Patterns of geophyte diversity and storage organ size in the winter‐rainfall region of southern Africa
Patterns of geophyte diversity and storage organ size in the winter‐rainfall region of southern Africa
复制标题
南部非洲冬季降雨区地球植物多样性和储存器官大小的模式
DOI：
10.1111/j.1366-9516.2005.00132.x
复制
发表时间：
2005
影响因子：
4.6
通讯作者：
D. D. du Preez
中科院分区：
文献类型：
--
作者：
Ş. Procheş;R. Cowling;D. D. du Preez
非洲南部的冬季降雨区，大部分被fynbos和多肉的karoo生物群系覆盖，拥有世界上最集中的地植物物种。物种多样性在西南地区最大，在四分之一度的面积内共有500多种物种；在东南部，该值通常在100左右，而在干旱的西北部，总是小于50（通常小于10）。在至少三个物种丰富的属（Moraea， Eriospermum和Oxalis）中，储存器官（球茎，球茎，块茎）的大小呈反比变化，最大的平均值出现在物种较少的地区-包括西北部和东南部地区。然而，平均储存器官大小与物种多样性之间的负相关关系仅在相对较大的空间尺度上观察到，这表明储存器官大小与物种多样性之间没有直接关系。更有可能的是，这两种测量都是由冬季降雨量和可靠性驱动的，两者都在西南开普省达到峰值。我们认为，可靠的冬季降雨使大型储存器官变得不必要，从而降低了灭绝率，从而导致物种的积累。
The winter‐rainfall region of southern Africa, covered largely by the fynbos and succulent karoo biomes, harbours the world's greatest concentration of geophyte species. Species diversity is greatest in the south‐west, where more than 500 species co‐occur in one quarter‐degree square; in the south‐east the values are generally around 100, and in the arid north‐west, always less than 50 (more often less than 10). In at least three species‐rich genera (Moraea, Eriospermum and Oxalis), the size of storage organs (bulbs, corms, tubers) varies inversely, with the largest average values occurring in the species‐poorer areas — both in the north‐western, and in the south‐eastern parts of the region. This negative correlation between average storage organ size and species diversity is, however, only observed at relatively large spatial scales, which suggests that there is no direct relationship between storage organ size and species diversity. More likely, both these measures are driven by winter rainfall amount and reliability, both of which peak in the south‐western Cape. We suggest that reliable winter rainfall makes large storage organs unnecessary and depresses extinction rates, thus leading to the accumulation of species.