人工油松林土壤线虫密度垂直分布及其影响因素

Vertical Distribution of Soil Nematodes Density and the its Driving Factors in Pinus tabulaeformis Plantations

土壤线虫对有机质的分解及养分循环起重要作用。为了解油松人工林土壤线虫数量的垂直分布规律,以北京八达岭林场2种不同密度的油松人工林(林分1的密度为820株·hm^(-2);林分2的密度为1 620株·hm^(-2))土壤为研究对象,对新鲜凋落物层(L)、半分解凋落物层(F)以及0~2、2~5、5~10、10~20、20~50cm和50~80cm矿质土壤层的土壤pH、土壤有机碳、水溶性有机碳、土壤微生物生物量碳和氮以及土壤线虫的数量进行分析。结果表明,林分1和林分2凋落物L层的线虫数量分别为12 010、12 410条·100g^(-1)干土,均显著低于凋落物的F层。2个林分凋落物层的线虫数量与矿质土壤层的线虫数量相比,存在显著差异。在林分1和林分2的矿质土壤层,0~2cm土壤线虫的数量分别为3 593条·100g^(-1)干土和4 968条·100g^(-1)干土,二者分别高出2~5cm土层土壤线虫数量的118%和120%。从5~10cm土层以下,不同土壤线虫的数量变化无显著差异。相关分析表明,土壤线虫的数量与土壤pH呈显著负相关,而与土壤水溶性有机碳、土壤有机碳、土壤微生物生物量碳和氮呈显著正相关。总的来看,土壤线虫的垂直分布与土壤有机质以及土壤微生物生物量碳氮的垂直递减规律一致。

Soil nematodes play an important role in the decomposition of organic matter and nutrient cycling. In order to understand the vertical distribution pattern of soil nematodes under Pinus tabulaeformis plantations,soil samples in different layers including fresh litter layer （L）, sub-decomposing litter layer （F） ,0-2,2-5,5-10,10-20,20-50,50-80 cm were collected under two different forest densities （820 · hm^-2 in forest stand No. 1 and 1 620 · hm^-2 forest stand No. 2） in Badaling Forest Farm, Beijing to measure the soil pH, content of soil organic carbon, soil dissolved organic carbon, soil microbial biomass and the soil nematode density in different soil layers. The results showed that soil nematode density in L layer were 12 010 individuals per 100 g dry soil and 12 410 individuals per 100 g dry soil respectively. These were obviously lower than those in F layer. On the other hand, soil nematode individuals in litter layer were significantly higher than those in mineral soil layer. In forest stand No. 1 and forest stand No. 2, the soil nematode density in 0 to 2 cm layer were 3 593 individuals per 100 g dry soil and 4 968 individuals per 100 g dry soil respectively,118% and 120% higher than those in 2 to 5 cm layer. Under 5 to 10 cm layer,the obvious decreasing tendency of soil nematode individuals with the increase of soil layers was not found. Our results showed the soil nematode individuals per 100 g dry soil was obviously and negatively correlated to soil pH; whereas it was positively correlated to the content of soil dissolved organic carbon, soil organic carbon, soil microbial biomass carbon and soil microbial biomass nitrogen. In a word, the distribution pattern of soil nematodes was similar with tendency the soil organic carbon and soil microbial biomass.