井冈山森林凋落物分解动态及磷、钾释放速率

应用网袋分解法对井冈山地区亚热带常绿阔叶林、针阔叶混交林和高山矮林地上和地下(10 cm)2个分解组的叶凋落物进行了连续2年的分解试验，测定了凋落物的分解速率以及P、K元素的释放动态.结果表明: 3种林分叶凋落物残留率与时间呈负指数衰减关系.各林分凋落物干质量损失前期较快，第1年末两组平均质量损失率分别为50.6%(常绿阔叶林)、41.7%(针阔叶混交林)和40.13%(高山矮林),且地上组显著高于地下组；后期较慢，至第2年末2组平均质量损失率分别达到60.95%(常绿阔叶林)、57.06%(针阔叶混交林)和56.60%(高山矮林)，均以常绿阔叶林、针阔叶混交林、高山矮林为序递减，地上组与地下组的差异不显著.根据Olson指数衰减模型对质量损失率结果进行拟合，发现3种林分样地上凋落物分解95%所需的时间(t_0.95)为6.8～9.9年，其大小排序为常绿阔叶林＜针阔叶混交林＜高山矮林.P在不同林分凋落物分解过程中均存在明显的净固持效应，其强度顺序为高山矮林＞针阔叶混交林＞常绿阔叶林，凋落物初始P含量和C/P可能是导致上述情形的原因.K在各林分的多数时间均表现为净释放.以试验末期的元素释放量计算，P的释放速率在地上组和地下组之间无显著差异，而K则为地上组显著高于地下组.

Arthropod community diversity in jujube orchards with integrated and conventional pest management

An investigation was made on the diversities of arthropod community, pest sub-community, and natural enemy sub-community in the mono-cultured and wheat-intercropped jujube orchards with integrated pest management (IPM) and conventional management (CM) in Taigu area of Shanxi Province. The results indicated that there were significant differences (P<0.05) in the diversity indices of the community and sub-communities among these four treatments at different stages of jujube tree growth. The F-test indicated that wheat-jujube intercropping combined with IPM was the main factor affecting the diversity indices of arthropod community, pest sub-community and natural enemy sub-community in jujube orchard ecosystem.