不同沼泽地对神农架大九湖湿地土壤—植被碳氮磷化学计量比的影响

Effects of different land use modes on soil-vegetation C,N and P stoichiometry in Dajiuhu Wetland,Shennongjia,China

湿地生态系统碳氮磷(C、N、P)生态化学计量比已成为当前探索群落生态动态过程的热点.然而,人类活动对沼泽湿地生态化学计量比的影响规律及其影响机制尚未明确.以神农架大九湖沼泽湿地为研究对象,探索植被—土壤碳氮磷生态化学计量比及其对人类活动的响应规律,以期为该区域湿地保护恢复提供决策支撑.研究表明:随着人类活动的影响,与泥炭沼泽比较,放牧区沼泽草甸和退耕区沼泽草甸土壤碳、氮、磷含量及其碳磷比、氮磷比显著降低(50%~90%),对碳氮比无显著影响.旅游干扰区沼泽除了显著降低土壤氮磷比外,其它无显著变化.放牧区沼泽草甸、退耕区沼泽草甸植被磷含量较泥炭沼泽和旅游区沼泽明显增加(40%~130%),植被碳、氮含量之间无明显差异.与泥炭沼泽比较,旅游区沼泽、放牧区沼泽草甸和退耕区沼泽草甸植被碳磷比显著降低(30%~50%),但植被碳氮比和氮磷比数据组之间无显著差异.植被—土壤生态化学计量比分析结果显示,氮磷比数值均小于阈值14,表明了该区域泥炭沼泽、草甸生态系统植被生长发育受到氮元素的限制,可能导致沼泽趋向富磷植被生长,为该区域沼泽湿地应对气候变化和氮沉降的研究提供理论支撑.

Ecological stoichiometric ratio of C(carbon),N(nitrogen),P(phosphorus)in wetland ecosystem has become a hot spot to explore the ecological dynamic process of community at present.However,the influence of human activities on the ecological stoichiometry of swamps and its influencing mechanism are not yet clear.To provide decision support for wetland conservation and restoration in this region,the C,N,P ecological stoichiometric ratio of the vegetation-soil and its response to human activities from the Shennongjia Dajiuhu swamp wetland were studied.The results showed that with the influence of human activities,the contents of C,N,and P and the C∶P,N∶P ratios in the swamp meadow soil for the grazing disturbance and the abandoned farmland zones decreased significantly(50%~90%)compared with the peat swamp,while changes on the C∶N ratios were not significance.As for the tourist swamp zone,there was no significant change in soil C∶N,C∶P ratios,except for the significant decrease in soil N∶P ratio.Compared with peat swamp and tourist swamp zones,the P content of the swamp meadow vegetation from the grazing disturbance and the abandoned farmland zones increased significantly(40%~130%),but there was no significant difference in the C and N content among the data groups on the four sampling zones.Compared with peat swamp,the C∶P ratio of the vegetation in the tourist swamp zone,the grazing and the abandoned farmland zones were significantly decreased(30%~50%),while no significant difference on the C∶N and N∶P ratios data groups were found among the four sampling zones.In this study,the ecological stoichiometric ratio on both vegetation and soil were studied.The N∶P ratios were all less than the threshold value of 14,suggesting that the vegetation growth and development of peat swamp and meadow ecosystems in this region were restricted by nitrogen,which might elevate the growth of the phosphorus-enriched plant.This study provided theoretical support for the future research on the response of swamp wetlands in this region to global climate change and nitrogen deposition.