Werger M J A, Ellenbroek G A
Division of Geobotany, University of Nijmegen, Toernooiveld, Nijmegen, The Netherlands.
Oecologia. 1978 Jan;34(3):297-308. doi: 10.1007/BF00344908.
The riverine forest formation on the levees along the Orange River in South Africa shows a shift in floristic composition as the river traverses various climatic zones on its course through the temperate area in the eastern parts of the subcontinent, the central semi-desert region, and the desert area near the Atlantic in the west. Leaf size classes and leaf consistency types of the woody species in the riverine forest were determined for each community. Analysis of these data revealed a diversification of leaf sizes as the climate changed from temperate to hot and arid and particularly microphylls became relatively less important and were replaced by smaller leaves in the hot areas. In the same direction malacophylls, which are of the "low-cost, quick-profit" strategy type and are well represented in the temperate, frosty areas, disappear and xeromorphic leaves ("high-cost, slow-profit" strategy type) increase in importance. It is suggested that the cooler conditions with higher wind speeds and higher degrees of average air humidity near the Atlantic coast are reflected by an increase in mesophylls which are sclerophyllous as an adaptation to the frequently and rapidly changing temperature conditions here.
南非奥兰治河沿岸堤坝上的河滨森林群落，随着河流在穿越该次大陆东部温带地区、中部半荒漠地区以及西部靠近大西洋的沙漠地区的过程中跨越不同气候带，其植物区系组成发生了变化。针对每个群落，确定了河滨森林中木本物种的叶片大小等级和叶片质地类型。对这些数据的分析表明，随着气候从温带变为炎热干旱，叶片大小出现了多样化，特别是小叶在炎热地区相对变得不那么重要，并被更小的叶片所取代。同样地，具有“低成本、快收益”策略类型且在温带、霜冻地区大量存在的肉质叶消失了，而旱生叶（“高成本、慢收益”策略类型）变得更加重要。有人提出，靠近大西洋海岸风速较高、平均空气湿度较大的较凉爽条件，表现为中叶的增加，这些中叶为硬叶，是对这里频繁且快速变化的温度条件的一种适应。
