BackgroundInvasive plant species strongly affect native plant communities, often with strong influences belowground. Some native plants respond with rapid trait change from multigenerational interactions with invasives, including via root biomass allocation. Native plant root allocation responses to multigenerational invasive exposure are poorly typified, and researchers have yet to summarise whether resource availability mediates the responses of native plants that have co-occurred with invasive plant species (invader-experienced) and those that have not (invader-experienced).AimsEvaluate root partitioning from invader-experienced and invader-na & iuml;ve native plant populations, in experiments in which native plants were grown alone or with the co-occurring invasive species at varying resource levels.MethodsUse 242 effect sizes on 17 native species in meta-analysis models to compare root allocation between invader-experienced and invader-na & iuml;ve and under varying resource levels.ResultsI found that differences in response to the presence or absence of multigenerational invasive exposure were only apparent when testing different resource levels. Specifically, when grown alone, invader-experienced plants had greater root allocation under stress, whereas invader-na & iuml;ve plants had lower root allocation under resource limitation.ConclusionInteractions with invasive plant species produced adaptive responses in native plant species to resources which are observed even without interactions with invasives. This indicates a significant effect of invasive species below-ground and calls for more research assessing eco-evolutionary root trait responses to coexistence by native species with invasive species.
BackgroundOne well-established hypothesis to explain high epiphyte diversity in the Neotropics is the vertical niche differentiation hypothesis (VNDH). The VNDH posits that Neotropical epiphytic biodiversity is driven by the differentiation of epiphytes into specialised niches throughout the forest canopy. However, few studies have taken an experimental approach to testing this hypothesis.AimsTo determine whether epiphyte morphospecies exhibit vertical niche specialisation and whether shifts in vertical position affect their survival.MethodsWe assessed the vertical distribution of 35 common epiphyte morphospecies across 30 focal host trees to characterise naturally occurring variability in epiphyte distributions. We then experimentally transplanted individuals from their original canopy positions to the understorey to test the effects of altered vertical strata on survival.ResultsNone of the 35 morphospecies were strictly specialised by height zone and many were non-uniformly distributed throughout the canopy. Survival rates declined with increasing original canopy height - epiphytes found higher in the canopy were less likely to persist after relocation to the understorey.ConclusionOur results support the notion of vertical stratification among Neotropical vascular epiphytes and experimentally demonstrate survival consequences linked to this stratification. These findings contribute to understanding mechanisms underlying tropical epiphyte diversity and offer insights for forest managers interested in the sustainable horticulture of tropical epiphytes.
BackgroundUnderstanding plant community assembly in montane ecosystems is vital, yet mechanisms in semiarid regions remain poorly resolved, particularly regarding cryptic environmental filters.AimsWe aimed to (1) determine whether lack of environment - abundance correlation reflects stochasticity or competition, and (2) evaluate whether phylogenetic structure is a more sensitive indicator of cryptic filters in semiarid mountains.MethodsIn 25 plots, we recorded species abundance and calculated phylogenetic metrics (NRI, NTI) from regional phylogeny. Mantel tests compared abundance - phylogeny correlations. Canonical Correspondence Analysis (CCA), PERMANOVA, and NMDS linked environmental variables (soil moisture, pH, EC; elevation, slope) to abundance. PERMANOVA and Principal Coordinates of Phylogenetic Structure (PCPS) assessed environment - phylogeny relationships.ResultsAbundance showed no significant correlation with environmental variables (CCA/PERMANOVA/NMDS). Mantel tests confirmed no abundance - phylogeny correlation. Phylogenetic overdispersion (negative NRI/NTI) indicated competitive exclusion. Phylogeny revealed significant filtering by soil moisture and pH (PERMANOVA) and moisture/pH/EC (PCPS) - undetected by abundance methods. Topography showed no effect.ConclusionPhylogeny revealed dual assembly dynamics: competitive overdispersion and cryptic filtering by soil moisture/pH. This shows the greater sensitivity of phylogeny, detecting deterministic filters where abundance data showed only weak trends. In semiarid mountains, local edaphic gradients override topography impact, underscoring essential role of phylogeny in revealing assembly mechanisms.
