Tree litter

The impacts of trees on soil fertility depend on nutrient recycling characteristics such as litter chemistry and decomposition rates. Tree litter can be used as mulch with different outcomes a fast mulch decomposition rate may accelerate the growth of associated crops on poor soils, while in other cases a more persistent litter may provide a steady source of nutrients and a better soil cover year round. In the experiments in Costa Rica described in the previous section, high rates of litterfall and slower decomposition resulted in high litter accumulation and high... 

Damage to epicuticular waxes Altered photosynthesis Increased water loss Accumulation of acidic anions Leaching of ions, sugars, etc. Mineral imbalances Altered metabolism Increased susceptibility to winter freezing injury Death of fine roots Destabilization of trees Reduced water/mineral uptake Reduced water uptake Cations leached below roots Accumulation of acidic anions Altered structure/texture Altered microflora Reduced litter decomposition Altered N transformations Solubilization of metal ions... 

A positive feedback between vegetation and atmospheric CO2 will occur if biomass declines. This will happen to the extent that climatic warming causes increased water stress, either through decreased precipitation or increased evap-otransporation, particularly on soils of low water-holding capacity. Decreases in soil nutrient availability, either directly caused by drought or indirectly caused by replacement with taxa with more recalcitrant litter, may further decrease the net release of carbon from the biosphere to the atmosphere. Positive feedback will also arise if the current standing biomass of trees is replaced by small trees, shrubs, and herbs that store less carbon. 

Sydes, C. Grime, J.P. (1981a). Effects of tree leaf litter on herbaceous vegetation in deciduous woodland. I. Field investigations. Journal of Ecology, 69, 237-48. 

The allelopathic effects of dominant plants on other plants in phytocoenosis are caused by phenolic phytotoxins present in all parts of plants, but the highest amount of these compounds is accumulated in the leaves. Leaves of dominant trees represent the main components of the litter in the forest, thus analysis of phenolic compounds and measurements of their content in leaves and leaf litter is considered as very important. 

Mixed oak forest, southern France, experimentally irradiated for 18 years by a, 37Cs source at dose rates between 0.3 and 116 mGy/h, equivalent to a yearly rate between 2.6 and 1016 Gy At 60-100 mGy/h (525-876 Gy yearly), all trees, shrubs, and litter were absent low overall insect density soil deficient in carbon, nitrogen, and water. At 15 mGy/h (131 Gy yearly), woody plants were present, but visibly abnormal 6... 

Herbs that enjoy dappled shade thrive on the edges of shrubs or by groups of small trees. Add a low-fertility soil improver on an annual basis in order to mimic the leaf litter layer that occurs naturally in woodland areas. Vigorous... 

In a conifer forest, litter production and decomposition release about 80% of the total minerals in the biomass of the stand the remainder is retained in the living parts of the tree. Standing dead material is not considered litter. 

The decomposition of tree leaves is not entirely confined to the litter layer on the forest floor. Leaves and needles are invaded by bacteria and fungi even as they grow these microorganisms may be either pathogens or saprophytes. ... 

The concentration of plant nutrients in litter influences both the rate of decomposition and the amount of nutrients released after decomposition. Ozone-injured foliage may be deficient in inorganic nutrients, because of the concomitant decay of the root systems of chronically injured trees. ... 

In the San Bernardino Mountains, studies are going on to describe the effects of oxidant injury to ponderosa and Jeffrey pines on the microarthropods and fiingi of the litter layer under trees with various degrees of injury. Initial observations suggested lower population densities of microarthropods in the classes Insecta, Arachnida, and Myriapoda under some severely injured trees. ... 

Jensen, V. Decomposition of angiosperm tree leaf litter, pp. 69-104. In C. H. Dickinson, and G. J. F. Pugh, Eds. Biology of Plant Litter Decomposition. Vol. 1. New York Academic Press, 1974. 

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