NSCI 102 Ch 10
Ecological benefits of occasional surface fires
- Burn away flammable material such as dry brush to help prevent fires that are more destructive - Free valuable plant nutrients trapped in slowly decomposing litter and undergrowth - Release seeds from the cones of tree species such as lodge pole pines and stimulate the germination of other seeds such as those of the giant sequoia - Help control destructive insects and tree diseases
What percentage of the U.S. land area is forested?
30%
How has this impacted forest cover and the economy?
The strategy has paid off financially. Today, Costa Rica's largest source of income is its $2.9-billion-a-year travel and tourism industry, almost two-thirds of which involves ecotourism.
Rehabilitation
Turning a degraded ecosystem into a functional or useful ecosystem without trying to restore it to its original condition. Examples include removing pollutants from abandoned mining or industrial sites and replanting trees to reduce soil erosion in clear-cut forests.
Three ways that the demand for harvested trees can be reduced
- By producing tree-free paper, paper manufacturers can also use fibers from non-tree sources. - Reduce the use of throwaway paper products made from trees. Reusable plates, cups, cloth napkins and handkerchiefs, and cloth bags can replace such products. - By planting and harvesting a fast-growing plant (kenaf).
What can be done to solve the fuelwood crisis?
- Establish small plantations of fast-growing fuelwood trees and shrubs around farms and in community woodlots. Providing villagers with affordable and more fuel-efficient wood stoves and solar-powered ovens is another way to reduce cutting down trees for fuelwood. - Another option is stoves that burn renewable biomass, such as sun-dried roots of various gourds and squash plants, or methane produced from crop and animal wastes. Doing this would also reduce the large number of deaths caused by indoor air pollution from open fires and poorly designed stoves.
Economic services provided by forests
- Fuelwood - Lumber - Pulp to make paper - Mining - Livestock grazing - Recreation
Ways to grow and harvest trees more sustainably
- Include ecosystem services of forests in estimates of their economic value - Identify and protect highly diverse forest areas - Stop clear-cutting on steep slopes - Reduce road-building in forests and rely more on selective and strip cutting - Leave most standing dead trees and larger fallen trees for wildlife habitat and nutrient cycling
Threats to national parks and nature preserves around the world/U.S.
- Invasions by harmful nonnative species that can outcompete and reduce the populations of native species - Popularity, Between 1960 and 2017, the number of recreational visitors to U.S. national parks more than tripled, reaching about 331 million - Mining, logging, livestock grazing, coal-fired power plants, and urban development
Three approaches to managing forests more sustainably
- Maximum sustainable yield - Ecosystem-based management - Adaptive management
Actions that individuals can take to sustain terrestrial biodiversity (Fig 10.28)
- Plant trees and take care of them - Recycle paper and buy recycled paper products - Buy sustainably produced wood and wood products and wood substitutes such as recycled plastic furniture and decking - Help restore a degraded forest or grassland - Landscape your yard with diverse native plants
Six ways to prevent or reduce tropical deforestation
- Protect the most diverse and endangered areas - Educate settlers about sustainable agriculture and forestry - Subsidize only sustainable forest use - Protect forests through debt-for-nature swaps and conservation concessions - Certify sustainably grown timber - Reduce poverty and slow population growth
Strategies for sustaining terrestrial biodiversity
- Protecting species from extinction - Setting aside wilderness areas that are protected from harmful human activities - Establishing parks and nature reserves where people and nature can interact with some restrictions - Identifying and protecting biodiversity hotspots that contain a high diversity of species, which are under severe threat of extinction from human activities - Protecting important ecosystem services.
Ecosystem services provided by grasslands
- Soil formation - Erosion control - Chemical cycling - Storage of atmospheric carbon dioxide in biomass - Maintenance of biodiversity
Ecosystem services provided by forests
- Support energy flow and chemical cycling - Reduce soil erosion - Absorb and release water - Purify water and air - Influence local and regional climate - Store atmospheric carbon
Types of forest fires
- Surface fires, usually burn only undergrowth and leaf litter on the forest floor. They kill seedlings and small trees, but spare most mature trees and allow most wild animals to escape. - Crown fires, an extremely hot fire that leaps from treetop to treetop, burning whole trees. destroy most vegetation, kill wildlife, increase topsoil erosion, and burn or damage buildings and homes.
