Transient dominance in a central African rain forest

The large-crowned emergent tree Microberlinia bisulcata dominates rainforest groves at Korup, along with two co-dominants Tetraberlinia bifoliolata and T. korupensis. M. bisulcata has a pronounced modal size frequency distribution around ~110 cm stem diameter: its recruitment potential is very poor. It is a long-lived light-demanding species, one of many found in African forests. Tetraberlinia species lack modality, are more shade-tolerant and recruit better. All three species are ectomycorrhizal. M. bisulcata dominates grove basal area, even though it has similar numbers of trees (≥ 50 cm stem diameter) as each of the other two species. This situation presented a conundrum which prompted a long-term study of grove dynamics. Enumerations of two plots (82.5 and 56.25 ha) between 1990 and 2010 showed mortality and recruitment of M. bisulcata to be very low (both rates ~0.2 %/yr) compared with Tetraberlinia (2.4, 0.8 %/yr), and M. bisulcata grows twice as fast as the Tetraberlinia. Ordinat...

冠幅宽大的上层乔木双褶小柏林木（Microberlinia bisulcata）与两个共优种双叶四柏林木（Tetraberlinia bifoliolata）和科鲁普四柏林木（T. korupensis）共同主导了科鲁普地区的雨林林斑。双褶小柏林木的径级频率分布存在显著众数，集中于茎直径约110厘米的区间，但其更新潜力极差。该物种为长寿命喜光树种，是非洲森林中常见的类群之一。四柏林木属物种的径级分布无明显众数，更耐荫蔽且更新能力更强。上述三个物种均为外生菌根植物。尽管双褶小柏林木的茎直径≥50厘米的个体数量与另外两个物种大致相当，但其主导着林斑的断面积占比。这一现象构成了一个生态学难题，由此推动了针对该林斑动态的长期研究。1990年至2010年间对两块样地（面积分别为82.5公顷与56.25公顷）的清查结果显示：双褶小柏林木的死亡率与更新率均极低（二者速率均约为0.2%/年），相较之下四柏林木属物种的死亡率与更新率分别为2.4%/年、0.8%/年；同时双褶小柏林木的生长速率是四柏林木属物种的两倍。本次研究的排序分析（Ordinat...）内容未完整呈现。