Most of the West African forests have disappeared or have been deeply fragmented. This deforestation dynamic is still ongoing under a strong demographic pressure, forests being mostly replaced by agricultural lands. On the other hand, some reforestation projects are also undertaken, in particular by planting non-native species like Cedrela odorata. To our knowledge, this study is the first to investigate the causes and consequences of Cedrela odorata spread in West African natural forests. We studied a 400ha area of natural forest where 100ha of permanent plots have been affected by a major fire in 1983. Within these permanent plots, 21,444 trees were mapped, botanically determined and their diameters at breast height were measured in 2018. Using a bayesian hierarchical framework, we modelled the causes of the spread of Cedrela odorata in the studied plots, and its consequences on aboveground biomass and tree community diversity. Regarding the causes, the occurrence of Cedrela odorata is significantly linked to the fire occurence 25 years ago, to the proximity of the forest edge and to the presence of hydromorphic soils. Regarding the consequences, Cedrela odorata invasion doesn’t have any significant impact on the above-ground biomass but has a strong negative effect on the tree community diversity, as far as decreasing Simpson diversity in Hill numbers from 27 equivalent species in slightly invaded plots to 2 equivalent species in largely invaded plots. Our results highlight the long-lasting impacts of human disturbance (fire, Cedrela odorata introduction) on forest ecosystems and the need to use local species for ongoing reforestation plans in West African semi-deciduous forests.

西非的大多数森林都消失了或被严重分割了。在强烈的人口压力下，这种砍伐森林的动态仍在继续，森林大部分被农业用地所取代。另一方面，还进行了一些造林项目，特别是通过种植非天然物种如雪松（Cedrela odorata）。据我们所知，该研究是第一个研究香雪草的原因和后果的研究。传播于西非天然森林。我们研究了1983年发生大火的400公顷天然林面积，其中100公顷永久性地块受到大火的影响。在这些永久性地块中，绘制了21444棵树，进行了植物学确定，并在2018年测量了它们在胸高的直径。在此框架下，我们模拟了香积雪 草在所研究地块中传播的原因，及其对地上生物量和树木群落多样性的影响。关于原因，雪松雪松的发生与25年前的火灾，森林边缘的邻近地区以及水溶土壤的存在密切相关。关于后果，Cedrela odorata入侵对地上生物量没有任何显着影响，但对树木群落多样性具有强烈的负面影响，就希尔山的辛普森多样性而言，从轻度入侵地的27个等价物种减少到大面积入侵的2个等价物种，就可以了。情节。我们的研究结果强调了人为干扰（火灾，雪松木香的引入）对森林生态系统的长期影响，以及需要在西非半落叶森林中将当地物种用于正在进行的造林计划。