不同果园土壤线虫的群落结构与多样性

Soil nematode community structure and diversity in different orchards

2012年7月,对粤东地区柑橘园、番石榴园、荔枝园和芒果园4种不同果园土壤线虫群落进行调查,应用土壤线虫群落生态学指数、土壤线虫各食性类群组成、c?p类群结构及营养结构特征指数,分析4种不同果园土壤线虫群落的功能结构特征,探讨果树栽植年限、果园管理方式对土壤线虫群落功能结构的影响。共分离获得土壤线虫53551条,隶属2纲11目20科28属。对不同果园土壤线虫的生态指数分析表明,4种果园的Shannon指数(H′)、Pielou均匀性指数(J)、Simpson指数(D)、Margalef丰富度指数(SR)和密度?类群指数(DG)均具有显著差异(P<0.05)。Gower系数表明,种植年限短的果园土壤线虫群落结构与种植年限长的果园之间具有显著相异性。食细菌线虫的H′、J、SR指数排序为柑橘园>番石榴园>芒果园>荔枝园,植食性线虫的H′、J、SR指数排序为荔枝园>芒果园>番石榴园>柑橘园。c?p类群组成结构特征分析结果显示,4种果园的cp1—cp2类群的相对丰度均显著高于cp3—cp5类群(P<0.05),土壤线虫生活策略组成以cp2类群占优势。PPI指数表明:荔枝园和芒果园受扰动程度大于柑橘园和番石榴园,MI、PPI/MI值则表明:柑橘园和番石榴园土壤线虫群落的稳定性较高,受到的干扰程度小。NCR值均说明了4种果园的土壤有机质分解主要依靠细菌分解途径。综合线虫功能类群的指数分析结果显示,果树的栽植年限对果园土壤线虫的PPI/MI值有很大影响,随着果树栽植年限的增加,PPI/MI值呈上升趋势。土壤线虫各营养类群统计结果表明,荔枝园和芒果园植食性线虫数量增加虽未达到对果树的伤害阈值,但种植年限较长的果园土壤环境受到的扰动较大。

We conducted a survey on soil nematode communities in four different fruit orchards, i.e. orange, guava, lychee and mango orchards, in Eastern Guangdong Province during July 2012. The ecological indices, trophic group composition, c-p class structure, and characteristic indices of trophic structure were used to determine the functional and structural features of the soil nematode communities in these orchards, and to analyze the effects of planting ages of fruit tree and orchard management practices on the functional structure of soil nematode communities. A total of 53551 nematodes were isolated, in which 28 genera belonging to 2 classes, 11 orders and 20 families were identified from the orchards mentioned above. The analysis of ecological indices of different orchards soil nematodes showed significant differences （P 〈 0.05） in the Shannon index （H3, Pielou evenness index（J）, Simpson dominance index （D）, Margalef richness index （SR）, and density group index （DG）. The H＇, J, and SR values for orchards soil nematodes of younger trees were higher than those of older trees. Gower index showed that structure of soil nematode community had significant heterogeneity between younger and older trees. However, the D values showed the opposite trend. Analysis of the trophic group ecological indices showed that the H＇, J, and SR values for bacterial-feeding nematodes were the highest in the orange orchard, followed by the guava, mango, and lychee orchards. On the contrary, the D index was the highest in the lychee orchard, followed by the mango, guava, and orange orchards. The H＇, J, and SR values for plant-feeding nematodes were the highest in the lychee orchard, followed by the mango, guava, and orange orchards, whereas the D values in these orchards showed the opposite trend. The value of each index was significantly different for predatory and omnivorous nematodes. The H＇, J, and SR indices were higher in the orange and guava orchards but lower in the lychee and mango orchards. The DG values for bacterial-feeding nematodes of the guava and orange orchards were comparatively higher than those of the mango and lychee orchards. The DG values for plant-feeding nematodes were higher in the lychee and orange orchards and the lowest in the guava orchard. The DG values for predatory and omnivorous nematodes were high in the orange and guava orchards and low in the lychee and mango orchards. The relative abundances of cp 1-cp2 were higher than those of cp3-cp5 nematodes in four fruit orchards, and showed significant differences （P〈0.05）. The cp2 soil nematodes were predominant in all four of the fruit orchards, and the life strategy was mainly r-strategy. Analysis of PPI index showed higher disturbing degree in the lychee and mango orchards than that in the orange and guava orchards. The Mland PPI/MI indices indicated that the orange and guava orchards had higher stability and were the least disturbed among the four orchards. The NCR values suggested that soil organic matter decompositions in these four types of plant communities were mainly dependent on the bacterial decomposition pathway. Differences in the functional and structural features of soil nematode communities suggested that soil nematodes influenced soil environmental factors, which in turn affected the potential of the soil ecosystem. The results showed that the planting age of fruit trees affected the PPI/MI value of soil nematodes, and the PPI/MI value increased with fruit tree planting years. The statistical results of soil nematode trophic groups indicated an increase in the number of plant-feeding nematodes, although this did not reach the damage threshold of lychee and mango, could cause greater soil environment disturbances and result in the deterioration of the soil environment.