DYNAMICS OF LEAF-LITTER ACCUMULATION AND IT EFFECTS ON RIPARIAN VEGETATION - A REVIEW

The total production of plant litter and the proportion of leaf litter are higher in riparian corridors than in upland ecosystems throughout the world, Periodical water-level fluctuation is believed to be the m ajor cause of these differences, During flood periods, much plant litt er is redistributed locally and between regions, following erosion, tr ansport, and deposition of litter. The importance of litter redistribu tion varies with factors such as flood regime, topography, and vegetat ion. Litter from the riparian corridor is usually a major constituent of the litter transported by the river. The decomposition of litter is faster in riparian corridors than in upland systems due to a higher r ate of leaching and a higher decomposer activity. Relative warmth and soil fertility may also enhance litter decomposition in riparian corri dors. In general, accumulated litter affects plants physically by bury ing them, chemically by adding nutrients and phytotoxins, and biologic ally by adding diaspores. The physical impact of a certain amount of l itter may be weaker in riparian corridors than in uplands because the rapid decomposition reduces the time that litter is present. In other words, higher amounts of litter are needed to affect riparian vegetati on than are needed to affect other types of vegetation. The nutrient c ontent of riverborne litter is reduced by leaching, but dissolved nutr ients from litter might still reach the riparian vegetation, e.g., by adsorbing to inorganic particles. Phytotoxins are probably unimportant in riparian systems. The input to the riparian corridor of plant dias pores, borne by litter packs in the river, may be large. Indirect biol ogical effects of litter, including its diaspores, are the attracting of animals and microbes that may influence the plant community, and th e creation of bare soil for plant colonization.