Journal of Arid Environments Journal of Arid Environments 63 (2005) 353–365 Ecophysiological acclimation to different soil moistures in plants from a semi-arid sandland S.L. Niu, G.M. Jiang à , S.Q. Wan, M.Z. Liu, L.M. Gao, Y.G. Li Laboratory of Quantitative Vegetation Ecology, Institute of Botany, The Chinese Academy of Sciences, 20 Nanxincun, 100093 Beijing, China Received 9 December 2003; received in revised form 30 December 2004; accepted 9 March 2005 Available online 24 May 2005 Abstract In order to explore the functional significance of ecophysiological heterogeneity among three arid microhabitats (sand dune, lowland and wetland), we investigated the stomatal and photosynthetic acclimation to soil moistures in different plants of highly diversified Hunshandak Sandland, Inner Mongolia, China. Wetland was found to have the highest soil water potential (0–40cm), while the fixed sand dune had the lowest (Po0:001). The three microhabitats appeared in a similar pattern in leaf water potential (C leaf ), stomatal conductance (g s ), photosynthetic rate (P n ) and photochemical efficiency of photosystem IIðF v =F m Þ with that of soil water potential, i.e. wetland4lowland4fixed sand dune (po0:01). Inversely, however, root depths in both fixed sand dune and lowland was 58% deeper (po0:05) than wetland. Photosynthetic characteristics (e.g. g s , P n , and F v =F m ) were found to be linearly correlated with C leaf in fixed sand dune and lowland (po0:05), but no linear relation among these traits were noted in wetland. Such a result indicated that water played an important role in controlling the ecophysiological process. Stomata sensitivity to leaf water potential changes increased with drought. In the microhabitats with contrasting soil water availabilities, plants may display feedback responses to the arid environment through elongating their root lengths and/or reducing their stomatal conductance. r 2005 Elsevier Ltd. All rights reserved. Keywords: Chlorophyll fluorescence; Leaf water potential; Photosynthetic rate; Root depth; Stomatal conductance ARTICLE IN PRESS www.elsevier.com/locate/jnlabr/yjare 0140-1963/$-see front matter r 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.jaridenv.2005.03.017 à Corresponding author. Tel: +861062595380. E-mail address: jgm@ht.rol.cn.net (G.M. Jiang).