| Summary: | Recent legislation requires that lands surface mined for coal be returned to approximate original topography and vegetative cover be restored. Spoils provide poor rooting habitat because of extreme stoniness or excessive slope steepness which provide few niches for seeds to become lodged and also spoil may provide poor mineral nutrition, poor water retention and sometimes the spoil may even have chemical properties detrimental to plant growth (acidity, alkalinity or even unusually large amounts of toxic mineral elements i.e., copper, sodium). To provide a substrate better suited for plant growth, recommendations for restoration call for deep burial of unfavorable substrate components i.e., rocks and materials of unusual chemistry and the dressing of reshaped spoil with topsoil i.e., material with the most favorable properties for plant growth. Even though all the substrate requirements for healthy plant growth may be met, such as adding a form of available nitrogen as fertilizer, plants will not grow if weather conditions are extreme. For example, in very dry (desert) climates precipitation may be too scanty or too erratic to permit the successful establishment of many kinds of plants. Even under the most favorable conditions plant productivity averaged over a period of years is low. Also in very cold climates the growing season may be limited to only a few weeks in summer e.g., arctic and alpine tundra regions. This shortens the time available for photosynthesis and keeps plant productivity low.
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