间种牧草枣林刈草对树上昆虫群落结构及动态的影响

为了有效地管理枣树害虫，2004年在太谷地区间种牧草枣林，运用物种丰富度、多样性与相对丰盛度指数作为多样性分析的综合指标，系统地研究不同刈草次数对树上昆虫群落结构及动态的影响，结果表明：刈草对害虫亚群落的物种数的影响较小，对天敌亚群落与中性昆虫的物种数影响较大，随着刈割次数的增加，昆虫群落各类群的多样性与相对丰盛度指数的时序变化凸现明显的差异与规律性，且受刈割次数的影响较大，当6月上旬进行第1次刈割后，对昆虫群落的结构动态影响明显，但很快即可得到恢复，当7月中旬实施第2次刈割后，对害虫亚群落物种数影响较小，但对天敌亚群落与中性昆虫的物种数影响较大，并且对昆虫群落的多样性与相对丰盛度的影响较为明显，这种影响待枣果采收后才逐渐得到恢复，因此刈割后应对枣树害虫及时给予管理。

Mowing effects no the insect community structure and dynamics on jujube trees at jujube forests intercropped with pasture

To understand the Mowing effects on the insect community structure and dynamics of jujube trees at jujube forests intercropped with pasture, a systematic survey was made at the four different treatments of jujube fields located 2.5 km west of Taigu, Shanxi Province in 2004. The three treatments of the four different treatments of jujube fields were intercropped with pasture (Lotus comiculotus), of which the first treatment was no mowing, and the second one was mowing at just one time on the 5 June, and the third one was mowing just twice on the 5 June and 16 July respectively, and the other one wasn't intercropped with any pasture. Trees were 10 years old and in full fruit production, with a height of 5 m and a shading-degree of 0.4-0.6 . In each of the four different treatments of jujube fields, five trees were chosen according to the chessboard sampling method to monitor the population structure and seasonal dynamics of the insects. The trees were monitored every 10 days from March 10th to September 30th. Each of four treatments was replicated three times. The insects were distinguished based on their taxonomy. Number of species, diversity, and relative abundance indices of the insects were used to analyze and compare the differences at the four different treatments of jujube fields. The results showed that there was little mowing influence on the species of pests compared with that of the natural enemies and neutral insects. With increased mowing times, the clear differences and regularity of the temporal change of the index of diversity and relative abundance of each group of insect community were showed. There was significant influence on the structure and dynamics of the insect community after initial mowing in the first ten days of June, however, the influence was soon recovered. There were more mowing influences on the species of natural enemies and neutral insects than on that of pests, and there significant influence to the index of diversity and relative abundance of insect community after second mowing in the middle ten days of July, and the influence was not recovered until the jujube fruit was picked. Therefore, the pests of jujube trees should be managed at the right time after mowing.