土地利用方式对高寒草甸生态系统土壤无机碳的影响

Effects of Different Land Use Patterns on Soil Inorganic Carbon in Alpine Meadow Ecosystem

[目的]探明土地利用方式对高寒草甸生态系统土壤无机碳含量及储量的影响,为青藏高原区域碳增汇原理及草地管理实践提供科学支撑。[方法]选取围栏封育地、自由放牧地、多年生人工草地、补播地及黑土滩型退化草地5类不同土地利用类型,对无机碳的含量和储量、土壤主要理化性质的变化及其相关性进行比较分析。[结果]在高寒草甸生态系统中,无机碳含量较低且不同土地利用下土壤无机碳的储量(以C含量表示)有显著差异,表现为多年生人工草地(3 381.28kg/hm2)>围栏封育地(739.27kg/hm2)>自由放牧地(712.12kg/hm2)>补播地(647.64kg/hm2)>黑土滩型退化草地(361.26kg/hm2)。不同土地利用类型草地的土壤pH值、容重和含水量差异显著。土壤无机碳与土壤容重和含水量分别为线性正相关和负相关关系,与pH值为正相关关系,当pH值<7时,无机碳含量很低,基本保持不变;当pH值>7时,表现为指数函数关系。[结论]在高寒退化草地改良重建的技术与综合治理模式中,黑土滩型退化草地上建植多年生人工草地的管理策略在无机碳固定方面较其他措施更加有效,是维持草地碳汇功能的有效措施。

[Objective] We aimed to understand the effects of different land use patterns on soil inorganic carbon（SIC） content and storage, in order to provide scientific support for regional carbon transfer principle and grassland management.[Methods] The content and storage of SIC and the main soil physicochemical properties are analyzed, in five different land use patterns including fencing grassland（WF）, free grazing land（NG）, perennial artificial grassland（RG）, reseeding land（BB） and an extreme degradation meadow （HTT）.[Results] In alpine meadow ecosystem, SIC content was low, and the SIC storages differed among different land use patterns：RG（3 381.28 kg/hm^2） 〉 WF（739.27 kg/hm^2） 〉 NG（712.12 kg/hm^2） 〉 BB（647.64 kg/hm^2） 〉 HTT（361.26 kg/hm^2）. Soil pH value, bulk density and water content varied greatly among different land use types. SIC content showed a positive relation with soil bulk density while a negative relation with water content. When pH〈7, the SIC content was very low and remained constant, in contrast, when pH〉7, SIC content increased exponentially.[Conclusions] The planting perennial artificial grassland was more effective than other measures in terms of SIC sequestration and maintaining the function of carbon sink.