Agricultural village is an important rural type in China. The evolution process and mechanism of its cultural landscape are different from those of the industrialized village. The paper focuses this theme by a case st...Agricultural village is an important rural type in China. The evolution process and mechanism of its cultural landscape are different from those of the industrialized village. The paper focuses this theme by a case study of Qianzhai Village of Qufu City, Shangdong Province. In the case of Qianzhai Village, the evolution of its settlement has experienced three stages: mechanical expansion, sprawling expansion and hollowing, and recentralization. The land- scape evolution of residents' houses has undergone three phases: traditional quadrangle house, one-storied house and multistoried house. The evolution of its land use has experienced three stages: circled stratification, fragment and intensive use, and concentration and extensive use. We can see that the main driving factors of cultural landscape evolu- tion of agricultural village are the changes of rural population, society, economy and culture, which are influenced by the change of urban-rural relation, the national modernization process and economic development, the reform of family planning and land system, and the changes in governmental policies. In the future, the modernization, ecological trend, and individualization for residents' houses of agricultural villages in China will develop step by step. The recentralization of settlement and the scaled, sustainable, intensive land use are likely to be the trends of agricultural villages in China.展开更多
The combination of different topographic and climatic conditions results in varied precipitation-runoff relations,which in turn influences hillslope erosion,sediment transport and bedrock incision across mountainous l...The combination of different topographic and climatic conditions results in varied precipitation-runoff relations,which in turn influences hillslope erosion,sediment transport and bedrock incision across mountainous landscapes.The runoff coefficient is a suitable tool to represent precipitation-runoff relations,but the spatial distribution of the runoff coefficient across tectonically active mountains in semi-arid environments has received little attention because of limited data availability.We calculated annual runoff coefficients over 22 years for 26 drainage basins across the semi-arid Qilian Mountains based on:(i)annual discharge records;and(ii)the China Meteorological Forcing Dataset to enhance our understanding of the precipitation-runoff processes.The mean annual runoff coefficients show no obvious spatial trends.When compared to potential controlling factors,mean annual runoff coefficients are highly correlated with mean slope rather than any climatic characteristics(e.g.,mean annualprecipitation and Normalized Difference Vegetation Index).The slope-dependent runoff coefficient could theoretically have enhanced the topographic control on erosion rates and dampen the influence of precipitation.The enhanced discharge for drainage basins with less precipitation but steep topography in the western Qilian Mountains will enable fluvial incision to keep pace with ongoing uplift caused by the northward growth of the Qilian Mountains.The geomorphic implications are that tectonic rather than climatic factors are more significant for long-term landscape evolution in arid and semi-arid contexts.展开更多
In-situ cosmogenic nuclide s are receiving growing attention in surface Earth system science in which the steady-state denudation is an important assumption for estimating the surface denudation of long-lived(103-106 ...In-situ cosmogenic nuclide s are receiving growing attention in surface Earth system science in which the steady-state denudation is an important assumption for estimating the surface denudation of long-lived(103-106 years)surfaces.However,distinguishing steady-state denudation and deciphering a reliable denudation rate from non-steady state denudation region are difficult.Recent depth profile models for investigating the denudation rate,exposure age and inheritance are widely used for sediment and regolith of steady-state denudation region.Here we present in-situ co smogenic nuclides^(10)Be and^(26)Al from two typical granite regolithes from Jixian in Tianjin and Tengchong in Yunnan to model non-steady landscape evolution process by using steady state(Model 1)and non-steady state(Model 2,continuous exposure;Model 3 a,changed denudation rate;Model 3 b,abrupt denudation event)models.The results of steady state model show that both regolithes are in non-steady state.^(10)Be non-steady state models of Jixian regolith reveal that the surface has likely experienced a denudation rate change or an abrupt denudation event during the past several millennia,resulting in a non-steady state.The similar Model 3 a and 3 b denudation rates of 14.6-12.9^(+9.4)and 14.7-14.7^(+9.0)mmkyr^(-1),respectively,might demonstrate the long-term denudation rate rather than the exaggerated rate s of 39.0-2.3^(+2.6)and 39.0-2.4+^(2.5)mm kyr^(-1)calculated by assuming steady-state denudation and ignoring inheritance.The non-steady state model results of Tengchong regolith suggest that the surface has likely experienced a strong denudation about 157 ka(^(10)Be)or 127 ka(^(26)Al)ago.This timing is basically consistent with the termination of the MIS 6(TII:130 ka)and the climate change events in the Tibetan Plateau,suggesting a strong surface landscape denudation during the transition from glacial to interglacial.The compiling of basin-wide denudation rates in the Tibetan Plateau shows a good positive correlation with the regional tectonic activity,indicating that the denudation rate derived from non-steady state region with strong tectonic activity is likely to be overestimated by assuming steady state.We suggest that a combination of steady state and non-steady state depth profile models should be used to quantify denudation rate and exposure age more accurately and effectively in strong tectonic activity or climate change regions.展开更多
The Jianglangshan Geopark in the western Zhejiang Province of Southeast China is well-known for its spectacular red-colored sandstone landforms. Little is known about the depositional processes of the conglomerate-dom...The Jianglangshan Geopark in the western Zhejiang Province of Southeast China is well-known for its spectacular red-colored sandstone landforms. Little is known about the depositional processes of the conglomerate-dominated Fangyan Formation, the lithologic base of the Danxia landforms in this geopark. Based on detailed field investigation of lithology, sedimentary structures, bed thickness and geometry, five facies are recognized: facies A(matrixsupported cobble conglomerate), facies B(pebble conglomerate), facies C(pebbly sandstone), facies D(fine-grained sandstone) and facies E(mudstone). The results show that streamflow-dominated fans were the main depositional processes responsible for the accumulation of the Fangyan Formation along the mountain fronts. These fan conglomerates form the base for the evolution of the Danxia landscapes owing to the uplift and erosion of the study area. In contrast, the fine-grained sedimentary successions produced by fluvial floodplains in the distal part of the fans were thinner and more easily weathered. Such sedimentary facies distribution patterns were thought to be similar during Late Cretaceous across Southeast China. The Danxia landforms are largely the geographical expressions of the conglomerate-dominated redbeds in the proximal-middle fans.展开更多
