1.College of Patacultural Science,Gansu Agricultural University,Key Laboratory of Grassland Ecosystem,Ministry of Education;2.Forestry Science and Technology Extension Station of Gansu Province
Phosphorus is the key support element in alpine grassland ecosystem. Alpine meadow degradation has caused many important ecological and production problems in pasturing area, and also produced the changes of nutrients recycling in ecosystems. The effects of degradation on phosphorus in alpine meadow ecosystem is complex because of the special climax and utilization strategies. Thus phosphorus recycling and its effects on productivity in degraded alpine meadow ecosystem was overlooked in the past years. Three typical phases of degraded alpine meadow, lightly degraded(LD), middle degraded(MD), and seriously degraded(SD) alpine meadow phases were chosen to study the effects of alpine meadow degradation on soil and vegetation phosphorus characteristics and their relationships with the vegetation biomass in eastern Qilian Mountain, and the control experiment treatment was the fenced restoration alpine meadow (FG). Soil phosphorus characteristics, such as soil total phosphorus, available phosphorus, microbial phosphorus content, and alkaline phosphatase activity of different alpine meadow phases in spring and summer, and the corresponding vegetation above-ground plant biomass and phosphorus content in growth season were studied, respectively. The results showed that the above-ground plant biomass decreased seriously after degradation in the alpine meadows of eastern Qilian Mountain. The above-ground plant dry weight of SD was only 35.93% of FG. The above-ground phosphorus content also decreased significantly after degradation, but there were no significant differences among different degradation degrees. The above-ground phosphorus content of the degraded alpine meadow was only 60% of the FG. Soil total and available phosphorus content in surface soil depth increased after degradation in the alpine meadows. Soil available phosphorus content of LD, MD and SD increased by 16.67%, 36.67%, 3.33% in spring, and 4.35%, 26.09%, 4.35% in summer, respectively. Meanwhile, soil available phosphorus content showed the seasonal difference which was higher in spring than summer. Degradation induced soil microbial phosphorus content to decrease, but it had no obvious rule on soil alkaline phosphatase activity. But soil alkaline phosphatase activity of FG in summer was higher than spring. Pearson correlation analyses showed that above-ground plant dry weight was positively correlated with soil total phosphorus content, and negatively correlated with soil alkaline phosphatase activity, while there was no significantly correlated relationship between the above-ground plant phosphorus and soil phosphorus characteristics, which reflected that soil phosphorus characteristics was not the reason for the reduction of above-ground plant phosphorus content. This study revealed phosphorus characteristics and their relationships in soil-plant system, which could provide basis for the management and restoration of degraded grassland in alpine area.
李亚娟,瞿丹,高亚君,达朝玲,鱼小军,史志翯,徐晶晶.东祁连山高寒草甸不同退化阶段植被/土壤磷素特征及其与生物量关系.生态学报,,(). http://dx. doi. org/[doi]复制