Determining tree water acquisition zones with stable isotopes in a temperate tree-based intercropping system
Determining tree water acquisition zones with stable isotopes in a temperate tree-based intercropping system
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DOI：
10.1007/s10457-015-9795-9
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发表时间：
2015-02
影响因子：
2.2
通讯作者：
Candice M. Link;N. Thevathasan;A. Gordon;M. Isaac
中科院分区：
文献类型：
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作者：
Candice M. Link;N. Thevathasan;A. Gordon;M. Isaac
树木间作（TBI）系统诱导小气候的变化，可以提高作物的性能，通过水分利用效率。然而，这种效率的程度取决于在这种农林系统中树木的水获取策略。绘制TBI系统中树木-作物根界面的吸水区对于管理水资源至关重要，特别是随着气候变化造成的水压力增加。在这项研究中，我们确定了美国黑核桃（核桃）和杨树的吸水区。（美洲黑杨×黑杨DN-177的杂种）（杨树）与冬大麦（大麦）在温带TBI系统中间作。对加拿大安大略圭尔夫农林研究站的早季（作物前）和晚季（作物后）土壤水和树木木质部水进行了δ 18 O同位素分析。确定吸水区的两种方法：直接推理和多源质量平衡分析。这两种方法都表明，白杨表现出优势的土壤水分吸收区在20厘米的土壤剖面在早期的季节，而优势的核桃吸收区在10厘米的土壤剖面更高。两个物种的土壤剖面（40-70厘米）中的水分吸收深度较低，在晚季。这项研究表明：（i）树种依赖的水分采集区，（ii）树木水分采集的变化，以更深的土壤剖面在生长季节。利用同位素技术，我们认为，白杨和核桃根系活动分层低于作物根区后，在生长季节，潜在地减少对水资源的竞争。
Tree-based intercropping (TBI) systems induce microclimate modifications that can enhance crop performance through water use efficiency. However, the extent of this efficiency is dependent on water acquisition strategies of trees in such agroforestry systems. Charting water uptake zones at the tree-crop root interface in TBI systems is essential for managing water resources, particularly with increasing water stress from a changing climate. In this study, we identify the water uptake zones ofJuglans nigra(walnut) andPopulus sp.(hybrid ofPopulus deltoids X Populus nigra clone DN-177)(poplar) intercropped with winter barley (Hordeum vulgare) in a temperate TBI system. Water isotopic analysis using δ18O was conducted on paired soil water and tree xylem water samples in early season (pre-crop) and late season (with crop) collected from the Agroforestry Research Station in Guelph, Ontario, Canada. Two approaches for identifying the water uptake zones were used: direct inference and multiple source mass-balance analysis. Both approaches showed that poplar exhibits a dominant soil water uptake zone at 20 cm in the soil profile in the early season, while the dominant walnut uptake zone was higher in the soil profile at 10 cm. Depth of water uptake was lower in the soil profile (40–70 cm) in the late season for both species. This study indicates: (i) tree species dependent water acquisition zones, and (ii) a shift in tree water acquisition to deeper in the soil profile over the growing season. Using isotopic techniques, we suggest that poplar and walnut root activity stratify below the crop root zone later in the growing season, potentially reducing competition for water resources.