人工林与其紧邻农田中野生植物与土壤线虫群落特征对比

我国北方农耕区休耕地种植杨树现象较为普遍，但是人工林对农业生态系统中生物多样性的保护作用却鲜有关注.在山东省宁津县选取3块样地，均为休耕地种植杨树林且紧邻小麦玉米轮作田，对比人工林下、田埂及农田内的草本植物群落特征、土壤线虫群落特征及土壤化学性质，以探究人工林对农业生态系统中生物多样性的作用.结果表明:①植物样方总物种数和样方平均物种数均呈现农田 < 距田埂30 m人工林下 < 距田埂10 m人工林下 < 田埂 < 距田埂20 m人工林下 < 距田埂5 m人工林下的变化规律，其中，距田埂5 m人工林下植物样方总物种数为21种，农田内11种.人工林下草本植物群落多样性指数、丰富度指数均显著高于农田内杂草植物群落相应指数（P < 0.05）.②农田、田埂及距田埂5 m的人工林下的土壤线虫组成存在差异，农田和人工林下土壤线虫优势属为头叶属（Cephalobus），而田埂中为真头叶属（Eucephalobus）.土壤线虫群落多样性指数、成熟指数、植物寄生线虫成熟指数及线虫通路比在人工林下、田埂和农田之间差异均不显著（P≥0.05），土壤线虫均为耐环境压力类群.③人工林下与农田土壤中总氮（TN）、总碳（TC）含量差异不显著（P≥0.05），而田埂和人工林下土壤碳氮比（C/N）显著高于农田内（P < 0.01），表明林下和田埂土壤中有机物分解矿化速度低于农田内.土壤TN含量、TC含量、C/N和pH均与植物群落具有显著关联，而对土壤线虫群落均无显著影响.研究显示，在我国北方休耕地种植杨树林，对于农业生态系统中草本植物多样性保护具有积极作用，但是难以在几年内有效地改善土壤质量. 

Comparison of Wild Plant Community and Soil Nematode Community in Fast-Growing Poplar Plantation and Wheat Maize Rotation Fields

Poplar plantations in fallow fields are common in agricultural areas in northern China, and little is known about the protection of poplar plantation to biodiversity in agroecosystem. In this study, wild plant community, soil nematode community and soil chemical properties in 3 sample areas of poplar plantations, field ridges and wheat maize rotation fields were surveyed in Ningjin County, Shandong Province to explore the protection of poplar plantation to biodiversity. The results showed that the total number and the average number of species in plant quadrats were both the fields < the 30 m from the field ridges in poplar plantation < the 10 m from the field ridges in poplar plantation < the field ridges < the 20 m from the field ridges in poplar plantation < the 5 m from the field ridges in poplar plantation. The total number of species in plant quadrats at the 5 m from the field ridges in poplar plantation was 21, and that in the fields was 11. The Shannon-Wiener diversity index and the Margalef species richness of wild plants in poplar plantation was significantly higher than that in the fields and the field ridges (P < 0.05). The species composition of soil nematode in different habitats were difference. The dominant genus of soil nematodes was Cephalobus in the fields and the poplar plantation, while Eucephalobus was dominant in the field ridges. There was no significant difference in soil nematode diversity, maturity index, plant parasite index and nematode channel ration in the poplar plantations, the field ridges and the fields (P≥0.05). The soil nematodes in different habitats were all resistant to environmental pressure. There is no significant difference in the total nitrogen (TN) content and total carbon (TC) content of soil between the poplar plantation and the fields (P≥0.05), while the carbon and nitrogen ratio (C/N)of soil in the poplar plantation and the field ridges was significantly higher than that in the fields (P < 0.01). There was a significant correlation between the pH value, TN content, TC content, C/N of soil and plant communities. There was no significant correlation between the pH value, TN content, TC content, C/N of soil and the soil nematode communities. Poplar plantation in fallows had a positive protection effect on the diversity of wild plants in agroecosystem, but it was difficult to improve the soil quality in a few years.