Tree species diversity in relation to environmental variables and disturbance gradients in a northeastern forest in Bangladesh

Biodiversity has become an issue of global attention because of growing awareness of its importance and its rapid depletion worldwide.Diversity of tree species in relation to environmental and disturbance gradients was examined in three managed forests.Trees were randomly sampled in a survey of 75 circular plots(radius=13 m)with 5 subplots(radius=1 m).Generalized linear model analysis was used with a Poisson distribution log link function to understand the effects of variables(organic matter,organic carbon,nitrogen,potassium,pH,elevation and disturbance)on tree species richness.Canonical correspondence analysis was used to explore ecological relationships among plots.Our result found that the stand characteristics was an important influencing factor in the three forests.Our result showed that the variables had a highly positive influence on tree species richness in the three forests.In ordination,the selected variables governed the richness of tree species.Our study can help identify the most important factors that drive tree species richness in the three managed forests in Bangladesh and in similar ecosystems and inform forest management decisions for conservation according to ecological importance.

No treeline shift despite climate change over the last 70 years

Background:The recent rise in temperature and shifting precipitation regimes threaten ecosystems around the globe to different degrees.Treelines are expected to respond to climate warming by shifting to higher elevations,but it is unclear whether they can track temperature changes.Here,we integrated high-resolution aerial imagery with local climatic and topographic characteristics to study the treeline dynamic from 1945 to 2015 on the semiarid Mediterranean island of Crete,Greece.Results:During the study period,the mean annual temperature at the treeline increased by 0.81℃,while the average precipitation decreased by 170 mm.The treeline is characterized by a diffuse form,with trees growing on steep limestone slopes(>50°)and shallow soils.Moreover,the treeline elevation decreases with increasing distance from the coast and with aspect(south>north).Yet,we found no shift in the treeline over the past 70 years,despite an increase in temperature in all four study sites.However,the treeline elevation correlated strongly with topographic exposure to wind(R^(2)=0.74,p<0.001).Therefore,the temporal lag in treeline response to warming could be explained by a combination of topographic and microclimatic factors,such as the absence of a shelter effect and a decrease in moisture.Conclusion:Although there was no treeline shift over the last 70 years,climate change has already started shifting the treeline altitudinal optimum.Consequently,the lack of climate-mediated migration at the treeline should raise concerns about the threats posed by warming,such as drought damages,and wildfire,especially in the Mediterranean region.Therefore,conservation management should discuss options and needs to support adaptive management.

Tree sapling vitality and recovery following the unprecedented 2018 drought in central Europe

Background:Ongoing climate change is anticipated to increase the frequency and intensity of drought events,thereby affecting forest recovery dynamics and elevating tree mortality.The drought of 2018,with its exceptional intensity and duration,had a significant adverse impact on tree species throughout Central Europe.However,our understanding of the resistance to and recovery of young trees from drought stress remains limited.Here,we examined the recovery patterns of native deciduous tree sapling species following the 2018 drought,and explored the impact of soil depth,understory vegetation,and litter cover on this recovery.Methods:A total of 1,149 saplings of seven deciduous tree species were monitored in the understory of old-growth forests in Northern Bavaria,Central Germany.The vitality of the saplings was recorded from 2018 to 2021 on 170 plots.Results:Fagus sylvatica was the most drought-resistant species,followed by Betula pendula,Acer pseudoplatanus,Quercus spp.,Corylus avellana,Carpinus betulus,and Sorbus aucuparia.Although the drought conditions persisted one year later,all species recovered significantly from the 2018 drought,albeit with a slight decrease in vitality by 2021.In 2018,the drought exhibited a more pronounced adverse effect on saplings in deciduous forests compared to mixed and coniferous forests.Conversely,sapling recovery in coniferous and mixed forests exceeded that observed in deciduous forests in 2019.The pivotal factors influencing sapling resilience to drought were forest types,soil depth,and understory vegetation,whereas litter and forest canopy cover had a negative impact.Conclusion:Long-term responses of tree species to drought can be best discerned through continuous health monitoring.These findings demonstrate the natural regeneration potential of deciduous species in the context of climate change.Selective tree species planting,soil management practices,and promoting understory diversity should be considered when implementing adaptive management strategies to enhance forest resilience to drought events.

