Seed and pollen dispersal distances in two African legume timber trees and their reproductive potential under selective logging

The natural regeneration of tree species depends on seed and pollen dispersal. To assess if limited dispersal could be critical for the sustainability of selective logging practices, we performed parentage analyses in two Central African legume canopy species displaying contrasted floral and fruit traits: Distemonanthus benthamianus and Erythrophleum suaveolens. We also developed new tools linking forward dispersal kernels with backward migration rates to better characterize long-distance dispersal. Much longer pollen dispersal in D. benthamianus (mean distance dp=700m, mp=52% immigration rate in 6 km2 plot, s=7% selfing rate) than in E. suaveolens (dp=294m, mp=22% in 2 km2 plot, s=20%) might reflect different insect pollinators. At a local scale, secondary seed dispersal by vertebrates led to larger seed dispersal distances in the barochorous E. suaveolens (ds=175m) than in the wind-dispersed D. benthamianus (ds=71m). Yet, seed dispersal appeared much more fat-tailed in the latter spec...

树木物种的自然更新依赖于种子与花粉传播过程。为评估有限的传播能力是否会对择伐经营的可持续性构成关键制约，我们针对两种具有显著花部与果实性状差异的中非豆科冠层树种开展了亲本分析：弯柄香榄（Distemonanthus benthamianus）与厚荚苏木（Erythrophleum suaveolens）。本研究还开发了全新的分析工具，将正向传播核（forward dispersal kernels）与反向迁移率（backward migration rates）相结合，以更精准地表征长距离传播特征。相较于厚荚苏木（平均花粉传播距离dp=294m，2km²样地内移民率mp=22%，自交率s=20%），弯柄香榄的花粉传播距离显著更远（平均花粉传播距离dp=700m，6km²样地内移民率mp=52%，自交率s=7%），这一差异可能源于二者传粉昆虫类群的不同。在局域尺度下，脊椎动物介导的次级种子传播使得重力传播型（barochorous）的厚荚苏木的种子传播距离（ds=175m）显著高于风传播的弯柄香榄（ds=71m）。然而，后者的种子传播似乎呈现出更强的厚尾分布特征……