Evaluating the role of fire over a decade in a tropical mountainous forestgrassland mosaic

Forest-grassland mosaics comprise a major component of tropical landscapes,hosting invaluable biodiversity and providing essential ecosystem services to hundreds of millions of people worldwide.While open biomes often benefit from disturbance,forests can particularly be susceptible to structural changes resulting from such disruptions.Here we evaluate the influence of fire on the structure and landscape properties within natural forest islands immersed in a matrix of megadiverse montane grasslands.We conducted this study in 15 forest islands located in southeastern Brazil,assessing its fire frequency,intensity,and post-fire time over an eleven-year period from January 2012 to December 2022.Our results show that fire frequency is linked to soil characteristics and the percentage of herbaceous cover within the forest islands.We also found that the post-fire time is related to the percentage cover of the forest islands’associated herbs and shrubs.However,neither fire frequency,intensity,nor post-fire time was connected to significant changes in plant species richness,abundance,or in the upper vegetation strata(tree species richness and abundance,and canopy cover)in the interior of the forest islands.Furthermore,these fire-related variables did not result in temporal changes in the forest island’s canopy variation or landscape metrics.Our results underscore a low fire frequency and intensity within our study area,potentially explaining the limited fire-associated impact,and primarily on the lower vegetation strata.Despite acknowledging the relative stability of these forest islands under current fire regimes,we suggest further studies that can experimentally manipulate not only fire but also other anthropic disturbances for understanding the temporal dynamics of the forest islands and,consequently,their preservation.This perspective is indispensable for comprehensively understanding the ecological consequences of anthropogenic disturbances in natural forest islands.

Assemblage-based biomonitoring of freshwater ecosystem health via multimetric indices:A critical review and suggestions for improving their applicability

Freshwater biota are more comprehensive and direct indicators of biological impacts,and more meaningful to the public than water quality or physical habitat surrogates.Freshwater biotic data and the multiple biological indicators developed from them offer a much richer array of data for assessing the impacts of pollution controls than a limited set of physical or chemical measures.In recent decades,assemblage-based assessments by ecologists,environmental scientists,and water quality agencies have been employed globally for determining the condition of,and threats to,freshwater ecosystems.A key step in this advance has been the development of multimetric indices(MMIs)or indices of biotic integrity(IBIs)based on quantitative assessments of algae,macrophyte,macroinvertebrate,fish or riparian bird assemblages.In Europe,where biological assemblages are mandated for assessing freshwater ecosystem health,many indices are multimetric.However,the proliferation of MMIs globally has not always occurred through the application of rigorous study designs and monitoring protocols,nor have they always effectively incorporated functional metrics,stressor assessments,and statistical analyses.Therefore,in this review,we discuss eleven major concerns with the development and application(including logistical limitations)of multimetric indicators based on freshwater biota to encourage more rigorous and widely applicable(transferable)MMI use and implementation.Specifically,our concerns focus on reference conditions;sampling effort,methods,and season;trophic guild definition;metric comprehensiveness,options,screening and scoring;and MMI validation.MMIs could also benefit from increased attention to ecological mechanisms and metric development,to further improve our understanding of anthropogenic impacts as well as rehabilitation effects on freshwater ecosystems globally.Paying closer attention to study designs,ecological mechanisms and metric development should further improve our understanding of anthropogenic impacts and better facilitate rehabilitation of degraded freshwater ecosystems,as well as aiding in the conservation of healthy freshwater ecosystems globally.

What physical habitat factors determine the distribution of gastropods in neotropical headwater streams?

Freshwater gastropods play a pivotal role in the structure and functioning of freshwater ecosystems,but despite their importance,there are still gaps in their ecology.Our goal was to understand what physical habitat factors are the most important for the distribution of freshwater gastropods in headwater stream ecosystems in the Neotropical Savanna and provide a baseline for conservation and management efforts for freshwater gastropods in this biome.We identified five taxa,each with different environmental prefferences.Littoridina presence related negatively with stream slope,Biomphalaria presence related positively with total dissolved solids and the proportions of cobble,fine sediment and organic matter.Gundlachia presence correlated positively with elevation and the proportion of pools in the site.Physa presence related negatively with total dissolved solids and positively with alkalinity.Melanoides tuberculata presence correlated positively with the proportion of coarse gravel.Our results highlight the challenge for protecting native freshwater gastropod assemblages(and managing non-native invasive species),because environmental preferences vary widely amongst taxa and most are vulnerable to common anthropogenic disturbances.