A Seventeen-Year Quantitative Study of Succession in Central European Grassland

The objective of this paper is to test three main hypotheses in grassland succession by using 17-year observational data： （i） species diversity increases during early pioneering stages; （ii） the similarity rate of experimental plant communities increases along with the succession process （dissimilarity rate among plots decrease with succession age）;and （i i） plant communities in different ifeld plots converge towards a quite similar composition during the initial years of succession. Results draw from quantitative statistics which including： the general development of plant communities, Shannon’s H and E, Bray-Curtis dissimilarity and community turnover, indicate that after first 5 years of succession, species diversity rapidly becomes alike among all the plots. The average species number in al plots increased constantly from 8 to 25. Meanwhile, the total species number for al plots increased constantly from 23 to 55, accompanied by a steady decrease in Standard Deviation （S.D.） from 4.6 to 0.3. Additional y, dissimilarity of al stands in species composition decreased, indicating a clear trend towards a rapid convergence in species richness and composition. The most important effect of cessation of weeding is that the artiifcial diversity gradient from 1 to 16 species gets diminished by immigration in species poor plots.

Enhanced aboveground biomass by increased precipitation in a central European grassland

Background:Global climate change is projected to increase temperature and alter precipitation pattern,which could affect grassland ecosystem.Long-term observation at a field experiment can be a powerful approach to explore the impacts of climate change on biomass productivity in grassland.In attempting to understand how climatic variability regulates biomass productivity,we analyzed long-term records of temperature and precipitation to examine how variation of temperature and precipitation across 19 years affect biomass productivity.Methods:We established the experiment with 64 plots in two blocks and planted 31 species in 30 different mixtures.We harvested aboveground biomass twice a year,sorted biomass by functional groups,and weighed dry biomass.The site was mown after each harvest.We did not apply any fertilizer and water.Using linear regression model,we examined the influences of growing season temperature and precipitation on biomass productivity.Results:The results showed that aboveground biomass productivity in September and annual were significantly increased in post-drought(2003–2015).The relationships of aboveground biomass productivity with growing season precipitation were significantly positive.The results showed that aboveground biomass productivity in June and annual were sensitive to growing season temperature.The relationships of aboveground biomass productivity of the functional group of grasses with early growing season temperature were significantly negative.Early growing season precipitation had a significant positive effect on aboveground biomass productivity of the functional groups of grasses and legumes.Post-drought aboveground biomass productivity of the functional groups of grasses in June and September were declined,whereas legumes significantly increased,which suggests that the role of dominant grasses may shift by legumes with global climate change.Conclusions:Our results highlight that early and late growing temperature and precipitation variability may reduce the aboveground biomass productivity in grassland.Our study implies that the combination of several functional groups is essential for the maintenance of stable productivity in temperate grassland ecosystem.

Predicting the effectiveness of protected areas of Natura 2000 under climate change

Background:Protected areas(PAs)are aimed to hold the environmental conditions that facilitate species and ecosystems to persist.PAs can become climatically unsuitable and unable to sustain their current number of species under climate change.The Natura 2000(N2K)is the largest coordinated conservation tool assigned to maintain the long-term survival of Europe’s most significant species and habitats.In attempting to understand the effectiveness of PAs in the face of climate change scenarios,we tested two hypotheses:(1)PAs in the Alpine and the Boreal biogeographical regions will experience more newly emerged climate conditions(hotter and drier)compared to the climate representation of other biogeographical regions under future climate in Europe and(2)PAs in the Mediterranean and the Continental biogeographical regions will face more consistency in climate conditions due to less area of disappearing and novel climate in future.Methods:Current climate data(1960–1990)and projections for 2050 and 2070 of PAs of N2K were extracted from WorldClim global climate data.Principal components analysis(PCA)was performed to construct climate space for the PAs across the biogeographical regions based on 19 climatic variables assessed at 5-km resolution.ArcMap 10.1 was used to map the location of the novel and disappearing climates.Results:PAs in the Alpine region will experience more novel climate conditions in the future compared to other biogeographical regions.The future projections showed that 17.70%of the PAs in the Alpine region will experience novel climate by 2070.Considerable climate consistency was observed in the PAs in the Continental region compared to the other biogeographical regions.Our results showed that about 176 km2 of the selected PAs in the Continental region will face new emerging climate,while about 110 km2 will disappear under RCP 8.5 scenario.The prediction also revealed that in the Mediterranean region 08 PAs will experience novel climate and 786 km2 areas in these PAs will face disappearing climate by 2070.We found that fewer areas of PAs in the Boreal regions will experience disappearing climate in both the scenarios.Conclusions:The portion of novel climate conditions can be seen as a future opportunity to assign new reserves for the species.Our study highlights the importance of conservation planning to increase the connectivity between PAs,identifying novel conservation zones to maximize representation of habitats during the emerging climatic changes as well as designing strategies,management,and monitoring of the individual PAs.

Correction to: Predicting the effectiveness of protected areas of Natura 2000 under climate change

Correction to:Ecol Process https://doi.org/10.1186/s13717-019-0168-6 In the original publication of this article(Nila and Hossain 2019),co-authors‘Carl Beierkuhnlein,Anja Jaeschke and Samuel Hoffmann’need to be added to the author list.Additionally,two parts of the Declarations section below need to be updated。