Global change threatens mountainous plant communities,causing habitat displacement.Phylogenetic studies reveal evolutionary and ecological processes in community assembly.We examined taxonomic and phylogenetic diversi...Global change threatens mountainous plant communities,causing habitat displacement.Phylogenetic studies reveal evolutionary and ecological processes in community assembly.We examined taxonomic and phylogenetic diversity in Andean Páramos across altitudes.Our hypotheses were that increasing altitude is an environmental filter,as altitude is expected to be a stronger variable than soil depth.The Páramos,alpine vegetation in the Andes,range from 3,000 to 4,700 meters,with our plots spanning 3,200 to 4,100 meters.Sampling was conducted at six altitudinal levels,measuring soil depth,taxonomic,and phylogenetic diversity.Data analysis employed multiple linear regressions and mixed-effects models to assess the effects of soil depth and altitude.We sampled 110 angiosperm species from 70 genera,30 families,and 18 orders.Asterales and Poales were prominent.Species richness generally decreased with altitude but increased at the summit.Soil depth affected species richness and taxonomic diversity,while altitude did not.Phylogenetic diversity increased with soil depth and decreased with altitude.Phylogenetic turnover increased with altitude differences.The hypothesis that increasing altitude intensifies environmental filtering in the altitudeadapted Páramos resulting in lower species richness and more clustered phylogenetic structures,was rejected.Although species richness,Shannon diversity,and Simpson diversity decreased initially with increasing altitude,this trend was not linear because the summit presented intermediate species richness.The hypothesis that altitude is a stronger explanatory variable than soil depth was also rejected.Despite expectations,taxonomic results did not support altitude as an environmental filter,but soil depth.Greater altitude differences increased beta phylogenetic dissimilarity,supporting niche conservatism.展开更多
Minquartia guianensis Aubl.is a slow-growing species with several uses.In the juvenile state,it is well-adapted to low light conditions of the forest understory.However,it is still unknown how climate variability affe...Minquartia guianensis Aubl.is a slow-growing species with several uses.In the juvenile state,it is well-adapted to low light conditions of the forest understory.However,it is still unknown how climate variability affects transpiration of this species,particularly under drought stress.In this study,we aimed to assess the effect of climatic variability on sap flow rates(SFR).SFR and radial growth were measured in six trees(14-50 cm diameter)in 2015 and 2016.Climate(precipitation,irradiance,relative humidity and temperature)and soil water content(SWC)data were also collected.SFR tended to increase in the dry season,with a negative relationship between SFR and SWC and precipitation(p<0.001),while there was a positive association between radial growth and monthly precipitation(p=0.004).Irradiance and temperature were the environmental factors more closely correlated with SFR during daytime(p<0.001),whereas relative humidity and vapor pressure deficit were the most important factors at night(p<0.001).Although negative SFR were sometimes recorded at night,the mean nocturnal sap flow was positive and across trees the nighttime sap flow accounted for 12.5%of the total daily sap flow.Increased transpiration during the dry season suggests that the root system of Minquartia was able to extract water from deep soil layers.These results widen our understanding of the ecophysiology of Amazonian trees under drought and provide further insight into the potential effect of the forecasted decline in precipitation in the Amazon region.展开更多
基金the Botany Graduate Program of Universidade Federal de Vicosa - PPGBot-UFV for the infrastructure and scholarshipsprovided by FAPEMIG (FORTIS/PPGBot-UFV, PPM00584-16, APQ-01309-16)+1 种基金CAPES (PROAP and Pr Int/PPGBot-UFV)CNPq (307591/2016-6, 306335/2020-4)
文摘Global change threatens mountainous plant communities,causing habitat displacement.Phylogenetic studies reveal evolutionary and ecological processes in community assembly.We examined taxonomic and phylogenetic diversity in Andean Páramos across altitudes.Our hypotheses were that increasing altitude is an environmental filter,as altitude is expected to be a stronger variable than soil depth.The Páramos,alpine vegetation in the Andes,range from 3,000 to 4,700 meters,with our plots spanning 3,200 to 4,100 meters.Sampling was conducted at six altitudinal levels,measuring soil depth,taxonomic,and phylogenetic diversity.Data analysis employed multiple linear regressions and mixed-effects models to assess the effects of soil depth and altitude.We sampled 110 angiosperm species from 70 genera,30 families,and 18 orders.Asterales and Poales were prominent.Species richness generally decreased with altitude but increased at the summit.Soil depth affected species richness and taxonomic diversity,while altitude did not.Phylogenetic diversity increased with soil depth and decreased with altitude.Phylogenetic turnover increased with altitude differences.The hypothesis that increasing altitude intensifies environmental filtering in the altitudeadapted Páramos resulting in lower species richness and more clustered phylogenetic structures,was rejected.Although species richness,Shannon diversity,and Simpson diversity decreased initially with increasing altitude,this trend was not linear because the summit presented intermediate species richness.The hypothesis that altitude is a stronger explanatory variable than soil depth was also rejected.Despite expectations,taxonomic results did not support altitude as an environmental filter,but soil depth.Greater altitude differences increased beta phylogenetic dissimilarity,supporting niche conservatism.
基金supported by research project(MCTI/INPA:PRJ-15.120)。
文摘Minquartia guianensis Aubl.is a slow-growing species with several uses.In the juvenile state,it is well-adapted to low light conditions of the forest understory.However,it is still unknown how climate variability affects transpiration of this species,particularly under drought stress.In this study,we aimed to assess the effect of climatic variability on sap flow rates(SFR).SFR and radial growth were measured in six trees(14-50 cm diameter)in 2015 and 2016.Climate(precipitation,irradiance,relative humidity and temperature)and soil water content(SWC)data were also collected.SFR tended to increase in the dry season,with a negative relationship between SFR and SWC and precipitation(p<0.001),while there was a positive association between radial growth and monthly precipitation(p=0.004).Irradiance and temperature were the environmental factors more closely correlated with SFR during daytime(p<0.001),whereas relative humidity and vapor pressure deficit were the most important factors at night(p<0.001).Although negative SFR were sometimes recorded at night,the mean nocturnal sap flow was positive and across trees the nighttime sap flow accounted for 12.5%of the total daily sap flow.Increased transpiration during the dry season suggests that the root system of Minquartia was able to extract water from deep soil layers.These results widen our understanding of the ecophysiology of Amazonian trees under drought and provide further insight into the potential effect of the forecasted decline in precipitation in the Amazon region.