High-magnitude glacial debris flows in small basins in Himalayas have a significant impact on landscape.The Peilong catchment,a tributary of the Parlung Zangbo river in southeastern Tibet,was chosen as a case study of...High-magnitude glacial debris flows in small basins in Himalayas have a significant impact on landscape.The Peilong catchment,a tributary of the Parlung Zangbo river in southeastern Tibet,was chosen as a case study of topographic response to multi-period glacial debris flows.There are few large debris flow records in the catchment before 1983,but four large-scale glacial debris flows with peak discharge up to 8195 m3/s blocked the river during 1983–1985 and in 2015.A combination of field survey,examination of historical records and interpretation of multi-period remote sensing images was used to assess triggering factors and geomorphic impact of the events.The results show that the debris flows during 1983 and 1985 may be attributed to seismic events in 1981 and 1982,while the event in 2015 resulted from large amount of landslide deposits caused by glacier retreat during 1993~2013 and high precipitation in 2015.In the upper-midstream broad valley,erosion and accumulation of the debris flows changed the channel morphology,resulting in course diversion.In the lower-midstream narrow valley,lateral erosion of debris flows induced a large number of landslides but had little impact on the channel longitudinal profile.The ability of massive glacial debris flows to change valley topography is more than ten times that of regular water flows.The landscape of the accumulation fan at the outlet of the valley is controlled by the interaction between the sediment transportation capacity of debris flows and erosional capacity of the main river.The sediment transport capacity of the Peilong river is greater than the delivery capacity of the Parlung Zangbo river,resulting in continuous aggradation of the confluence zone.展开更多
Cosmogenic Ne isotopes are stable and are routinely used for constraining the timing of events and the rate of surface change beyond the limit that can be studied with radionuclides ^10Be, ^26Al, and ^36Cl. Cosmogenic...Cosmogenic Ne isotopes are stable and are routinely used for constraining the timing of events and the rate of surface change beyond the limit that can be studied with radionuclides ^10Be, ^26Al, and ^36Cl. Cosmogenic Ne analysis can be used in quartz and in a range of other minerals. Analysis typically requires significantly less material than do cosmogenic ^10Be and ^26Al, opening up the technique for small samples--individual pebbles in fiver sediments, for example. Analysis is easier and faster than for radionuclides, not least because Ne measurements do not require significant chemical procedures. However, the presence of other sources of Ne in minerals tends to restrict the use of cosmogenic ^21Ne to old landscapes and long exposure durations. In this review we briefly outline the background of cosmogenic Ne production in rocks and minerals at the Earth＇s surface, then document the key uses of the technique by highlighting some earlier studies, and finish with a short perspective on the future of the technique.展开更多
The landscape pattern of Da’an County, Northeast China has undergone significant changes since the 1950s as a result of climatic change and human activities. The aim of this paper is to quantitatively study landscape...The landscape pattern of Da’an County, Northeast China has undergone significant changes since the 1950s as a result of climatic change and human activities. The aim of this paper is to quantitatively study landscape pattern and its spatial dynamics of Da’an County at the landscape level over the nearly 50-year span. Patch dynamics were examined ac-cording to land use and land cover change processes built from a series of images, as well as topographic maps, and tem-poral patterns built from landscape pattern metrics. The transition matrix of landscape patch types and changes of various landscape metrics were applied. The results showed that, from 1956 to 2000, the landscape within the study area had un-dertaken a complicated evolution in landscape structure and composition. The outstanding characteristic is that sa-line-alkali land increased and grassland decreased. As some smaller patches amalgamated, the heterogeneity of patch de-creased. All those changes were the synthetic result of both climatic and anthropogenic influences, but the predominant factor was different in different parts. In the southern part of the study area, the landscape pattern changes resulted from the modification of climate obviously, while in the northern part, the landscape pattern changes were mainly caused by human activities, such as the conversion between farmland and saline-alkali land. This phenomenon showed that human activities played more important role in the north than in the south of Da’an County.展开更多
The regional distribution of landslide dams can provide valuable insights into the interactions among various factors,including lithology,topography,climate,and fluvial landforms in tectonically active mountains.Himal...The regional distribution of landslide dams can provide valuable insights into the interactions among various factors,including lithology,topography,climate,and fluvial landforms in tectonically active mountains.Himalayan rivers are frequently impacted by large-scale landslide damming,which profoundly influence fluvial geomorphology.In this study,we identified 1652 landslide dams in four major rivers of Bhutan and its surrounding area by remote sensing interpretation.Notably,approximately 71%of these landslide dams are found in regions composed of quartzite or gneiss.Fault-related tectonic activity plays a significant role in governing the distribution of these landslide dams,as approximately 83%of the mapped landslide dams are found within a 10 km radius of the nearest fault.The majority of the identified landslide dams are situated in areas with relatively modest local relief,ranging from 227 m to 327 m.These dams tend to cluster in the tributaries,and the stream power of almost 95%of them is typically below 1×10^(6) kg m^(2) s^(-3).Our data,combining the erosion rate and kernel density map of the landslide dams,reveals that regions with high erosion rates do not consistently align with the major high-density distribution of landslide dams.It is shown that the distribution of landslide dams is strongly influenced by the valley form.In comparison to U-shaped valleys,V-shaped valleys exhibit a higher density of landslide dams.Intriguingly,we also find a positive correlation between the landslide-dam distribution density and the erosion rate only in relatively arid regions with mean annual rainfall less than 500 mm.Moreover,the length of the upstream reach protected by the knickpoint associated with both lithology and landslide damming is about three times longer than that protected by the knickpoint associated only with landslide damming.展开更多
Landscape evolution models(LEMs)are essential tools for analyzing tectonic-climate interactions and reproducing landform-shaping processes.In this study we used a LEM to simulate the evolution of the mountains from th...Landscape evolution models(LEMs)are essential tools for analyzing tectonic-climate interactions and reproducing landform-shaping processes.In this study we used a LEM to simulate the evolution of the mountains from the central Hexi Corridor in the northeastern Tibetan Plateau,where the climate is arid and the surface processes are relatively uniform.However,there are pronounced differences in the topography between the mountains around the central Hexi Corridor.The East Jintanan Shan,West Jintanan Shan and Heli Shan are located in the northern part of the corridor;and the Yumu Shan in the southern part.Firstly,several representative areas were selected from these mountains to analyze the topographic characteristics,including the uniform valley spacing,local relief,and the outlet number.Secondly,a LEM for these areas was constructed using the Landlab platform,and the landscape evolution was simulated.With uniform valley spacing and other topographic characteristics as the criteria,we compared the realistic and simulated terrain for different model ages.Finally,based on the similarity of the simulated and realistic terrain,we estimated the timing of the initial uplift and the uplift rate of the four mountain ranges.The results are consistent with previous geological and geomorphological records from these youthful stage mountains that have not yet reached a steady state.Our findings demonstrate that LEMs combined with topographic characteristics are a reliable means of constraining the timing of the initial uplift and the uplift rate of the youthful stage mountain.Our approach can potentially be applied to other youthful stage mountains and it may become a valuable tool in tectonic geomorphology research.展开更多