The two major factors that contribute to the richness of biodiversity found in Costa Rica
- The country's tropical location - The government's strong commitment to biodiversity conservation
Why we need to put a price tag on ecosystem services
- The earth's ecosystem services are essential for all humans and their economies - The economic value of these services is huge - These ecosystem services will be an ongoing source of ecological income, as long as the ecosystems that provide these services are used sustainably - We need to use full-cost pricing principle of sustainability to include the huge economic value of these irreplaceable ecosystem services in the prices of goods and services provided by the earth's ecosystems.
Four approaches to limiting the harmful effects of forest fires
- Use carefully planned and controlled fires, called prescribed burns, to remove flammable small trees and underbrush in the highest-risk forest areas. - Allow some fires on public lands to burn underbrush and smaller trees, as long as the fires do not threaten human-built structures or human lives. - Protect houses and other buildings in fire-prone areas by thinning trees and other vegetation in a zone around them and eliminating the use of highly flammable construction materials such as wood shingles. - To thin forest areas vulnerable to fire by clearing away small fire-prone trees and underbrush under careful environmental controls.
Harmful environmental effects of deforestation
- Water pollution and soil degredation from erosion - Acceleration of flooding - Local extinction of specialist species - Habitat loss for native and migrating species - Release of CO2 and loss of CO2 absorbtion
Negative consequences of overgrazing
-Reduces grass cover - Exposes the topsoil to erosion by water and wind - Compacts the soil which reduces its capacity to hold water - Promotes the invasion of rangeland by species such as sagebrush, mesquite, cactus, and cheat grass, which cattle will not eat
Four-step strategy for carrying out ecological restoration
1. Identify the causes of the degradation, such as pollution, farming, overgrazing, mining, or invasive species. 2. Stop the degradation by eliminating or sharply reducing these factors. 3. Reintroduce keystone species to help restore natural ecological processes, as was done with gray wolves in the Yellowstone ecosystem. 4. Protect the area from further degradation to allow natural recovery.
Points of an ecosystem approach to protecting biodiversity
1. Map the world's terrestrial ecosystems and create an inventory of the species contained in each of them, along with the ecosystem services they provide. 2. Identify terrestrial ecosystems that are resilient and can recover if not overwhelmed by harmful human activities, along with ecosystems that are fragile and need protection. 3. Protect the most endangered terrestrial ecosystems and species, with emphasis on protecting plant biodiversity and ecosystem services. 4. Restore as many degraded ecosystems as possible. 5. Make development biodiversity-friendly by providing significant financial incentives (such as tax breaks and subsidies) and technical help to private landowners who agree to help protect endangered ecosystems.
Tree plantations
A managed forest containing only one or two species of trees that are all the same age. It is also known as a tree farm or commercial forest. Old-growth or second-growth forests are often cleared for timber and then replaced by tree plantations.
Second-growth forests
A stand of trees resulting from secondary ecological succession. Such forests develop after the trees in an area have been removed by human activities, such as clear-cutting for timber or conversion to cropland, or by natural forces such as fire or hurricanes.
Extent of the conversion of original grasslands to croplands in the U.S.
After forests, grasslands are the ecosystems most widely used and altered by human activities. Only about 5% of the original grasslands in the U.S. remain. Most of the other 95% have been converted to cropland.
Old-growth forests
An uncut or regrown forest that has not been seriously disturbed by human activities or natural disasters for 200 years or more. Old-growth forests are reservoirs of biodiversity because they provide ecological niches for a multitude of wildlife species.
Biodiversity hotspots
Areas rich in highly endangered species found nowhere else and threatened by human activities. These areas have suffered serious ecological disruption, mainly due to rapid population growth and the resulting pressure on natural resources and ecosystem services. They cover only about 2% of the earth's land surface, but are home for the majority of the world's endangered species, as well as for 1.2 billion people.
How can reconciliation ecology help protect species and the ecosystems where they live?
By encouraging sustainable forms of ecotourism, people can protect local wildlife and ecosystems and provide economic resources for their communities.
How can rotational grazing protect rangeland and riparian zones from overgrazing?
Cattle prefer to graze around ponds and other natural water sources, especially along streams or rivers lined by strips of vegetation known as riparian zones. Overgrazing can destroy the vegetation in such areas. Ranchers can protect overgrazed land through rotational grazing and by fencing off damaged areas, which eventually leads to their natural restoration by ecological succession. Ranchers can also move cattle around by providing feed at selected sites and by strategically locating watering ponds or tanks and salt blocks.
