Biogeographically distinct controls on C3 and C4 grass distributions: merging community and physiological ecology
Biogeographically distinct controls on C3 and C4 grass distributions: merging community and physiological ecology
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DOI：
10.1111/geb.12265
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发表时间：
2015-03-01
影响因子：
6.4
通讯作者：
Still, Christopher J.
中科院分区：
文献类型：
--
作者：
Griffith, Daniel M.;Anderson, T. Michael;Still, Christopher J.
目的：C-4光合作用是一种适应，在强光，高温条件下保持有效的碳同化。由于C-4牧草对碳通量和地表能量通量的重要性，已经提出了许多模型来描述它们的空间分布和预测它们对气候变化的响应。这些模型往往依赖于广泛的气候预测（如温度和降水），但未能整合其他生态相关因素，如干扰和竞争，这可能会改变实现C-3/C-4草分布。在这里，我们提出了一个综合评价的生态因子和气候预测实现C-3/C-4草分布的贡献。我们认为多个地理区域的北美使用一个multisampled数据库的40,000多个植被plots.Location：美国（USA）的毗连：我们确定了一个全面的池的气候模型在文献中，并使用信息理论的标准，选择一个主要的气候预测C-3和C-4草分布。随后，最好的模型相结合的生态预测（如火灾，树木覆盖），使用多元回归框架和8个regions.Results内测试：令人惊讶的是，草占主导地位的社区在美国主要存在于C-3或C-4占主导地位的国家。C-3/C-4优势之间的转换最好的解释模型，集成温度和降水与生态因子，根据区域而异。对于某些地区，如东部温带森林，当地的生态因素是可比的强度大规模的气候预测C-3/C-4 abundance.Main：conclusionLocal生态因素修改C-3/C-4草响应大规模的气候驱动程序的方式，表现在区域尺度。例如，在东部温带森林，C-4草的丰度保持在低于气候预期的树木覆盖造成光限制，但高于预期的频繁火灾减少树木覆盖。因此，不同地理区域的局部生态因素不同，导致了大范围的气候不平衡。
Aim: C-4 photosynthesis is an adaptation that maintains efficient carbon assimilation in high-light, high-temperature conditions. Due to the importance of C-4 grasses for carbon and surface energy fluxes, numerous models have been proposed to describe their spatial distribution and forecast their responses to climate change. These models often rely on broad climatic predictors (e.g. temperature and precipitation) but fail to integrate other ecologically relevant factors like disturbance and competition, which may modify realized C-3/C-4 grass distributions. Here, we present a combined evaluation of the contribution of ecological factors and climatic predictors to realized C-3/C-4 grass distributions. We consider multiple biogeographic regions of North America using a multisource database of over 40,000 vegetation plots.Location: The conterminous United States of America (USA).Methods: We identified a comprehensive pool of climatic models in the literature and used information theoretic criteria to select a primary climatic predictor of C-3 and C-4 grass distributions. Subsequently, the best model was combined with ecological predictors (e.g. fire, tree cover) using a multiple regression framework and tested within eight regions.Results: Surprisingly, grass-dominated communities across the USA exist largely in C-3- or C-4-dominated states. Transitions between C-3/C-4 dominance were best explained by models that integrated temperature and precipitation with ecological factors that varied according to region. For some regions, like Eastern Temperate Forests, local ecological factors were comparable in strength to broad-scale climatic predictors of C-3/C-4 abundance.Main: conclusionLocal ecological factors modify C-3/C-4 grass responses to broad-scale climatic drivers in ways that manifest at regional scales. In Eastern Temperate Forests, for example, C-4 grass abundances are maintained below climatic expectations where tree cover creates light limitation but above expectations where frequent fires reduce tree cover. Thus, local ecological factors, which vary among biogeographic regions, contribute to large-scale climate disequilibrium.