Lammerant Roel, Rita Angelo, Borghetti Marco, Muscarella Robert
Department of Ecology & Genetics Uppsala University Uppsala Sweden.
Present address: Tvärminne Zoological Station University of Helsinki Hanko Finland.
Ecol Evol. 2023 Aug 8;13(8):e10406. doi: 10.1002/ece3.10406. eCollection 2023 Aug.
The link between biodiversity and ecosystem function can depend on environmental conditions. This contingency can impede our ability to predict how biodiversity-ecosystem function (BEF) relationships will respond to future environmental change, causing a clear need to explore the processes underlying shifts in BEF relationships across large spatial scales and broad environmental gradients. We compiled a dataset on five functional traits (maximum height, wood density, specific leaf area [SLA], seed size, and xylem vulnerability to embolism [P]), covering 78%-90% of the tree species in the National Forest Inventory from Italy, to test (i) how a water limitation gradient shapes the functional composition and diversity of forests, (ii) how functional composition and diversity of trees relate to forest annual increment via mass ratio and complementarity effects, and (iii) how the relationship between functional diversity and annual increment varies between Mediterranean and temperate climate regions. Functional composition varied with water limitation; tree communities tended to have more conservative traits in sites with higher levels of water limitation. The response of functional diversity differed among traits and climatic regions but among temperate forest plots, we found a consistent increase of functional diversity with water limitation. Tree diversity was positively associated with annual increment of Italian forests through a combination of mass ratio and niche complementarity effects, but the relative importance of these effects depended on the trait and range of climate considered. Specifically, niche complementarity effects were more strongly associated with annual increment in the Mediterranean compared to temperate forests. : Overall, our results suggest that biodiversity mediates forest annual increment under water-limited conditions by promoting beneficial interactions between species and complementarity in resource use. Our work highlights the importance of conserving functional diversity for future forest management to maintain forest annual increment under the expected increase in intensity and frequency of drought.
生物多样性与生态系统功能之间的联系可能取决于环境条件。这种偶然性可能会妨碍我们预测生物多样性 - 生态系统功能（BEF）关系将如何应对未来环境变化的能力，这就明确需要探索在大空间尺度和广泛环境梯度上BEF关系转变背后的过程。我们汇编了一个关于五个功能性状（最大高度、木材密度、比叶面积 [SLA]、种子大小和木质部栓塞脆弱性 [P]）的数据集，涵盖了意大利国家森林清查中78% - 90%的树种，以测试：（i）水分限制梯度如何塑造森林的功能组成和多样性；（ii）树木的功能组成和多样性如何通过质量比和互补效应与森林年生长量相关；以及（iii）功能多样性与年生长量之间的关系在地中海和温带气候区域之间如何变化。功能组成随水分限制而变化；在水分限制程度较高的地点，树木群落往往具有更保守的性状。功能多样性的响应在性状和气候区域之间存在差异，但在温带森林样地中，我们发现功能多样性随水分限制而持续增加。通过质量比和生态位互补效应的结合，树木多样性与意大利森林的年生长量呈正相关，但这些效应的相对重要性取决于所考虑的性状和气候范围。具体而言，与温带森林相比，生态位互补效应与地中海地区的年生长量关联更强。总体而言，我们的结果表明，在水分受限条件下，生物多样性通过促进物种间的有益相互作用和资源利用的互补性来调节森林年生长量。我们的工作强调了保护功能多样性对于未来森林管理的重要性，以便在预期干旱强度和频率增加的情况下维持森林年生长量。
