Tree morphology responds to neighbourhood competition and slope in species-rich forests of subtropical China
Tree morphology responds to neighbourhood competition and slope in species-rich forests of subtropical China
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DOI：
10.1016/j.foreco.2010.08.015
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发表时间：
2010-10
影响因子：
3.7
通讯作者：
Anne Lang;W. Härdtle;H. Bruelheide;C. Geißler;K. Nadrowski;Andreas Schuldt;Mingjian Yu;G. Oheimb
中科院分区：
文献类型：
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作者：
Anne Lang;W. Härdtle;H. Bruelheide;C. Geißler;K. Nadrowski;Andreas Schuldt;Mingjian Yu;G. Oheimb
树木能够通过形态调整来响应当地的生物和非生物环境，从而提高资源获取和生长。在森林中，光被广泛认为是决定生长的主要因素之一，形态学响应包括树冠结构和茎高的变化。在倾斜地形上，向光性和向地性的相互作用可能进一步影响形态生长特征。然而，不同的树种预计会表现出物种特异性的反应。本研究分析了中国亚热带物种丰富的森林中2个功能类群(常绿木荷（Schima superba）、核桃（Castanopsis eyrei）、落叶栎（Quercus serrata var. brevipetiolata）、核桃（Castanea henryi） 4种树种的3个生长特征。树冠投影面积、相对树冠位移和树干倾斜度与当地邻近的生物（本地物种丰富度、功能丰富度、竞争、林龄）和非生物（坡向和倾斜度、土壤深度）变量有关。我们假设(i)树冠结构和茎高的形态响应存在物种特异性差异；（ii）树冠大小和不对称以及茎倾斜受到生物和非生物因素的影响。与我们的预期相反，我们无法揭示三种生长特征中任何一种的物种特异性差异。混合效应模型结果表明，树冠面积主要受目标树胸径和与邻居相关的生物变量（竞争、功能多样性）的影响，而茎倾主要受坡度的影响。相对冠位移受生物和非生物变量的影响。我们得出的结论是，在我们的研究区域，导致树冠位移和茎倾斜的生长响应似乎是改善觅食光的重要机制，但这些响应似乎是物种独立的。树干倾斜和树冠位移的相互作用使得树木个体在生物和非生物异质环境中的塑性响应成为可能。研究结果表明，该地区的森林经营应侧重于功能多样化的林分，这些林分对促进林冠面积有积极作用，从而提高单株生长率。
Trees are able to respond to their local biotic and abiotic environment with morphological adjustments which improve resource acquisition and, thus, growth. In forests, light is broadly recognised as one of the major factors determining growth, and morphological responses comprise changes in crown architecture and stem stature. On sloping terrain, the interplay of phototropism and gravitropism may further affect morphological growth characteristics. However, different tree species are expected to show species-specific responses. In this study, we analysed three growth characteristics of tree individuals belonging to four species of two functional groups (evergreen: Schima superba, Castanopsis eyrei, deciduous: Quercus serrata var. brevipetiolata, Castanea henryi) in a species-rich Chinese subtropical forest. Crown projection area, relative crown displacement and stem inclination were related to biotic (local species richness, functional richness, competition, stand age) and abiotic (slope aspect and inclination, soil depth) variables in the local neighbourhood of the tree individuals. We hypothesised that (i) there are species-specific differences in the morphological response of crown architecture and stem stature and (ii) that crown size and asymmetry as well as stem inclination are influenced by both, biotic and abiotic factors. In contrast to our expectations we were unable to reveal any species-specific differences in any of the three growth characteristics. The results of mixed effects models showed that crown area was mainly affected by the target tree's dbh and biotic variables related to neighbours (competition, functional diversity), whereas stem inclination was mainly influenced by slope. Relative crown displacement was influenced by both, biotic and abiotic variables. We conclude that growth responses resulting in crown displacement and stem inclination seem to be an important mechanism to ameliorate foraging for light in our study area, but that these responses appear to be species-independent. The interplay of stem inclination and crown displacement allows for a plastic response of tree individuals in biotically and abiotically heterogeneous environments. Our results indicate that forest management in this region should focus on functionally diverse stands which are promoting crown area positively resulting in increased growth rates of individual trees.