青藏工程走廊沿线不同植被类型带土壤典型理化特征

Soil physicochemical characteristics of different vegetation types along Qinghai-Tibet Engineering Corridor

为制订科学合理的青藏工程走廊沿线植被恢复策略,掌握沿线土壤的理化特征及其与植被分布的相关关系,本文研究沿线不同植被类型带的土壤典型理化特征,共设置样带27条,测定指标包括有机质、全氮、全磷、全钾、p H值、阳离子交换量和碳酸钙质量分数。结果表明,沿线土壤有机质和全氮质量分数,由北至南均表现出逐渐增高的趋势,并与植被类型密切相关,土壤有机质质量分数多在10.0～40.0 g/kg之间,全氮则多介于0.4～2.0 g/kg之间。线性模型拟合结果表明：有机质和全氮呈明显的线性相关;全磷质量分数多在0.3～0.8 g/kg之间,由北至南呈“两端高,中间低”变化趋势;全钾质量分数多介于13.0～30.0 g/kg,由北至南增高趋势明显;土壤p H值则表现为“北高南低”;沿线阳离子交换量多在6.0～24.0 cmol（＋）/kg之间;碳酸钙质量分数呈现“南北迥异”的变化规律,北部样带多在8.0%～15.0%之间,南部样带则多只有1.0%～3.0%,这与土壤钙积作用密切相关。综上所述,沿线土壤各理化指标表现出不同的变化规律,部分指标与植被类型存在一定的相关性。

[ Background] It is necessary to analyze the soil physicochemical characteristics along the Qinghai-Tibet Engineering Corridor （QTEC） for formulating scientific and reasonable vegetation restoration measures. [ Methods] Soil physicochemical characteristics of different vegetation types along QTEC were surveyed. Altogether 27 transects were set up, 8 plots of 20 m× 20 m were selected in each transect, randomly sampling 5 times in the soil layer of 0 - 20 cm and 20 - 40 em of each plot, then 5 samples were mixed into 1 soil sample. The soil sample in each transect was tested, the detection indexes of soil samples including the contents of soil organic matter, total nitrogen, total phosphorus, total potassium, pH value, cation exchange capacity, and calcium carbonate content were analyzed. Also the vegetation types, community structure of each transect were investigated. [ Results] The results showed that the contents of soil organic matter and total nitrogen increased gradually from north to south along QTEC, and were closely correlated to vegetation types. The content of soil organic matter changed in the range of 10.0 -40.0 g/kg. And the content of total nitrogen distributed within the scope of 0.4 -2.0 g/ kg. The contents of soil organic matter and total nitrogen presented a significantly linear correlation with each other. The content of soil total phosphorus mostly was in the range of 0. 3 - 0.8 g/kg. From north to south, there was significant uptrend of the soil total potassium content along QTEC,the total potassium of the transects in south of Nagqu mostly was among 22.0 -30.0 g/kg, however, the value in the north transects of Nagqu was in the range of 13.0 - 22.0 g/kg. The soil pH value of the transects in the northern part of QTEC were mostly higher than the transects in the southern part. The soil cation exchange capacity of the transects along QTEC was in the range of 6.0 - 24.0 cmol （ ＋ ）/kg. The content of soil calcium carbonate mostly was among 8.0% - 15.0% , but the southern part from Gaqia to Lhasa mostly was only in the range of 1.0% - 3.0% , this obvious distinction was mainly concerned with the soil calcium deposition. [ Conclusions ] In summary, there were very regular dynamic change discipline of soil chemical characteristics along the QTEC. The result showed that some soil indexes were closely correlated to vegetation types, such as organic matter, total nitrogen, et al, while other indexes had no obvious correlation with the vegetation types like exchange capacity of soil cation. In the future, the dynamic monitoring of soil physical and chemical characteristics should be further proceeded.