Plant Diversity ›› 2008, Vol. 30 ›› Issue (03): 325-332.DOI: 10.3724 SP.J.1143.2008.07239

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The Effect of Seasonal Drought to Plant Hydraulics and Photosynthesis of Three Dominant Evergreen Tree Species in Seasonal Tropical Rainforest of
Xishuangbanna Limestone Area

WANG Ai-Ying1 , 2 , JIANG Yan-Juan1 , 2 , HAO Guang-You1 , 2 , CAO Kun-Fang1   

  1. 1 Xishuangbanna Tropical Botanical Garden , Chinese Academy of Sciences , Mengla 666303 , China ;
    2 Graduate University of Chinese Academy of Sciences, Beijing 100049 , China
  • Received:2007-10-15 Online:2008-06-25 Published:2008-06-25
  • Contact: CAO Kun-Fang

Abstract: To investigate the adaptive mechanisms of evergreen species to seasonal drought, we studied seasonal changes of plant hydraulics , photosynthesis and leaf osmotic related traits in three dominant evergreen species ( Celtis wightii, Cleistanthus sumatranus and Lasiococca comberi var. pseudoverticillata) of a limestone mountain area of Xishuangbanna, SW China . Compared to the wet season, the predawn leaf water potential in the dry season is significantly lower in all the three species , indicating a relatively strong soil drought stress. During the dry season, sapwood specific hydraulic conductivity ( Ks ) was significantly lower compared to that of the wet season in Cleistanthus sumatranus and Lasiococca comberi var . pseudoverticillata , but there was no significant change in Celtis wightii . There was no significant change in leaf area specific hydraulic conductivity ( Kl ) between the two seasons in all the three species, which may caused by the adjustment in hydraulic architecture through partial loss of leaves during the dry season . In the dry season , maximum carbon assimilate rate ( Amax ) was significantly lower than that of the wet season in all the three species . There were strong correlations between Amax and both of the two hydraulic traits ( i. e . Ks and Kl ), especially during the wet season, indicating a relatively strong independence of photosynthesis to water transport in stems . Leaf turgor loss point osmotic potential and saturation osmotic potential during the dry season were both significantly lower in all the three species, indicating a strong osmotic adjustment in adaptive to seasonal drought. Compared to the two coccurring deciduous species, the ability to tolerate drought-induced cavitation in stem xylems were substantially higher in the three evergreen species. These results indicated that the adaptation of these three evergreen species to seasonal drought mainly involves an adjustment in hydraulic architecture and a strong osmotic regulation in leaves .

Key words:

Limestone seasonal rainforest

CLC Number: