Quantitative Plant Ecology and Biodiversity Research Lab, Department of Biology, Faculty of Science, Ferdowsi University of Mashhad, Mashhad, Iran.
Department of Range and Watershed Management, Faculty of Natural Resources and Environment, Ferdowsi University of Mashhad, Mashhad, Iran.
Sci Rep. 2022 May 30;12(1):9022. doi: 10.1038/s41598-022-13123-2.
Climate and soil factors induce substantial controls over plant biodiversity in stressful ecosystems. Despite of some studies on plant biodiversity in extreme ecosystems including rocky outcrops, simultaneous effects of climate and soil factors have rarely been studied on different facets of biodiversity including taxonomic and functional diversity in these ecosystems. In addition, we know little about plant biodiversity variations in such extreme ecosystems compared to natural environments. It seems that environmental factors acting in different spatial scales specifically influence some facets of plant biodiversity. Therefore, we studied changes in taxonomic and functional diversity along precipitation and soil gradients in both landscapes (i) rocky outcrops and (ii) their nearby rangeland sites in northeast of Iran. In this regard, we considered six sites across precipitation and soil gradients in each landscape, and established 90 1m quadrates in them (i.e. 15 quadrats in each site; 15 × 6 = 90 in each landscape). Then, taxonomic and functional diversity were measured using RaoQ index, FDis and CWM indices. Finally, we assessed impacts of precipitation and soil factors on biodiversity indices in both landscapes by performing regression models and variation partitioning procedure. The patterns of taxonomic diversity similarly showed nonlinear changes along the precipitation and soil factors in both landscapes (i.e. outcrop and rangeland). However, we found a more negative and significant trends of variation in functional diversity indices (except for CWMSLA) across precipitation and soil factors in outcrops than their surrounding rangelands. Variations of plant biodiversity were more explained by precipitation factors in surrounding rangelands, whereas soil factors including organic carbon had more consistent and significant effects on plant biodiversity in outcrops. Therefore, our results represent important impacts of soil factors in structuring plant biodiversity facets in stressful ecosystems. While, environmental factors acting in regional and broad scales such as precipitation generally shape vegetation and plant biodiversity patterns in natural ecosystems. We can conclude that rocky outcrops provide suitable microenvironments to present plant species with similar yields that are less able to be present in rangeland ecosystems.
气候和土壤因素对胁迫生态系统中的植物生物多样性有很大的控制作用。尽管已经有一些关于包括岩石露头在内的极端生态系统中植物生物多样性的研究，但很少有研究同时研究气候和土壤因素对这些生态系统中生物多样性的不同方面（包括分类学和功能多样性）的影响。此外，与自然环境相比，我们对这些极端生态系统中植物生物多样性的变化知之甚少。似乎在不同空间尺度上起作用的环境因素会特别影响植物生物多样性的某些方面。因此，我们研究了伊朗东北部的两种景观（岩石露头和附近的牧场）中降水和土壤梯度对分类学和功能多样性的影响。为此，我们在每个景观中考虑了降水和土壤梯度上的六个地点，并在每个地点建立了 90 个 1m 平方（即每个地点 15 个平方；每个景观 15×6=90）。然后，使用 RaoQ 指数、FDis 和 CWM 指数来测量分类学和功能多样性。最后，我们通过回归模型和变异划分程序评估降水和土壤因素对两种景观中生物多样性指数的影响。分类多样性的模式也显示了在两种景观（露头和牧场）中沿着降水和土壤因素的非线性变化。然而，我们发现，在露头中，功能多样性指数（除了 CWMSLA 之外）的变化趋势更为负面和显著，而在其周围的牧场上，这种变化趋势更为负面和显著。在周围的牧场上，植物生物多样性的变化更多地由降水因素解释，而土壤因素（包括有机碳）对露头中植物生物多样性的影响更一致且更显著。因此，我们的研究结果代表了土壤因素在构建胁迫生态系统中植物生物多样性方面的重要影响。虽然在区域和广泛尺度上起作用的环境因素（如降水）通常会塑造自然生态系统中的植被和植物生物多样性模式。我们可以得出结论，岩石露头为具有相似产量的现有植物物种提供了合适的微环境，而这些植物物种在牧场生态系统中则不太可能存在。
