By using barotropic model equations, this article analyzed the characteristics of Rossby waves, the propaga- tion features of wave energy and the influence of dynamic and thermal effects of the Tibetan Plateau on Ross...By using barotropic model equations, this article analyzed the characteristics of Rossby waves, the propaga- tion features of wave energy and the influence of dynamic and thermal effects of the Tibetan Plateau on Rossby waves, and the focus is on discussing the plateau＇s topographic gradient effects on atmospheric Rossby waves. Then based on the WRF3.2 and the NCEP/NCAR FNL reanalysis data, we devised comparative tests of changing the plateau＇s topo- graphic gradient and simulated a process of persistent heavy rain that happened in May 2010 in South China. The re- sults are shown as follows. The Tibetan Platean＇s topography is conducive to the formation of atmospheric Rossby waves, while the platean＇s terrain, its friction and heating effects can all make the atmospheric Rossby waves develop into the planetary waves; The effects of platean＇s north and south slopes on the Rossby wave＇ phase velocity is opposite, and when the slope reached a certain value can the quasi-steady normal fluctuations be generated; Simultaneously, due to the plateau＇s topographic gradient, descending motion appears at the west side of the plateau while ascending motion appears at the east side, and the vertical movement increased with the amplification of topographic gradients. The plateau＇s topographic gradient also obviously amplified the precipitation in South China, and the rainfall area increased with the amplification of topographic gradients and gradually moved from south to north and from west to east, which is conducive to the occurrence and development of convective activities in the downstream areas of the Tibetan Plateau; Moreover, for the plateau＇s dynamic and thermal effects, the Rossby wave＇ propagation shows upstream effects of ener- gy dispersion, so the plateau can then affect the weather in downstream areas. Moreover, the wave group velocity in- creased with the degree of topographic slope.展开更多
Habitat quality plays a crucial role in enhancing the regional ecological environment and safeguarding biodiversity,with topography being a key element influencing the structure and function of ecosystem services.This...Habitat quality plays a crucial role in enhancing the regional ecological environment and safeguarding biodiversity,with topography being a key element influencing the structure and function of ecosystem services.This research aims to assess habitat suitability across various topographic gradients,analyze the spatial heterogeneity of habitat quality between 2000 and 2020,and explore the relationship between influencing factors and habitat quality.InVEST model is used to evaluate the spatial-temporal evolution characteristics of habitat quality in Zhao-tong City,focusing on how topographic gradients impact habitat quality distribution.The study also delves into the factors affecting habitat quality in Zhaotong City,including land use patterns,elevation,slope,average annual temperature and other variables.The results indicate three key aspects of this system.(1)During the study period,the land use types were mainly forest land,farmland and grassland,with construction land experiencing the most significant increase.(2)From 2000 to 2020,the quality areas of high and medium habitats in Zhaotong City de-creased,while the quality areas of medium-high,medium-low and low habitats increased.(3)The study revealed a notable topographic gradient effect on habitat quality,with the primary driver shifting from GDP to land use type and subsequently to average annual precipitation in Zhaotong City.The transfer between different grades of habitat quality mainly presents the characteristics of“descending”transfer,with medium-low quality habitats typically found on medium-low topographic gradients and medium-high quality habitats on medium-high gradients.Cross-detection results show that land use type exhibited the strongest correlation with other influencing factors.Therefore,this study can provide a scientific basis for policy makers to protect biodiversity,enhance ecosystem services and promote regional economic development.展开更多
Based on geomorphologic and digital elevation model(DEM) data, the topographic characteristics of the northwestern edge of the Qinghai-Tibet Plateau are analyzed. Five representative peaks are first determined accordi...Based on geomorphologic and digital elevation model(DEM) data, the topographic characteristics of the northwestern edge of the Qinghai-Tibet Plateau are analyzed. Five representative peaks are first determined according to the topographic profile maps for the ridge and piedmont lines, and then the topographic gradient characteristics are analyzed according to the representative topographic profile acquisition method.Based on the geomorphologic database data, the regions between the ridge and the piedmont lines are divided into four geomorphologic zones; and the topographic characteristics are finally analyzed for the different geomorphologic zones regions using the DEM data. The research results show that from the piedmont to the ridge, there exist four geomorphologic zones: arid, fluvial, periglacial and glacial. The arid has the lowest elevation, topographic gradient, relief and slope characteristics. The fluvial has lower elevation and the highest topographic gradient, but with lower relief and slope characteristics. With higher elevation, the periglcial has lower topographic gradient, but the highest relief and slope characteristics. The glacial has the highest elevation with higher topographic gradient, relief and slope characteristics.展开更多
