Studies on the relationship between biodiversity and ecosystem productivity have suggested that species richness and functional diversity are the main drivers of ecosystem processes. Several patterns on this relationship have been found, including positive, unimodal, negative, and neutral trends, keeping the issue controversial. In this study, taxonomic diversity and functional diversity as drivers of above-ground biomass (AGB) were compared, and the mechanisms that influence biomass production were investigated by testing the complementarity and the mass-ratio hypotheses. Using data from 414 permanent sample plots, covering 23% of temperate forest in the Sierra Madre Oriental (México), we estimated the above-gound biomass (AGB), taxonomic and functional diversity indices, as well as community weighted mean values (CWM) for three functional traits (maximum height, leaf size and wood density) for trees ≥7.5 cm DBH, in managed and unmanaged stands. To compare taxonomic diversity differences between managed and unmanaged stands we carried out a rarefaction analysis. Furthermore, we evaluated the relationship between AGB and taxonomic and functional diversity metrics, as well as CWM traits throught spatial autoregressive models. We found a hump-shaped relationship between AGB and species richness in managed and unmanaged forests. CMW of maximum height was the most important predictor of AGB in both stands, which suggested that the mechanism underlaying the AGB-diversity relationship is the dominance of some highly productive species, supporting the mass-ratio hypothesis. Above-ground biomass was significantly correlated with three of the five functional diversity metrics, CWM maximum height and species richness. Our results show the importance of taking into account spatial autocorrelation in the construction of predictive models to avoid spurious patterns in the AGB-diversity relationship. Species richness, maximum height, functional richness, functional dispersion and RaoQ indices relate with above-ground biomass production in temperate mixed-species and uneven-aged forests of northern Mexico. These forests show a hump-shaped AGB-species richness relationship. Functional diversity explains better AGB production than classical taxonomic diversity. Community weighted mean traits provide key information to explain stand biomass in these forests, where maximum tree height seems to be a more suitable trait for understanding the biomass accumulation process in these ecosystems. Although the impact of forest management on biodiversity is still debated, it has not changed the AGB-diversity relationships in the forests of the Sierra Madre Occidental, Mexico.

中文翻译：

---

在墨西哥北部温带森林中评估地上生物量功能多样性关系

关于生物多样性与生态系统生产力之间关系的研究表明，物种丰富度和功能多样性是生态系统过程的主要驱动力。已经发现了关于这种关系的几种模式，包括积极，单峰，消极和中性的趋势，使这个问题引起争议。在这项研究中，比较了作为地上生物量（AGB）驱动因素的生物分类多样性和功能多样性，并通过检验互补性和质量比假设，研究了影响生物量生产的机制。利用414个永久性样地的数据，覆盖了墨西哥东部Sierra Madre的23％的温带森林，我们估算了地上生物量（AGB），分类学和功能多样性指数，以及在管理和非管理林分中，≥7.5cm DBH的树木的三个功能性状（最大高度，叶片大小和木材密度）的社区加权平均值（CWM）。为了比较管理和非管理林分之间的分类学多样性差异，我们进行了稀疏性分析。此外，我们通过空间自回归模型评估了AGB与分类学和功能多样性指标以及CWM特征之间的关系。我们发现在管理和非管理森林中，AGB和物种丰富度之间呈驼峰状关系。在两个林分中，最大高度的CMW是AGB的最重要预测指标，这表明，AGB-多样性关系背后的机制是某些高产物种的优势，支持了质量比假说。地上生物量与五个功能多样性指标中的三个，CWM最大高度和物种丰富度显着相关。我们的结果表明，在构建预测模型时要考虑空间自相关性，以避免AGB-多样性关系中的虚假模式，这一点很重要。物种丰富度，最大高度，功能丰富度，功能分散度和RaoQ指数与墨西哥北部温带混合物种和不规则年龄森林的地上生物量生产有关。这些森林表现出驼峰形的AGB-物种丰富度关系。功能多样性比传统的分类学多样性更好地解释了AGB的产生。社区加权平均特征提供了解释这些森林中林分生物量的关键信息，其中最大树高似乎是更适合了解这些生态系统中生物量积累过程的特征。尽管森林管理对生物多样性的影响仍存在争议，但它并未改变墨西哥西马德雷山脉森林中AGB-多样性的关系。