Forest-scale sap flux responses to rainfall in a dryland eucalyptus plantation
Forest-scale sap flux responses to rainfall in a dryland eucalyptus plantation
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DOI：
10.1007/s11104-008-9558-8
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发表时间：
2008-02
期刊：
影响因子：
4.9
通讯作者：
H. Morgan;C. Barton
中科院分区：
文献类型：
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作者：
H. Morgan;C. Barton
旱地盐碱化是由于地下咸水水位上升造成的，这是相对较近的景观尺度上对深根植被清除的结果。解决这个问题的一个显而易见的办法是在这些景观中重新引入深根植被，最有可能是非落叶树。理想情况下，持续蒸腾的深根树木将从整个土壤剖面中除去水分，增加土壤储水的能力，从而通过有效减少有助于地下水补给的降雨事件的次数来降低地下水位。在这项研究中，我们研究了桉树对水的利用。Cunn。在四年的树液通量监测中，生长在盐碱地的ex Woolls种植园对降雨事件的反应有所不同。在多个季节观测到人工林的响应，从高于平均降雨量到远低于平均降雨量。我们观察到，人工林在干旱期间能够持续利用水分，同时对降雨事件也非常敏感。在最干旱的时期，浅层土壤水分降至稳定的最低水平，森林继续以每天约1毫米的速度取水。一般来说，我们观察到只有5毫米的降雨会增加森林用水，而邻近的原生植被则会增加20毫米。我们比较了一系列似是而非的经验模型来描述森林用水对降雨的响应。最佳模型表明，降雨大小、雨后PET以及降雨大小与前期土壤水分的相互作用对降雨事件中森林水分利用的变化有显著贡献。有趣的是，该模型显示，在其他条件相同的情况下，较高的前期土壤湿度往往会减少森林对降雨的潜在用水增加。
Dryland salinity is caused by rising saline water tables, the result of relatively recent landscape-scale clearance of deep-rooted vegetation. One obvious solution to this problem is the reintroduction of deep-rooted vegetation into these landscapes, most likely non-deciduous trees. Ideally, continually-transpiring deep-rooted trees would remove moisture from throughout the soil profile, increasing the capacity of the soil to store water, thus lowering water tables by effectively reducing the number of rainfall events that contribute to groundwater recharge. In this study, we examined how water use by aEucalyptus sideroxylonA. Cunn. ex Woolls plantation, growing in a salinity-prone landscape, varied in response to rainfall events across four years of sap flux monitoring. Responses of the plantation were observed across multiple seasons, from above average to well below average rainfall. We observed that the plantation forest, while capable of continuous water use during drought, was also quite responsive to rainfall events. During the driest periods, during which shallow soil moisture was reduced to a stable minimum, the forest continued using water at around 1 mm/day. Generally we observed increases in forest water use following only 5 mm of rainfall, in contrast to 20 mm for neighbouring native vegetation. We compared a range of plausible empirical models for describing forest water use responses to rainfall. The best model demonstrated that rainfall size, post-rainfall PET and the interaction between rainfall size and antecedent soil moisture made significant contributions to variation in forest water use across rainfall events. Interestingly, the model showed that all else equal, higher antecedent soil moisture tended to reduce potential increases in forest water use in response to rainfall.