长白山原始阔叶红松林土壤有机质组分小尺度空间异质性

土壤有机质(SOM)对于维持生态系统生产力具有非常重要的意义,有机质的组成、空间分布和空间关联性是影响和控制诸多生态系统过程的重要因素。应用地统计学方法,对长白山原始阔叶红松林局部尺度内0—20 cm土壤有机质与活性有机质的空间异质性进行了研究,并通过交叉半方差分析探讨了二者之间的相关性。研究结果表明:(1)总体上来说,土壤有机碳(SOC)、全氮(TN)、颗粒态有机碳(POC)和颗粒态有机氮(PON)空间异质性较小;而土壤微生物量碳(MBC)、微生物量氮(MBN)和表层(0—10 cm)溶解性有机碳(DOC)的空间异质性较大;(2)SOC、TN、MBC、DOC、POC和PON随着深度的增加空间自相关性增加;而溶解性有机氮(DON)的空间自相关性随深度的增加变化不大;(3)SOC与TN在表层和下层(10—20 cm)均存在空间上的正相关关系;(4)SOC、TN在表层和下层分别与MBC、MBN、DOC、DON和POC呈空间上的正相关性,但是与PON之间的空间相关关系较差;(5)不同土层深度的土壤活性有机质之间的相关关系存在差异。在表层,除POC,PON外,其余土壤活性有机质组分在空间上两两相关;但是随着土壤深度的增加,活性有机质变量之间在空间上两两相关。研究结果表明土壤有机质组分在长白山原始阔叶红松林小尺度内存在不同空间异质性和空间关联性,这为人们更好的理解森林生态系统功能(如土壤养分循环)提供了重要的理论依据。

Small-scale spatial heterogeneity of soil organic matter fractions within an original broad-leaved korean pine forest in Changbai Mountain, China

Soil organic matter (SOM) plays an important role in the maintenance of ecosystem productivity. In particular, the fractions, spatial distribution, and spatial dependency of SOM are important factors influencing multiple ecosystem processes including nutrient cycling, retention, and availability for plant growth. In the present study, geostatistical approaches were used to study the spatial variability of total and labile SOM fractions from the soil at a depth of 0-20 cm, in a Broad-Leaved Korean Pine forest in Changbai Mountain, China. Furthermore, the dependency between total SOM and labile organic matter was analyzed by calculating the cross-variogram. The results showed that:(1) The spatial heterogeneity of soil organic carbon (SOC), total nitrogen (TN), particulate organic carbon (POC), and particulate organic nitrogen (PON) was smaller than soil microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), and the dissolved organic carbon (DOC) in the surface horizon (0-10 cm); (2) With increased soil depth, the autocorrelation of SOC, TN, MBC, DOC, POC, and PON increased, but remained unchanged for dissolved organic nitrogen (DON); (3) SOC and TN were positively correlated in space within both the 0-10 cm and 10-20 cm soil layers; (4) SOC and TN were both spatially correlated to MBC, MBN, DOC, DON, and POC, respectively, but were not related to PON; (5) The correlations between labile organic matter varied with soil depth. The labile organic matter fractions were spatially correlated with each other at all depths, except POC and PON on the surface. Our results suggest that the spatial heterogeneity and dependency of SOM fractions are different at small scales in a Broad-Leaved Korean Pine forest in Changbai Mountain, providing an important theoretical basis to understand the ecological function of soil nutrient cycling in forest ecosystems.