Distribution patterns of plant species are believed to be impacted by small-scale habitat heterogeneity. However, there have been few comparative studies examining how woody vegetation composition and diversity varies...Distribution patterns of plant species are believed to be impacted by small-scale habitat heterogeneity. However, there have been few comparative studies examining how woody vegetation composition and diversity varies with aspects of different orientations in the Trans-Himalayan region at a local scale. Here, we examined the effects of incoming solar radiation on variation in woody species composition and compared the diversity between the northeast- and southwest-facing slopes in a Trans-Himalayan valley of Nepal. We also examined the implicit interactions between slope orientation and land use in determining the compositional variations between the slopes. We selected two pairs of northeast- and southwest-facing slopes where the first pair has a similar land use and differs in exposure only(Pisang site) while the other pair has clear differences in land use in addition to slope exposure(Braka site). In each site, we sampled 72 plots(36 on each slope) in which the presence and absence of woody species, environmental variables, and disturbance were recorded. Correspondence Analysis(CA) results suggested that the woody species composition significantly varied between northeast- and southwest-facing slopes at both sites, and was significantly correlated with measured environmental variables such as radiation index, altitude, and canopy openness. In the Braka site,mean alpha diversity was significantly higher on southwest-facing slopes. In contrast, beta diversity and gamma diversity were greater on northeast-facing slopes at both sites. Our results suggest that topographic variables(e.g., radiation index) affect species composition between the slopes, likely due to their influence on small scale abiotic environmental variables. However, the effects of land use, such as livestock browsing/grazing may interact with the effects of slope exposure, effectively reducing differences in species composition within slopes but enhancing the differences in beta diversity between contrasting slopes in the Braka. We conclude that slope orientation and land use are important factors in structuring the woody species composition and diversity in the arid Trans-Himalayan region. We suggest that both environmental and land use variables should be taken into consideration in future studies on plant community structure along the cultural landscapes.展开更多
Background:Understanding how soil fertility changes due to topographical conditions and forest attributes is an essential premise for local-scale forest management practices.We evaluated the efects of topographic vari...Background:Understanding how soil fertility changes due to topographical conditions and forest attributes is an essential premise for local-scale forest management practices.We evaluated the efects of topographic variables and forest attributes on soil fertility along a local topographical gradient in a Brazilian Atlantic Forest.We hypothesised that soil fertility is positively afected by topographic variability and forest attributes(structure and diversity).We used tree species richness,composition,abundance,and aboveground biomass as forest attributes.We analysed two 1-ha for‑est patches with contrasting topographical conditions.We used diferent linear mixed efects models(LMMs)to test the main efects of diferent forest attributes and topography variables on soil fertility.Results:The results showed that higher topographic variability determines soil fertility along a fne-scale gradient.The frst two axes of the PCA explained 66.8%of the variation in soil data,with the frst axis(PCA_(1))explaining 49.6%of the variation in soil data and positively correlating with fertility-related soil properties.The second axis(PCA_(2))explained 17.2%of the variation in topographical data and positively correlated with convexity(the elevation of a plot minus the average elevation of all immediate neighbour plots)and elevation.Our best models showed that topo‑graphic variables(elevation and convexity)are the main predictors that afect fne-scale soil fertility.Conclusions:Our study demonstrates that the topographic variability,mainly elevation and convexity,determines fne-scale soil fertility in an Atlantic Forest.These results advance our understanding that context-dependent condi‑tions based on topography and soil properties have a high variability at a fne scale,which can infuence variations in forest attributes(i.e.,species distribution,diversity and structure of tree communities).In addition,the information generated in this research may be important for planning forest restoration activities(passive and active)based on the high variability of environmental variables at a fne scale.展开更多
