Interspecific variation in tropical tree height and crown allometries in relation to life history traits
Interspecific variation in tropical tree height and crown allometries in relation to life history traits
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热带树高和树冠异速性的种间变异与生活史特征的关系
DOI：
10.5194/bg-2018-314
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
S. Pacala
中科院分区：
文献类型：
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作者：
Isabel Martínez Cano;H. Muller‐Landau;S. Wright;Stephanie A. Bohlman;S. Pacala
摘要。树木异速生长关系被广泛用于估算森林生物量和产量，是动态植被模型的基本组成部分。在热带森林中，异速生长关系通常通过拟合来自多个物种的汇总数据的尺度不变幂函数来建模，这种方法无法反映最小和最大尺寸的有限尺寸效应，并且忽略了异速生长的种间差异。利用巴拿马巴罗科罗拉多岛（Barro Colorado Island）地区162种树种的形态和生活史资料，分析了树高（9884株）和树冠面积（2425株）与树干直径的异速生长关系。我们拟合了基于物种特征的非线性层次模型，并评估了三种可选择的函数形式的性能：标度不变幂函数、饱和Weibull和广义Michaelis-Menten （gMM）函数。饱和gMM模型最适合树高与树干直径的关系，其中异速生长参数的变化与幼苗生长速率的种间差异有关，而幼苗生长速率是衡量再生光需求的指标。需要光的种在幼体时在相对较小的直径处具有较高的高度，而在成年时在较大直径处具有较短的渐近高度。树冠面积与树干直径的关系最适合幂函数模型，其中树冠面积与种特异木材密度呈弱正相关。利用饱和功能形式和在树木异速生长模型中纳入功能性状是改善森林生物量和生产力估算的一种有前途的方法。我们的研究结果为热带树木功能类型在植被模型中的参数化提供了改进的基础。
Abstract. Tree allometric relationships are widely employed to estimate forest biomass and production, and are basic building blocks of dynamic vegetation models. In tropical forests, allometric relationships are often modeled by fitting scale-invariant power functions to pooled data from multiple species, an approach that fails to reflect finite size effects at the smallest and largest sizes, and that ignores interspecific differences in allometry. Here, we analyzed allometric relationships of tree height (9884 individuals) and crown area (2425) with trunk diameter using species-specific morphological and life history data of 162 species from Barro Colorado Island, Panamá. We fit nonlinear, hierarchical models informed by species traits and assessed the performance of three alternative functional forms: the scale-invariant power function, and the saturating Weibull and generalized Michaelis-Menten (gMM) functions. The relationship of tree height with trunk diameter was best fit by a saturating gMM model in which variation in allometric parameters was related to interspecific differences in sapling growth rates, a measure of regeneration light demand. Light-demanding species attained taller heights at comparatively smaller diameters as juveniles and had shorter asymptotic heights at larger diameters as adults. The relationship of crown area with trunk diameter was best fit by a power function model incorporating a weak positive relationship between crown area and species-specific wood density. The use of saturating functional forms and the incorporation of functional traits in tree allometric models is a promising approach to improve estimates of forest biomass and productivity. Our results provide an improved basis for parameterizing tropical tree functional types in vegetation models.