Changes in rainfall amount and seasonality modulate taxonomic, functional, and phylogenetic diversity in a gypsophilous plant community in the Chihuahuan Desert

Climate change is expected to alter future rainfall regime in arid zones, which may impact gypsophilous plant diversity components in the Chihuahuan Desert. We investigated the effects of different rainfall timings and amounts on the taxonomic, functional, and phylogenetic components of a gypsophilous plant community. We used soil monoliths extracted from the southern Chihuahuan Desert in a greenhouse experiment with three rainfall timings (typical, early, and late) and two rainfall amounts (100% and 50%) and evaluated the effects on taxonomic, functional, and phylogenetic diversity. Irrigation treatment with 50% of average rainfall reduced species richness and plant abundance and altered species composition. At 100% irrigation, specific leaf area was lower in the treatments with typical and late rainfall timing than in the treatment with early rainfall. Phylogenetic diversity was significantly lower in the late timing treatment in November. Our study evidence that the water shortage impacted drastically on the plant community by decreased species richness and diversity. Nevertheless, late rainfall can buffer the effects of water diminution but only on taxonomic and functional diversity, with the opposite effect on the phylogenetic diversity, in the gypsophilous communities in the Chihuahuan Desert.

气候变化预计将改变干旱地区未来的降雨格局，进而影响奇瓦瓦沙漠（Chihuahuan Desert）内嗜石膏植物（gypsophilous plant）的多样性组分。本研究探讨了不同降雨时序与降雨量对嗜石膏植物群落的分类、功能及系统发育多样性组分的影响。研究团队采用从奇瓦瓦沙漠南部采集的土壤柱芯，设置三种降雨时序（典型、提前、延后）与两种降雨量（100%与50%）开展温室实验，评估其对分类、功能及系统发育多样性的影响。结果显示，采用50%平均降雨量的灌溉处理，会降低物种丰富度与植株多度，并改变物种组成。在100%灌溉处理下，典型与延后降雨时序组的比叶面积（specific leaf area）低于提前降雨时序组。11月时，延后降雨时序组的系统发育多样性显著更低。本研究表明，水分短缺会通过降低物种丰富度与多样性，对植物群落产生剧烈影响。但在奇瓦瓦沙漠的嗜石膏植物群落中，延后降雨仅能缓解水分减少对分类与功能多样性的负面影响，却会对系统发育多样性产生相反的效应。