Coniferous forests cover about 15 per cent of the Earth's surface. They sit primarily over the northern hemisphere, through North America, Europe and Asia, south of the tundra and north of the grasslands and deciduous forests.The tallest conifers are redwoods, the tallest reaching 368 feet in height. Average tree diameter ranges between 5 and 8 feet. Various problems -- mostly man-made -- afflict the coniferous forests and threaten their existence.
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Acid rain problems persist in the coniferous forests, particularly in northern Asia and Canada. Acid rain forms from deposited materials in the atmosphere mixing with rain and precipitation. Natural deposits from volcanoes and decaying vegetation contribute to acid rain, but according to the Environmental Protection Agency, two-thirds of all sulphur dioxide and a quarter of nitrogen oxide emissions in the U.S. come from burning fossil fuels for electricity.
Acid Rain's Effects on the Forest
Acid rain causes slowed growth, injury and even death to coniferous forests. Forests in higher elevations are at an especially higher risk for browning and dying needles and even trees. The rain seeps into the soil, rivers, streams and lakes. Since coniferous forests have thin soil layers, the acid isn't neutralised, so it affects and even kills off trees.
Coniferous trees like the fir are some of the most sought-after timber in the world. Clear-cut logging also occurs to create ski slopes, housing, new roads and landfills. Logging and clear cutting remove the forest's canopy, changing its climate by removing the misty precipitation from the trees that leaves the forest moist and cool. Removing the trees means that creatures living there lose their habitat and food source, endangering them or causing their extinction. Even when trees are replanted after logging, replacing a forest population with a single species creates a monoculture, which prevents biodiversity for plants and animals in the ecosystem. Logging also speeds up soil erosion.
Exclusion of fires, especially in western coniferous forests, has had significant negative effect. Suppressing naturally occurring fires results in dense overgrowth with a closed canopy and little shrub cover in the forests. Animals like fox sparrows and other bird species rely on openings in the canopy and high shrub cover. Fires also provide habitats for creatures who nest in cavities created by burning off limbs and trees. Increased amounts of "edge habitat," forest that is located at the perimeter of the ecosystem, increases with logging and clearing, and many creatures and plants need suitable habitats away from forest edges.
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