Habitat corridors
Corridors between isolated reserves can benefit more species and allow migration by vertebrates that need large ranges. Corridors also allow some species to move to areas that are more favorable if climate change alters their existing areas. On the other hand, corridors can threaten isolated populations by allowing movement of fire, disease, and pest and invasive species between reserves. They can also increase exposure of migrating species to natural predators, human hunters, and pollution.
Creating artificial ecosystems
For example, artificial wetlands have been created in some areas to help reduce flooding and to treat sewage.
China's reforestation program
In 2000, China established the world's largest payments for ecosystem services (PES) program, in response to extensive flooding from deforestation. It pays individuals to stop logging forests and to reforest already logged lands. It worked. By 2010, the program had cut the country's deforestation rate in half and sharply reduced flooding. It also helped participants work their way out of poverty.
Ecological restoration of Guanacaste Park in Costa Rica
In the lowlands of Guanacaste National Park, a tropical dry forest was burned, degraded, and fragmented for conversion to cattle ranches and farms. Now it is being restored and reconnected to a rain forest on nearby mountain slopes. local farmers are paid to remove nonnative species and to plant tree seeds and seedlings started in Janzen's laboratory. Local grade school, high school, and university students and citizens' groups study the park's ecology during field trips. This project also serves as a training ground in tropical forest restoration for scientists from around the world. Research scientists working on the project give guest classroom lectures and lead field trips.
Strip cutting
Involves clear-cutting a strip of trees along the contour of the land within a corridor narrow enough to allow the natural forest to grow back within a few years. After one strip grows back, loggers cut another strip next to the first, and so on.
What effects has the reintroduction had on the park's ecosystem?
It has decreased populations of elk, the wolves' primary food source. The leftovers of elk killed by wolves have also been an important food source for scavengers such as bald eagles and ravens. They have cut in half the Yellowstone population of coyotes—the top predators in the absence of wolves. This has reduced coyote attacks on cattle from area ranches and has led to larger populations of small animals such as ground squirrels, mice, and gophers, which are hunted by coyotes, eagles, and hawks.
Ecosystem-based management
Its goal is to harvest a renewable resource such as trees in ways that minimize the harmful impacts of harvesting on an ecosystem and the ecological services it provides. This can be a useful approach. However, it is often limited because of a lack of knowledge about how ecosystems in different areas work.
The role that kenaf and similar plant materials can play in reducing demand for wood
Kenaf and other non-tree fibers such as hemp yield more paper pulp per area of land than tree farms and can be grown using fewer pesticides and herbicides. It could replace wood-based paper within 20-30 years.
How does the size of the reserve influence biodiversity?
Large nature reserves typically sustain more species and provide greater habitat diversity than do small reserves. Research also indicates that in some areas, several well-placed medium-size reserves may better protect a variety of habitats and sustain more biodiversity than a single large reserve can.
The impacts that logging roads have on forest ecosystems
Logging roads can have harmful effects, including topsoil erosion, sediment runoff into waterways, habitat loss, and loss of biodiversity. Logging roads also increase chances of invasion by disease-causing organisms and nonnative pests, as well as disturbances from human activities such as mining, farming, and ranching.
Pastures
Managed grasslands or fenced meadows often planted with domesticated grasses or other forage crops such as alfalfa and clover.
Buffer zone
Means strictly protecting an inner core of a reserve, usually by establishing one or more buffer zones in which local people can extract resources sustainably without harming the inner core.
The fuelwood crisis
More than 2 billion people in less-developed countries use fuelwood and charcoal made from wood for heating and cooking. Most of these countries are experiencing fuelwood shortages because people have been harvesting trees for fuelwood and forest products 10 to 20 times faster than new trees are being planted.
What conditions led to the rich biodiversity on madagascar?
Most of Madagascar's numerous species have evolved in near isolation from mainland Africa and all other land areas for at least 40 million years. As a result, roughly 90% of the more than 200,000 plant and animal species found in this Texas-size biodiversity hotspot are found nowhere else on the earth.
Which insect is currently devastating large areas of forest in western areas of Canada and the U.S.?
Mountain pine bark beetles
The difference between the amount of land actually protected and the amount of protected land that conservation biologists believe is needed to preserve biodiversity
No more than 6% of the earth's land is strictly protected from potentially harmful human activities. Conservation biologists call for strictly protecting at least 20% and ideally 50% of the earth's land area in a global system of biodiversity reserves.
