Flores Olivier, Hérault Bruno, Delcamp Matthieu, Garnier Éric, Gourlet-Fleury Sylvie
Cirad - Université de La Réunion, UMR PVBMT, 7 chemin de l'IRAT, Saint Pierre, France.
Cirad, UMR Ecologie des Forêts de Guyane, Kourou, France.
PLoS One. 2014 Sep 16;9(9):e105022. doi: 10.1371/journal.pone.0105022. eCollection 2014.
How tropical tree species respond to disturbance is a central issue of forest ecology, conservation and resource management. We define a hierarchical model to investigate how functional traits measured in control plots relate to the population change rate and to demographic rates for recruitment and mortality after disturbance by logging operations. Population change and demographic rates were quantified on a 12-year period after disturbance and related to seven functional traits measured in control plots. The model was calibrated using a Bayesian Network approach on 53 species surveyed in permanent forest plots (37.5 ha) at Paracou in French Guiana. The network analysis allowed us to highlight both direct and indirect relationships among predictive variables. Overall, 89% of interspecific variability in the population change rate after disturbance were explained by the two demographic rates, the recruitment rate being the most explicative variable. Three direct drivers explained 45% of the variability in recruitment rates, including leaf phosphorus concentration, with a positive effect, and seed size and wood density with negative effects. Mortality rates were explained by interspecific variability in maximum diameter only (25%). Wood density, leaf nitrogen concentration, maximum diameter and seed size were not explained by variables in the analysis and thus appear as independent drivers of post-disturbance demography. Relationships between functional traits and demographic parameters were consistent with results found in undisturbed forests. Functional traits measured in control conditions can thus help predict the fate of tropical tree species after disturbance. Indirect relationships also suggest how different processes interact to mediate species demographic response.
热带树种如何应对干扰是森林生态学、保护和资源管理的核心问题。我们定义了一个层次模型，以研究在对照样地中测量的功能性状如何与种群变化率以及伐木作业干扰后的招募和死亡率等人口统计学率相关。在干扰后的12年期间对种群变化和人口统计学率进行了量化，并将其与对照样地中测量的七个功能性状相关联。该模型使用贝叶斯网络方法在法属圭亚那帕拉库的永久森林样地（37.5公顷）中调查的53个物种上进行了校准。网络分析使我们能够突出预测变量之间的直接和间接关系。总体而言，干扰后种群变化率的种间变异性的89%由两个人口统计学率解释，招募率是最具解释力的变量。三个直接驱动因素解释了招募率变异性的45%，包括具有正向影响的叶片磷浓度，以及具有负向影响的种子大小和木材密度。死亡率仅由最大直径的种间变异性解释（25%）。木材密度、叶片氮浓度、最大直径和种子大小在分析中未由变量解释，因此似乎是干扰后种群统计学的独立驱动因素。功能性状与人口统计学参数之间的关系与在未受干扰森林中发现的结果一致。因此，在对照条件下测量的功能性状有助于预测干扰后热带树种的命运。间接关系还表明了不同过程如何相互作用以介导物种的人口统计学响应。
