Functional composition of tall-statured trees underpins aboveground biomass in tropical forests

The influences of trait diversity(i.e.,the niche complementarity effect)and functional composition(i.e.,the mass ratio effect)on aboveground biomass(AGB)is a highly debated topic in forest ecology.Therefore,further studies are needed to explore these mechanisms in unstudied forest ecosystems to enhance our understanding,and to provide guidelines for specific forest management.Here,we hypothesized that functional composition would drive AGB better than trait diversity and stem size inequality in the(sub-)tropical forests of Nepal.Using data from 101 forest plots,we tested 25 structural equation models(SEMs)to link elevation,stem DBH inequality,trait diversity(i.e.,trait richness,evenness,dispersion and divergence),functional composition[i.e.,community-weighted of maximum height mean(CWM of Hmax),specific leaf area(CWM of SLA),leaf dry matter content(CWM of LDMC),and wood density(CWM of WD)]and AGB.The best-fitted SEMs indicated that CWM of Hmax promoted AGB while overruling the impacts of trait diversity indices on AGB.However,low trait diversity indices were linked with higher AGB while overruling the effects of CWM of SLA,LDMC and WD on AGB.In addition,AGB decreased with increasing elevation,whereas stem size inequality did not influence AGB.Our results suggest that divergent species’functional strategies could shape AGB along an altitudinal gradient in tropical forests.We argue that forest management practices should include plant functional traits in the management plan for the co-benefits of biodiversity conservation and carbon sequestration that underpins human wellbeing.

Distribution Pattern of Vascular Plant Species of Mountains in Nepal and their Fate Against Global Warming

This study aims to find the altitudinal distribution pattern of vascular plant species reported from high mountain of Nepal(Manang) along the whole Himalayan elevation gradient, and evaluate their fate against climate change. Data was gathered from multiple sources, field investigations, literatures, and herbarium specimens. Altogether, 303 vascular plant species were reported from Manang. We used a published data to calculate distribution range of each species by interpolating between its upper and lower elevation limits. The relationship between elevation and species richness is elucidated by generalized linear model. The consequence of global warming upon Manang's vascular plant species was estimated based on projected temperature change for next century and adiabatic lapse rate along the elevation gradient of the Himalayas. The vascular plant species richness has a unimodel relationship with elevation along the whole elevation gradient of Nepal as well as in three biogeographical regions of Nepal. Vascular plants of Manang are found distributed from low land Terai to high alpine regions of Nepal and their elevation distribution range varies from 200 to 4700 m. Out of 303 vascular plants of Manang, only seven species might be affected if temperature increase by 1.5°C, whereas at least 70 species will be affected with 5°C temperature increased. However, the majority of species(233 species) have wider distribution range(> 1000 m) and more than 5°C temperature tolerance range, thus they are likely to be less affected from global warming by the end of 21 st century.

Niche breadth and overlap of spotted deer and domestic cattle with swamp deer in tropical region of Nepal

Background:Knowledge about the niche overlap among wild species and domestic cattle is helpful to conserve and manage wildlife.We assessed the habitat niche breadth and overlap of sympatrically living spotted deer(Axis axis)and domestic cattle with swamp deer(Cervus duvaucelii)in Shuklaphanta National Park,Nepal during the dry season to explore the possibility of interspecific competition by studying the habitat use by these species.The assumption was made that the presence of pellets is proof of habitat used by species.Methods:Grids of 2 km×2 km have four subgrids,each with four sample plots,making a total of 16 plots(20 m×20 m)in each grid.The size of each sub-grid was 200 m×200 m and they were placed randomly inside the grid but at least 1 km apart from one another.The data was collected in a 96 plots in total.Levin’s niche breadth and Morisita’s overlap index were calculated to determine the niche breadth and the habitat overlap,respectively.Results:The Levin’s measure of niche breadth suggested that spotted deer had the highest acclimatization with an index value of 0.94,followed by domestic cattle at 0.50,and swamp deer at 0.33 in our study area.Thus,our findings supported the evidence that spotted deer are habitat generalists,whereas swamp deer are habitat specialists.The swamp deer had lower niche breadth and more overlap with domestic cattle.Conclusion:Our study showed the least niche breadth of swamp deer in comparison to spotted deer and domestic cattle.The domestic cattle had the highest and least niche overlap with spotted deer and swamp deer,respectively,in terms of habitat use.Our study suggests that domestic cattle grazing should be stopped,and grassland management should be carried out for the benefit of ungulates.Similar studies should be conducted,including different seasons and places,prior to appropriate habitat management.In addition,further studies are needed to quantify the extent of interspecific competition by incorporating more species.