Overgrazing
Occurs when too many animals graze an area for too long damaging or killing the grasses and exceeding the area's carrying capacity for grazing.
What are the reasons why this biodiversity is now threatened?
Primarily because of habitat loss. People have cut down or burned more than 90% of Madagascar's original forests to get firewood and lumber and to make way for small farms, large rice plantations, and cattle grazing. Huge quantities of its topsoil have run off its hills, flowing as sediment in its rivers and emptying into its coastal waters.
What percentage of forested land in the U.S. is held in public lands?
Protected forests make up about 40% of the country's total forest area, mostly in the National Forest System, which consists of 155 national forests managed by the U.S. Forest Service but owned jointly by the citizens of the United States.
Ecological benefits of grazing
Provides food for people, secures clean water and wildlife habitat, and stores carbon in the soil, which helps to mitigate climate change.
What is projected to happen to the climate and ecosystems in the Amazon Basin in the next 60 years if current rates of deforestation continue?
Removing large areas of trees can lead to drier conditions that dehydrate the topsoil by exposing it to sunlight and allowing it to be blown away. This makes it difficult for a forest to grow back in the area and tropical grassland or savanna often grows there instead. Scientists project that if current burning and deforestation rates continue, 20-30% of the Amazon Basin could become savanna by 2080.
Replacement
Replacing a degraded ecosystem with another type of ecosystem. For example, a degraded forest might be replaced by a productive pasture or tree plantation.
Restoration
Returning a degraded habitat or ecosystem to a condition as close as possible to its original one.
Reconciliation ecology (define and examples)
Science of inventing, establishing, and maintaining habitats to conserve species diversity in places where people live, work, or play. Ex. People have worked together to protect bluebirds within human-dominated habitats. In such areas, bluebird populations have declined because most of their nesting trees have been cut down. Specially designed boxes have provided artificial nesting places for bluebirds. Their widespread use has allowed populations of this species to grow.
Costa Rica's strategy for reducing deforestation and the results
The government eliminated subsidies for converting forestland to grazing lands. Instead, it pays landowners to maintain or restore tree cover. Costa Rica has gone from having one of the world's highest deforestation rates to having one of the lowest. Over three decades, forests went from covering 20% of its land to covering 50%.
Maximum sustainable yield
The is to harvest trees of an intermediate size at the midpoint of the growth curve between planting and the area's carrying capacity. This approach sounds good, but there are difficulties. Calculating the MSY is almost impossible because it is difficult to know an area's carrying capacity and the point at which the MSY has been reached. In addition, changes in environmental conditions over several decades of forest growth can change an area's carrying capacity.
The Greenbelt Movement
The main goal of this movement was to organize poor women in rural Kenya to plant and protect trees in order to replenish forests, provide fuelwood, and reduce soil erosion and stream pollution. This helped women to escape poverty by earning money for their reforestation work.
Direct causes of tropical deforestation
The major direct causes of tropical deforestation vary by location. Tropical forests in Brazil and other South American countries are cleared or burned primarily for cattle grazing and large soybean plantations. In Indonesia, Malaysia, and other areas of Southeast Asia, large plantations of oil palm trees are replacing diverse tropical forests. In Africa, the primary direct cause of deforestation is people clearing plots for small-scale farming and harvesting wood for fuel.
Clear-cutting
The most efficient and sometimes the most cost-effective way to harvest trees. It also provides profits in the shortest time for landowners and timber companies. However, clear-cutting can harm or destroy an ecosystem by causing forest soil erosion, increased sediment pollution of nearby waterways, and losses in biodiversity. It also contributes to atmospheric warming by releasing stored carbon dioxide and reducing the uptake of CO2 by forests.
What effects might destructive insects and climate change have on forests?
The primary reason for the population explosion of pine bark beetles and several other insect pests is a warmer climate with winters that do not get cold enough to kill off the insects and control their populations. The warmer winters also allow the beetles to spread to forests at higher elevations and latitudes. According to forest and wildlife scientist Phil Townsend, mountain pine bark beetles have destroyed ten times the area of conifer forests that fire has destroyed.
