Ice storm damage to oak forests in subtropical China

Ice storms,as important sources of frequent and injurious disturbances,drive forest dynamics in the Northern Hemisphere.However,stand-level differential vulnerability to ice storms and the associated factors that predispose forest stands remain unclear.This is particularly concerning in the subtropics where the frequency of ice storms is predicted to increase with global warming.Here we assessed how the impact on three forest stands(early and late secondary-growth forests,and old-growth forests)differed after an extreme ice storm during 20–21 March 2022,and identified the abiotic and biotic factors that determine the damage intensity in the Shennongjia World Natural Heritage Site,a biodiversity conservation hotspot in central China.We found a stand-specific‘middomain effect’where the late secondary-growth forest sustained the most severe damage,the early secondarygrowth forest sustained the least,and the old-growth forest suffered an intermediate amount.‘Crown broken’was the most severe damage type across all three forest stands,although the proportion of‘branch broken’was also high in the old-growth forest.Topography played a significant role in determining the vulnerability of the early secondary-growth forest to severe ice storms whereas the forest structure and composition were important factors in explaining the damage rates in the old-growth forest,although they differed among the damage categories.In contrast,topography,forest structure and composition generally explain the intensity of damage in the late secondary-growth forests.Our results highlight that,in subtropical forests,the intensity of damage caused by severe ice storms and related determining factors are stand-level dependent.We also suggest exploring potential management strategies(e.g.,slow-growing hardwood species that can resist storms should be the main species for reforestation in early secondary-growth forests)to mitigate the risk of future severe ice storms,as well as other wind-related climatic extremes.

Ecotourist trail-use affects the taxonomic, functional and phylogenetic diversity of mammals in a protected area: lessons for conservation management

Ecotourism,by definition,aims to engage peoples’interest in wildlife and the environment.The use of tourist roads and trails to access sites within protected areas(PAs)can detrimentally affect the behavior and distribution of species.The way mammals respond to anthropogenic pressures may differ across taxonomic,functional,and phy-logenetic groups;nevertheless,how ecotourist trail-use affects these different diversity remains under-investigated.Here,we assessed 6 metrics of taxonomic,phylogenetic,and functional diversity for a mammal community in a PA in central China,recording how Trail use(using Trail type as a proxy)and habitat variables affected sightings and signs of mammals across 60 replicate 0.5 km transects.We then examined how Trail use affected the taxonomic,functional,and phylogenetic diversity indices of species(>1 kg).Using generalized liner mixed modeling,we identified that more used trail types had a greater adverse effect on all diversity richness indices than did less used trail types.Consequently,tourist pressure was associated with a general tendency to homogenize the site’s mammal community.In contrast,the effects of Trail Types on all diversity evenness indices were non-significant.Further-more,more developed and more heavily used trail types had a greater,significant negative effect on taxonomic,functional,and phylogenetic richness,whereas these richness indices were unaffected by minor trail types,used less intensively.As a general principle,lower biodiversity indices reduce ecosystem resilience,and so it is vital to better understand these responses to balance public access against biodiversity management in PAs.

Conflicting selection pressures on seed size and germination caused by carnivorous seed dispersers

Plants produce nutritious,fleshy fruits that attract various animals to facilitate seed dispersal and recruitment dynamic.Species-specific differential selection of seed size by multiple frugivorous disperser assemblages may affect the subsequent germination of the ingested seeds.However,there is little empirical evidence supporting this association.In the present study,we documented conflicting selection pressures exerted on seed size and germination by five frugivorous carnivores on a mammal-dispersed pioneer tree,the date-plum persimmon(Diospyros lotus),in a subtropical forest.Fecal analyses revealed that these carnivores acted as primary seed dispersers of D.lotus.We also observed that seed sizes were selected based on body mass and were species-specific,confirming the“gape limitation”hypothesis;three small carnivores(the masked palm civet Paguma larvata,yellow-throated marten Martes flavigula,and Chinese ferret-badger Melogale moschata)significantly preferred to disperse smaller seeds in comparison with control seeds obtained directly from wild plants whereas the largest Asiatic black bears(Ursus thibetanus)ingested larger seeds.Seeds dispersed by medium-sized hog badgers(Arctonyx albogularis)were not significantly different from control seeds.However,regarding the influence of gut passage on seed germination,three arboreal dispersal agents(martens,civets,and bears)enhanced germination success whereas terrestrial species(ferret-badgers and hog badgers)inhibited the germination process compared with undigested control seeds.These conflicting selection pressures on seed size and germination may enhance the heterogeneity of germination dynamics and thus increase species fitness through diversification of the regeneration niche.Our results advance our understanding of seed dispersal mechanisms and have important implications for forest recruitment and ecosystem dynamics.