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Pak. J. Bot., 46(5): 1621-1629, 2014.

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IMPACT OF MULTIPLE SOIL NUTRIENTS ON DISTRIBUTION PATTERNS OF SHRUBS IN AN ARID VALLEY, IN SOUTHWEST CHINA

CHENG JUN SONG¹, LAI YE QU², TIAN YISHUI¹, KE MING MA^2*, LI XIN ZAO¹ AND XU XIANLI³

Abstract: Shrubs play key roles in arid regions and multiple interacting resources limit their distribution patterns. Identifying limiting resources and their coupling effects on shrubs is essential for developing restoration theory and practice. A survey of shrub composition, soil properties and topography was conducted in fifty-seven 15-m×15-m plots in an arid valley of the upper Minjiang River, Southwest China. With quantitative classification method and ordination technique, 48 shrubs species were classified into four clusters and two categories along soil gradient. Cluster I and II composed Category I and had a significantly higher percentage of dominant legume shrubs than in Cluster III and Cluster IV, which made up Category II. Correlation analysis indicated that both multi-resource limitation and single resource limitation were coexisting simultaneously in this arid area, the extent of which was functional cluster-specific and also quantified hierarchical structure of multiple resource limitation: soil water played a primary limitation role, available nitrogen the next, and available phosphorus the third at community scale. Moreover, this study affirmed that both soil pH and soil texture could effectively regulate retention of soil moisture and available nutrients, respectively. Distinguishing critical limiting resources and their regulators is very meaningful to clarify couplings and controlling mechanisms in restoration practices. Therefore, decreasing soil pH and increasing soil clay content should be conducted thoroughly in plantation sites to remain abundant soil moisture and available nutrients in native restoration projects.

Key words: Shrub pattern, Multi-resource limitation, Hierarchical limiting structure, Co-limitation, Ecological restoration

¹Key Laboratory of Energy Resource Utilization from Agricultural Residues, Ministry of Agriculture, Institute of Energy and Environmental Protection, Chinese Academy of Agricultural Engineering, Beijing 100125, PR China

²State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, PR China

³Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, PR China

^*Corresponding author’s e-mail: mkm@rcees.ac.cn; Tel/Fax: +86 10 6284 9104