柴达木盆地水生植物多样性格局及多假说验证

物种多样性格局同时受到多个因子和过程的综合作用。以往对水生植物多样性格局形成机制的研究主要集中在几何限制、水分能量状况或随机过程等少数因子方面。该研究通过野外调查, 研究柴达木盆地水生植物沿经度和纬度梯度的分布格局, 并验证了对物种多样性分布格局影响较大的水分-能量假说、栖息地异质性假说、空间自相关、物种-面积效应和中域效应这5种假说。主要结果表明柴达木盆地水生植物多样性沿经度和纬度梯度均呈现“∩”形单峰格局。回归分析显示中域效应和物种-面积效应显著影响柴达木盆地水生植物多样性格局, 而水分-能量、栖息地异质性假说及空间自相关对该区域水生植物多样性格局影响较小。方差分解显示中域效应对柴达木盆地水生植物多样性经度和纬度格局的单独解释率分别为68.41%和66.91%, 该结果表明柴达木盆地水生植物多样性格局主要受几何限制和扩散限制影响。结合以往研究结果, 该研究进一步证实几何限制和随机效应可能是影响中国干旱区水生植物多样性分布格局的重要自然因素。

Testing multiple hypotheses for the richness pattern of macrophyte in the Qaidam Basin of Northwest China

Aims Patterns of species richness are influenced by both ecological factors and processes. The formation mechanisms of macrophyte richness pattern have been mainly concentrated in a few aspects, such as geometric constraints, water-energy status, or random processes. Methods In this study, using collected macrophyte species-level data in the Qaidam Basin, we examined macrophyte richness patterns along latitudinal and longitudinal gradients, and tested the mid-domain effect (MDE), area effect (AE), water-energy hypothesis, spatial autocorrelation, and habitat heterogeneity hypothesis for the geographical patterns. Important findings Our study showed that the macrophyte richness in the Qaidam Basin showed a hump- shaped pattern along latitudinal and longitudinal gradients. Regression analyses indicated that MDE and AE, rather than water-energy hypothesis, spatial autocorrelation, or habitat heterogeneity hypothesis significantly influenced macrophyte richness in the Qaidam Basin. Variation partitioning showed that the explanatory power of MDE for longitudinal and latitudinal richness patterns of macrophyte was 68.41% and 66.91%, respectively. This result implies that macrophyte richness in the Qaidam Basin is mainly affected by geometric and dispersal restrictions. This study further confirms that geometric constraints and random processes may be important natural factors affecting the pattern of macrophyte richness in the arid area of Northwest China.