Vegetation and weathering

If the weathering rate equals or exceeds the rate of H release by the biota, such as would be the case in a calcareous soil, the soil will maintain a buffer in base cations and residual alkalinity. On the other hand, in noncalcareous acid soils, the rate of H release by the biomass may exceed the rate of H" consumption by weathering and cause a progressive acidification of the soil. In some instances, the acidic atmospheric deposition may be sufficient to disturb an existing H" balance between aggrading vegetation and weathering reactions. 

Our understanding of seasonal and interannual variation in global terrestrial vegetation dynamics is, however, very sketchy at present. Ecosystem respiration measurements have been made for various soil-vegetation types for variable lengths of time Relationships between ecosystem respiration and weather data have been derived from these data for four major biomes 88), However, additional systematic collection of field respiration measurements would be necessary for placing much confidence in such a relationship. 

Poultry must have access to an open-air run whenever the weather conditions permit and, whenever possible, must have such access for at least one-third of their life. These open-air runs must be mainly covered with vegetation and provided with protective facilities, and permit animals to have easy access to adequate numbers of drinking and feeding troughs. 

Soil is the superficial, unconsolidated, and weathered part of the geosphere. This surface earth is a bioherm that can be tilled and a locale where vegetation grows. 

Modem analytical methods can detect some concentration of most elements in soils. The concentration varies as a function of several factors including the age of the soil, its parent material, climate and weathering regimes, vegetation, and human activity. Whether an element is present naturally in soil or water, or has been introduced... 

Clay is an erosion product of igneous and sedimentary rocks. The weathering proceeds via mechanical and chemical processes. Its result depends on many factors, among which climate, vegetation and composition and texture of the rocks. 

Range quality Mainly covered with vegetation and with protective facilities. Specified rest periods Mainly covered with vegetation and with protective facilities. Specified rest periods Trees and shelter to provide shade and weather protection. Appropriate rest periods Access to suitable shelter. Rested 1 year in 3 if set stocked... 

Mattina, M.I. White, J. Eitzer, B. lannucci-Berger, W., Cycling of weathered chlordane residues in the environment Compositional and chiral profiles in contiguous soil, vegetation, and air compartments Environ. Toxicol. Chem. 2002, 21, 281-288,... 

The majority of rate studies are based on watershed solute fluxes normalized to catchment area and are equivalent to rates of chemical denudation. Previous efforts have tabulated these rates, which have proved to be valuable in evaluating the importance of a number of environmental controls on chemical weathering including precipitation, temperature, vegetation, and rock type. The present chapter summarizes... 

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