Hydraulic traits and water use of Eucalyptus on restored versus natural sites in a seasonally dry forest in southwestern Australia
Hydraulic traits and water use of Eucalyptus on restored versus natural sites in a seasonally dry forest in southwestern Australia
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DOI：
10.1016/j.foreco.2012.02.029
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发表时间：
2012-06-15
影响因子：
3.7
通讯作者：
Adams, Mark A.
中科院分区：
文献类型：
--
作者：
Bleby, Timothy M.;Colquhoun, Ian J.;Adams, Mark A.
桉树是全球重要的造林树种，但桉树在非原生环境中的生长具有不确定的生态水文后果。本研究调查了在澳大利亚西南部季节性干旱气候条件下恢复矿山和森林的边缘桉幼株（2.5-10 m高）的水力结构和功能。我们测量了树干液流，叶面积，边材面积，叶水势，气孔导度和天气变量，并应用一个简单的模型，植物水分利用，以检查在每个环境中的树木（使用高度作为年龄指数）的时序水力性状。恢复的网站上的年轻的树木生长速度快三倍，每单位叶面积（0.53公斤米（-2）天（-1））比森林树木多使用四倍的水，与恢复网站上更大的光，水和养分的可用性相一致。为了保持水力平衡，恢复网站上的树木减少叶面积/边材面积比的25%，边材渗透性增加20%，气孔导度和蒸腾作用减少50%，以抵消四倍增加的高度和叶面积。相比之下，林木叶面积/边材面积比减少了33%，但边材渗透性增加了100%，气孔导度和蒸腾作用增加了50%，以响应水的可用性，除了增加高度和叶面积。森林树木的叶面积和水分利用之间的线性关系表明水文平衡，而恢复网站上的树木的曲线关系表明从高到低的水供应过渡。年轻的Euclidae可能会发展出与其气候和基质水力相容的特性，但随着时间的推移，它们也可能会调整其结构和生理，以应对水资源的变化。在重新造林的景观中，经过改良的土壤和最初丰富的土壤水分可能会发展出比原生森林更有效的水力结构，如果它们只能进入固定体积的土壤，这可能会带来风险。这种系统的长期可持续性很可能取决于树木最终发展出适当的水力结构，以科普更类似于原生森林的水供应制度，特别是在易发生干旱的环境中。(C)2012爱思唯尔有限公司版权所有。
Eucalyptus is a globally important genus for reforestation but eucalypt growth in non-native environments has uncertain ecohydrological consequences. This study investigated the hydraulic structure and function of juvenile (2.5-10 m height) Eucalyptus marginata on restored mine sites and forest sites in a seasonally dry climate in southwestern Australia. We measured sap flow, leaf area, sapwood area, leaf water potential, stomatal conductance and weather variables and applied a simple model of plant water use to examine hydraulic traits across chronosequences of trees (using height as an index of age) in each environment. Younger trees on restored sites grew three times faster and used four times more water per unit leaf area (0.53 kg m(-2) day(-1)) than forest trees, consistent with greater light, water and nutrient availability on restored sites. To maintain hydraulic homeostasis, trees on restored sites reduced leaf area/sapwood area ratio by 25%, increased sapwood permeability by 20%, and reduced stomatal conductance and transpiration by 50% to counterbalance fourfold increases in height and leaf area. In contrast, forest trees reduced leaf area/sapwood area ratio by 33% but increased sapwood permeability by 100% and stomatal conductance and transpiration by 50% in response to increased water availability, in addition to increased height and leaf area. A linear relationship between leaf area and water use for forest trees was indicative of hydrological equilibrium, whereas a curvilinear relationship for trees on restored sites suggested transition from high to lower water availability. Young eucalypts are likely to develop traits that are hydraulically compatible with their climate and substrate, but they may also adjust their architecture and physiology over time in response to changes in water availability. Trees in reforested landscapes with modified soils and initially abundant soil moisture may develop hydraulic architectures that are more efficient than found in native forests, which may pose risks if they can only access a fixed volume of soil. The long-term sustainability of such systems is likely to depend on trees eventually developing appropriate hydraulic architectures to cope with regimes of water availability more akin to native forests, especially in drought-prone environments. (C) 2012 Elsevier B.V. All rights reserved.