不同整地方式对长江滩地防护林土壤有机碳和全氮含量及密度的影响

Effects of different site preparations on the content and density of soil organic carbon and total nitrogen of shelter forests in low land of Yangtze River

湿地土壤碳(C)和氮(N)在湿地生态系统和全球碳氮循环中起着重要作用。为了阐明人类活动对湿地生态系统C库和N库的影响,本研究以西洞庭湖开沟和不开沟整地滩地防护林为研究对象,通过系统调查和土壤样品采集分析,探讨了不同整地方式对长江中下游滩地防护林土壤C和N的影响。研究结果表明:在不开沟样地中,0~100 cm土层土壤有机碳(SOC)和全氮(TN)含量及密度的变化均表现为CK>8年林龄>3年林龄;在开沟造林样地中,SOC和TN含量和密度在0~30 cm和30~60 cm土层随林龄增大先增加后减小,而在60~100 cm土层随林龄增大而减小。整地方式显著影响土壤SOC和TN含量,但对土壤SOC和TN密度影响不显著。因此,应合理确定长江中下游滩地防护林的规模,禁止在相对高程较低的区域采用开沟方式营建防护林。

Wetland soil carbon(C)and nitrogen(N)play important roles in wetland ecosystem and global carbon and nitrogen cycles.In order to clarify the impact of human activities on C and N pools of wetland ecosystem,the effects of site preparations on soil C and N pools of shelter forests in lowland of Yangtze River were evaluated by taking the beachland of West Dongting Lake as example,and investigated through the analysis of the change characteristics of SOC and TN contents and densities in two poplar plantations with bedding and unbedding,respectively.The results showed that the contents and densities of SOC and TN in unbedding plots were differed by the following orders as CK>8 a>3 a,and significant differences were detected in 0~30 cm and 30~60cm of soil layers.Meanwhile,in bedding plots,the contents and densities of SOC and TN in 0~30 cm and 30~60 cm of soil layers were increased firstly,and then decreased with the highest values in 6-year-old plots.However,the contents and densities of SOC and TN in 60~100 cm soil layers were decreased significantly with the increase of forest stands.Soil preparation significantly affected the contents of SOC and TN,but had no significant effects on densities of SOC and TN.Therefore,we suggested to reasonably determine the shelter forest scales,and forbidden to planting trees with bedding in those beach land with low elevations in the middle and lower reaches of the Yangtze River.