Conceptual models are suitable for describing internal relationships of complex systems, including soil. We used conceptual models, the Jenny＇s and Johnson and Watson-Stegner＇s models to understand the formation and...Conceptual models are suitable for describing internal relationships of complex systems, including soil. We used conceptual models, the Jenny＇s and Johnson and Watson-Stegner＇s models to understand the formation and evolution of soil. We studied 20 pedons in granitic hilly lands, loessial piedmont, and piedmont plain in southern Mashhad, northeast Iran. These soils were characterized by high levels of gypsum, especially in the granitic saprolites, which suggested the importance of the wind in shaping the soil structure. Jenny＇s model is a developmental and equilibrium model, which only describes the state of the soil formation factors and considers that each bioclimatie zone has a specific climax soil. It focuses on the genesis of the surface soil and is not suitable for buried soils and paleosols. Johnson and Watson-Stegner＇s model describes soil as a product of progressive and regressive processes due to horizonation or haploidization. Progressive processes during the last interglacial cycle created a well-developed paleosol with an argillic horizon in all landforms, except the piedmont plain. Developmental soil up-building by aeolian addition led to gypsum enrichment of the granitic saprolite. Erosion decreased soil thickness and exposed the argillic horizon. The Last Glacial Maximum led to greater deposition of loess, covering the paleosol. Humidity was higher during the early Holocene than today, leading to the development of a Bk horizon. This horizon was preserved in the stable surfaces of granitic hilly land and in the loessial piedmont, but buried on the piedmont plain via the deposition of alluvial sediments. Jenny＇s model could be used for current soil formation factors, whereas Johnson and Watson-Stegner＇s model required morphological characteristics of pedons for interpretation.展开更多
In order to investigate the dynamic evolution of the sandy land-lake-vegetation landscape in Songnen Sandy Land(SSL)and its response to climate change and human activities,the distribution pattern,evolution,and drivin...In order to investigate the dynamic evolution of the sandy land-lake-vegetation landscape in Songnen Sandy Land(SSL)and its response to climate change and human activities,the distribution pattern,evolution,and driving mechanisms of the landscape were analyzed based on Landsat satellite images and meteorological and socio-economic data during 1980–2020.The results indicate that the area of sandy land exhibited an upward fluctuation during the last 40 yr,with a net increase of 251.75 km^(2) at an increment rate of 3.80%/10 yr.The lake area also exhibited an upward fluctuation,with a net increase of 1200.95 km^(2) at an increment rate of 20.42%/10 yr.Vegetation coverage decreased by 2633.30 km^(2),with areas of low vegetation coverage exhibiting a trend of initial decline and subsequent increase,areas of medium vegetation coverage showed an upward fluctuation,and areas of high vegetation coverage showed a trend of initial increase and subsequent decrease,with overall changes of–0.67%/yr,1.12%/yr,and 0.17%/yr,respectively.The relationships between sandy land,lakes,and vegetation coverage were significant,with areas of sandy land and low vegetation coverage showing the strongest correlation.The dynamic evolution of landscape is controlled by regional climatic and socio-economic factors,with socio-economic factors as the first principal component contributing up to 59.64%.展开更多
Mountain area is an important geographical unit of land,and its ecology is sensitive and fragile.Over the past few decades,human activities have caused dramatic changes in land use in mountainous areas,which caused ch...Mountain area is an important geographical unit of land,and its ecology is sensitive and fragile.Over the past few decades,human activities have caused dramatic changes in land use in mountainous areas,which caused changes in landscape patterns and impacts on the ecological environment.It is unknown how the mechanism of land use affects the landscape pattern at different scales.The Hantai District,a typical human settlement in the mountain area in Shaanxi,China,was chosen as the study area.Based on the remote sensing images,the mathematical models and landscape indexes were adopted to evaluate the impact of land use change from 1998 to 2017 on the landscape pattern at different scales,and its main driving forces were analyzed.The results showed that the urbanized land expanded largest from 15.39%to 24.30%,and cultivated land experienced the largest decline from 43.54%to 35.35%.Changes in land use have made the patch morphology of most land types developed from a natural random to a sawtooth shape,and its spatial pattern evolved from a ruleset to a fragmented expansion.This reflects the continuous strengthening of human intervention in the process of regional development.Under the jurisdiction of Hantai District,the biggest change in landscape pattern is in Hanzhong City and Qili Town.The improved economy and increasing population and urbanization rate were the main factors that cause these changes.This research could provide necessary information for understanding the evolution mechanism of land resources in mountainous human settlements for mountainous areas with significant geomorphic differentiation.展开更多
Himalaya and its foreland acted as a coupled system that responded to the climate variability and evolved as a thrust and fold belt.The river systems draining the Himalaya,the Ganga foreland act as an artery that help...Himalaya and its foreland acted as a coupled system that responded to the climate variability and evolved as a thrust and fold belt.The river systems draining the Himalaya,the Ganga foreland act as an artery that helps registering climate and tectonic signals into its geomorphology and sedimentary history.The paper discusses the late Quaternary landscape evolution of the mountain and its foreland and reviews the published literature in the context.展开更多
The study deals with stream response to sustained tectonic during the Cenozoic and development of two parallel scarps in the western Kachchh. The study encompasses fluvial networks developed over the Jara and Jumara d...The study deals with stream response to sustained tectonic during the Cenozoic and development of two parallel scarps in the western Kachchh. The study encompasses fluvial networks developed over the Jara and Jumara domes, which are a part of the laterally extensive belt of flexures bounded by the Kachchh Mainland Fault(KMF) to their north and called as Northern Hill Range(NHR). Parameters such as longitudinal profile, Hack profile, stream length gradient index(SL), hypsometric curve, hypsometric integral(HI), valley floor width to height ratio(Vf), elongation ratio(Re) and escarpment sinuosity(ES) were analysed. Hack profiles of the major rivers draining through the area show similar convex up nature suggesting primary influence of the tectonics in controlling and shaping the landscape of the region. Elongation ratio <6 and undergone higher degree of fluvial erosion indicated by the low values of hypsometric integral suggest the tendency of river systems to increase the basin area longitudinally rather than laterally. The study suggests that higher net uplift in the eastern half(Jumara dome) caused the rivers to overcome the structural control and to carve out generally straight north oriented channels. The rivers of western part(Jara dome) show more prominent structural control of cuesta girdles formed in compact lithologies and attributed to the domal structure. The ~10 km long Jaramara scarp believed to the remnant of older KMF scarp, is a product of headward erosion of the fluvial channels through different hard and soft litho-units of the area. The similar orientation of Jaramara scarp and morphology of the Ukra intrusive body suggests that the Ukra intrusive played a significant role in controlling the formation and morphology of the Jaramara scarp.展开更多
