SHOOT DYNAMICS OF THE GIANT GRASS GYNERIUM-SAGITTATUM IN PERUVIAN AMAZON FLOODPLAINS, A CLONAL PLANT THAT DOES SHOW SELF-THINNING
SHOOT DYNAMICS OF THE GIANT GRASS GYNERIUM-SAGITTATUM IN PERUVIAN AMAZON FLOODPLAINS, A CLONAL PLANT THAT DOES SHOW SELF-THINNING
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DOI：
10.1007/bf00328909
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发表时间：
1995-01-01
期刊：
影响因子：
2.7
通讯作者：
KALLIOLA, R
中科院分区：
文献类型：
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作者：
DEKROON, H;KALLIOLA, R
巨型根状草矢状Gynerium sagitatum是秘鲁亚马逊洪泛区形成密集单一栽培的早期演替物种。通过记录林分密度和林分高度，研究了林分的种群结构。叶面积和茎体积以异速估算。研究了两个品种矢状木的林分高度和枝条分枝程度的差异。随着林龄的增加，林分密度显著降低，平均枝长增加。单位地面面积的树干体积与树干密度呈显著负相关，至少在两个品种中有一个具有显著的自疏性。根据Weller （1987b）的异速生长模型进行的计算表明，不同品种间伐坡度的差异在很大程度上可以由它们不同的茎部几何形状来解释。每枝原木叶面积与密度呈极显著负相关，斜率接近-1。随着每枝平均茎体积的增加，枝长不平等减少，这可能是由于小枝的死亡率与密度有关。这些结果都符合茎部自疏的预期。矢状Gynerium sagittatum是在自然单株林分中表现出自疏性的克隆植物物种的第一个明显例子。有人认为，这种巨大的热带草会发生自我间伐，因为它的芽是多年生的，不会经历季节性枯死（周期性密度无关的死亡），这与迄今为止研究的许多无性系植物物种形成鲜明对比。
The giant rhizomatous grass Gynerium sagitatum is an early successional species that forms dense monocultures in Peruvian Amazon floodplains. We studied the shoot population structures by recording shoot densities and shoot heights. Leaf areas and stem volumes were allometrically estimated. Stands of two varieties of G. sagittatum were examined that differ in height and in the degree of shoot branching. In stands of increasing age, marked decreases in shoot densities were accompanied with an increase in mean shoot size. Self-thinning was indicated by the negative correlation between log stem volume per unit ground area and log shoot density, significant at least for one of the two varieties. The difference in thinning slope between the varieties could be largely accounted for by their different shoot geometry, as was revealed by calculations based on the allometric model of Weller (1987b). The relationship between log leaf area per shoot and log shoot density was significantly negative with slopes close to -1. Shoot size inequalities decreased with increasing mean stem volume per shoot, probably as a result of density-dependent mortality of the smaller shoots. All of these results accord with expectations for shoot self-thinning. Gynerium sagittatum is the first clear example of a clonal plant species that exhibits self-thinning in natural monospecific stands. It is argued that self-thinning occurs in this giant tropical grass because its shoots are perennial and do not experience seasonal die-back (periodic density-independent mortality), in contrast to many of the clonal plant species that have been studied so far.