SUSTAINING BIODIVERSITY : THE ECOSYSTEM APPROACH. MAJOR THREATS TO FOREST ECOSYSTEMS FOREST VARY IN THEIR AGE, MAKE-UP, AND ORIGINS There are two major types of natural forests, based on their age and structure:
SUSTAINING BIODIVERSITY :
THE ECOSYSTEM APPROACH
FORESTS PROVIDE IMPORTANT ECONOMIC AND ECOLOGICAL SERVICES
Through photosynthesis, forests help stabilize the earths temperature and slow projected climate change as a part of the global carbon cycle.
HALF OF THE WORLD’S FOREST ARE CUT DOWN
DEFORESTATION: Is the temporary or permanent removal of large expanses of forest for agriculture, settlements, or other uses.
Surveys by the World Resources Institute (WRI) indicate that over the past 8,000 years, human activities have reduced the earth’s original forest cover by about 46%, with most of this loss occurring in the last 60 years.
NATURAL CAPITAL DEGRADATION
Harmful environmental effects of deforestation.
CAUSES OF TROPICAL DEFORESTATION ARE VARIED AND COMPLEX
NATURAL CAPITAL DEGRADATION
Major Causes of the Destruction and Degradation of tropical Forests
A 2005 study by forest scientists found that widespread fires in the Amazon basin are changing weather patterns by raising temperature and reducing rainfall.
This is converting large deforested areas of tropical forests to tropical grassland (savanna) , if the current burning and deforestation continues, 20-30% of the amazon will turn into a savanna in the next 50 years. And most of it will become a savanna by 2080.
Philippines and the African country of Nigeria on the other hand are experiencing settler farming, cash crops and logging, which have made them lost most of their once-abundant tropical hardwood forest.
HOW SHOULD WE MANAGE AND SUSTAIN FORESTS?
We can sustain forests by emphasizing the economic value of their ecological services, removing government subsidies that hasten their destruction, protecting old-growth forests, harvesting trees no faster than they are replenished, and planting trees.
WE CAN IMPROVE THE MANAGEMENT OF FOREST FIRES
In the USA, the Smokey Bear educational campaign undertaken by the Forest Service and the National Advertising Council has prevented countless forest fires.Ecologists warn that trying to prevent all forest fires may increase the likelihood of destructive crown fires by allowing accumulation of highly flammable under-brush and smaller trees in some forests.
Ecologist and forest fire experts have proposed several strategies for reducing fire-related harm to forests and people.
1ST APPROACH: Is to set small, contained surface fires to remove flammable trees and under-brush in the highest-risk forest areas.
2nd APPROACH: Is to allow many fires on public lands to burn, thereby removing flammable underbrush and smaller trees, as long as the fires do not threaten human structures and life.
3rd APPROACH: Is to protect houses and other buildings in fire-prone areas by thinning a zone of about 60 meters(200 feet) around them and eliminating the use of flammable materials such as wooden roofs.
4th APPROACH: Is to thin forest areas vulnerable to fire by clearing away small fire-prone trees and underbrush under careful environmental controls. Many forest fire scientist warn that such thinning should not involve removing economically valuable medium size and large trees for two reasons.
First reason: These are the most fire-resistant trees.Second reason: Their removal encourages dense growth of more flammable young trees and underbrush leaves behind highly flammable slash, or brush and deadwood left over after thinning.
It is estimated that within 2-3 decades, we could essentially eliminate the need to use trees to make paper.
Sustaining Tropical Forests
Encourage regrowth through secondary succession
Rehabilitate degraded areas
Concentrate farming and ranching in already-cleared areas
Protect the most diverse and endangered species
Educate settlers about sustainable agriculture and forestry
Subsidize only sustainable forest use
Protect forests with debt-for-nature swaps and conservation concessions
Certify sustainably grown timber
Slow population growth
HOW SHOULD WE MANAGE AND SUSTAIN GRASSLANDS?
We can sustain the productivity of grasslands by controlling the number and distribution of grazing livestock and by restoring degraded grasslands.
Some Rangelands Are Overgrazed
Grassland provide many important ecological services, including soil formation. Erosion, control, nutrient cycling, storage of atmospheric carbon dioxide in biomass, and maintenance of biodiversity.
Rangelands are unfenced grasslands in temperate and tropical climates that supply forage, or vegetation for grazing(grass-eating) and browsing(shrub-eating) animals.
Livestock also graze in Pastures, which are managed grasslands or enclosed meadows usually planted with domesticated grasses or other forage.
Overgrazing occurs when too many animals graze for too long and exceed the carrying capacity of a rangeland area.
WE CAN MANAGE RANGELANDS MORE SUSTAINABLY
The most widely used method for more sustainable management of rangeland is to control the number of grazing animals and the duration of their grazing in a given area so the carrying capacity of the area is not exceeded.
One way of doing this is rotational grazing in which cattle are confined by portable fencing to one area for a short time(often1-2days) and then moved to a new location. Riparian zones are streams or rivers lined by thin strips of lush vegetation.
