Effects of topography on tropical forest structure depend on climate context
Effects of topography on tropical forest structure depend on climate context
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DOI：
10.1111/1365-2745.13261
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发表时间：
2019-08
影响因子：
5.5
通讯作者：
Robert Muscarella;Samira Kolyaie;D. Morton;J. Zimmerman;M. Uriarte
中科院分区：
文献类型：
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作者：
Robert Muscarella;Samira Kolyaie;D. Morton;J. Zimmerman;M. Uriarte
地形影响非生物条件，从而影响生态群落的结构、功能和动态。越来越多的研究已经证明了精细尺度地形异质性的生物后果，但我们对这些影响如何取决于气候背景的理解有限。我们将机载激光雷达获得的地形和林冠高度的高分辨率（1 m2）数据与波多黎各15个森林样地的地面数据合并，这些森林样地沿着降雨梯度分布，跨度为c。800- 3500毫米/年。基于地面的数据包括物种组成，估计的地上生物量（AGB）和两个关键的功能性状（木材密度和单位面积叶质量，LMA），反映了资源利用策略和水力安全与水力效率之间的权衡。我们使用分层贝叶斯模型来评估地形×气候之间的相互作用如何与森林结构指标（即冠层高度和AGB）以及分类和功能α和β多样性相关。细尺度地形（以地形湿度指数（TWI）为特征）显著影响森林结构，这些影响的强度（在某些情况下，方向）在降水梯度上各不相同。在所有的地块，冠层高度增加，地形湿度，但效果更强，在干相比，湿森林地块。在干燥的森林地块，地形较潮湿的微型网站也有较高水平的AGB，但在潮湿的森林地块，地形较干燥的微型网站有较高的AGB。精细尺度地形影响功能组成，但对分类和功能α和β多样性的影响很弱或不显著。例如，社区加权木材密度遵循与AGB相似的模式。我们还发现，木材密度和地形异质性的变化，取决于气候背景之间的关系轻微显着。合成.细尺度地形异质性对热带森林结构和组成的影响取决于气候背景。我们的研究表明，如何更强的整合地形异质性降水梯度可以提高森林结构和生物量的估计，并可能提供洞察的方式，地形可能介导的物种对干旱和气候变化的反应。
Topography affects abiotic conditions which can influence the structure, function and dynamics of ecological communities. An increasing number of studies have demonstrated biological consequences of fine‐scale topographic heterogeneity but we have a limited understanding of how these effects depend on the climate context. We merged high‐resolution (1 m2) data on topography and canopy height derived from airborne lidar with ground‐based data from 15 forest plots in Puerto Rico distributed along a precipitation gradient spanning c. 800–3,500 mm/year. Ground‐based data included species composition, estimated above‐ground biomass (AGB), and two key functional traits (wood density and leaf mass per area, LMA) that reflect resource‐use strategies and a trade‐off between hydraulic safety and hydraulic efficiency. We used hierarchical Bayesian models to evaluate how the interaction between topography × climate is related to metrics of forest structure (i.e. canopy height and AGB), as well as taxonomic and functional alpha‐ and beta‐diversity. Fine‐scale topography (characterized with the topographic wetness index, TWI) significantly affected forest structure and the strength (and in some cases direction) of these effects varied across the precipitation gradient. In all plots, canopy height increased with topographic wetness but the effect was much stronger in dry compared to wet forest plots. In dry forest plots, topographically wetter microsites also had higher levels of AGB but in wet forest plots, topographically drier microsites had higher AGB. Fine‐scale topography influenced functional composition but had only weak or non‐significant effects on taxonomic and functional alpha‐ and beta‐diversity. For instance, community‐weighted wood density followed a similar pattern to AGB across plots. We also found a marginally significant association between variation of wood density and topographic heterogeneity that depended on climate context. Synthesis. The effects of fine‐scale topographic heterogeneity on tropical forest structure and composition depend on the climate context. Our study demonstrates how a stronger integration of topographic heterogeneity across precipitation gradients could improve estimates of forest structure and biomass, and may provide insight to the ways that topography might mediate species responses to drought and climate change.