THE COMMUNITY STUDY ON INTERACTION AMONG NUTRIENT CYCLE, ANIMALS, AND PLANTS

本研究的目的是阐明土壤肥力对植物生长和表型可塑性的影响，2)食草动物和捕食者的群落结构，3)养分循环的流量和储量。在温室草食性破坏区和非草食性破坏区分别施用高、低两种施肥水平的锯齿栎和脆皮栎幼树。在个体水平上，草食破坏的幼树叶片数量显著增加；然而，无论土壤肥力如何，草食损害均不显著影响剑齿苋和crispula剑齿苋延伸单元的总长度。此外，随着母本EU叶片损伤程度的增加，锯齿木的冲红概率也随之增加。这些结果表明，为了降低机械支持的成本和分散后续食草动物伤害的风险，锯齿木或crispula树苗对食草动物伤害的反应产生更短的EUs。在高土壤肥力条件下，叶片生物量在茎部和个体水平上显著降低。无论土壤肥力如何，昆虫损害都降低了锯齿蒿叶片生物量。在低土壤肥力条件下，两种受虫害的幼树浓缩单宁浓度均较高。这些结果可能反映了一种特定物种的生长策略；Q.serrata投资于光合组织和更高的叶片质量，而Q.serrata投资于非光合组织。分析了试验地块病虫害破坏与未破坏土壤养分含量（移植后3年）的差异，阐明病虫害对土壤养分循环的影响。测定体外水萃取有机碳（WEOC）、氮浓度、氮矿化率和硝化速率。虫害土壤中WEOC浓度高于未虫害土壤，而其他养分未受虫害影响。WEOC一般对土壤氮素的沉降速度起重要作用。因此，本研究结果表明，长期虫害对土壤养分循环有较大影响。少

The purposes of this research are to clarify the effects of soil fertility on 1)plant growth and phenotypic plasticity, 2)community structure of herbivory and predators, and 3)flows and stocks of nutrient cycles. Quercus serrata and Q.crispula saplings were grown in herbivore-damaged or undamaged areas of the greenhouse with the two fertilization treatment levels, low or high.At the individual level, herbivore-damaged saplings exhibited a significant increase in leaf numbers ; however, the total length of the extension units (EUs) in Q.serrata or Q.crispula was not significantly affected by herbivore damage, regardless of soil fertility. Furthermore, the probability of flushing in Q.serrata increased with an increase in the leaf damage of the parent EU. These results suggest that Q.serrata or Q.crispula saplings produce shorter EUs in response to herbivore damage in order to reduce the cost of mechanical support and spread the risk for any subsequent herbivore damage.For Q.serrata, ins … More ect damage significantly reduced leaf biomass at high soil fertility at the shoot and individual level. For Q.serrata, insect damage reduced leaf biomass regardless of soil fertility at both levels. Condensed tannin concentrations were high in saplings receiving insect damage at low soil fenility in both species. These results were likely to reflect a species-specific growth strategy ; Q.serrata invests in photosynthetic tissues and higher leaf quality, while Q.serrata invests in non-photosynthetic tissues.The difference of soil nutrient contents (three-year passed after transplanted) between insect damaged and undamaged soil on the experimental plot were analyzed to clarify the effect of insect damage on soil nutrient cycles. Water-extractable organic carbon (WEOC), nitrogen concentration, nitrogen mineralization rate, and nitrification rate were measured in vitro. The concentration of WEOC on insect damaged soil was higher than that on insect undamaged soil, whilst the effects of insect damage on the other nutrients were not observed. WEOC generally plays an important role on speed of nitrogen minedization in soil. Therefore, the results obtained here imply that long-term insect damage gives large impacts on nutrient cycles in soil. Less