The interaction between fluvial and aeolian processes can significantly change surface morphology of the Earth. Taking the Horqin Sandy Land as the research area and using Landsat series satellite remote sensing image...The interaction between fluvial and aeolian processes can significantly change surface morphology of the Earth. Taking the Horqin Sandy Land as the research area and using Landsat series satellite remote sensing images, this study utilizes geomorphology and landscape ecology to monitor and analyze the aeolian geomorphology characteristics of the Horqin Sandy Land. Results show that the sand dunes of the Horqin Sandy Land are mainly distributed on alluvial plains along the banks of the mainstream and tributaries of the Western Liao River, and the sand dune types tend to simplify from west to east and from south to north. The aeolian geomorphology coverage tend to be decreasing in the past 40 years, with an average annual change rate of 0.31%. While the area of traveling dunes decreased, the area of fixed and semi-fixed dunes increased. The fractal dimensions of various types of sand dune have all remained relatively constant between 1.07 and 1.10, suggesting that they are experiencing a relatively stable evolutionary process. There is a complex interaction between fluvial and aeolian processes of the Horqin Sandy Land, which plays a central role in surface landscape molding. Sand dunes on both sides of different rivers on the Horqin Sandy Land present certain regularity and different characteristics in terms of morphology, developmental scale, and spatial pattern. There are six fluvial-aeolian interaction modes in this area: supply of sand sources by rivers for sand dune development, complete obstruction of dune migration by rivers, partial obstruction of dune migration by rivers, influence of river valleys on dune developmental types on both sides, influence of river valleys on dune developmental scale on both sides, and river diversion due to obstruction and forcing by sand dunes. This study deepens our understanding of the surface process mechanism of the interaction between fluvial and aeolian processes in semi-arid regions, and provides a basis for researches on regional landscape responses in the context of global environmental change.展开更多
Large-scale rock-ice avalanches resulting from the interaction of tectonics and climate are characterized with high mobility,huge volumes of sediment,and rapid denudation,being a major agent of landscape evolution in ...Large-scale rock-ice avalanches resulting from the interaction of tectonics and climate are characterized with high mobility,huge volumes of sediment,and rapid denudation,being a major agent of landscape evolution in high altitude mountainous regions.Specifically,the extreme glaciated slope failures often transform into extraordinarily large and mobile debris flows,resulting in disastrous consequences such as sedimentation and desertification.Due to a dearth of on-site observation data and experimental data collection,our comprehension of the geomorphic and kinematic characteristics of rock-ice avalanches remains poor.Here we report a cluster of ancient rock-ice avalanches spreading along the Chomolhari range of the China-Bhutan Himalayas.By integrating remote sensing image interpretation with detailed field investigations,we demonstrate the geomorphic and sedimentary characteristics of four events among the avalanches.The estimated volumes of the four are 23.73 Mm³,39.69 Mm³,38.43 Mm³,and 38.25 Mm³,respectively.The presence of pre-existing moraines or alluvial fans constrained their movement,resulting in deposition features such as marginal digitated lobes at higher elevations and large depressed areas in the interior.Applying the Savage-Hutter theory,we calculate the basal friction angle and travel angle of these ancient rock-ice avalanches that are both less than 10°,affirming the similarity of these avalanches in the study area to those occurring in other regions.Our study significantly contributes to understanding the geomorphic and kinematic characteristics of rock-ice avalanches in high-altitude mountainous regions,providing valuable insights into their response to the disproportionate growth of Himalayan peaks.展开更多
Land use/land cover(LULC)change monitoring is critical for understanding environmental and socioeconomic processes and to identify patterns that may affect current and future land management.Forest cover evolution in ...Land use/land cover(LULC)change monitoring is critical for understanding environmental and socioeconomic processes and to identify patterns that may affect current and future land management.Forest cover evolution in the Mediterranean region has been studied to better understand forest succession,wildfires potential,and carbon stock assessment for climate change mitigation,among other reasons.However,though multiple sources of current LULC exist,data from last century's forest cover are less common,and are normally still reliant on locally orthophoto-interpreted data,making continuous maps of historical forest cover relatively uncommon.In this work,a pipeline based on image segmentation and random forest LULC modeling was developed to process three high resolution orthophotos(1956,1989,and 2021)into LULC continuous land cover maps of Spain's island of Ibiza.Next,they were combined to quantify forest evolution of Mediterranean Aleppo pine(Pinus halepensis Mill.)and to generate a continuous map of forest age classes.Our models were able to differentiate forestland with an accuracy higher than 80%in all cases,and were able to approximate forestland cover change since the mid-twentieth century,estimating 21,165±252 ha(37.0±0.4%)in 1956,27,099±472 ha(46.8±0.8%)in 1989,and 30,195±302 ha(52.8±0.5%)in 2021,with a mean increase of 139±6 ha(0.46±0.02%,calculated from current forest cover estimate)per year.The most important variables for the identification of the forestland were the terrain slope and the image gray level or color information in all orthophotos.When combining the information from the three periods,the analysis of forest evolution revealed that a significant portion of current forest cover,approximately 15,776 ha,fell within the 75-120 year age range,while 5388 ha fell within the range of 42-74 years,and 9022 ha within the 10-41 years forest age class.Younger forests,except when mapped after known wildfires,were not considered due to the limitations of the methodology.When compared to forest age data based on ground measurements,significant differences were found among each of the remotely sensed forest age classes,with a mean difference of 13 years between the theoretical age class central value and the real observed plot average age.Overall,63%of the forest inventory plots were assigned with the correct forest age class.This work will allow a better understanding of long-term Mediterranean forest dynamics and will help landowners and policymakers to better respond to new landscape planning challenges and achieve sustainable development goals.展开更多
