论文部分内容阅读
在桂西北喀斯特地区选取玉米-红薯轮作地(KMS)、放牧+冬季火烧草地(KGB)、自然恢复地(KNR)和原生林地(KPF)4种典型生态系统,研究了土壤有机碳、全氮、全磷,微生物生物量碳、氮、磷和土壤结构对生态系统退化的响应.结果表明:KPF土壤有机碳、全氮、全磷和微生物生物量碳、氮、磷均极显著高于其他3种土壤;其他3种土壤中,有机碳和全氮为:KNR>KGB>KMS,但差异不显著;KMS土壤全磷含量(0.87g·kg-1)分别是KNR和KGB的2.07和9.67倍(P<0.01);KGB和KNR土壤微生物生物量碳、氮、磷含量均显著大于KMS;KGB中微生物生物量碳显著大于KNR,但二者间微生物生物量氮和磷含量差异不显著.说明减少人为干扰后喀斯特退化生态系统可以缓慢增加土壤有机碳含量,适当放牧和自然恢复都可以作为退化生态系统恢复的方式;土壤微生物生物量对生态系统的变化响应较灵敏,可以作为喀斯特地区土壤养分变化或生态系统退化的一个敏感指标.土壤结构以>0.25mm水稳性大团聚体为主(>70%)(KMS除外,以2～0.25mm团聚体为主),并以>2mm团聚体为主;土壤结构破坏率KMS(51.62%)大于KGB(23.48%),KNR和KPF较小(分别为9.09%和9.46%).说明人为干扰或农业耕作破坏了土壤水稳性大团聚体,使其向小粒级转变,土壤结构破坏率增大.对喀斯特地区退化严重的生态系统应减少人为干扰,以自然恢复等保护性措施为主.
In this study, KMS, KGB, KNR and KPF were selected to study the effects of soil organic carbon, total nitrogen , Total phosphorus, microbial biomass carbon, nitrogen, phosphorus and soil structure responses to ecosystem degradation.The results showed that soil organic carbon, total nitrogen, total phosphorus and microbial biomass carbon, nitrogen and phosphorus in KPF were significantly higher than those in the other 3 kinds of soil. Among the other three kinds of soil, the contents of total organic carbon and total nitrogen were KNR> KGB> KMS, but the difference was insignificant. The total phosphorus content (0.87g · kg-1) in KMS was 2.07 and 9.67 (P <0.01). The contents of soil microbial biomass carbon, nitrogen and phosphorus in KGB and KNR were significantly higher than those in KMS. The microbial biomass carbon in KGB was significantly higher than that in KNR, but there was no significant difference in microbial biomass N and P between them. The results showed that the reduction of man-made disturbance could lead to the slow increase of soil organic carbon content in the degraded karst ecosystem. Appropriate grazing and natural restoration could be used as the means of restoration of degraded ecosystems. The response of soil microbial biomass to ecosystem changes was sensitive and could be used as soil of karst area support (> 70%) with the exception of KMS (mainly 2 ~ 0.25mm aggregates), and soil aggregates with> 2mm aggregates (51.62%) were greater than KGB (23.48%) and KNR and KPF were smaller (9.09% and 9.46% respectively), indicating that man-made disturbances or agricultural tillage destroyed the soil water-stable macroaggregates, So as to change it to small grain size and increase the rate of destruction of soil structure.It should reduce man-made disturbance to the seriously degraded ecosystems in karst areas and mainly take protective measures such as natural recovery.