新疆塔里木河下游灌丛地上生物量及其空间分布

Analysis of the aboveground biomass and spatial distribution of shrubs in the lower reaches of Tarim River,Xinjiang,China

对塔里木河下游断流河道2004年7个地下水监测断面和19个植被样地的实测监测资料分析得出灌木生物量在空间分布的变化特征。在分析中分别选取了3个指标：灌木总生物量、多枝柽柳和刚毛柽柳的生物量。研究发现在纵向和横向上3项指标均呈现先增加后减小的单峰形式变化。在纵向上分别对3项指标在距离河道0～200m和200—400m范围内的分布情况进行比较，发现灌木在距离河道200～400m样地内分布占到总量近70％；横向上灌木生物量的最大值出现在距离河道450m的样地内。总体来看，对于两个优势物种，由于两个物种生理生态特性的差异对于异质性环境的适应能力也不同，导致分布状况也各异。多枝柽柳有较广的生态适应性，因此广泛分布于塔里木河下游的各个环境梯度上，而刚毛柽柳对水盐条件的要求较高，仅分布在其中个别断面。影响灌木生物量变化的主要因子是地下水埋深，当地下水埋深小于5m时，柽柳处于良好生长状态；当地下水埋深大于6m后，柽柳的生长受到抑制，开始朝衰败方向发展。浅层土壤含水对于植物吸收利用水分而言意义不大，同时由于优势种柽柳具有独特的抗盐和适盐机制，该区的盐分对柽柳的生长也不构成威胁。本文旨在通过分析塔里木河下游灌木生物量变化特征及其影响因子，为干旱、半干旱地区植被的恢复和保护提供了理论依据。

The aboveground biomass and spatial distribution of shrubs were obtained by analysing the data of 7 groundwater observation wells and 19 vegetation plots in the lower reaches of the Tarim River in 2004. It was found that the respective biomass of Tamarix ramosissima and T. hispida all presented a unimodal pattern of decreasing before increasing： Longitudinally, the aboveground biomass account for 70% of all within the scope of 0-200m by comparing the distribution of 0 -200m and 200 -400m apart from the river course; Transversely, the maximum appeared at the plot of 450m distance from the river course. As a whole, the different adaptability to environmental heterogeneity of T. ramosissima and T. hispida, resulted from the difference of physiological and ecological characteristics, led to the distribution of their own. T. ramosissima distributed widely in the lower reaches of Tarim River due to its eurytopicity, however, T. hispida appeared only at a few sections for its high requirement to moisture and salinity conditions. Groundwater depth was the main factor that influenced the change of the shrub biomass. When groundwater depth was less than 5m, T. grew well, however, it would be coerced seriously when the groundwater depth was more than 6m. The shallow water content of soil was meaningless to water utilization of plants, in addition, salinity is not the primary intimidator in this region because of having unique mechanism to adaptive and resistant the salinity. The aim of this paper was to provide theoretical bases for the restoration and protection of vegetation in the arid and semi-arid region by studying the spatial distribution and influencing factors of shrub biomass.