Contrasting seasonal leaf habits of canopy trees between tropical dry-deciduous and evergreen forests in Thailand
Contrasting seasonal leaf habits of canopy trees between tropical dry-deciduous and evergreen forests in Thailand
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DOI：
10.1093/treephys/26.5.643
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发表时间：
2006-05-01
期刊：
影响因子：
4
通讯作者：
Puangchit, L
中科院分区：
文献类型：
--
作者：
Ishida, A;Diloksumpun, S;Puangchit, L
我们比较了干旱落叶和万年青树木在热带干旱森林，土壤养分不同，但降雨量相似的叶特性，叶气体交换和光化学性质之间的差异。3种冠层乔木（Shorea siamensis Miq.，木果木霉Xylia xylocarpa（Roxb.）W.西奥布和蔓荆（Vitex peduncularis Wall.）ex Schauer）和万年青林中的林冠树（Hopea urea Lanessan）。万年青林土壤养分有效性低于落叶林。与万年青树种相比，落叶树种叶片寿命短，单位面积叶质量低，叶质量氮含量高，叶质量光合速率（mass-based P-n）和叶氮光合速率（N-based P-n）高，日最大气孔导度（g（s））高，木质部导管较宽。质量为基础的P-N下降，从湿到旱季的所有物种。旱季开始后，每天最大g（s）和敏感性的g（s）叶-空气蒸汽压赤字保持相对不变的落叶树木，而这两个属性在万年青树在旱季下降。光化学能力和非光化学猝灭（NPQ）的光系统II（PSII）也保持相对不变的落叶树木，即使在旱季开始后。相反，在干旱季节，万年青树的光化学能力下降，NPQ增加，表明叶片通过下调PSII应对长期干旱。因此，耐旱性落叶树种的特征是高N分配用于叶片碳同化、高水分利用和避免光抑制，而耐旱性万年青的特征是低N分配用于叶片碳同化、保守水分利用和耐光抑制。
We compared differences in leaf properties, leaf gas exchange and photochemical properties between drought-deciduous and evergreen trees in tropical dry forests, where soil nutrients differed but rainfall was similar. Three canopy trees (Shorea siamensis Miq., Xylia xylocarpa (Roxb.) W. Theob. and Vitex peduncularis Wall. ex Schauer) in a drought-deciduous forest and a canopy tree (Hopea urea Lanessan) in an evergreen forest were selected. Soil nutrient availability is lower in the evergreen forest than in the deciduous forest. Compared with the evergreen tree, the deciduous trees had shorter leaf life spans, lower leaf masses per area, higher leaf mass-based nitrogen (N) contents, higher leaf mass-based photosynthetic rates (mass-based P-n), higher leaf N-based P-n, higher daily maximum stomatal conductance (g(s)) and wider conduits in wood xylem. Mass-based P-n decreased from the wet to the dry season for all species. Following onset of the dry season, daily maximum g(s) and sensitivity of g(s) to leaf-to-air vapor pressure deficit remained relatively unchanged in the deciduous trees, whereas both properties decreased in the evergreen tree during the dry season. Photochemical capacity and non-photochemical quenching (NPQ) of photosystem II (PSII) also remained relatively unchanged in the deciduous trees even after the onset of the dry season. In contrast, photochemical capacity decreased and NPQ increased in the evergreen tree during the dry season, indicating that the leaves coped with prolonged drought by down-regulating PSII. Thus, the drought-avoidant deciduous species were characterized by high N allocation for leaf carbon assimilation, high water use and photoinhibition avoidance, whereas the drought-tolerant evergreen was characterized by low N allocation for leaf carbon assimilation, conservative water use and photoinhibition tolerance.