Institute of Geographical Science, Taiyuan Normal University, Jinzhong, 030619, China.
Key Laboratory of Restoration Ecology of Cold Area in Qinghai Province, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining, 810008, China.
Sci Rep. 2021 May 26;11(1):10974. doi: 10.1038/s41598-021-90561-4.
The mid-domain effect (MDE) explains altitudinal patterns of species diversity of mountainous plants at different elevations. However, its application is limited by the species life form and family flora in different layers of plant communities. To verify the MDE hypothesis at the plant community level, we chose a mountain with representative characteristics of the study area in the east of the Loess Plateau, China, such as obvious elevation (from 1324 to 2745 m) and latitude (from 36° 23' to 39° 03') gradients and considerable vegetation types (mainly coniferous and broad-leaved forests). We measured the life forms, families, and species diversity indices of tree, shrub, and herb communities along different elevations. We determined that the family numbers of the herb and shrub communities presented unimodal patterns across an altitudinal gradient, and the highest values occurred at intermediate elevations. The importance values of dominant families in the shrub and tree communities presented unimodal patterns, but the lowest values occurred at intermediate elevations. The species diversity indices of the herb, shrub, and tree communities conformed to unimodal change patterns following an altitudinal gradient, but the greatest diversity occurred at high, low, and intermediate elevations, respectively. At higher elevations, forbs and grasses grew well, whereas sedges grew well at lower elevations. Responses of different tree life forms to the altitudinal gradient were greater for evergreen coniferous tree species than for deciduous coniferous and deciduous broad-leaved tree species. We concluded that the MDE hypothesis of species diversity for mountainous plants is influenced greatly by the community life form and family at the plant community level in a temperate semi-arid region of the Loess Plateau, China. This conclusion tested and modified the MDE hypothesis and may be valuable for fueling prediction of biodiversity models and for the comparison with similar studies in arid and semi-arid mountainous regions.
中域效应（MDE）解释了不同海拔高度山地植物物种多样性的垂直分布模式。然而，它的应用受到植物群落不同层次中物种生活型和科区系的限制。为了在植物群落水平上验证 MDE 假说，我们选择了中国黄土高原东部一个具有代表性特征的山区，该山区具有明显的海拔（从 1324 米到 2745 米）和纬度（从 36°23'到 39°03'）梯度以及相当多的植被类型（主要是针叶林和阔叶林）。我们沿着不同的海拔高度测量了树木、灌木和草本群落的生活型、科和物种多样性指数。我们确定，草本和灌木群落的科数沿海拔梯度呈单峰模式，中间海拔高度的科数最高。灌木和乔木群落中优势科的重要值呈单峰模式，但中间海拔高度的重要值最低。草本、灌木和乔木群落的物种多样性指数遵循海拔梯度的单峰变化模式，但多样性最高分别出现在高、低和中间海拔高度。在较高海拔地区，草本植物和草类生长良好，而在较低海拔地区，莎草科植物生长良好。不同树木生活型对海拔梯度的响应，常绿针叶树种比落叶针叶树种和落叶阔叶树种更为显著。我们得出结论，在黄土高原半干旱温带地区，山地植物物种多样性的 MDE 假说受到植物群落生活型和科区系的强烈影响。这一结论检验和修正了 MDE 假说，对于推动生物多样性模型的预测以及与干旱和半干旱山区类似研究的比较可能具有重要价值。
