贡嘎山冰川退缩区植物-土壤反馈与植物间相互作用

植物-土壤反馈是揭示陆地生物群落动态变化的关键环节,为理解植物间相互作用及植被群落变化过程奠定基础。本研究以贡嘎山冰川退缩区原生演替早(5~10年)、中(30~40年)和晚期(80~100年)3个阶段典型土壤以及各阶段优势植物为对象,采用盆栽控制试验,比较优势植物在不同土壤条件下的生物量,并量化植物间相互作用以及植物-土壤反馈的方向与强度,为探究贡嘎山冰川退缩区植被群落演替规律提供依据。结果表明:(1)植物-土壤反馈作用显著影响植物在本土中的生物量,早期沙棘(Hippophae rhamnoides)在本土中生长最差,沙棘的植物-土壤反馈系数为负值;演替中期冬瓜杨(Populus purdomii)的反馈系数趋于零;晚期峨眉冷杉(Abies fabri)在本土中生长最好,峨眉冷杉的反馈系数为正值。(2)混种时,早期沙棘与演替中、晚期植物间相互作用指数为负值;中期冬瓜杨、川滇柳(Salix rehderiana)与演替早、晚期植物的相互作用指数接近于零,晚期植物峨眉冷杉、麦吊云杉(Picea brachytyla)与演替早、中期植物相互作用指数为正值。从植物-土壤反馈的方向来看,贡嘎山植被演替从早期负反馈,中期中性反馈,过渡到晚期正反馈。此外,演替早期沙棘促进演替中晚期植物生长,演替中期冬瓜杨、川滇柳对演替早晚期植物无显著影响,晚期峨眉冷杉、麦吊云杉更利于与演替早中期植物相互竞争。结果显示,植物-土壤反馈与植物间相互作用共同驱动了贡嘎山冰川退缩区植被快速演替,直至顶极群落。

Plant-soil feedback and plant-plant interaction in the glacier retreat area of Gongga Mountain

Plant-soil feedback is a key link for revealing the dynamics of terrestrial communities,thus laying a foundation to improve our understanding on the interactions among different plant groups and on the vegetation successional trajectories.We explored the relationships between soils and dominant plant species at three stages of the glacier retreat area of the Gongga Mountain including the early succession(5-10 years),mid-term succession(30-40 years),and late succession(80-100 years).The results showed that:(1)Plant-soil feedback significantly affected plant biomass in the native soil.Hippophae rhamnoides grew worst in the native soil of the early succession,with a negative plant-soil feedback coefficient.In the middle succession,the feedback coefficient of Populus purdomii tended to be zero.Abies fabri grew best in native soil at the late succession,with a positive feedback coefficient.(2)The competition interaction index between the early succession species H.rhamnoses and species of middle and late succession was negative,while it closed to zero for mid-succession species P.purdomii and Salix rehderiana,and was positive for the late succession species A.fabri and Picea brachytyla mixed with early and mid-succession species.Therefore,plant-soil feedback shifted from negative in early succession,neutral in mid-term succession,to positive in late succession.The early-succession species H.rhamnoides promoted the growth of species in later stages.P.purdomii and S.rehderiana in the mid-succession stage had no interaction with early and late succession species.Late-succession species A.fabri and P.brachytyla were more conducive to competing with early and mid-succession species.The results suggest that plant-soil feedback and plant-plant interaction together drive the rapid succession of plant community up to the climax community in the glacier retreat area of Gongga Mountain.