花椒农林复合生态系统的简化对某些相关因子的影响

EFFECT OF SIMPLIFIED AGRO-FOREST SYSTEM OF SICHUAN PEPPER (ZANTHOXYLUM AVICENNIA) ON SOME ECOLOGICAL FACTORS

对单一种植和复合种植两种模式的花椒林地(即有草模式和无草模式)进行了相关生态因子的对比调查,以评价现存花椒林单一模式的合理性.结果表明,在单一种植模式下,花椒林的高度、地径和冠幅虽显著优于复合模式,但是病虫害严重;两种模式中土壤含水率均是随土层厚度的增加而增大,但是变幅有较大差异:复合模式的变幅较稳定,为7.59%～23.79%;而单一模式的变化较剧烈,为4.73%～49.72%,复合模式的土壤含水率显著高于单一模式.复合模式的昆虫种类、多样性、丰富度和均匀度也明显高于单一模式,其中单一模式中的肉食性和寄生性昆虫种类低于复合模式,而植食性蚜虫数量则高于复合模式,暗示单一模式中天敌的栖境和资源以及特定的食草昆虫与有益菌缺少.讨论认为,杂草在花椒林生态系统中起着重要的生态作用,现存的单一种植模式虽然对花椒的生长和产量有利,但却是以牺牲农林系统的可持续发展以及生物多样性为代价的. 表3

On sloping field in Mao County, Sichuan, farmers developed simplified Sichuan pepper(Zanthoxylum avicennia) systems by cleaning up weeds. During growing seasons, several field surveys on complex system (Sichuan pepper plantation system with weeds) and monoculture system (Sichuan pepper plantation system without weeds) were conducted and some related ecological factors of the two systems were compared. Field measurements were carried out to elucidate the trends in growing situation, soil water content, plant diseases and insect pests in the two systems, and to evaluate rationality of the monoculture system. The results showed that in monoculture system, height, base diameter and canopy size of Sichuan pepper were significantly better than those of complex system, but diseases and insect pests seemed more prevalent in monoculture system, which also received increased fungicide applications when compared to the complex system. Soil water contents in the two systems were both increasing with the increase of soil depth, but their difference was great. The soil water content in complex system stably ranged from 7.59% to 23.79%, while that in monoculture system varied greatly and ranged from 4.73% to 49.72%. Soil water content in complex system was much higher than that of monoculture system. There were a similar tendency in insect species, and species richness, diversity and evenness. Our surveys revealed that the monoculture system exhibited lower number of species of predators and parasites, and correspondingly higher density of aphids than the complex system. These results indicated that accelerating rates of Sichuan pepper insect pests and diseases might be increased due to lack of habitat and resources for natural enemies or to a concentration of preferred host plants for specific pathogens and herbivores. Therefore, weeds played an important role in Sichuan pepper agro-forest systems. This study suggests that monoculture system may be more productive, but such gains occur at the cost of biodiversity and agricultural sustainability, reflecting higher pest vulnerability. Tab 3, Ref 9