The Tibetan Plateau is bounded by the Altyn Tagh left-lateral strike-slip fault system in the northwest,unlike the common thrust fault-bounded margins in the south or east.Quantifying surface denudation rate along thi...The Tibetan Plateau is bounded by the Altyn Tagh left-lateral strike-slip fault system in the northwest,unlike the common thrust fault-bounded margins in the south or east.Quantifying surface denudation rate along this enigmatic margin is important for understanding tectonic-geomorphic evolution and deep dynamic processes at margins of the Tibetan Plateau.In this study,we collected modern river sand samples from 29 drainage basins along the eastern section of the Altyn Tagh fault zone and analyzed the concentrations of terrestrial in-situ cosmogenic nuclides26Al and10Be.The26Al-10Be paired-nuclide method is effective in verifying the assumptions of steady-state denudation and short-term sediment transportation time in these basins,thereby ensuring the reliability of derived denudation rates.We found that10Be-derived basin-wide denudation rates range from15 to 610 mm kyr^(-1).Denudation rates are notably enhanced in locations with structural complexities that allow enhanced vertical uplift along this strike-slip fault system,such as restraining double bends and kinematic transition zones of fault junctions,and that the local topography becomes significantly steeper.This finding indicates that local tectonic uplift is the dominant factor governing topographic relief,as well as the intensity and spatial distribution of surface denudation.Basin-wide denudation rates exhibit a non-linear positive correlation with slope gradient,topographic relief,and channel steepness index(k_(sn)),suggesting that topographic indexes constitute robust proxies for estimating denudation rates in this region.Conversely,no discernible correlation was detected between denudation rates and rainfall or vegetation indices.Moreover,the spatial heterogeneity in rock type and thus erodibility exert non-negligible effects on surface denudation and landscape evolution,particularly in areas where tectonic uplift is less dominant.Our study provides for the first time millennial basin-wide denudation rates and their spatial distribution patterns along the northwestern margin of the Tibetan Plateau,and reveals the interplay between surface denudation and tectonic deformation along the Altyn Tagh fault.The results thereby fill an important knowledge gap in understanding surface processes across the poorly-understood plateau's northwestern margin.展开更多
Background Ecological land evolution is pivotal in shaping regional landscapes and ecosystem functions.However,existing metrics are limited in quantifying patch-scale dynamics of connectivity and fragmentation during ...Background Ecological land evolution is pivotal in shaping regional landscapes and ecosystem functions.However,existing metrics are limited in quantifying patch-scale dynamics of connectivity and fragmentation during the processes of ecological land degradation and restoration.This study introduces the Ecological Land Evolution Index(ELEI),a novel framework integrating spatial proximity and connectivity to evaluate spatiotemporal complexities of ecological land changes at the patch level.By incorporating adjacency rules and continuous value systems,ELEI offers a granular analysis of connectivity-fragmentation tradeoffs,addressing limitations in traditional landscape metrics.Results Using four temporal land use datasets(1990–2020)from the urban agglomeration in the middle reaches of the Yangtze River(UAMRYR)in China,we applied ELEI to characterize ecological land restoration(ELR)and degradation(ELD).Sensitivity analysis confirmed ELEI’s robustness,identifying connected patch area and spatial proximity as primary drivers.Monte Carlo simulations validated formula stability,highlighting symmetrical responses to connectivity changes but residual uncertainties in extreme scenarios(|ELEI|>60).Additionally,the results demonstrate significant spatiotemporal heterogeneity in ecological land evolution.Degradation of ecological land initially intensified from 2000 to 2010,but then decelerated from 2010 to 2020,while the restoration process first weakened and subsequently strengthened.Notably,the area of degraded ecological land steadily expanded throughout the study period,reaching 17,684.20 km^(2) between 1990 and 2020,while the restored area totaled 12,025.56 km^(2).Fragmentation dominated degradation processes,while connection patterns drove restoration.Urban centers like Wuhan and Changsha experienced severe fragmentation aligned with rapid urbanization,whereas cities such as Yichang,Hengyang,and Jiujiang achieved significant restoration via infilling and connection.Conclusions ELEI provides a nuanced understanding of ecological land dynamics in rapidly urbanizing regions by identifying restoration successes and ongoing degradation hotspots.Additionally,the integration of ELEI variants(arithmetic mean ELEI(MELEI)and area-weighted mean ELEI(AWMELEI))highlights their value in tracking long-term connectivity trends and degradation processes.This framework offers actionable insights for balancing urban development and conservation,underscoring its value in regional planning and sustainable landscape management.展开更多
Initiation and recession of the knickpoints are significant boundary condition for processes of fluvial system. The distribution and recession rates of knickpoints contain information that provides a fundamental under...Initiation and recession of the knickpoints are significant boundary condition for processes of fluvial system. The distribution and recession rates of knickpoints contain information that provides a fundamental understanding of geomorphic processes. In the Yalu River-Wangtian＇e volcanic region of northeastern China, broadly distributed fiat lava terrain provides an ideal site to study the recession of fluvial knickpoints because knickpoints and waterfalls are well preserved here. Here we describe the distribution of knickpoints in the Yalu River-Wangtian＇e volcanic region by combining DEM analysis and numerical modeling Furthermore, we present a knickpoint celerity model, derived from stream-power incision model, to relate knickpoint recession rate to drainage area. We calibrate important empirical coefficients with our knickpoint celerity model; the best fit erosion coefficient （K） is 1.32×10^-8, and the best fit drainage area exponent （m） is 0.69. Error analysis indicates a close correspondence between synthetic and real knickpoints. Finally, we show that knickpoint recession rates in the Yalu River-Wangtian＇e volcanic region are -1-10 mm/a during the early stages of transient incision, and that the present rates are -1-6 mm/a. Our recession rate results are in good agreement with previous findings from the Aso Volcano and volcanoes near Boso Peninsula （Japan）, which have a similar geologic history to the Yalu River-Wangtian＇e volcanic region. Our present effort provides new insight into landscape evolution in the Yalu River-Wangtian＇e volcanic region in northeastern China.展开更多
基金Under the auspices of Natural Science Youth Foundation of Northeast Normal University (No. 20070501)National Natural Science Foundation of China (No. 40635030)Geographical Frontiers Foundation of Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences (No. KZCX3-SW-NA3-19)
文摘Agricultural village is an important rural type in China. The evolution process and mechanism of its cultural landscape are different from those of the industrialized village. The paper focuses this theme by a case study of Qianzhai Village of Qufu City, Shangdong Province. In the case of Qianzhai Village, the evolution of its settlement has experienced three stages: mechanical expansion, sprawling expansion and hollowing, and recentralization. The land- scape evolution of residents' houses has undergone three phases: traditional quadrangle house, one-storied house and multistoried house. The evolution of its land use has experienced three stages: circled stratification, fragment and intensive use, and concentration and extensive use. We can see that the main driving factors of cultural landscape evolu- tion of agricultural village are the changes of rural population, society, economy and culture, which are influenced by the change of urban-rural relation, the national modernization process and economic development, the reform of family planning and land system, and the changes in governmental policies. In the future, the modernization, ecological trend, and individualization for residents' houses of agricultural villages in China will develop step by step. The recentralization of settlement and the scaled, sustainable, intensive land use are likely to be the trends of agricultural villages in China.
