Data from: Plant diversity and density predict belowground diversity and function in an early successional alpine ecosystem

Despite decades of interest, few studies have provided evidence supporting theoretical expectations for coupled relationships between aboveground and belowground diversity and ecosystem functioning in non-manipulated naturalecosystems. We characterized plant species richness and density, soil bacterial, fungal and eukaryotic species richness and phylogenetic diversity (using 16S, ITS, and 18S gene sequencing), and ecosystem function (levels of soil C and N, and rates of microbial enzyme activities) along a natural gradient in plant richness and density in high-elevation, C-deficient soils to examine the coupling between above- and belowground systems. Overall, we observed a strong positive relationship between aboveground (plant richness and density) and belowground (bacteria, fungi, and non-fungal eukaryotes) richness. In addition to the correlations between plants and soil communities, C and N pools, and rates of enzyme activities increased as plant and soil communities became richer and more diverse. Our results suggest that the theoretically expected positive correlation between above- and belowground communities does exist in natural systems, but may be undetectable in late successional ecosystems due to the buildup of legacy organic matter that results in extremely complex belowground communities. In contrast, microbial communities in early successional systems, such as the system described here, are more directly dependent on contemporary inputs from plants and therefore are strongly correlated with plant diversity and density.尽管数十年来学界对此持续关注，但鲜有研究能为未受人为干扰的自然生态系统中，地上（aboveground）与地下（belowground）多样性及生态系统功能（ecosystem functioning）间的耦合关系的理论预期提供实证支撑。本研究依托高海拔缺碳土壤中植物丰富度与密度的自然梯度，对植物物种丰富度与密度、土壤细菌、真菌及真核生物的物种丰富度与系统发育多样性（phylogenetic diversity，采用16S、ITS及18S基因测序技术），以及生态系统功能指标（土壤碳氮含量与微生物酶活性速率）进行了表征，以此探究地上与地下系统的耦合关系。整体而言，我们观测到地上群落（植物丰富度与密度）与地下群落（细菌、真菌及非真菌真核生物）的多样性之间存在显著正相关关系。除植物与土壤群落间的相关性外，随着植物与土壤群落的丰富度与多样性提升，土壤碳氮库及酶活性速率也随之升高。我们的研究结果表明，理论预期的地上与地下群落间正相关关系确实存在于自然生态系统中，但在晚期演替生态系统中可能难以被检测到——这是因为遗留有机质的积累会形成极为复杂的地下群落。与之相反，本研究涉及的早期演替生态系统中的微生物群落，更直接依赖于植物的当代输入物，因此与植物多样性及密度呈现强相关性。