A simplified GIS approach to modeling global leaf water isoscapes.
A simplified GIS approach to modeling global leaf water isoscapes.
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DOI：
10.1371/journal.pone.0002447
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发表时间：
2008-06-18
期刊：
影响因子：
3.7
通讯作者：
Ehleringer JR
中科院分区：
文献类型：
--
作者：
West JB;Sobek A;Ehleringer JR
有机和无机物质的稳定氢（δ 2 H）和氧（δ 18 O）同位素比值通过反应进行时发生的底物同位素组成和分馏的影响记录生物和物理过程。在大尺度上，由于地球表面连贯的气候模式的影响，这些过程可以表现出空间可预测性。几十年来，人们一直试图模拟水的稳定同位素比的空间变化。叶水对某些应用特别重要，包括记录空间和时间气候变化的植物有机材料，可能是迁徙动物的食物来源。它也是大气气体同位素组成变化的一个重要来源。虽然已经努力模拟全球尺度的叶水同位素比空间变化（特别是δ 18 O），但在模型及其跨空间域的执行中仍然存在显着的不确定性。我们在这里介绍一个地理信息系统（GIS）的方法来生成全球性的，空间上明确的同位素景观（= isoscape）的“气候正常”叶水同位素比。 我们评估的方法和由此产生的产品比较模拟模型的输出和点测量，在可获得的，在地球表面。使用同位素分馏和空间连续降水同位素和气候层的生物物理模型作为输入模型驱动程序生成的isoscape。叶水δ 18 O等值线与GCM/生物物理模式产品的纬度平均值以及点测量的平均值基本一致。这些结果表明，全球尺度的空间一致性叶水同位素比值，类似于降水和验证GIS方法来建模叶水同位素。这些结果表明，相对简单的叶片水富集模型结合空间连续的降水同位素比和气候数据层产生准确的全球叶片水估计适用于生态学和大气科学中的重要问题。
The stable hydrogen (δ2H) and oxygen (δ18O) isotope ratios of organic and inorganic materials record biological and physical processes through the effects of substrate isotopic composition and fractionations that occur as reactions proceed. At large scales, these processes can exhibit spatial predictability because of the effects of coherent climatic patterns over the Earth's surface. Attempts to model spatial variation in the stable isotope ratios of water have been made for decades. Leaf water has a particular importance for some applications, including plant organic materials that record spatial and temporal climate variability and that may be a source of food for migrating animals. It is also an important source of the variability in the isotopic composition of atmospheric gases. Although efforts to model global-scale leaf water isotope ratio spatial variation have been made (especially of δ18O), significant uncertainty remains in models and their execution across spatial domains. We introduce here a Geographic Information System (GIS) approach to the generation of global, spatially-explicit isotope landscapes ( = isoscapes) of “climate normal” leaf water isotope ratios. We evaluate the approach and the resulting products by comparison with simulation model outputs and point measurements, where obtainable, over the Earth's surface. The isoscapes were generated using biophysical models of isotope fractionation and spatially continuous precipitation isotope and climate layers as input model drivers. Leaf water δ18O isoscapes produced here generally agreed with latitudinal averages from GCM/biophysical model products, as well as mean values from point measurements. These results show global-scale spatial coherence in leaf water isotope ratios, similar to that observed for precipitation and validate the GIS approach to modeling leaf water isotopes. These results demonstrate that relatively simple models of leaf water enrichment combined with spatially continuous precipitation isotope ratio and climate data layers yield accurate global leaf water estimates applicable to important questions in ecology and atmospheric science.
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