Impact of patch size on woody tree species richness and abundance in a tropical montane evergreen forest patches of south India

We examined the effects of forest patch size on woody tree species richness and abundance in tropical montane evergreen forest patches of the Nilgiri region,south India. We sampled woody trees(>1 cm dbh) from 21 forest patches in the upper Nilgiri hills(> 2000 m elevation) and recorded a total of 35,146 individuals of 61 species, 45 genera and 30 families. Species richness and abundance of sapling/shrubs(≥ 1 to < 10 cm dbh)increased significantly with increasing patch size, but the species richness and abundance of small, medium and larger trees(≥ 10 to < 30, ≥ 30 to < 60 and ≥ 60 cm dbh,respectively) did not. Overall, forest interior species richness and abundance increased significantly with increasing patch size but edge species richness did not. Species richness and abundance of shade-tolerant and shade-demanding tree species also increased with increasing patch size. The abundance of zoochory dispersed tree species was significantly related to increasing patch size, but those dispersed by autochory did not display any clear relationship between patch size and species richness or abundance.Our findings suggest that with increasing forest patch area,tree compositional patterns may be driven by species specific shade-tolerance adaptations and dispersal patterns.Differential responses in these traits by the plant community within the individual habitat zones of forest edge and interiors likely plays a major role in determining the inherent plant community and thus the subsequent ecological processes of forest patches, including their responses to increasing patch area.

Presence of Black Carbon in Soil due to Forest Fire in the New Jersey Pine Barrens

Fire is an important ecological factor and what constitutes appropriate fire management is much debated in the US and elsewhere. The role of fire as a source of greenhouse gases has been intensively investigated, but less is known about the production rate of the solid black carbon residue from fires. Black carbon accumulates in soil as it has longer turnover times than plant residues. To understand the significance of black carbon production during wildfire, we quantified black carbon using hydropyrolysis in O and A horizons before and after a prescribed bum at four sites in the New Jersey Pine Barrens forest in the North-Eastern US. Black carbon was found in both O- and A-horizons at all investigated sites, stocks in the range of 61.31-168.15 g m^-2 in the O-horizon and 169.59-425.25 g m^-2 in the A-horizon. Total black carbon stocks did not increase following the fire suggesting that either black carbon production in fires may be small compared to the variability, or that equivalent amounts of black carbon formed in previous fires may have been consumed in the fire. The study raises questions about how black carbon production and consumption in ftres can be quantified separately.

The effects of an experimental drought on the ecophysiology and fruiting phenology of a tropical rainforest palm

Aims Anthropogenic climate change is predicted to increase mean temperatures and rainfall seasonality.How tropical rainforest species will respond to this climate change remains uncertain.Here,we analysed the effects of a 4-year experimental throughfall exclusion(TFE)on an Australian endemic palm(Normambya normanbyi)in the Daintree rainforest of North Queensland,Australia.We aimed to understand the impact of a simulated reduction in rainfall on the species’physiological processes and fruiting phenology.Methods We examined the fruiting phenology and ecophysiology of this locally abundant palm to determine the ecological responses of the species to drought.Soil water availability was reduced overall by~30%under a TFE experiment,established in May 2015.We monitored monthly fruiting activity for 8 years in total(2009–2018),including 4 years prior to the onset of the TFE.In the most recent year of the study,we measured physiological parameters including photosynthetic rate,stomatal conductance and carbon stable isotopes(δ13C,an integrated measure of water use efficiency)from young and mature leaves in both the dry and wet seasons.Important Findings We determined that the monthly fruiting activity of all palms was primarily driven by photoperiod,mean solar radiation and mean temperature.However,individuals exposed to lower soil moisture in the TFE decreased significantly in fruiting activity,photosynthetic rate and stomatal conductance.We found that these measures of physiological performance were affected by the TFE,season and the interaction of the two.Recovery of fruiting activity in the TFE palms was observed in 2018,when there was an increase in shallow soil moisture compared with previous years in the treatment.Our findings suggest that palms,such as the N.normanbyi,will be sensitive to future climate change with long-term monitoring recommended to determine population-scale impacts.