基金supported financially by the Natural Science Foundation of China(Grant Nos.41971001,41730637 and 41501002]supported by the Open Foundation of Research institute of Qilian Mountains
文摘The combination of different topographic and climatic conditions results in varied precipitation-runoff relations,which in turn influences hillslope erosion,sediment transport and bedrock incision across mountainous landscapes.The runoff coefficient is a suitable tool to represent precipitation-runoff relations,but the spatial distribution of the runoff coefficient across tectonically active mountains in semi-arid environments has received little attention because of limited data availability.We calculated annual runoff coefficients over 22 years for 26 drainage basins across the semi-arid Qilian Mountains based on:(i)annual discharge records;and(ii)the China Meteorological Forcing Dataset to enhance our understanding of the precipitation-runoff processes.The mean annual runoff coefficients show no obvious spatial trends.When compared to potential controlling factors,mean annual runoff coefficients are highly correlated with mean slope rather than any climatic characteristics(e.g.,mean annualprecipitation and Normalized Difference Vegetation Index).The slope-dependent runoff coefficient could theoretically have enhanced the topographic control on erosion rates and dampen the influence of precipitation.The enhanced discharge for drainage basins with less precipitation but steep topography in the western Qilian Mountains will enable fluvial incision to keep pace with ongoing uplift caused by the northward growth of the Qilian Mountains.The geomorphic implications are that tectonic rather than climatic factors are more significant for long-term landscape evolution in arid and semi-arid contexts.
基金supported by the National Key Research and Development Program of China(Grant No.2020YFA0607700)the Tianjin Graduate Research Innovation Project(Grant No.2019YJSB182)the National Natural Science Foundation of China(Grant No.41930642)。
文摘In-situ cosmogenic nuclide s are receiving growing attention in surface Earth system science in which the steady-state denudation is an important assumption for estimating the surface denudation of long-lived(103-106 years)surfaces.However,distinguishing steady-state denudation and deciphering a reliable denudation rate from non-steady state denudation region are difficult.Recent depth profile models for investigating the denudation rate,exposure age and inheritance are widely used for sediment and regolith of steady-state denudation region.Here we present in-situ co smogenic nuclides^(10)Be and^(26)Al from two typical granite regolithes from Jixian in Tianjin and Tengchong in Yunnan to model non-steady landscape evolution process by using steady state(Model 1)and non-steady state(Model 2,continuous exposure;Model 3 a,changed denudation rate;Model 3 b,abrupt denudation event)models.The results of steady state model show that both regolithes are in non-steady state.^(10)Be non-steady state models of Jixian regolith reveal that the surface has likely experienced a denudation rate change or an abrupt denudation event during the past several millennia,resulting in a non-steady state.The similar Model 3 a and 3 b denudation rates of 14.6-12.9^(+9.4)and 14.7-14.7^(+9.0)mmkyr^(-1),respectively,might demonstrate the long-term denudation rate rather than the exaggerated rate s of 39.0-2.3^(+2.6)and 39.0-2.4+^(2.5)mm kyr^(-1)calculated by assuming steady-state denudation and ignoring inheritance.The non-steady state model results of Tengchong regolith suggest that the surface has likely experienced a strong denudation about 157 ka(^(10)Be)or 127 ka(^(26)Al)ago.This timing is basically consistent with the termination of the MIS 6(TII:130 ka)and the climate change events in the Tibetan Plateau,suggesting a strong surface landscape denudation during the transition from glacial to interglacial.The compiling of basin-wide denudation rates in the Tibetan Plateau shows a good positive correlation with the regional tectonic activity,indicating that the denudation rate derived from non-steady state region with strong tectonic activity is likely to be overestimated by assuming steady state.We suggest that a combination of steady state and non-steady state depth profile models should be used to quantify denudation rate and exposure age more accurately and effectively in strong tectonic activity or climate change regions.
基金supported by the National Natural Science Foundation of China (Grant No. 41602113)the Open Research Fund fromthe State Key Laboratory Breeding Base of Nuclear Resources and Environment (East China University of Technology) (Grant No. NRE1605)
文摘The Jianglangshan Geopark in the western Zhejiang Province of Southeast China is well-known for its spectacular red-colored sandstone landforms. Little is known about the depositional processes of the conglomerate-dominated Fangyan Formation, the lithologic base of the Danxia landforms in this geopark. Based on detailed field investigation of lithology, sedimentary structures, bed thickness and geometry, five facies are recognized: facies A(matrixsupported cobble conglomerate), facies B(pebble conglomerate), facies C(pebbly sandstone), facies D(fine-grained sandstone) and facies E(mudstone). The results show that streamflow-dominated fans were the main depositional processes responsible for the accumulation of the Fangyan Formation along the mountain fronts. These fan conglomerates form the base for the evolution of the Danxia landscapes owing to the uplift and erosion of the study area. In contrast, the fine-grained sedimentary successions produced by fluvial floodplains in the distal part of the fans were thinner and more easily weathered. Such sedimentary facies distribution patterns were thought to be similar during Late Cretaceous across Southeast China. The Danxia landforms are largely the geographical expressions of the conglomerate-dominated redbeds in the proximal-middle fans.