A more expensive and less widely used method of rangeland management is to suppress the growth of unwanted invader plants by use of herbicides, mechanical removal, or controlled burning.A cheaper way to discourage unwanted vegetation in some areas is through controlled. Short-term trampling by large numbers of livestock.
In the mid – 1980’s, cattle had degraded the vegetation and soil on this stream bank along the San Pedro River in the U.S state of Arizona. Within 10 years, the area was restored through natural regeneration after grazing and off-road vehicle use were banned.
HOW SHOULD WE MANAGE AND SUSTAIN PARKS AND NATURE RESERVES?
We need to put more resources into sustaining existing parks and nature reserves and into protecting much more of the earth’s remaining undisturbed land are.
National parks face many environmental threatstoday, more than 1,100 major national parks are located in more than 120 countries. However, most of these national parks are too small to sustain many large animal species and many parks suffer from invasions by nonnative species that compete with and reduce the population of native species.
Parks in developing cities have the greatest biodiversity of all parks, but only about 1% of these parklands are protected.
Protecting Wilderness Is an important Way to preserve Biodiversity
One way to protect undeveloped lands from human exploitation is by legally setting them aside as large areas of undeveloped land called wilderness.
Two important reasons for protecting wilderness and other areas from exploitation.
One is to preserve biodiversity, as a vital part of the earths natural capital.
Second is to protect wilderness area as centers for evolution.
HOW CAN WE HELP SUSTAIN TERRESTRIAL BIODIVERSITY?
We can help to sustain terrestrial biodiversity by identifying and protecting severely threatened areas(biodiversity hotspots), rehabilitating damaged ecosystems(using restoration ecology), and sharing with other species much of the land we dominate(using reconciliation ecology).
Protecting Global Biodiversity Hotspots Is an Urgent Priority
To protect much of the earth’s remaining biodiversity as possible, some biodiversity scientists urge adoption of an emergency action strategy to identify and quickly protect biodiversity hotspots. An idea first proposed in 1988 by environmental scientist Norman Myers.
There are 34 global terrestrial biodiversity hotspots identified by biologists. Although these hotspots cover only a little more than 2% of the earth’s land surface, they contain an estimated 50% of the worlds flowering plant species and 42% of all terrestrial vertebrates(mammals, birds, reptiles and amphibians) and are also home to a large majority of the world’s endangered or critically endangered species.
Rehabilitate and Restore Ecosystems That We Have Damaged
Ecological Restoration the process of repairing damage caused by humans to the biodiversity and dynamics of natural ecosystems. Examples: replanting forests, restoring grasslands, reintroducing invasive species, and freeing river flows by removing dams.
Variety of approaches in repair operations:
Restoration: Returning a particular degraded habitat or ecosystem to a condition as similar as possible to its natural state.
Rehabilitation: Turning a degraded ecosystem into a functional or useful ecosystem without trying to restore it to its original condition. Example: removing pollutants and replanting soil erosion in abandoned mining and landfills and in clear-cut forests.
What Can You Do?
HOW CAN WE HELP TO SUSTAIN AQUATIC BIODIVERSITY?
We can help to sustain aquatic biodiversity by establishing protected sanctuaries, managing costal development, reducing water pollution, and preventing overfishing.
Human Activities Are Destroying and Degrading Aquatic Biodiversity
Human activities have destroyed a large portion of the world’s coastal wetlands, coral reefs, mangroves, and ocean bottom, and disrupted many of the world’s freshwater ecosystems. By 2006, Scientist claim that costal habitats are disappearing 2-10 times higher. ‘
Another major threat is ,loss and degradation of many-sea-bottom habitats caused by dredging operations and trawler fishing boats.
FISHERY: Is a concentration of a particular aquatic species (usually fish or shellfish) suitable for commercial harvesting in a given ocean area or inland body of water.
Methods of Fishing
Trawler Fishing is used to catch fish and shellfish-especially shrimp, cod, flounder and scallops-that live on or near the ocean floor. It involves dragging a funnel-shaped net held open at the neck along the ocean bottom; the net is weighted down with chains or metal plates. This process is clear-cutting the ocean floor. Newer trawling nets are large enough to swallow 12 jumbo jet planes and even larger ones are on the way.
With this method fish are caught by huge drifting nets that can hang as deep as 15 meters (50 feet) below the surface and extend to 64 kilometers (40miles) long. This method can lead to overfishing of the desired species and may trap and kill large quantities of unwanted fish, marine mammals, sea turtles, and seabirds.
Use side-meshed nets to allow escape of smaller fish
Use net escape devices for seabirds and sea turtles
Ban throwing edible and marketable fish back into the sea
Set catch limits well below the maximum sustainable yield
Improve monitoring and enforcement of regulations
Sharply reduce or eliminate fishing subsidies
Charge fees for harvesting fish and shellfish from publicly owned offshore waters
Certify sustainable fisheries
Restrict coastal locations for fish farms
Control pollution more strictly
Depend more on herbivorous fish species
Establish no-fishing areas
Establish more marine protected areas
Rely more on integrated coastal management
Label sustainably harvested fish
Publicize overfished and threatened species.
Kill organisms in ship ballast water
Filter organisms from ship ballast water
Dump ballast water far at sea and replace with deep-sea water