Functional convergence in regulation of net CO2 flux in heterogeneous tundra landscapes in Alaska and Sweden
Functional convergence in regulation of net CO2 flux in heterogeneous tundra landscapes in Alaska and Sweden
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DOI：
10.1111/j.1365-2745.2007.01259.x
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发表时间：
2007-07
影响因子：
5.5
通讯作者：
G. R. Shaver;L. Street;E. Rastetter;M. Wijk;M. Williams
中科院分区：
文献类型：
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作者：
G. R. Shaver;L. Street;E. Rastetter;M. Wijk;M. Williams
1北极地貌的特点是极端的植被斑块，在非常不同的植被类型之间往往有清晰的边界。这种斑块特征使得预测景观水平的碳平衡及其对环境的响应变得困难。2在这里，我们开发了一个与植被组成无关的北极地貌的二氧化碳净通量模型，取而代之的是使用NDVI(归一化差异植被指数)得到的叶面积的度量。3利用在北极阿拉斯加和瑞典大范围的植被中测量的二氧化碳通量的光响应(净生态系统交换，NEE)，我们使用不同的数据子集来训练模型，用于参数估计和预测检验。4总体而言，该模型一致地解释了仅知道估计叶面积指数(LAI)、光合作用活性光子通量密度(PPFD)和气温的NEE的~80%的方差。5根据在一个地点或植被类型进行的测量得出的模型参数可用于以可接受的准确度和精密度预测其他地点或植被类型的NEE。模型预测的进一步改进可能来自于在LAI之外加入苔藓面积的估计，以及使用特定于植被的LAI估计。6该模型在独立于物种组成的任何信息的情况下成功地预测了需求，这表明北极地貌的树冠结构和功能具有高度的汇聚性。
1 Arctic landscapes are characterized by extreme vegetation patchiness, often with sharply defined borders between very different vegetation types. This patchiness makes it difficult to predict landscape‐level C balance and its change in response to environment. 2 Here we develop a model of net CO2 flux by arctic landscapes that is independent of vegetation composition, using instead a measure of leaf area derived from NDVI (normalized‐difference vegetation index). 3 Using the light response of CO2 flux (net ecosystem exchange, NEE) measured in a wide range of vegetation in arctic Alaska and Sweden, we exercise the model using various data subsets for parameter estimation and tests of predictions. 4 Overall, the model consistently explains ~80% of the variance in NEE knowing only the estimated leaf area index (LAI), photosynthetically active photon flux density (PPFD) and air temperature. 5 Model parameters derived from measurements made in one site or vegetation type can be used to predict NEE in other sites or vegetation types with acceptable accuracy and precision. Further improvements in model prediction may come from incorporating an estimate of moss area in addition to LAI, and from using vegetation‐specific estimates of LAI. 6 The success of this model at predicting NEE independent of any information on species composition indicates a high level of convergence in canopy structure and function in the arctic landscape.