Yin Xinyou, Lantinga Egvert A, Schapendonk Ad H C M, Zhong Xuhua
Crop and Weed Ecology Group, Wageningen University, PO Box 430, 6700 AK Wageningen, The Netherlands.
Ann Bot. 2003 Jun;91(7):893-903. doi: 10.1093/aob/mcg096. Epub 2003 Apr 15.
In a previous study (Yin et al. 2000. Annals of Botany 85: 579-585), a generic logarithmic equation for leaf area index (L) in relation to canopy nitrogen content (N) was developed: L=(1/ktn)1n(1+ktnN/nb). The equation has two parameters: the minimum leaf nitrogen required to support photosynthesis (nb), and the leaf nitrogen extinction coefficient (ktn). Relative to nb, there is less information in the literature regarding the variation of ktn. We therefore derived an equation to theoretically estimate the value of ktn. The predicted profile of leaf nitrogen in a canopy using this theoretically estimated value of ktn is slightly more uniform than the profile predicted by the optimum nitrogen distribution that maximizes canopy photosynthesis. Relative to the optimum profile, the predicted profile is somewhat closer to the observed one. Based on the L-N logarithmic equation and the theoretical ktn value, we further quantified early leaf area development of a canopy in relation to nitrogen using simulation analysis. In general, there are two types of relations between L and N, which hold for canopies at different developmental phases. For a fully developed canopy where the lowest leaves are senescing due to nitrogen shortage, the relationship between L and N is described well by the logarithmic model above. For a young, unclosed canopy (i.e. L < 1.0), the relation between L and N is nearly linear. This linearity is virtually the special case of the logarithmic model when applied to a young canopy where its total nitrogen content approaches zero and the amount of nitrogen in its lowest leaves is well above nb. The expected patterns of the L-N relationship are discussed for the phase of transition from young to fully developed canopies.
在之前的一项研究中（Yin等人，2000年。《植物学年鉴》85：579 - 585），得出了一个关于叶面积指数（L）与冠层氮含量（N）关系的通用对数方程：L = (1/ktn)ln(1 + ktnN/nb)。该方程有两个参数：支持光合作用所需的最低叶片氮含量（nb）和叶片氮消光系数（ktn）。相对于nb，文献中关于ktn变化的信息较少。因此，我们推导了一个方程来从理论上估算ktn的值。使用这个理论估算的ktn值预测的冠层叶片氮分布曲线，比通过使冠层光合作用最大化的最佳氮分布预测的曲线略均匀一些。相对于最佳曲线，预测曲线更接近观测曲线。基于L - N对数方程和理论ktn值，我们进一步通过模拟分析量化了冠层早期叶面积相对于氮的发育情况。一般来说，L和N之间有两种关系，适用于不同发育阶段的冠层。对于一个因氮短缺最低层叶片开始衰老的完全发育冠层，L和N之间的关系可以用上述对数模型很好地描述。对于一个年轻的、未封闭的冠层（即L < 1.0），L和N之间的关系几乎是线性的。这种线性实际上是对数模型应用于年轻冠层时的特殊情况，此时其总氮含量接近零，最低层叶片中的氮含量远高于nb。讨论了从年轻冠层到完全发育冠层过渡阶段L - N关系的预期模式。
