常绿阔叶林中栲树展叶期叶片的虫食格局

INSECT HERBIVORY PATTERNS ON LEAVES OF CASTANOPSIS FARGESII DURING LEAF EXPANSION IN EVERGREEN BROAD-LEAVED FOREST IN EASTERN CHINA

叶片的虫食主要发生在展叶期。虽然展叶期短暂,它却可能是了解植食性昆虫和植物之间相互关系的关键。为了解栲树(Castanopsis fargesii)在展叶期叶片的虫食格局和展叶方式对叶片虫食的影响,研究了栲树展叶期内的虫食动态变化,结果表明:栲树展叶的两个阶段(折叠期和打开期),虫食叶片的格局存在较大的差异,打开阶段的日虫食频度和日虫食率显著高于折叠阶段(F1,32=8.97,p=0.0054;F1,32=12.38,p=0.0014),展叶期最终叶片虫食频度为50.72%,叶片虫食率为8.25%。折叠期叶片主要受到低强度的虫食,打开期叶片虫食则以较大强度的虫食为主。展叶期叶片的虫食主要发生在夜间,夜间虫食率显著高于日间虫食率(t=2.51,p=0.017),变化趋势与日虫食率一致。栲树叶片在展叶的两个阶段可能采用了不同的防御对策。

Aims The majority of damage by herbivores occurs during the leaf expansion period,yet the pattern of leaf damage and its influence are poorly known. Our objective is to measure damage throughout leaf expansion to understand the herbivory pattern and the defense strategy for young leaves of Castanopsis fargesii. Methods We examined variation of leaf area and specific leaf weight （SLW） and measured herbivory frequency and herbivory rate dynamics twice a day during leaf expansion of 35 seedlings of C. fargesii in Tiantong National Forestry Park, eastern China. Important findings Leaf herbivory frequency and herbivory rate on young leaves in the unfolded stage were significantly higher than in the folded stage （F1. 32=8.97, p=0.005 4; F1.32=12.38, p=0.001 4）. Herbivory in the folded stage consisted of a large amount of low proportion herbivory, while leaves in the folded stage mainly had high proportion herbivory. Leaves were intensively grazed at night （t=2.51, p=0.017）, which accounted for about 85% of the total leaf herbivory. Young leaves of C. fargesii might follow different strategies in the two expansion stages.