The terrestrial cosmogenic nuclide dataset consisting of 1233^(10)Be measurements of fluvial sediment samples across the Asian mountain belts is used to constrain the influence of climate,tectonics and topography on E...The terrestrial cosmogenic nuclide dataset consisting of 1233^(10)Be measurements of fluvial sediment samples across the Asian mountain belts is used to constrain the influence of climate,tectonics and topography on Earth-surface denudation processes.^(10)Be-derived basin-wide denudation rates were recalculated using a Monte Carlo simulation approach that relied on pixel-by-pixel production rates.The rates derived span four orders of magnitude,from 7.4±0.7 mm kyr^(-1)(1σ;Central Tibetan Plateau)to 9,646_(-744)^(+777)mm kyr^(-1)(1σ;Southern Tibetan Plateau),with a median of 186 mm kyr^(-1).Comparing our results with the traditional basin-wide production rate scaling model using a centroid coordinate and mean elevation,suggests that 96.6%of production rates will be underestimated using the latter method,especially for basins with a large relief.The bias between both methods reaches as large as 40%,caused by basin hypsometry and the nonlinear scaling of production rate with elevation and latitude.Quantification of the correlations between uniformly recalculated denudation rates and tectonics,climate,topography and rock lithology will facilitate the extrapolation of denudation rates in unknown basins using available data.From the perspective of local scales,precipitation coupled with neotectonics-driven landslides is likely the most influential factor in subtropical Taiwan Island,while topography primarily constrains surface denudation rates in the eastern Tibetan Plateau within a narrow range of precipitation.In highland regions with glacier coverage,such as the Pamir,central and southern Tibetan Plateau high denudation rates are affected by glaciation,whereas lower precipitation and high erosion base level may limit river incision and evolving relief in the Central Tibetan Plateau.In contrast to local-scale findings highlighting a dominant factor constraining denudation rate,our large-scale quantitative analyses across the Asian mountain belts finds that(1)topographic metrics including slope,relief and normalized channel steepness index show similar,first-order,power-law relationships with denudation rates over millennial timescales,as opposed to the linear relationships suggested to control the surface denudation rate;(2)precipitation,temperature,and vegetation cover relative to elevation and a modern tectonic metric of neotectonic activity based on the kernel density distribution of earthquakes,subordinately constrain the surface denudation,approximating a first-order power-law correlation with denudation rate;and(3)the lithology,as represented by an erodibility index,appears not to correlate with denudation rates at the macro-scale of the Asian mountain belts,possibly due to the complex mixture of different types of rocks and the relative low resolution of erodibility index database.展开更多
基金National Key Basic Research and Development Project of China(2012CB417202)National Natural Science Foundation of China(91337215,41175045)Special Fund for Meteorological Research in the Public Interest(GYHY201206042)
文摘By using barotropic model equations, this article analyzed the characteristics of Rossby waves, the propaga- tion features of wave energy and the influence of dynamic and thermal effects of the Tibetan Plateau on Rossby waves, and the focus is on discussing the plateau＇s topographic gradient effects on atmospheric Rossby waves. Then based on the WRF3.2 and the NCEP/NCAR FNL reanalysis data, we devised comparative tests of changing the plateau＇s topo- graphic gradient and simulated a process of persistent heavy rain that happened in May 2010 in South China. The re- sults are shown as follows. The Tibetan Platean＇s topography is conducive to the formation of atmospheric Rossby waves, while the platean＇s terrain, its friction and heating effects can all make the atmospheric Rossby waves develop into the planetary waves; The effects of platean＇s north and south slopes on the Rossby wave＇ phase velocity is opposite, and when the slope reached a certain value can the quasi-steady normal fluctuations be generated; Simultaneously, due to the plateau＇s topographic gradient, descending motion appears at the west side of the plateau while ascending motion appears at the east side, and the vertical movement increased with the amplification of topographic gradients. The plateau＇s topographic gradient also obviously amplified the precipitation in South China, and the rainfall area increased with the amplification of topographic gradients and gradually moved from south to north and from west to east, which is conducive to the occurrence and development of convective activities in the downstream areas of the Tibetan Plateau; Moreover, for the plateau＇s dynamic and thermal effects, the Rossby wave＇ propagation shows upstream effects of ener- gy dispersion, so the plateau can then affect the weather in downstream areas. Moreover, the wave group velocity in- creased with the degree of topographic slope.
