type of ecosystem. ex. a productive pasture or tree plantation may replace a degraded forest.
> creating artificial ecosystems. ex. 1) the ecological waste water treatment systems developed by John Todd and 2) artificial wetlands developed to treat sewage in Arcata, California
– recreate important ecological niches that have been lost
– rely on pioneer species and natural ecological succession to make easier the restoration process
– control or remove harmful non-native species
– eliminate or sharply reduce those factors. ex. remove toxic soil pollutants, add nutrients to the depleted soil, adding new topsoil, and eliminating disruptive non-native species.
– if necessary, reintroduce species (especially keystone species) to restore natural ecological processes
– protect the area from further degradation and from the disruptive effects of fire
– monitor restoration efforts, assess success, and use adaptive ecosystem management to modify strategies as needed.
– speeding up natural secondary ecological succession. ex. 1. planting young trees in a clear-cut forest area and 2. preventing fires that can set back succession in areas such as degraded tropical seasonal forests
– allowing natural secondary succession to proceed. ex. much of the land set aside in 1935 as the Shenandoah National Park in Virginia in 1935 had suffered from over 200 yrs of grazing, mining, logging, and burning. Primarily by protection and allowing nature to take its course through secondary succession, most of the area is now a diverse temperate forest dominated by oak and hickory trees.
> the technology involved is similar to that in gardening and agriculture
> the process is well suited for volunteer labor needed to plant native species and weed out invasive species (until the natural species can take over)
> however, ecologists point out that preventing ecosystem damage in the first place is cheaper and more effective than any form of ecological restoration
> keep intact the world’s five remaining frontier forests, which are the earth’s last remaining true wilderness areas. they are the remaining 1) rain forests of the Amazon, central Africa, and New Guinea, and 2) temperate coniferous forests (has cone-bearing trees, mostly evergreens, that have needle-shaped or scale-like leaves) of North America, Russia, Finland, and Scandinavia.
> cease all logging of old-growth forests everywhere
> concentrate on protecting and restoring everywhere the world’s lakes and river systems, which are the most threatened ecosystems of all
> determine precisely the world’s marine hot spots, and assign them the same priority for immediate action as for those on land
> complete the mapping of the world’s terrestrial and aquatic biodiversity so we know what we have and can make conservation efforts more precise and cost-effective
> ensure the full range of the earth’s terrestrial and aquatic ecosystems are included in a global conservation strategy
>make conservation profitable. this involves 1) finding ways to raise the income of people who live in or near nature reserves so they can become partners in their protection and sustainable use, 2) providing financial help from private and government sources to governments that protect their forests and other nature reserves, and 3) helping governments understand that ecotourism, bioprospecting, and eventually greenhouse gas (carbon) trading credits for protecting remaining wild land can yield more income than logging or clearing such land for agriculture.