内蒙古典型草原区四种主要物种的植物-土壤反馈作用

Plant-soil feedback effects of four common species in the Inner Mongolia Steppe,China

植物-土壤反馈对解释群落组成变化和预测群落动态具有重要意义,是群落生态学与恢复生态学研究的热点领域。本研究以内蒙古典型草原区4种主要物种羊草(Leymus chinensis)、大针茅(Stipa grandis)、克氏针茅(Stipa krylovii)和冰草(Agropyron cristatum)为研究对象,采用植物-土壤反馈研究的两阶段法进行盆栽实验,研究了单种种植植物对土壤的影响(所得土壤用S-植物种拉丁名首字母表示,分别为S-Lc、S-Sg、S-Sk、S-Ac),以及这些受影响土壤对后续种植植物个体水平和群落水平的植物-土壤反馈作用。结果表明:(1)4种植物单种后对土壤C∶N、速效磷含量以及p H值3个指标具有显著影响(P<0.05);(2)个体水平的植物-土壤反馈具有物种特异性,羊草和冰草的分蘖数、株高、地上部生物量、地下部生物量以及总生物量5个观测指标的最高值均出现在S-Sk;克氏针茅5个观测指标的最高值出现在S-Lc;大针茅分蘖数和株高的最高值出现在S-Ac,而生物量的最高值出现在SLc;(3)大针茅和克氏针茅的反馈效应值(FV)显著小于0,表现为负反馈;冰草表现为中性反馈;羊草表现为中性至弱正反馈;(4)4种物种两两间净配对反馈值(I)均为负值,且克氏针茅-羊草以及克氏针茅-冰草间反馈值显著小于0,表明这些物种两两间能稳定共存。这些结果为内蒙古草原区植物群落组成变化对地下部土壤、后续植物的生长状况以及主要物种种间关系的影响的预测提供了实验数据。

Plant-soil feedback plays an important role in explaining the change of community composition and in predicting the community dynamics, and thus becomes a hot point in the field of community ecology and restoration ecology. In the present study, we selected four common species, Leymus chinensis, Stipa grandis, Stipa krylovii and Agropyron cristatum from a community in the Inner Mongolia Steppe, and examined the plant-soil feedback with a two-phase method. In the first phase, we planted those four species in monoculture and compared the soil difference among different monocuhures. The soil was then named as S-the initial of the Latin name of a plant species, i.e., S-Lc, S-Sg, S-Sk, S-Ac, respectively. In the second phase, we examined the plant-soil feedback effects on the subsequent plants at both species and community levels. There were significant differences among species treatments in soil C ： N ratio, soil available phosphorus content and soil pH value （P 〈 0. 05 ）. The plant-soil feedback effects were species-specific. L. chinensis and A. cristatum showed the best performance for all five variables observed （tiller number, plant height, aboveground biomass, belowground biomass and total biomass） in the S-Sk, S. krylovii showed the best performance for all five variables observed in S- Lc, S. grandis showed the largest tiller number and greatest plant height in S-Ac, and the largest amount of biomass in S-Lc. There were significant negative feedbacks for S. grandis and S. krylovii, neutral feedback for A. cristatum, and neutral to weak positive feedback for L. chinensis as indicated by the feedback effect value. The net pairwise feedback values among the four species were negative, and the values between S. krylovii and L. chinenses, and between S. krylovii and A. cristatum were significantly less than zero, indicating the probability of coexistence for these pair-wised species. These results would help to predict the effects of plant community composition change on soil properties and the performance of subsequent plants and interspecific relationships among common species in the Inner Mongolia Steppe.