Functional biogeography of Neotropical moist forests: Trait–climate relationships and assembly patterns of tree communities

Abstract

Aim Here we examine the functional profile of regional tree species pools across the latitudinal distribution of Neotropical moist forests, and test trait–climate relationships among local communities. We expected opportunistic strategies (acquisitive traits, small seeds) to be overrepresented in species pools further from the equator, but also in terms of abundance in local communities in currently wetter, warmer and more seasonal climates. Location Neotropics. Time period Recent. Major taxa studied Trees. Methods We obtained abundance data from 471 plots across nine Neotropical regions, including c. 100,000 trees of 3,417 species, in addition to six functional traits. We compared occurrence‐based trait distributions among regional species pools, and evaluated single trait–climate relationships across local communities using community abundance‐weighted means (CWMs). Multivariate trait–climate relationships were assessed by a double‐constrained correspondence analysis that tests both how CWMs relate to climate and how species distributions, parameterized by niche centroids in climate space, relate to their traits. Results Regional species pools were undistinguished in functional terms, but opportunistic strategies dominated local communities further from the equator, particularly in the Northern Hemisphere. Climate explained up to 57% of the variation in CWM traits, with increasing prevalence of lower‐statured, light‐wooded and softer‐leaved species bearing smaller seeds in more seasonal, wetter and warmer climates. Species distributions were significantly but weakly related to functional traits. Main conclusions Neotropical moist forest regions share similar sets of functional strategies, from which local assembly processes, driven by current climatic conditions, select for species with different functional strategies. We can thus expect functional responses to climate change driven by changes in relative abundances of species already present regionally. Particularly, equatorial forests holding the most conservative traits and large seeds are likely to experience the most severe changes if climate change triggers the proliferation of opportunistic tree species.

Global relationships in tree functional traits

“…6 ). In line with previous work, seed dry mass has moderate correlations with various other traits underpinning leaf economics and tree size 5 , 28 (e.g. ρ = 0.28, −0.22, and 0.22 for tree height, leaf K, and leaf density, using the raw data), yet it exhibits relatively weak correlation with most other traits, placing it in a distinct functional cluster.…”

“…Traits such as seed characteristics and crown dimensions can be critical drivers of successional trajectories, canopy positioning, and life-history strategies across the landscape 24 – 26 . Identifying the multidimensional trait relationships that integrate these different tree parts is urgently needed to create standardized, systematic metrics of forest functional biodiversity across the globe 12 , 27 , 28 .…”

Variation partitioning in double-constrained multivariate analyses: linking communities, environment, space, functional traits, and ecological niches

“…We selected maximal shell size of mollusks (SizeM), an ordinal variable ranging from (1) < 2.5 to (6) > 100 mm, and feeding type (FeedT), a factor with the levels: scraper (SCR), scraper and sediment feeder (SS), sediment feeder (SED), scraper and filter feeder (SF), filter feeder (F), sediment and filter, or suspension and deposit feeders (SEDF). The values for the traits were based on the works of Falkner et al (2001), Glöer (2019), Killeen et al (2004), Piechocki and Wawrzyniak-Wydrowska (2016), and Sîrbu and Benedek (2018).…”

Unravelling Trait–Environment Relationships at Local and Regional Scales in Temperate Forests

“…Trait–environment relationships at the global scale have been gradually unraveled in previous studies using global plant trait databases ( Bruelheide et al, 2018 ; Wieczynski et al, 2019 ). Nevertheless, these large-scale trait patterns were failed to account for ecological processes operating at local scales that govern the functional profile of community assemblages ( Pinho et al, 2021 ). The functional composition of communities sampled at fine-grained plots was the direct outcome of the interaction both local and large-scale factors ( Bruelheide et al, 2018 ).…”

“…The functional composition of communities sampled at fine-grained plots was the direct outcome of the interaction both local and large-scale factors ( Bruelheide et al, 2018 ). For instance, communities across Neotropical moist forests share similar sets of functional strategies driven by current climatic conditions ( Pinho et al, 2021 ). However, it remains unknown to what extent community-level trait composition depends on regional-scale environmental drivers, particularly the effects of local-scale environmental factors (e.g., soil and topography factors) in temperate forests.…”