Chin J Plant Ecol ›› 2013, Vol. 37 ›› Issue (3): 248-255.DOI: 10.3724/SP.J.1258.2013.00025

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Effects of soil thickness on dry-season water relations and growth in Robinia pseudoacacia

WANG Lin, FENG Jin-Xia, WAN Xian-Chong*()   

  1. Chinese Academy of Forestry, Institute of New Forestry Technology, Beijing 100091, China
  • Published:2014-02-12
  • Contact: WAN Xian-Chong


Aims Our main purposes were to explore effects of soil thickness on the soil water carrying capacity of black locust (Robinia pseudoacacia) forests and to investigate the role of soil moisture in causing decline of black locust forests in regions of northern China in recent years.

Methods We measured soil moisture, pre-dawn twig water potential and gas exchange of black locust in the dry season and wet season. We also measured stable carbon isotope ratio (δ13C) of leaf, leaf morphology and growth of black locust. Combined with the differential response in the dry season and wet season, we analyzed the relationship between water status of black locust and the soil thickness.

Important findings In the dry season, the twig pre-dawn water potential and soil moisture significantly declined with decreased soil thickness, and the net photosynthetic rate and stomatal conductance of black locust also decreased. But there were no significant differences in these indexes in the wet season. Average soil moisture in the dry season was only 60% that in the wet season. With decrease in soil thickness, δ13C increased, area of leaf decreased and leaf mass per area increased. As a result, tree height and diameter at breast height significantly decreased with decrease in soil thickness. Results revealed that the water status of black locust in the different seasons strongly reflected water supply capacity of the soil, and that thin soil thickness was the main cause for the decline of black locust forests due to low carrying capacity of vegetation caused by inadequate water storage in the dry season.

Key words: gas exchange, leaf morphogenesis, predawn water potential, Robinia pseudoacacia, soil thickness, stable carbon isotope ratio (δ13C)