基金The Scientific Research Fund Project of Yunnan Education Department (2024J0634)The Talent Project of Yunnan University of Finance and Economics (2022D13)The Foundation of Yunnan Key Laboratory of Service Computing (YNSC24305)。
文摘Habitat quality plays a crucial role in enhancing the regional ecological environment and safeguarding biodiversity,with topography being a key element influencing the structure and function of ecosystem services.This research aims to assess habitat suitability across various topographic gradients,analyze the spatial heterogeneity of habitat quality between 2000 and 2020,and explore the relationship between influencing factors and habitat quality.InVEST model is used to evaluate the spatial-temporal evolution characteristics of habitat quality in Zhao-tong City,focusing on how topographic gradients impact habitat quality distribution.The study also delves into the factors affecting habitat quality in Zhaotong City,including land use patterns,elevation,slope,average annual temperature and other variables.The results indicate three key aspects of this system.(1)During the study period,the land use types were mainly forest land,farmland and grassland,with construction land experiencing the most significant increase.(2)From 2000 to 2020,the quality areas of high and medium habitats in Zhaotong City de-creased,while the quality areas of medium-high,medium-low and low habitats increased.(3)The study revealed a notable topographic gradient effect on habitat quality,with the primary driver shifting from GDP to land use type and subsequently to average annual precipitation in Zhaotong City.The transfer between different grades of habitat quality mainly presents the characteristics of“descending”transfer,with medium-low quality habitats typically found on medium-low topographic gradients and medium-high quality habitats on medium-high gradients.Cross-detection results show that land use type exhibited the strongest correlation with other influencing factors.Therefore,this study can provide a scientific basis for policy makers to protect biodiversity,enhance ecosystem services and promote regional economic development.
基金supported by the strategic plan project of science and technology of Institute of Geographic Sciences and Natural Resources Research (Grant No. 2012ZD009)the National Science Technology Support Plan Project (Grant No. 2012BAH28B01-03)+1 种基金the National Natural Science Foundation of China (Grant No. 41171332)the National Science Technology Basic Special Project (Grant No.2011FY110400-2)
文摘Based on geomorphologic and digital elevation model(DEM) data, the topographic characteristics of the northwestern edge of the Qinghai-Tibet Plateau are analyzed. Five representative peaks are first determined according to the topographic profile maps for the ridge and piedmont lines, and then the topographic gradient characteristics are analyzed according to the representative topographic profile acquisition method.Based on the geomorphologic database data, the regions between the ridge and the piedmont lines are divided into four geomorphologic zones; and the topographic characteristics are finally analyzed for the different geomorphologic zones regions using the DEM data. The research results show that from the piedmont to the ridge, there exist four geomorphologic zones: arid, fluvial, periglacial and glacial. The arid has the lowest elevation, topographic gradient, relief and slope characteristics. The fluvial has lower elevation and the highest topographic gradient, but with lower relief and slope characteristics. With higher elevation, the periglcial has lower topographic gradient, but the highest relief and slope characteristics. The glacial has the highest elevation with higher topographic gradient, relief and slope characteristics.
基金Annapurna Conservation Area Project (ACAP)Norwegian State Educational Loan Fund (Lnekassen)+2 种基金Faculty of Mathematics and Natural Sciences,University of Bergen for financingfunded by Norwegian Research Council(project no.148910/730)supported by The Norwegian Council for Higher Education Programme for Development Research and Education(NUFU Project ID:PRO 04/2002)
文摘Distribution patterns of plant species are believed to be impacted by small-scale habitat heterogeneity. However, there have been few comparative studies examining how woody vegetation composition and diversity varies with aspects of different orientations in the Trans-Himalayan region at a local scale. Here, we examined the effects of incoming solar radiation on variation in woody species composition and compared the diversity between the northeast- and southwest-facing slopes in a Trans-Himalayan valley of Nepal. We also examined the implicit interactions between slope orientation and land use in determining the compositional variations between the slopes. We selected two pairs of northeast- and southwest-facing slopes where the first pair has a similar land use and differs in exposure only(Pisang site) while the other pair has clear differences in land use in addition to slope exposure(Braka site). In each site, we sampled 72 plots(36 on each slope) in which the presence and absence of woody species, environmental variables, and disturbance were recorded. Correspondence Analysis(CA) results suggested that the woody species composition significantly varied between northeast- and southwest-facing slopes at both sites, and was significantly correlated with measured environmental variables such as radiation index, altitude, and canopy openness. In the Braka site,mean alpha diversity was significantly higher on southwest-facing slopes. In contrast, beta diversity and gamma diversity were greater on northeast-facing slopes at both sites. Our results suggest that topographic variables(e.g., radiation index) affect species composition between the slopes, likely due to their influence on small scale abiotic environmental variables. However, the effects of land use, such as livestock browsing/grazing may interact with the effects of slope exposure, effectively reducing differences in species composition within slopes but enhancing the differences in beta diversity between contrasting slopes in the Braka. We conclude that slope orientation and land use are important factors in structuring the woody species composition and diversity in the arid Trans-Himalayan region. We suggest that both environmental and land use variables should be taken into consideration in future studies on plant community structure along the cultural landscapes.
基金fnanced in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior–Brasil(CAPES)–Finance Code 001.
