Theory predicts positive effects of species richness on the productivity of plant communities through complementary resource use and facilitative interactions between species. Results from manipulative experiments with tropical tree species indicate a positive diversity–productivity relationship (DPR), but the existing evidence from natural forests is scarce and contradictory. We studied forest aboveground productivity in more than 80 humid tropical montane old-growth forests in two highly diverse Andean regions with large geological and topographic heterogeneity and related productivity to tree diversity and climatic, edaphic and stand structural factors with a likely influence on productivity. Main determinants of wood production in the perhumid study regions were elevation (as a proxy for temperature), soil nutrient (N, P and base cation) availability and forest structural parameters (wood specific gravity, aboveground biomass). Tree diversity had only a small positive influence on productivity, even though tree species numbers varied largely (6–27 species per 0.04 ha). We conclude that the productivity of highly diverse Neotropical montane forests is primarily controlled by thermal and edaphic factors and stand structural properties, while tree diversity is of minor importance.

中文翻译：

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控制热带安第斯森林生产力的因素：气候和土壤比树木多样性更重要

理论预测物种丰富度通过互补性资源利用和物种间的促进性相互作用对植物群落生产力的积极影响。对热带树种进行的操纵性实验结果表明，多样性与生产力之间存在正相关关系，但天然林的现有证据很少且相互矛盾。我们研究了两个高度不同的安第斯山地区80多个湿润的热带山地老林的地上生产力，这些地区具有较大的地质和地形异质性，并且与树木的多样性，气候，深水和林分结构因素相关，并且可能对生产力产生影响。在全湿研究区，木材产量的主要决定因素是海拔（作为温度的代用指标），土壤养分（N，磷和碱阳离子）的可用性和森林结构参数（木材比重，地上生物量）。即使树木种类数量变化很大（每0.04公顷有6-27种），树木的多样性对生产力也只有很小的积极影响。我们得出的结论是，高度多样化的新热带山地森林的生产力主要受热力和土壤因子以及林分结构特性的控制，而树木的多样性则次要。