西藏色季拉山西坡不同海拔梯度表层土壤碳氮变化特性的研究

为探讨海拔梯度变化对表层土壤(0～20 cm)全量养分的影响,以西藏色季拉山西坡的高山灌丛(AS)、杜鹃林(RF)、急尖长苞冷杉林(AGSF1-6)和林芝云杉林(PLLF)为试验对象,研究了林地土壤有机碳(SOC)、全氮(TN)、微生物生物量碳(MBC)、微生物生物量氮(MBN)、易氧化态碳(ROC)和颗粒有机碳(POC)的变化特征.结果表明:在色季拉山西坡,高海拔植被类型具有较高的土壤活性有机碳含量和分配比例.表层土壤SOC随着海拔的升高而增大.SOC最大的是AS,为77.167 g·kg-1,PLLF最低为22.351 g·kg-1.表层土壤TN随着海拔的升高而增大.TN最大的是AS,为2.430g·kg-1,PLLF最低为0.830 g·kg-1.表层土壤C/N最大者为AGSF4,达到了43.57,最小者是PLLF为26.93.海拔和林分对土壤MBC和MBN含量具有显著的影响.随着海拔高度的降低,POC占TOC含量的比率从44.81％降至19.32％,ROC占TOC含量的比率从41.72％降至7.07％.不同林地POC和ROC含量与SOC含量具有正相关关系.土壤活性有机碳与土壤总有机碳显著相关,土壤易氧化有机碳与颗粒有机碳的相关性也比较显著(p＜0.05).

Changes of Soil Organic Carbon and Total Nitrogen at Different Altitudes in West Slope of Sejila Mountain of Tibet

In order to explore the effects of total nutrient on surface soil (0 20cm), the alpine shrub, Rhododendron forest, Abies georgei var. smithii forest and Picea likiangensis var. linzhiensis forest were selected as experimental sites, the soil organic carbon (SOC), total nitrogen (TN), microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), readily oxidizable organic carbon (ROC), and particulate organic carbon (POC) were studied at different altitudes. The results showed that compared with lower-elevation vegetation types, the higher ones were found significantly higher in their SOC content and proportion. The SOC and TN contents were increasing along the elevation gradient in Sejila Mountain. The surface SOC of alpine shrub was the largest (77.167) and P. likiangensis var. linzhiensis forest the smallest(22.351). The TN of alpine shrub was the largest(2.430) and P. likiangensis var. linzhiensis forest the smallest(0.830). The surface C/N ratio of A.georgei var. smithii forest was the largest(43.57) and P. likiangensis var. linzhiensis forest the smallest(26.93). The elevation and wood stand had a significant impact on MBC and MBN. With lower altitude, the ratio of the POC in TOC decreased from 44.81% to 19.32%, the ratio of ROC in TOC decreased from 41.72% to 7.07%. The POC and ROC of different wood lands were significantly related to SOC. And the active SOC was significantly related to total SOC. The relationship between soil microbial biomass and readily oxidizable organic carbon was significant(p<0.05).