塔里木盆地北缘绿洲土壤化学计量特征

选择塔里木盆地北缘阿拉尔垦区灌漠土、棕漠土、盐土和风沙土四种土壤为研究对象,在分析土壤C、N、P化学计量特征基础上,利用排序方法中的冗余分析(Redundancy analysis,RDA)技术深入解析了土壤C、N、P含量及其化学计量比与其他理化因子的关系。结果表明:研究区土壤C、N、P含量整体水平不高,土壤C、N、P元素含量均值分别为2.97、0.27、0.64 mg g-1。由C、N、P含量的相关性分析可知C、N元素含量变化几乎同步,P元素含量变化滞后于二者。C∶N∶P为11∶1∶2.37,在四种土壤类型中N∶P、C∶P较C∶N变化范围大,土壤C、N、P计量比表明N是研究区主要的限制因素。冗余分析结果表明,土壤含水量是土壤C、N、P含量及其化学计量比变化的主要驱动因子,土壤含水量与土壤C、N元素含量和N∶P、C∶P呈现极显著正相关关系,土壤容重与土壤C、N元素含量和N∶P、C∶P呈现极显著负相关关系;土壤盐度对土壤C、N、P含量及其化学计量比的影响并未达到显著程度,可能是因为研究区土壤本身盐碱性差异不大。

Stoichiometric characteristics of soil in an oasis on northern edge of Tarim Basin, China

Carbon (C), nitrogen (N) and phosphorus (P) are the three most important basic elements in soils of arid regions because biogeochemical circulations are closely related to ecological structures, processes and functions of the soils. Ecological stoichiometry combining the first law of thermodynamics, the theory of natural selection during biological evolutions, and the central dogma of molecular biology, has organically integrated biological studies of different scales in the fields of molecules, cells, species groups, communities and ecosystems. As soil is an important component of the terrestrial ecosystem, its elements stoichiometry characteristics plays a substantial role in terrestrial cycling of carbon and nutrients. Four types of soils, i.e. irrigated desert soil, brown desert soil, saline soil and aeolian sandy soil, in the Alar Reclamation Zone at the north edge of the Tarim Basin were selected as objects of the study to explore stoichiometry characteristics soil C, N and P, and to to analyze in-depth their relationships with other physical and chemical factors using the redundancy analysis (RDA) technique of the sorting method. Results show that the mean content of soil C, N and P was 2.97, 0.27 and 0.64 mg g-1, respectively; and soil C: N, N: P and C: P ratio was 12.14, 0.40 and 4.55, respectively. Soil C and P varied moderately and soil N quite sharply in stoichiometrical characteristics in all the four soils. Correlation analysis of the elements shows that extremely significant correlations exist between C and N, and between C and P, (P <0.01) and between N and P (P <0.05). And C and N were almost synchronous in variation, while P always lagged behind the two. Compared with the average of the global soil (C: N: P=186: 13: 1), the soils in this area, regardless of type of soil, were lower in C: N: P ratio (11: 1: 2.37), thus leading to lower soil nutrient availability. In terms of C, N and P contents, the four soils followed an order of irrigated desert soil > Saline soil > brown desert soil > aeolian sandy soil. Stoichiometrical ratios of the three elements varied somewhat with the type of soil. C: N was more stable than N: P and C: P. In terms of C: N, the four soils followed an order of saline soil > aeolian sandy soil > brown desert soil > irrigated desert soil, and in terms of. N: P and C: P, they did an order of irrigated desert soil > brown desert soil > saline soil > aeolian sandy soil. RDA shows that soil water content is the major factor affecting stoichiometrical properties of soil C, N and P in the study area and soil bulk density followed. However, pH and total salt did not have much significant impact. Soil moisture content was significantly and positively related to C, N and P contents, and also positively to N: P and C: P, but negatively to C: N. Soil bulk density was significantly and negatively related to C, N, N: P and C: P, but positively to P content and C: N. Soil N: P and surface soil C: N are two factors that can be used jointly as a good indicator of soil N supply. Overall consideration of soil C: N and N: P in the region reveals that soil C: N is <30 and N: P <14, which determines variation of stoichiometrical characteristics of C, N and P in the soils of the study area.