Ecological restoration
The process of repairing damage to ecosystems caused by human activities. Exs. replanting forests, reintroducing keystone native species, removing harmful invasive species, freeing river flows by removing dams, and restoring grasslands, coral reefs, wetlands, and stream banks
Reforestation
The replanting of forests, especially on degraded and abandoned land. Throughout the world, reforestation promotes biodiversity, conserves topsoil, and reduces flooding. It also provides firewood and helps slow climate change by removing from the atmosphere.
Why were wolves reintroduced into Yellowstone National Park?
The wolves culled herds of bison, elk, moose, and mule deer, and kept down coyote populations. By leaving some of their kills partially uneaten, they provided meat for scavengers such as ravens, bald eagles, ermines, grizzly bears, and foxes. When the number of gray wolves declined, herds of plant-browsing elk, moose, and mule deer expanded and over browsed the willow and aspen trees growing near streams and rivers. This led to increased soil erosion and declining populations of other wildlife species such as beaver, which eat willow and aspen.
Why is it an urgent priority to protect ecosystem services?
The world's ecosystems are already dominated or influenced by human activities and that such pressures are increasing as the human population, urbanization, resource use, and the human ecological footprint all expand. Without addressing such issues as poverty, population growth, urbanization, and resource use, ecosystem services will continue to decline.
The major events in the history of wilderness protection in the U.S.
Theodore Roosevelt, the first U.S. president to set aside protected areas, summarized his thoughts on what to do with wilderness: "Leave it as it is. You cannot improve it." In 1964, the U.S. Congress passed the Wilderness Act, which allowed the government to protect undeveloped tracts of U.S. public land from development as part of the National Wilderness Preservation System.
Why are tree plantations less biologically diverse and less sustainable than old-growth and second-growth forests?
They contain only one or two tree species. This makes them less biologically diverse and less sustainable than old-growth and second-growth forests. They do not provide the amount of wildlife habitat and many of the ecosystem services that diverse natural forests do. Repeated cutting and replanting of trees can eventually deplete the nutrients in the area's topsoil. This can hinder the regrowth of any type of forest on such land.
What has Costa Rica done to establish nature reserves?
They have been using government and private research agencies to identify the plants and animals that make it one of the world's most biologically diverse countries. They have created several megareserves. Each reserve contains a protected inner core surrounded by two buffer zones that local and indigenous people can use for sustainable logging, crop farming, cattle grazing, hunting, fishing, and ecotourism.
Four characteristics of a forestry certification by the Forest Stewardship Council
To become certified, operators must demonstrate that they do not cut trees at a rate that exceeds long-term forest regeneration in a given area. They must maintain roads and use harvesting systems in ways that limit ecological damage. They must also prevent unreasonable damage to topsoil and leave in place some downed wood and standing dead trees to provide wildlife habitat.
How does deforestation relate to climate change?
Tropical forests absorb and store about one-third of the world's terrestrial carbon emissions as part of the carbon cycle. Thus, in reducing these forests, we reduce their global absorption of carbon dioxide (CO2) and contribute to atmospheric warming and climate change.
Indirect causes of tropical deforestation
Underlying causes, such as pressures from population growth and poverty, push subsistence farmers and the landless poor into tropical forests, where they cut or burn trees for firewood or try to grow enough food to survive. Government subsidies can accelerate other direct causes such as large-scale logging and livestock overgrazing by reducing the costs of these enterprises.
Rangelands
Unfenced natural grasslands in temperate and tropical climates that supply forage, or vegetation for grazing (grass-eating) and browsing (shrub-eating) animals.
Who created the Greenbelt Movement
Wangari Maathai, the first environmentalist to be awarded the Nobel Peace Prize, promoted tree planting in her native country of Kenya and throughout the world in what became the Green Belt Movement.
Selective cutting
When loggers cut intermediate-aged or mature trees singly or in small groups, leaving the forest largely intact. This allows a forest to produce economically valuable trees on a sustainable basis.
Rotational grazing
When small groups of cattle are confined by portable fencing to one area for a few days and then moved to a new location
Benefits of protecting large areas as wilderness
Wilderness areas are protected islands of biodiversity and ecosystem services needed to support life and human economies both now and in the future and to serve as centers for future evolution in response to changes in environmental conditions.
Adaptive management
involves using available knowledge to harvest forests or other resources, evaluating the results, and modifying the approach or using a different approach as needed. This approach recognizes that there will be failures because of inadequate ecological knowledge and that we can learn from such failures.
