Leaf Litter Redistribution and Relevant Ecological Processes in a Temperate Hardwood Forest of Mt. Jumbong Area, Korea
Lee, Dowon and Sinkyu Kang
Graduate School of Environmental Studies, Seoul National University, Korea
A temperate hardwood forest of Mt. Jumbong, dominated by Quercus mongolica, Acer pseudo-sieboldianum and Carpinus cordata, consists of three distinct types of patches which are visually characterized by aspect and understory plants. Two patch types are located on the southwest-facing slopes: one with understory dominated by herbaceous plants (Patch S), and the other covered with evergreen dwarf bamboo, Sasa borealis (Patch SS). The third patch type is on the opposite slopes with understory dominated by herbaceous plants (Patch N).
In the forest, soil temperature and moisture availability appeared to favor soil biological activities in Patch N, compared to the others. Relatively large amount of leaf litter accumulated in Patch N due to the movement of litter from the opposite southern slope, especially from Patch S, which might be related to topography and direction of influential wind. Leaf litter was retained by thick snowpack in Patch N from late fall to early spring while dwarf bamboo was responsible for trapping and/or retention of leaf litter in Patch SS. Although earlier greenness was observed in the southern aspect than in the northern aspect, canopy might be less effective in governing litter redistribution and processes in the forest floor and soil layers than understory.
It is speculated that crucial ecosystem processes may be influenced by the redistribution of leaf litter on the patchy soil environment of forest floor. The results and their ecological implications are summerized as follows:
1. A large amount of leaf litter was transported from the southwest-facing slope to the northeast facing slope, suggesting that leaf litter can move over the watershed boundary in a region subjected to strong wind, and that litter dynamics should be considered in nutrient budget estimation, especially in small forested watersheds.
2. Aspect and understory exerted an influence on redistribution and decomposition of leaf litter and that the effects could be different among the plant species.
3. The leaf litter redistribution resulted in spatial heterogeneity of soil metal contents, which in turn seemed to control soil enzyme activities and thus other nutrient processes.
4. The redistribution of leaf litter was of significance to heterogeneous distribution of soil respiration in the forest floor.
5. Spatial heterogeneity of leaf litter redistribution may have effects on soil temperature and moisture conservation, both of which are major factors controlling biochemical processes.
6. The subsequent substrate redistribution may also contribute to spatial heterogeneity of detritus food change.
7. It appeared that there were two fluxes of leaf litter input to stream in fall and spring every year. It is hypothesized that adjacent streams may have some interesting ecological processes to respond to the periodic inputs of leaf litter.
Finally, we wonder what is a major factor governing the heterogeneity of understory distribution in the forest floor, how it interacts with climate, topography and substrate redistribution, and how significant it is to ecological processes of other forest ecosystems. Spatial heterogeneity of understory would be also related to that of canopy level and biogeochemistry at a watershed level. The subject deserves further attention in the long-term ecological research and comparative studies of ecosystems.