How do altitude and soil properties influence the taxonomic and phylogenetic structure and diversity of Brazilian páramo vegetation?

Altitude and environmental variables such as edaphic properties are considered determinants of species distribution and community composition in mountain ecosystems.Here,we aimed to outline the effects of distinct mountain peaks,altitude and soil properties on community composition,species density,phylogenetic structure and diversity of angiosperm páramo communities from the Serra do Brigadeiro State Park,Minas Gerais,southeastern Brazil.For that,we identified all angiosperm species found in 300 plots(1 m×1 m)from three mountain peaks,measured soil depth and analyzed soil fertility and texture in each plot.To reduce the number of soil variables and species composition,we computed principal coordinates based on soil properties and principal coordinates based on species-plot matrix for each plot.Furthermore,we computed the standard effect sizes of the mean phylogenetic pairwise distance and the mean nearest phylogenetic taxon distance for each plot to investigate differences in the degree of relatedness among coexisting species.We compared differences in response variables between peaks and modelled them in function of altitude and principle components of soil properties using mixed effect models.Species density and phylogenetic diversity differed between peaks,but,contrary to the previous findings,no relationships between species richness or phylogenetic diversity and altitude or soil properties were found,indicating that further investigations are necessary to understand the altitude-biodiversity relationship in Brazilian páramo vegetation.Community composition differed between peaks and depended on altitude,soil properties and interactions between them,indicating that upward shifting of bioclimatic conditions due to climate changes may alter communities of this ecosystem.Phylogenetic structure differed between peaks and was influenced by altitude and soil properties.As phylogenetic clustering increased with altitude,eventual upward movements of species in Brazilian páramo vegetation due to climate change may alter community composition and the degree of relatedness among coexisting species,increasing the risk of species from higher altitudes to disappear.Therefore,conservation priorities arise for higher landscape portions,where these high altitude species may find refuges.

Geoecological parameters indicate discrepancies between potential and actual forest area in the forest-steppe of Central Mongolia

Background:Forest distribution in the forest-steppe of Mongolia depends on relief,permafrost,and climate,and is highly sensitive to climate change and anthropogenic disturbance.Forest fires and logging decreased the forest area in the forest-steppe of Mongolia.The intention of this study was to identify the geoecological parameters that control forest distribution and living-tree biomass in this semi-arid environment.Based on these parameters,we aimed to delineate the area that forest might potentially occupy and to analyse the spatial patterns of actual and potential tree biomass.Methods:We used a combination of various geographic methods in conjunction with statistical analyses to identify the key parameters controlling forest distribution.In several field campaigns,we mapped tree biomass and ecological parameters in a study area within the Tarvagatai Nuruu National Park(central Mongolia).Forest areas,topographic parameters and vegetation indices were obtained from remote sensing data.Significant correlations between forest distribution and living-tree biomass on one hand,and topographic parameters,climate data,and environmental conditions on the other hand,were used to delineate the area of potential forest distribution and to estimate total living-tree biomass for this area.Results:Presence of forest on slopes was controlled by the factors elevation,aspect,slope,mean annual precipitation,and mean growing-season temperature.Combining these factors allowed for estimation of potential forest area but was less suitable for tree-biomass delineation.No significant differences in mean living-tree biomass existed between sites exposed to different local conditions with respect to forest fire,exploitation,and soil properties.Tree biomass was reduced at forest edges(defined as 30m wide belt),in small fragmented and in large forest stands.Tree biomass in the study area was 20×10^(9) g(1,086 km^(2) forest area),whereas the potential tree biomass would reach up to 65×10^(9) g(>3168 km^(2)).Conclusions:The obtained projection suggests that the potential forest area and tree biomass under the present climatic and geoecological conditions is three times that of the present forest area and biomass.Forest fires,which mostly affected large forest stands in the upper mountains,destroyed 43% of the forest area and 45% of the livingtree biomass in the study area over the period 1986-2017.

Soil properties and habitats determine the response of bacterial communities to agricultural wastewater irrigation

Increasing temperatures and variability of precipitation events due to climate change will lead in the future to higher irrigation demands in agroecosystems.However,the use of secondary treated wasterwater(TWW)could have consequences for the receiving soil environment and its resident microbial communities.The objective of this study was to characterize the importance of soil properties and habitats to the response of soil bacteria and archaea to irrigation with TWW.Two agricultural soils with contrasting textures(loamy sand or silt loam)and,for each,three variants differing in soil organic carbon and nitrogen,as generated by long-term fertilization,were analyzed.For each of these six soils,prokaryotic communities from two habitats,i.e.,root-free bulk soil and the rhizosphere of developing cucumber plants in the greenhouse,were characterized.Communities were analyzed by the quantity and diversity of their polymerase chain reaction(PCR)-amplified 16S rRNA genes.To account for TWW-associated nutrient effects,potable water(PW)served as a control.Amplicon sequence analysis showed that prokaryotic communities mainly consisted of bacteria(99.8%).Upon irrigation,regardless of the water quality,prokaryotic diversity declined,p H increased,and no bacterial growth was detected in bulk soil.In contrast,the growth of cucumbers was stimulated by TWW,indicating that plants were the main beneficiaries.Moreover,strong responses were seen in the rhizosphere,suggesting an indirect effect of TWW by altered rhizodepositions.The main bacterial responders to TWW were Proteobacteria,Bacteroidetes,Actinobacteria,and Planctomycetes.Changes in bacterial communities due to TWW were less pronounced in all variants of the silt loam,indicating the importance of clay and soil organic carbon for buffering effects of TWW on soil bacterial communities.Hence,soil organic carbon and soil texture are important parameters that need to be considered when applying TWW in agriculture.

Effect of Wood-drying Condensate on Emission of Volatile Organic Compounds and Bonding Properties of Fibreboard

Potential use of condensate generated by cooling the steam obtained during high-frequency/vacuum drying step of hardwood lumber was investigated.The liquid condensates were obtained from oak,beech and walnut wood.This liquid condensate was then used as a replacement for deionized water in the synthesis of Urea-Formaldehyde(UF)resin(5 wt%of total resin)using a laboratory scale reactor.Medium Density Fibreboards(MDFs)were produced using control and modified resins.Emissions of Volatile Organic Compounds(VOCs)from the MDFs were determined by Micro Chamber method.The bonding properties of the MDFs were determined according to European standards.The main VOC emissions from MDFs produced using UF resin containing the condensate were a-Pinene,b-Pinene,careen,and acetic acid,which were lower than those of the control MDF,except for the acetic acid emission of MDF with oak condensate.In the tree species,the beech wood condensate gave the lowest VOC emissions(732μg·m^-3)from the MDFs,followed by the MDFs containing walnut wood condensate(852μg·m^-3),oak wood condensate(998μg·m^-3),and control MDF(3529μg·m^-3),respectively.However,the internal bond strength of MDFs containing the condensate was negatively impacted by the condensate(0.70 N·mm^-2 to 0.54 N·mm^-2 depending on the tree species).The results showed that the liquid wood-drying condensate which generally released to the ground could be efficiently used as an alternative to expensive VOCs scavenger used in the production of UF resin bonded MDF.This may be one of the most efficient uses of the condensate in high value-added materials.