Biology subjects

Broadbent, E. N.

Publications and source records attributed to Broadbent, E. N..

2 recordsLinked to original sources

bioRxiv2023

Plant-mediated effects of fire and fragmentation drive plant-pollinator interaction β-diversity in fire-dependent pine savannas

Interaction {beta}-diversity is an essential measure to understand and conserve species interactions and ecosystem functioning. Interaction {beta}-diversity explains the variation in species interactions across spatial and temporal gradients, resulting from species turnover or interaction rewiring. Each component of interaction {beta}-diversity has different ecological implications and practical consequences. While interaction {beta}-diversity due to species turnover is related to assembly processes and fragmentation, rewiring can support high biodiversity and confer resilience to ecological networks. Despite this, it is unclear whether both components respond to the same or different ecological drivers. Here, we assessed the ecological drivers of plant-pollinator interaction {beta}-diversity and its components across 24 sites in 9 Longleaf Pine (LLP) savannas in north and central Florida. We evaluated the effects of flowering plant composition and flower abundance, vegetation, fire regime, soil moisture, terrain characteristics, climate, spatial context, and geographic location. We used path analysis to evaluate the drivers of spatial interaction {beta}-diversity and its main components. We then used generalized linear mixed models to assess the temporal patterns of spatial {beta}-diversity among sites within preserves. We found that plant-pollinator networks in LLP savannas are highly variable across space and time, mainly due to species turnover and possibly in response to abiotic gradients and dispersal boundaries. Flower abundance and flowering plant composition, geographic location, fire seasonality, soil moisture, and landscape context were the main drivers of plant-pollinator {beta}-diversity, highlighting the role of fire management and habitat connectivity in preserving plant-pollinator networks.

ecology↗

bioRxiv2021

Liana optical traits increase tropical forest albedo and reduce ecosystem productivity

Lianas are a key growth form in tropical forests. Their lack of self-supporting tissues and their vertical position on top of the canopy make them strong competitors of resources. A few pioneer studies have shown that liana optical traits differ on average from those of colocated tree. Those trait discrepancies were hypothesized to be responsible for the competitive advantage of lianas over trees. Yet, in the absence of reliable modelling tools, it is impossible to unravel their impact on the forest energy balance, light competition and on the liana success in Neotropical forests. To bridge this gap, we performed a meta-analysis of the literature to gather all published liana leaf optical spectra, as well as all canopy spectra measured over different levels of liana infestation. We then used a Bayesian data assimilation framework applied to two radiative transfer models (RTMs) covering the leaf and canopy scales to derive tropical tree and liana trait distributions, which finally informed a full dynamic vegetation model. According to the RTMs inversion, lianas grew thinner, more horizontal leaves with lower pigment concentrations. Those traits made the lianas particularly efficient at light interception and completely modified the forest energy balance and its carbon cycle. While forest albedo increased by 14% in the shortwave, light availability was dramatically reduced in the understory (-30% of the PAR radiation) and soil temperature decreased by 0.5{degrees}C. Those liana-specific traits were also responsible for a significant reduction of tree (-19%) and ecosystem (-7%) gross primary productivity (GPP) while lianas benefited from them (their GPP increased by +27%). This study provides a novel mechanistic explanation to the increase in liana abundance, new evidence of the impact of structural parasitism on forest functioning, and paves the way for the evaluation of the large-scale impacts of woody vines on forest biogeochemical cycles.

plant biology↗