极端干旱环境下的胡杨细根分布与土壤特征

 以塔里木河下游的中龄胡杨为研究对象,采用开挖剖面分层取样法,对胡杨细根(D≤2 mm)的空间分布以及与土壤特征因子之间的关系进行了分析。结果表明:①在长期干旱胁迫下,胡杨细根(D≤2 mm)根长密度(RLD)、根表面积密度(SAD)从表层到地下100 cm土层内,呈逐渐增加趋势,100~140 cm土层内表现为减少的波动分布趋势；细根RLD、SAD集中分布在60~120 cm土层内,约占0~140 cm土层总细根RLD和SAD的74%以上；在水平方向上,距树干0.75～2.5 m范围内,呈逐渐减少趋势,而在3.5～5.5 m范围内呈波动的增加趋势。②胡杨细根(D≤2 mm)RLD和SAD与土壤总盐、土壤有效养分含量之间呈显著负相关关系,适合乘幂模型,与土壤含水率之间呈一定程度的正相关关系,适合三次曲线模型。

Fine Root Distribution of Populus euphratica Oliv.and Its Relations with Soil Factors under Extremely Arid Environment

In order to understand the spatial distribution of P. euphratica fine roots(D≤2 mm)and its relation with soil factors under the extremely arid environment, a middle aged P. euphratica tree which grown at the lower reaches of Tarim River, Xinjiang, China, was selected as a sample tree. By trench profile method, 168 root and soil samples were collected. Results showed that: (1)P. euphratica fine root length density (FRLD), fine root surface area density ( FRSAD) increased from the soil surface to 100-cm soil layer, and decreased from 100-cm to 140-cm layer; P. euphraticaFRLD, FRSAD was mainly concentrated on 60~120 cm soil depth, which accounted for over 74% of whole 0~140 cm soil profiles FRLD, FRSAD. In the horizontal direction, FRLD and FRSAD showed a decreasing trend with a distance between 75~250 cm from the tree trunk, and increased with fluctuation at distance between 350~550 cm. (2)There were negative significant correlations between P. euphratica FRLD and soil total salt, soil available nutrient, and power model can best fit their relations; there was positive correlations between P. euphratica FRLD and soil water, but the correlation was not significant at P=0.05 level, and Cubic model can best fit their relations.