Higher treefall rates on slopes and waterlogged soils result in lower stand biomass and productivity in a tropical rain forest
Higher treefall rates on slopes and waterlogged soils result in lower stand biomass and productivity in a tropical rain forest
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DOI：
10.1111/j.1365-2745.2009.01604.x
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发表时间：
2010-01-01
影响因子：
5.5
通讯作者：
Freycon, Vincent
中科院分区：
文献类型：
--
作者：
Ferry, Bruno;Morneau, Francois;Freycon, Vincent
P>1。热带雨林生物量与环境因素之间的关系已在区域范围内确定，例如亚马逊河流域，但对地方范围内森林生物量高度可变的原因知之甚少。地形、土壤性质、树木生长和死亡率以及树倒之间的相互作用可能是造成这种变异的原因。我们在法属圭亚那的低地雨林中使用永久性地块的重复测量来评估这些关系。这些地块从山顶到斜坡再到洼地的地形梯度取样，并伴随着土壤渍水沿着这些梯度的变化。计算了样地中> 175个树种的生物量，沿着生物量生产率和补充率。死亡率被确定为站立死亡和树倒。树倒率在洼地是山顶的两倍，树木补充率、径向生长率和需光树种的丰富度也较高。在洼地，平均木材密度比山顶低10%，断面积低29%，树木的高径比低，共同导致总木质生物量比山顶低43%。生物量生产率在洼地比在山顶低9%，即使土壤Olsen P浓度在洼地更高。合成.沿着地形梯度从山顶到洼地有较高的树木倒伏率，减少了林分断面积，有利于低分配的高度增长和招聘的光需求低的木材密度的物种。树木生物量沿着梯度的变化很大，这表明确定立地特征的重要性，并在将生物量估计从林分扩大到地方或区域尺度时包括这些特征。
P>1. Relationships between tropical rain forest biomass and environmental factors have been determined at regional scales, e.g. the Amazon Basin, but the reasons for the high variability in forest biomass at local scales are poorly understood. Interactions between topography, soil properties, tree growth and mortality rates, and treefalls are a likely reason for this variability.2. We used repeated measurements of permanent plots in lowland rain forest in French Guiana to evaluate these relationships. The plots sampled topographic gradients from hilltops to slopes to bottomlands, with accompanying variation in soil waterlogging along these gradients. Biomass was calculated for > 175 tree species in the plots, along with biomass productivity and recruitment rates. Mortality was determined as standing dead and treefalls.3. Treefall rates were twice as high in bottomlands as on hilltops, and tree recruitment rates, radial growth rates and the abundance of light-demanding tree species were also higher.4. In the bottomlands, the mean wood density was 10% lower than on hilltops, the basal area 29% lower and the height:diameter ratio of trees was lower, collectively resulting in a total woody biomass that was 43% lower in bottomlands than on hilltops.5. Biomass productivity was 9% lower in bottomlands than on hilltops, even though soil Olsen P concentrations were higher in bottomlands.6. Synthesis. Along a topographic gradient from hilltops to bottomlands there were higher rates of treefall, which decreased the stand basal area and favoured lower allocation to height growth and recruitment of light-demanding species with low wood density. The resultant large variation in tree biomass along the gradient shows the importance of determining site characteristics and including these characteristics when scaling up biomass estimates from stand to local or regional scales.