文摘Background:Understanding how soil fertility changes due to topographical conditions and forest attributes is an essential premise for local-scale forest management practices.We evaluated the efects of topographic variables and forest attributes on soil fertility along a local topographical gradient in a Brazilian Atlantic Forest.We hypothesised that soil fertility is positively afected by topographic variability and forest attributes(structure and diversity).We used tree species richness,composition,abundance,and aboveground biomass as forest attributes.We analysed two 1-ha for‑est patches with contrasting topographical conditions.We used diferent linear mixed efects models(LMMs)to test the main efects of diferent forest attributes and topography variables on soil fertility.Results:The results showed that higher topographic variability determines soil fertility along a fne-scale gradient.The frst two axes of the PCA explained 66.8%of the variation in soil data,with the frst axis(PCA_(1))explaining 49.6%of the variation in soil data and positively correlating with fertility-related soil properties.The second axis(PCA_(2))explained 17.2%of the variation in topographical data and positively correlated with convexity(the elevation of a plot minus the average elevation of all immediate neighbour plots)and elevation.Our best models showed that topo‑graphic variables(elevation and convexity)are the main predictors that afect fne-scale soil fertility.Conclusions:Our study demonstrates that the topographic variability,mainly elevation and convexity,determines fne-scale soil fertility in an Atlantic Forest.These results advance our understanding that context-dependent condi‑tions based on topography and soil properties have a high variability at a fne scale,which can infuence variations in forest attributes(i.e.,species distribution,diversity and structure of tree communities).In addition,the information generated in this research may be important for planning forest restoration activities(passive and active)based on the high variability of environmental variables at a fne scale.
基金supported by the National Natural Science Foundation of China(Grant Nos.42361144879&42303063)the National Key Research and Development Project(Grant No.2020YFA0607700)+2 种基金the Second Tibetan Plateau Scientific Expedition and Research(STEP)Program(Grant No.2019QZKK0707)the Tianjin Natural Science Foundation(Grant No.22JCQNJC00140)supported by the Science and Technology Innovation Project for Training Leading Talent of Tianjin University。
文摘The terrestrial cosmogenic nuclide dataset consisting of 1233^(10)Be measurements of fluvial sediment samples across the Asian mountain belts is used to constrain the influence of climate,tectonics and topography on Earth-surface denudation processes.^(10)Be-derived basin-wide denudation rates were recalculated using a Monte Carlo simulation approach that relied on pixel-by-pixel production rates.The rates derived span four orders of magnitude,from 7.4±0.7 mm kyr^(-1)(1σ;Central Tibetan Plateau)to 9,646_(-744)^(+777)mm kyr^(-1)(1σ;Southern Tibetan Plateau),with a median of 186 mm kyr^(-1).Comparing our results with the traditional basin-wide production rate scaling model using a centroid coordinate and mean elevation,suggests that 96.6%of production rates will be underestimated using the latter method,especially for basins with a large relief.The bias between both methods reaches as large as 40%,caused by basin hypsometry and the nonlinear scaling of production rate with elevation and latitude.Quantification of the correlations between uniformly recalculated denudation rates and tectonics,climate,topography and rock lithology will facilitate the extrapolation of denudation rates in unknown basins using available data.From the perspective of local scales,precipitation coupled with neotectonics-driven landslides is likely the most influential factor in subtropical Taiwan Island,while topography primarily constrains surface denudation rates in the eastern Tibetan Plateau within a narrow range of precipitation.In highland regions with glacier coverage,such as the Pamir,central and southern Tibetan Plateau high denudation rates are affected by glaciation,whereas lower precipitation and high erosion base level may limit river incision and evolving relief in the Central Tibetan Plateau.In contrast to local-scale findings highlighting a dominant factor constraining denudation rate,our large-scale quantitative analyses across the Asian mountain belts finds that(1)topographic metrics including slope,relief and normalized channel steepness index show similar,first-order,power-law relationships with denudation rates over millennial timescales,as opposed to the linear relationships suggested to control the surface denudation rate;(2)precipitation,temperature,and vegetation cover relative to elevation and a modern tectonic metric of neotectonic activity based on the kernel density distribution of earthquakes,subordinately constrain the surface denudation,approximating a first-order power-law correlation with denudation rate;and(3)the lithology,as represented by an erodibility index,appears not to correlate with denudation rates at the macro-scale of the Asian mountain belts,possibly due to the complex mixture of different types of rocks and the relative low resolution of erodibility index database.
