秦岭华山松小蠹生态位研究

通过对秦岭林区海拔１６００～２２００ｍ的中山地带华山松小蠹虫种类和生态位的研究，结果表明：在秦岭林区入侵危害寄主华山松的小蠹虫有１９种，其中能构成竞争和共存的小蠹虫主要有１１种。虽然，这１１种小蠹虫具有各自不同的生态位宽度，且存在不同程度的生态位重叠，但各小蠹虫可依据其对寄主树木营养和空间需求的不同、种群密度的相互制约，以及入侵寄主树木时序的差异达到竞争的平衡和共存。秦岭华山松小蠹生态系统的建立，首先是由华山松大小蠹入侵健康华山松，并通过携带蓝变真菌入侵寄主树木，迅速克服寄主树木抗性系统，使寄主树木树势衰弱；其次松六齿小蠹、暗额星坑小蠹和松十二齿小蠹，作为秦岭华山松的主要次期性小蠹，迅速入侵衰弱的寄主华山松；最后其它次期性小蠹虫入侵寄主树木，利用寄主华山松剩余营养和空间。从而实现秦岭华山松立木小蠹生态系统的动态稳定。

NICHE OF BARK BEETLES WITHIN %PINUS ARMANDI%=ECOSYSTEM IN INNER QINLING MOUNTAINS

The bark beetle species on %Pinus armandi% and their niches were studied in the middle areas of Qinling Mountains. The results showed that 19 species of bark beetles infecting and damaging %Pinus armandi% in pine ecosystem of Qinling Mountains were found, but only 11 species of them could be competitive and coexistent one another. Although each of the 11 species of the bark beetle had its own spatial niche and overlogs niche, they could attain competitive equilibrium and coexistance according to their requirment for different nutrition and space, the interference of population density and the different time interval attacking the host tree. In the construction of the ecosystems of bark beetles on %Pinus armandi% in Qinling Mountains, the bark beetles first attacked the healthy tree, carrying the blue stain fungi into it, quickly weakened the trees vigor, then the mainly secondary bark beetles %Ips acuminatus, Pityogenes japonicus% and %Ips sexdentatus %attacked the weakened trees. Finally, other bark beetles infected to the withered trees, and utilizing the surplus spatial niche and trophic niche of the host trees. Consequently, the relatively steady ecosystem of the bark beetles on %Pinus armandi% could be constructed.