模拟氮沉降对克氏针茅和碱韭种间竞争的影响

Effects of Nitrogen Deposition on Competition of Stipa krylovii and Allium polyrhizum

以克氏针茅和碱韭为研究对象,分析单播和混播种植方式下,氮沉降对两种植物地上生物量、地下生物量的影响,比较两种植物的竞争能力。结果表明:单播时,克氏针茅的株高随着施氮浓度的增加而上升且在施氮20 g/(m^2·yr)时显著高于其他处理(P<0.05),碱韭的株高在施氮20 g/(m^2·yr)时显著低于其他处理(P<0.05)。氮素对克氏针茅种群和碱韭种群都具有显著的调节效应,随着氮素梯度的增加,克氏针茅与碱韭的地上生物量、地下生物量、总生物量均有增加的趋势。克氏针茅对氮素添加的响应相比碱韭更明显,在单播时,克氏针茅在施氮10 g/(m^2·yr)时地上、地下及总生物量显著高于其他处理(P<0.05),混播时,克氏针茅在施氮20 g/(m^2·yr)时地上、地下及总生物量最大;在模拟氮沉降的过程中,克氏针茅与碱韭的种内竞争大于种间竞争,说明氮沉降对两者之间的竞争关系影响较小。

In order to study the effect of nitrogen deposition on the competition between two dominant species of the Stipa krylovii grassland of Hulun Buir.Pot control method with simulated nitrogen deposition was used in this experiment. S.krylovii and Allium polyrhizum were studied.The effects of nitrogen deposition on aboveground biomass and belowground biomass of the two plants were analyzed by monoculture and mixture, and the competitiveness of the two plants was compared.The results showed that plant height of S.krylovii increased with the increase of nitrogen concentration and was significantly higher than that of other treatments at 20 g/(m^2·yr)(P < 0.05) by monoculture.Plant height of A.polyrhizum was significantly lower than that of other treatments at 20 g/(m^2·yr)(P < 0.05).Nitrogen addition had a significant effect on the growth of the two species.With the addition of nitrogen, the aboveground biomass, underground biomass and total biomass increased significantly.The response of S.krylovii was more obvious than A.polyrhizum.The aboveground, underground and total biomass of S.krylovii were significantly higher than that of other treatments (P < 0.05) by monoculture at 10 g/(m^2·yr).The aboveground, underground and total biomass of S.krylovii were the largest by mixture at 20 g/(m^2·yr).In the process of simulating nitrogen deposition, the intraspecific competition between S.krylovii and A.polyrhizum is greater than that between species, it indicated that the nitrogen deposition will not change the competitive relationship between the two species.