Probing the interplay of biophysical constraints and photosynthesis to model tree growth
Probing the interplay of biophysical constraints and photosynthesis to model tree growth
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DOI：
10.1016/j.agrformet.2023.109852
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发表时间：
2023-12-14
影响因子：
6.2
通讯作者：
De Caceres，Miquel
中科院分区：
文献类型：
--
作者：
Cabon，Antoine;Ameztegui，Aitor;De Caceres，Miquel
树木生长是森林生产力和全球碳循环预测的一个关键不确定因素。虽然全球植被模型通常将树木生长表示为碳同化（源）驱动的过程，但越来越多的证据表明存在广泛的非光合作用（汇）限制。值得注意的是，生长生物物理潜力（定义为温度和细胞分裂的膨胀限制所施加的树木生长上限）被认为是观察到的树木生长与光合作用之间脱钩的有效驱动因素。了解生物物理潜力和光合作用之间的相互作用以及如何在模型中简洁地适应它仍然是一个挑战。在这里，我们使用土壤-植物-大气连续体模型以及森林结构和年度径向树木生长观测的区域网络，持续了三十年，以模拟西班牙东北部五个树种沿干旱梯度的树木光合作用和生物物理潜力。然后，我们应用线性建模框架来量化光合作用、生物物理潜力及其相互作用的相对重要性，以预测沿干旱梯度的树木每年生长情况。光合作用和生物物理潜力总体上相似的相对重要性是由于气候的强烈变化而造成的，光合作用在潮湿的地方更相关，而生物物理潜力在干燥的地方更相关。观察到的空间和时间趋势进一步表明，树木生长主要受到干燥条件下生物物理潜力的限制，忽视它可能会导致低估气候变化下干旱加剧导致的树木生长下降。我们的结果支持这样的观点，即生物物理潜力是树木径向生长汇限制的重要组成部分。它在植被模型中的表示可以适应树木生长的空间和时间动态源汇限制。
Tree growth is a key uncertainty in projections of forest productivity and the global carbon cycle. While global vegetation models commonly represent tree growth as a carbon assimilation (source)-driven process, accumulating evidence points toward widespread non-photosynthetic (sink) limitations. Notably, growth biophysical potential, defined as the upper-limit to tree growth imposed by temperature and turgor constraints on cell division, has been suggested to be a potent driver of observed decoupling between tree growth and photosynthesis. Understanding the interplay between biophysical potential and photosynthesis and how to accommodate it parsimoniously in models remains a challenge.Here, we use a soil-plant-atmosphere continuum model together with a regional network of forest structure and annual, radial tree growth observations extending over three decades to simulate tree photosynthesis and biophysical potential along an aridity gradient and across five tree species in NE Spain. We then apply a linear modelling framework to quantify the relative importance of photosynthesis, biophysical potential and their interactions to predict annual tree growth along the aridity gradient.Overall similar relative importance of photosynthesis and biophysical potential was underlain by strong variations with climate, photosynthesis being more relevant at wet sites and biophysical potential at dry sites. Observed spatial and temporal trends further suggested that tree growth is primarily limited by biophysical potential under dry conditions and that disregarding it could lead to underestimating tree growth decline with increased aridity under climate change.Our results support the idea that biophysical potential is an important component of sink limitations to tree radial growth. Its representation in vegetation models could accommodate spatially and temporally dynamic source-sink limitations on tree growth.