Characterizing forest structure variations across an intact tropical peat dome using field samplings and airborne LiDAR.
Characterizing forest structure variations across an intact tropical peat dome using field samplings and airborne LiDAR.
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使用现场采样和机载激光雷达来表征完整热带泥炭穹顶的森林结构变化。
DOI：
10.1890/15-0017
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
S. Raciti
中科院分区：
文献类型：
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作者：
Ha T. Nguyen;L. Hutyra;B. Hardiman;S. Raciti
热带泥炭沼泽森林（PSF）是全球碳密度最高的生态系统之一，正在经历大量的自然和人为干扰。在这项研究中，我们将直接现场采样和机载激光雷达相结合，对婆罗洲西北部一个大型、完整的热带泥炭穹顶的森林结构和地上活生物量（AGB）进行了实证量化。在海拔梯度上升4 m时，茎密度增加，冠层高度、冠层面积和冠层粗糙度减小。这些发现与养分和水文动态共同影响森林结构和冠层个体高度的假设一致，导致朝向圆顶内部的生产力降低。间隙频率随间隙大小的变化服从幂律分布，形状因子λ为1.76±0.06。地面和穹顶范围的AGB估计值分别为217.7±28.3 Mg C/ha和222.4±24.4 Mg C/ha，高于先前报道的PSF和热带森林的AGB。然而，穹顶范围的AGB估计是基于高度统计的，我们发现冠层高度的变异系数仅为0.08，比茎直径测量值小3倍，这表明激光雷达高度指标可能不是具有茂密冠层的热带高林AGB的可靠预测因子。我们对这一生态系统的结构表征促进了对完整热带泥炭丘生态学的理解，以及影响生物量密度和景观尺度空间变化的因素。这种生态学认识对于改善森林碳密度及其在PSF中的空间分布的估计，以及有效地模拟这些碳密集生态系统中干扰和森林砍伐的影响至关重要。
Tropical peat swamp forests (PSF) are one of the most carbon dense ecosystems on the globe and are experiencing substantial natural and anthropogenic disturbances. In this study, we combined direct field sampling and airborne LiDAR to empirically quantify forest structure and aboveground live biomass (AGB) across a large, intact tropical peat dome in Northwestern Borneo. Moving up a 4 m elevational gradient, we observed increasing stem density but decreasing canopy height, crown area, and crown roughness. These findings were consistent with hypotheses that nutrient and hydrological dynamics co-influence forest structure and stature of the canopy individuals, leading to reduced productivity towards the dome interior. Gap frequency as a function of gap size followed a power law distribution with a shape factor (λ) of 1.76 ± 0.06. Ground-based and dome-wide estimates of AGB were 217.7 ± 28.3 Mg C/ha and 222.4 ± 24.4 Mg C/ha, respectively, which were higher than previously reported AGB for PSF and tropical forests in general. However, dome-wide AGB estimates were based on height statistics, and we found the coefficient of variation on canopy height was only 0.08, three times less than stem diameter measurements, suggesting LiDAR height metrics may not be a robust predictor of AGB in tall tropical forests with dense canopies. Our structural characterization of this ecosystem advances the understanding of the ecology of intact tropical peat domes and factors that influence biomass density and landscape-scale spatial variation. This ecological understanding is essential to improve estimates of forest carbon density and its spatial distribution in PSF and to effectively model the effects of disturbance and deforestation in these carbon dense ecosystems.