Wednesday, March 17, 2010

Forests and Biodiversity

Forests support biodiversity through indirect means by helping water and soil conservation and climate regulation. Directly, forests provide habitat for about two-thirds of all species on Earth, and by so doing forests may be the single most important constituent in maintaining the Earth’s biodiversity. Forests support not only diverse animal species, small plants, and microbes, but forests also contain diverse mixtures of different trees that grow and recycle nutrients at different rates and provide biomass of varying compositions when the trees die.

In the United States, land designated as protected national forest covers 192 million acres (78 million km2). These forests contain almost every habitat in the country: tropical and temperate rain forests, coasts, rivers and lakes, grasslands, mountain and alpine areas, deciduous forests, conifer and mixed forests, old-growth forests, arctic tundra, deserts, and wetlands. National forestland gives habitat to at least one-third of all wildlife on the endangered species list. Rich biodiversity within any forest serves as an indicator of the health of that forest; the greater the diversity of plants, animals, and microbes, the healthier the forest.

Forests support biodiversity in a horizontal fashion as well as a vertical fashion. Horizontal forest growth refers to the forested land across continents, which provide different climates and terrain. This is the core reason why tropical rain forests at the Earth’s equator bear little resemblance to evergreen forests in Canada. Each forest possesses its unique biodiversity, and this diversity contributes hundreds of different types of habitats for animals, plants, and microbes. Vertical biodiversity in forests resides from the upper part of the tree line, the canopy, to the roots in the earth. From top to bottom, a single forest can house ecosystems containing raptors, seed- or insect-eating birds, tree-dwelling mammals, insects and snakes that live lower on trees, small rodents and plants on the ground, and invertebrates and microbes digesting biomass within the soil. This model describes merely a general look at the forest ecosystem; forest food webs contain many more complex animal-plant-microbe relationships within each different type of forest.

The world’s biodiversity concentrates in tropical rain forests, which cover only 7 percent of the Earth’s land, but hold at least 50 percent of all the Earth’s species. For this reason the tropical rain forests in many parts of the world have been designated biodiversity hot spots by Conservation International. Environmental expert Norman Myers first proposed the concept of biodiversity hotspots in 1988 to describe places that contain a high degree of biodiversity and are simultaneously under a high threat of being destroyed. In that year Myers wrote an essay titled “Tropical Forests and Their Species” stating, “Extinction has been a fact of life since the emergence of species almost four billion years ago. . . . Whereas past extinctions have occurred by virtue of natural processes, today the virtually exclusive cause is Homo sapiens, who eliminates entire habitats and complete communities of species in super-short order. It is all happening in the twinkling of an evolutionary eye.” Though Myers spent his career addressing both plant and animal diversity, his words can certainly be applied to the plight of forest loss taking place today.

Deforestation refers to any removal of trees from a forested area without adequate replanting, and it represents the biggest threat to tropical rain forests and the species dependent on them. Many of these forests are in areas with high population growth rates compared with the rest of the world. In general, a large area of the world’s tropical rain forests have fallen victim to population growth, poverty, and inadequate government protection. These are not simple matters to overcome when trying to design plans for protecting trees. The case study “Conservation in Costa Rica” provides a look into one ambitious forest recovery program.

Source of Information : Green Technology Conservation Protecting Our Plant Resources

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