Beyond leaf habit: generalities in plant function across 97 tropical dry forest tree species

Abstract

 Leaf habit has been hypothesized to define a linkage between the slow-fast plant economic spectrum and the drought resistance-avoidance trade-off in tropical forests ('slow-safe versus fast-risky').However, variation in hydraulic traits as a function of leaf habit has rarely been explored for a large number of species.  We sampled leaf and branch functional traits of 97 tropical dry forest tree species from four sites to investigate whether patterns of trait variation varied consistently in relation to leaf habit along the 'slow-safe versus fast-risky' tradeoff.  Leaf habit explained from 0 to 43.69 % of individual trait variation. We found that evergreen and semideciduous species differed in their location along the multivariate trait ordination when compared to deciduous species. While deciduous species showed consistent trait values, evergreen species trait values varied as a function of the site. Last, trait values varied in relation to the proportion of deciduous species in the plant community.  We found that leaf habit describes the strategies that define drought avoidance and plant economics in tropical trees. However, leaf habit alone does not explain patterns of trait variation, which suggests that quantifying site-specific or species-specific uncertainty in trait variation as the way forward.

The above–belowground functional space of tropical dry forest communities responds to local hydric habitats

“…Albeit, all three phenological categories were present in both forests, functional traits differed among the phenology categories in the dry, but not in the wet forest. Whether the degree of drought risk drives the coordination between phenology and other functional traits below and aboveground is an interesting hypothesis, that awaits to be tested by comparing more forests (see Arenas‐Navarro et al, 2020; Vargas et al, 2021).…”

“…Several aboveground traits have been shown to change based on water availability (Borchert, 1994;Markesteijn et al, 2011). However, changes in plants' overall strategies (including both aboveground and belowground traits) in response to water availability gradients in the TDF are still poorly understood Hulshof et al, 2013;Vargas et al, 2021). In addition, because spatial variation in water availability typically produces variation in vegetation cover, and thus, in light availability in the understory, it is unclear whether communities that differ in water availability and light show similar major trade-offs.…”

Phenological trajectories of Caribbean very dry tropical forests diverge under different geologic formations

“…First, this variability may contribute to the stability of community‐ and system‐level phenological patterns. Second, in more practical terms, it may preclude generalizations as has been suggested (Vargas et al, 2021). These authors indicate that “Interestingly, many of the traits of both evergreen and deciduous species differed among sites, suggesting that trait‐leaf habit relationships developed in one region should not be extrapolated to other regions.”…”

“…Many areas within CP were heavily affected by human activities until ~1950; thus, stand age ranges between 40 and 50 years. Activities in these areas like in other parts of Curaçao and TDF (Vargas et al, 2021) included intensive grazing, wood cutting for charcoal and even tilling for planting with seasonal crops such as peanuts, beans, and sorghum. Currently, the vegetation in CP is broadly classified as a very dry tropical forest sensu Holdridge (Debrot et al, 1999) or as a xeric scrubland (Beers et al, 1997).…”

“…Here, we leverage a phenological dataset from the very dry tropical forests of the island of Curaçao—an island with rainfall conditions well below those of intensively studied sites in the Americas (Vargas et al, 2021) to investigate the extent to which plant phenology diverges in regions underlain by different geologies. This dataset includes monthly observations obtained during a 30‐month period on leaves, flowers, and fruits of 69 plant species belonging to different life forms at three nearby sites underlain by basalt, chert, and limestone.…”