基金supported by the Second Tibetan Plateau Scientific Expedition and Research Program(Grant No.2019QZKK0902)the National Natural Science Foundation of China(Grant Nos.41790434 and 91747207)。
文摘High-magnitude glacial debris flows in small basins in Himalayas have a significant impact on landscape.The Peilong catchment,a tributary of the Parlung Zangbo river in southeastern Tibet,was chosen as a case study of topographic response to multi-period glacial debris flows.There are few large debris flow records in the catchment before 1983,but four large-scale glacial debris flows with peak discharge up to 8195 m3/s blocked the river during 1983–1985 and in 2015.A combination of field survey,examination of historical records and interpretation of multi-period remote sensing images was used to assess triggering factors and geomorphic impact of the events.The results show that the debris flows during 1983 and 1985 may be attributed to seismic events in 1981 and 1982,while the event in 2015 resulted from large amount of landslide deposits caused by glacier retreat during 1993~2013 and high precipitation in 2015.In the upper-midstream broad valley,erosion and accumulation of the debris flows changed the channel morphology,resulting in course diversion.In the lower-midstream narrow valley,lateral erosion of debris flows induced a large number of landslides but had little impact on the channel longitudinal profile.The ability of massive glacial debris flows to change valley topography is more than ten times that of regular water flows.The landscape of the accumulation fan at the outlet of the valley is controlled by the interaction between the sediment transportation capacity of debris flows and erosional capacity of the main river.The sediment transport capacity of the Peilong river is greater than the delivery capacity of the Parlung Zangbo river,resulting in continuous aggradation of the confluence zone.
基金supported by the basic scientific research fund, Institute of Geology, China Earthquake Administration (Grant Nos. IGCEA1504 and IGCEA1417)
文摘Cosmogenic Ne isotopes are stable and are routinely used for constraining the timing of events and the rate of surface change beyond the limit that can be studied with radionuclides ^10Be, ^26Al, and ^36Cl. Cosmogenic Ne analysis can be used in quartz and in a range of other minerals. Analysis typically requires significantly less material than do cosmogenic ^10Be and ^26Al, opening up the technique for small samples--individual pebbles in fiver sediments, for example. Analysis is easier and faster than for radionuclides, not least because Ne measurements do not require significant chemical procedures. However, the presence of other sources of Ne in minerals tends to restrict the use of cosmogenic ^21Ne to old landscapes and long exposure durations. In this review we briefly outline the background of cosmogenic Ne production in rocks and minerals at the Earth＇s surface, then document the key uses of the technique by highlighting some earlier studies, and finish with a short perspective on the future of the technique.
基金Under the auspices of National Natural Science Foundation of China (No. 40401003)Knowledge Innovation Program of Chinese Academy of Sciences (No. KZCX3-SW-356)Key Project of Chinese Academy of Sciences for Developing Science and Technology of Northeast China (DBZX-2-030)
文摘The landscape pattern of Da’an County, Northeast China has undergone significant changes since the 1950s as a result of climatic change and human activities. The aim of this paper is to quantitatively study landscape pattern and its spatial dynamics of Da’an County at the landscape level over the nearly 50-year span. Patch dynamics were examined ac-cording to land use and land cover change processes built from a series of images, as well as topographic maps, and tem-poral patterns built from landscape pattern metrics. The transition matrix of landscape patch types and changes of various landscape metrics were applied. The results showed that, from 1956 to 2000, the landscape within the study area had un-dertaken a complicated evolution in landscape structure and composition. The outstanding characteristic is that sa-line-alkali land increased and grassland decreased. As some smaller patches amalgamated, the heterogeneity of patch de-creased. All those changes were the synthetic result of both climatic and anthropogenic influences, but the predominant factor was different in different parts. In the southern part of the study area, the landscape pattern changes resulted from the modification of climate obviously, while in the northern part, the landscape pattern changes were mainly caused by human activities, such as the conversion between farmland and saline-alkali land. This phenomenon showed that human activities played more important role in the north than in the south of Da’an County.
基金supported by the National Natural Science Foundation of China(Grant No.91747207)the National Key R&D Program of China(Grant No.2018YFC1505205)the National Natural Science Foundation of China(Grant No.41790434)。
文摘The regional distribution of landslide dams can provide valuable insights into the interactions among various factors,including lithology,topography,climate,and fluvial landforms in tectonically active mountains.Himalayan rivers are frequently impacted by large-scale landslide damming,which profoundly influence fluvial geomorphology.In this study,we identified 1652 landslide dams in four major rivers of Bhutan and its surrounding area by remote sensing interpretation.Notably,approximately 71%of these landslide dams are found in regions composed of quartzite or gneiss.Fault-related tectonic activity plays a significant role in governing the distribution of these landslide dams,as approximately 83%of the mapped landslide dams are found within a 10 km radius of the nearest fault.The majority of the identified landslide dams are situated in areas with relatively modest local relief,ranging from 227 m to 327 m.These dams tend to cluster in the tributaries,and the stream power of almost 95%of them is typically below 1×10^(6) kg m^(2) s^(-3).Our data,combining the erosion rate and kernel density map of the landslide dams,reveals that regions with high erosion rates do not consistently align with the major high-density distribution of landslide dams.It is shown that the distribution of landslide dams is strongly influenced by the valley form.In comparison to U-shaped valleys,V-shaped valleys exhibit a higher density of landslide dams.Intriguingly,we also find a positive correlation between the landslide-dam distribution density and the erosion rate only in relatively arid regions with mean annual rainfall less than 500 mm.Moreover,the length of the upstream reach protected by the knickpoint associated with both lithology and landslide damming is about three times longer than that protected by the knickpoint associated only with landslide damming.
基金the National Natural Science Foundation of China(Grant Nos.41730637&41571003)。
文摘Landscape evolution models(LEMs)are essential tools for analyzing tectonic-climate interactions and reproducing landform-shaping processes.In this study we used a LEM to simulate the evolution of the mountains from the central Hexi Corridor in the northeastern Tibetan Plateau,where the climate is arid and the surface processes are relatively uniform.However,there are pronounced differences in the topography between the mountains around the central Hexi Corridor.The East Jintanan Shan,West Jintanan Shan and Heli Shan are located in the northern part of the corridor;and the Yumu Shan in the southern part.Firstly,several representative areas were selected from these mountains to analyze the topographic characteristics,including the uniform valley spacing,local relief,and the outlet number.Secondly,a LEM for these areas was constructed using the Landlab platform,and the landscape evolution was simulated.With uniform valley spacing and other topographic characteristics as the criteria,we compared the realistic and simulated terrain for different model ages.Finally,based on the similarity of the simulated and realistic terrain,we estimated the timing of the initial uplift and the uplift rate of the four mountain ranges.The results are consistent with previous geological and geomorphological records from these youthful stage mountains that have not yet reached a steady state.Our findings demonstrate that LEMs combined with topographic characteristics are a reliable means of constraining the timing of the initial uplift and the uplift rate of the youthful stage mountain.Our approach can potentially be applied to other youthful stage mountains and it may become a valuable tool in tectonic geomorphology research.
