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Understanding the factors and mechanisms shaping differences in species composition across space and time (β‐diversity) in human‐modified landscapes has key ecological and applied implications. This topic is, however, challenging because landscape disturbance can promote either decreases (biotic homogenization) or increases (biotic differentiation) in β‐diversity. We assessed temporal differences in intersite β‐diversity of medium‐bodied and large‐bodied mammals in the fragmented Lacandona rainforest, Mexico. We hypothesized that, given the relatively short history of land‐use changes in the region, and the gain and loss of some species caused by landscape spatial changes, β‐diversity would increase through time, especially its nestedness component. We estimated β‐diversity between 24 forest sites (22 forest patches and two continuous forest sites) in 2011 and 2017 to assess whether β‐diversity is decreasing or increasing in the region, and calculated its turnover and nestedness components to understand the mechanisms responsible for changes in β‐diversity, separately assessing mammal groups with different body mass, feeding guild, and habitat specialization. We then related such temporal changes in β‐diversity to temporal changes in five landscape variables (forest cover, matrix openness, number of patches, edge density and interpatch distance) to identify the landscape drivers of β‐diversity. In contrast with our expectations, β‐diversity decreased over time, suggesting an ongoing biotic homogenization process. This pattern was mostly driven by a decrease in species turnover in all mammal groups, especially in landscapes with decreasing forest cover and increasing forested matrices. Although the nestedness component showed a three‐fold increase through time, species turnover was 22 and six times higher than nestedness in 2011 and 2017, respectively. The decreased turnover appears to be driven by an increase in dispersal (i.e., spillover) of native species among patches. The prevalence of species turnover over nestedness indicates that different forest sites have a fairly distinct subset of species (i.e., high complementarity in species composition). Therefore, conserving all remaining forest patches and increasing forest cover is of utmost importance to effectively maintain β‐diversity and conserve the total diversity (γ) of mammal assemblages in this Mesoamerican biodiversity hotspot. [ABSTRACT FROM AUTHOR]

Tropical dry forest (TDF) is the most threatened of all tropical forest ecosystems worldwide. In the tropical dry forest of the Pacific Coast of Mexico, in addition to human disturbance, the vegetation has been subjected to natural disturbances such as droughts and hurricanes. The average cyclone intensity and the number of very intense category 4 and 5 storms are predicted to increase in this area and such extreme meteorological events generate further stress to the vegetation. Given that in October 2015 the category 4 hurricane “Patricia” landed on the Chamela-Cuixmala TDF, in this study we: (1) evaluated the effect of a high intensity hurricane on TDF vegetation at two habitat types (secondary forest and old-growth forest); and (2) determined how the vegetation attributes at the species and stand level could be defining the vegetation type of damage, and its recovery capacity. For this purpose, we evaluated species composition, vegetation structure and individuals biomechanical traits in eight vegetation plots, four corresponding to old-growth forests (OGF) and four corresponding to secondary forests (SF), before and after the hurricane. Additionally, after the hurricane we also evaluated the damage, leaf functional traits and resprouting ability at the individual level. In total, we evaluated 3732 individuals of 279 species. Data were analyzed by contrasting the vegetation damage and resprouting ability between SF and OGF. Then, we evaluated for the potential relationship between vegetation composition and structure (stand-level attributes) and vegetation damage and recovery capacity. Finally, we evaluated the association between biomechanical and leaf functional traits and the vegetation damage and recovery at the species level. In general, the most severe types of damage were biased toward taller trees as they could be more vulnerable to mechanical instability. We found that OGF received a greater proportion of severe types of damage than SF, although tall trees in SF could face a higher mortality. Harsh environmental conditions preceding the hurricane could also increase the mortality and limit the resprouting ability in SF. Besides, stems with low height and low wood density were related to a greater resprouting ability. This ability was also associated to leaf functional traits such as the relative chlorophyll content, specific leaf area, leaf fresh mass and leaf density, indicating a greater biomass acquisition in species with higher photosynthetic capacity and resistant tissues. These results suggest that in scenarios of increasing frequency and/or intensity of hurricanes, the TDF of the Pacific Coast of Mexico could change their physiognomy toward a canopy of lower height. The proportion of species combining the capacity to resist damage and harsh environmental conditions with a high resprouting ability (i.e. smaller sizes, productive and resistant tissues, such as the TDF pioneer species), could increase as well. [ABSTRACT FROM AUTHOR]

An abstract of the study "Frugivorous Bat Ensemble in Riparian Habitat in Tropical Dry Forest: Effect of Vegetation Structure and Seasonality," by Mariana Zarazúa-Carbajal, Luis Daniel Avila-Cabadilla and colleagues is presented.