Edaphic specialization in tropical trees: Physiological correlates and responses to reciprocal transplantation
Edaphic specialization in tropical trees: Physiological correlates and responses to reciprocal transplantation
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DOI：
10.1890/04-0598
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发表时间：
2005-11-01
期刊：
影响因子：
4.8
通讯作者：
Burslem, DFRP
中科院分区：
文献类型：
--
作者：
Baltzer, JL;Thomas, SC;Burslem, DFRP
最近的研究证明了土壤因素在决定许多热带雨林树种的栖息地关联性方面的重要性，但土壤关联性的潜在机制尚不清楚。在马来西亚婆罗洲沙巴州的Sepilok森林保护区，来自砂岩(山脊)和冲积层(山谷)的两种主要土壤类型在养分和水分有效性方面存在差异，其特点是森林在物种组成、结构和林下光有效性方面存在显著差异。我们使用调查和相互移栽来检验这些土壤类型之间对光、养分和水分有效性差异的生理适应，并测试资源利用效率在决定土壤专业化方面的重要性。对土壤专家的同属和同科对(每个土壤类型一个种)以及两种土壤类型共同的通才的光合作用调查表明，在给定的同化率下，专门研究砂岩土壤的物种的气孔导度低于冲积土壤上的物种，并且具有更高的瞬时和综合水分利用效率。砂岩山脊的单位光合作用叶片暗呼吸速率高于冲积低地专家。我们认为，这些较高的呼吸速率可能是由于光合酶浓度的增加，以补偿气孔关闭增加导致的较低的内部二氧化碳浓度。砂岩脊专家较低的光合氮素利用效率支持了这一点。当生长在更干燥、多沙的山脊上时，多面手物种的水分利用效率低于砂岩脊专家，但他们的氮素利用效率与专门种到资源更丰富的冲积山谷的物种没有区别。在相互移植实验中，我们改变了光环境和土壤养分的有效性，涉及每种土壤类型的两个专业物种。土壤型专用树种，当种植在非专门化的土壤类型上时，不能适应变化以实现与专用于该土壤类型的树种类似的资源利用效率。我们的结论是，不同的用水策略是导致土壤联想差异的重要机制，从而有助于维持婆罗洲热带雨林当地树种的高度多样性。
Recent research has documented the importance of edaphic factors in determining the habitat associations of tree species in many tropical rain forests, but the underlying mechanisms for edaphic associations are unclear. At Sepilok Forest Reserve, Sabah, Malaysian Borneo, two main soil types derived from sandstone (ridges) and alluvium (valleys) differ in nutrient and water availability and are characterized by forests differing markedly in species composition, structure, and understory light availability. We use both survey and reciprocal transplants to examine physiological adaptations to differences in light, nutrient, and water availability between these soil types, and test for the importance of resource-use efficiency in determining edaphic specialization. Photosynthetic surveys for congeneric and confamilial pairs (one species per soil type) of edaphic specialists and for generalists common to both soil types show that species specializing on sandstone-derived soil had lower stomatal conductance at a given assimilation rate than those occurring on alluvial soil and also had greater instantaneous and integrated water-use efficiencies. Foliar dark respiration rates per unit photosynthesis were higher for sandstone ridge than alluvial lowland specialists. We suggest that these higher respiration rates are likely due to increases in photosynthetic enzyme concentrations to compensate for lower internal CO2 concentrations resulting from increased stomatal closure. This is supported by lower photosynthetic nitrogen-use efficiencies in the sandstone ridge specialists. Generalist species had lower water-use efficiencies than sandstone ridge specialists when growing on the drier, sandy ridgetops, but their nitrogen-use efficiencies did not differ from the species specialized to the more resource-rich alluvial valleys. We varied light environment and soil nutrient availability in a reciprocal transplant experiment involving two specialist species from each soil type. Edaphic specialist species, when grown on the soil type for which they were not specialized, were not capable of acclimatory shifts to achieve similar resource-use efficiencies as species specialized to that soil type. We conclude that divergent water-use strategies are an important mechanism underlying differences in edaphic associations and thus contributing to maintenance of high local tree species diversity in Bornean rain forests.