This study was designed to examine the subtle effects of habitat, aspect and altitude on plant diversity and the timing of phenological stages. In this increasingly arid region, within-species differences would cause more reproductive isolation of local populations, making species more vulnerable to regional extinction. Fifty-two sites in the Jebel Marra region of the Central Darfur state of Sudan were compared in terms of species diversity and local variation in the phenology of plant communities. Five habitat types were compared: sandy plains, clay plains, wadis, north-facing slopes and south-facing slopes. Sites were classified into five altitudinal zones ranging from 750 m to > 1,150 m above sea level, and the phenology of three categories of plant life form (phanerophytes, chamaephytes and therophytes) was tracked in terms of the duration of each phenophase (vegetative, reproductive and dormant). Overall, most plants were dormant from December to April. Peak vegetative growth was in July, coinciding with peak rainfall in all study sites in the region (July-August). This was followed by peak reproduction in October. Life form and habitat type significantly affected the length of all phenological phases; altitude significantly affected all stages except the duration of dormancy. Some of the interactions between these factors were also statistically significant, indicating subtle regulation of the duration of phenophases. The possible impacts of overgrazing and ongoing climate change are discussed, with the concern that initiation of vegetative growth in most habitats (except the clay plains) appears to be triggered by day length, ‘anticipating’ the beginning of the rainy season. Further climate change may uncouple this signal and the beginning of the rainy season, impacting plant survival.

中文翻译：

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达尔富尔杰贝尔马拉地区植物群落物候的时空变化

本研究旨在检查栖息地、方位和海拔对植物多样性和物候阶段时间的微妙影响。在这个日益干旱的地区，物种内的差异会导致当地人口更多的生殖隔离，使物种更容易受到区域灭绝的影响。在物种多样性和植物群落物候的局部变化方面，对苏丹中达尔富尔州杰贝尔马拉地区的 52 个地点进行了比较。比较了五种栖息地类型：沙质平原、粘土平原、河谷、朝北的斜坡和朝南的斜坡。地点被分为五个海拔区域，从海拔 750 m 到 > 1,150 m，以及三类植物生命形式（显性植物、chamaephytes 和therophytes）根据每个物候期（营养期、繁殖期和休眠期）的持续时间进行跟踪。总体而言，大多数植物在 12 月至 4 月期间处于休眠状态。植物生长高峰出现在 7 月，恰逢该地区所有研究地点（7 月至 8 月）的降雨高峰。紧随其后的是 10 月的繁殖高峰。生命形式和栖息地类型显着影响所有物候阶段的长度；除休眠持续时间外，海拔高度对所有阶段都有显着影响。这些因素之间的一些相互作用也具有统计学意义，表明对物候期持续时间的微妙调节。讨论了过度放牧和持续气候变化的可能影响，担心在大多数栖息地（粘土平原除外）开始营养生长似乎是由白天的长度触发的，“预期”雨季的开始。进一步的气候变化可能会使这一信号与雨季的开始脱钩，从而影响植物的生存。