Tree succession across a seasonally dry tropical forest and forest-savanna ecotone in northern Minas Gerais,Brazil

Aims Understanding succession in tropical forest is an important aspect of vegetation science,but to date,successional processes in sea-sonally dry tropical forests(SDtFs)have received much less atten-tion than evergreen humid tropical forests.We aim to fill this knowledge gap.Methods We investigated vegetation succession in SDtF areas consisting of three different successional stages(early,intermediate,late),and a SDtF-savanna ecotone in the municipal district of Juramento,north of Minas Gerais State,Brazil.Using twelve 400 m2 plots in each area,we compared vegetation parameters and structural variables(absolute density and basal area)and examined the floristic composition of the tree component to find gradients of change.Important Findings We found evidence of species turnover along a successional gradi-ent,with the intermediate stage showing the highest species rich-ness and diversity.this was accompanied with a significant increase in the number of tree individuals and basal area from the early to intermediate successional stage.However,the intermediate and late SDtF successional stages were more similar in structure and floristics.the ecotone was the most species rich and was similar to the intermediate SDtF and early successional stage in species richness and floristic composition respectively.these results will have implications for guiding SDtF management and recovery programs.

Organic carbon isotope and molecular fossil records of vegetation evolution in central Loess Plateau since 450 kyr

Significant uncertainties remain regarding the temporal evolution of natural vegetation during the Quaternary, and drivers of past vegetation change, on the Chinese Loess Plateau （CLP）. This study presents analyses of total organic carbon isotopic composition （TOC） and n-alkane ratios （C31/C27） from the Lingtai loess-palaeosol sequence on the central CLP over the last 450 kyr. The results demonstrate that the vegetation in this region comprised a mix of C3 and C4 plants of herb and woody growth-form. C3 plants dominated for most of the last 450 kyr, but this did not lead to extensive forest. C3 woody plants were more abundant in MIS9 （S3 period） and MIS5 （S 1 period） during warm and humid climate conditions. Herbs increased in the region since 130 kyr, possibly as a result of increased aridity. On the orbital timescales, there was a reduction of C3 herbal plants in MIS 11 （$4） than in M1S 12 （L5）, and in Holocene than in the last glacial period. Our isotope and n-alkane proxy records are in agreement with Artemisia pollen changes in the region, which is/was the dominant species in this area and varying due to different heat and water conditions between glacial and interglacial periods. Though the climate in MIS1 （SO） was similar to that in MIS11 （S4）, a significant increase in woody plants during the Holocene suggests the impact of human activities and ecological effects of changes in fire activity.

Exploring behavioral traits over different contexts in four species of Australian funnel-web spiders

Australian funnel-web spiders are arguably the most venomous spiders in the world,with much research focusing on this aspect of their biology.However,other aspects related to their life history,ecology and behaviour have been overlooked.For the first time,we assessed repeatability.namely risk-taking behaviour,aggressiveness and activity in the contexts of predation,conspecific tolerance and exploration of a new territory in four species of Australian funnel-web spiders:two are closely related,Hadronyche valida and H.infensa,and two have overlapping distributions but occupy different habitats,H.cerberea and Atrax robustus.We also compared behaviors between species.At the species level,we found that H.valida showed consistency in risk-taking behavior when exposed to a predator stimulus,aggressiveness against conspecifics,and exploration of a new territory.In contrast,in the other species,only A.robustus showed repeatability in the context of exploration of a new territory.These results suggest that some behavioral traits are likely more flexible than others,and that the repeatability of behaviors may be species-specific in funnel-webs.When we compared species,we found differences in risk-taking behavior and defensiveness.This study provides novel insights to understanding variation in behavioral traits within and between species of funnel-web spiders,suggesting that some behavioral traits are likely context and/or species dependent,as a result of their evolutionary history.These findings provide key insights for understanding the ecological role of behavior and venom deployment in venomous animals,and a greater understanding of behavior in these medically significant and iconic spiders thatareof conservation concern.