文摘Conceptual models are suitable for describing internal relationships of complex systems, including soil. We used conceptual models, the Jenny＇s and Johnson and Watson-Stegner＇s models to understand the formation and evolution of soil. We studied 20 pedons in granitic hilly lands, loessial piedmont, and piedmont plain in southern Mashhad, northeast Iran. These soils were characterized by high levels of gypsum, especially in the granitic saprolites, which suggested the importance of the wind in shaping the soil structure. Jenny＇s model is a developmental and equilibrium model, which only describes the state of the soil formation factors and considers that each bioclimatie zone has a specific climax soil. It focuses on the genesis of the surface soil and is not suitable for buried soils and paleosols. Johnson and Watson-Stegner＇s model describes soil as a product of progressive and regressive processes due to horizonation or haploidization. Progressive processes during the last interglacial cycle created a well-developed paleosol with an argillic horizon in all landforms, except the piedmont plain. Developmental soil up-building by aeolian addition led to gypsum enrichment of the granitic saprolite. Erosion decreased soil thickness and exposed the argillic horizon. The Last Glacial Maximum led to greater deposition of loess, covering the paleosol. Humidity was higher during the early Holocene than today, leading to the development of a Bk horizon. This horizon was preserved in the stable surfaces of granitic hilly land and in the loessial piedmont, but buried on the piedmont plain via the deposition of alluvial sediments. Jenny＇s model could be used for current soil formation factors, whereas Johnson and Watson-Stegner＇s model required morphological characteristics of pedons for interpretation.
基金Under the auspices of National Natural Science Foundation of China(No.41871022)Natural Science Foundation of Jilin Province(No.20210101398JC)。
文摘In order to investigate the dynamic evolution of the sandy land-lake-vegetation landscape in Songnen Sandy Land(SSL)and its response to climate change and human activities,the distribution pattern,evolution,and driving mechanisms of the landscape were analyzed based on Landsat satellite images and meteorological and socio-economic data during 1980–2020.The results indicate that the area of sandy land exhibited an upward fluctuation during the last 40 yr,with a net increase of 251.75 km^(2) at an increment rate of 3.80%/10 yr.The lake area also exhibited an upward fluctuation,with a net increase of 1200.95 km^(2) at an increment rate of 20.42%/10 yr.Vegetation coverage decreased by 2633.30 km^(2),with areas of low vegetation coverage exhibiting a trend of initial decline and subsequent increase,areas of medium vegetation coverage showed an upward fluctuation,and areas of high vegetation coverage showed a trend of initial increase and subsequent decrease,with overall changes of–0.67%/yr,1.12%/yr,and 0.17%/yr,respectively.The relationships between sandy land,lakes,and vegetation coverage were significant,with areas of sandy land and low vegetation coverage showing the strongest correlation.The dynamic evolution of landscape is controlled by regional climatic and socio-economic factors,with socio-economic factors as the first principal component contributing up to 59.64%.
基金funded by Natural Science Foundation of China(51378067)the Natural Science Foundation of Shaanxi(806215594019)。
文摘Mountain area is an important geographical unit of land,and its ecology is sensitive and fragile.Over the past few decades,human activities have caused dramatic changes in land use in mountainous areas,which caused changes in landscape patterns and impacts on the ecological environment.It is unknown how the mechanism of land use affects the landscape pattern at different scales.The Hantai District,a typical human settlement in the mountain area in Shaanxi,China,was chosen as the study area.Based on the remote sensing images,the mathematical models and landscape indexes were adopted to evaluate the impact of land use change from 1998 to 2017 on the landscape pattern at different scales,and its main driving forces were analyzed.The results showed that the urbanized land expanded largest from 15.39%to 24.30%,and cultivated land experienced the largest decline from 43.54%to 35.35%.Changes in land use have made the patch morphology of most land types developed from a natural random to a sawtooth shape,and its spatial pattern evolved from a ruleset to a fragmented expansion.This reflects the continuous strengthening of human intervention in the process of regional development.Under the jurisdiction of Hantai District,the biggest change in landscape pattern is in Hanzhong City and Qili Town.The improved economy and increasing population and urbanization rate were the main factors that cause these changes.This research could provide necessary information for understanding the evolution mechanism of land resources in mountainous human settlements for mountainous areas with significant geomorphic differentiation.
文摘Himalaya and its foreland acted as a coupled system that responded to the climate variability and evolved as a thrust and fold belt.The river systems draining the Himalaya,the Ganga foreland act as an artery that helps registering climate and tectonic signals into its geomorphology and sedimentary history.The paper discusses the late Quaternary landscape evolution of the mountain and its foreland and reviews the published literature in the context.
基金The present study was funded by the Ministry of Earth Sciences(MoES),Government of India in the form of research project(Project 474 No.Mo ES/P.O.(Seismo)/1(170)/2013)MoES/P.O.(Seismo)/1(120)/AFM/2015 to DMM and LSC。
文摘The study deals with stream response to sustained tectonic during the Cenozoic and development of two parallel scarps in the western Kachchh. The study encompasses fluvial networks developed over the Jara and Jumara domes, which are a part of the laterally extensive belt of flexures bounded by the Kachchh Mainland Fault(KMF) to their north and called as Northern Hill Range(NHR). Parameters such as longitudinal profile, Hack profile, stream length gradient index(SL), hypsometric curve, hypsometric integral(HI), valley floor width to height ratio(Vf), elongation ratio(Re) and escarpment sinuosity(ES) were analysed. Hack profiles of the major rivers draining through the area show similar convex up nature suggesting primary influence of the tectonics in controlling and shaping the landscape of the region. Elongation ratio <6 and undergone higher degree of fluvial erosion indicated by the low values of hypsometric integral suggest the tendency of river systems to increase the basin area longitudinally rather than laterally. The study suggests that higher net uplift in the eastern half(Jumara dome) caused the rivers to overcome the structural control and to carve out generally straight north oriented channels. The rivers of western part(Jara dome) show more prominent structural control of cuesta girdles formed in compact lithologies and attributed to the domal structure. The ~10 km long Jaramara scarp believed to the remnant of older KMF scarp, is a product of headward erosion of the fluvial channels through different hard and soft litho-units of the area. The similar orientation of Jaramara scarp and morphology of the Ukra intrusive body suggests that the Ukra intrusive played a significant role in controlling the formation and morphology of the Jaramara scarp.
基金Under the auspices of Natural National Science Foundation of China(No.41671002,41401002)
文摘The interaction between fluvial and aeolian processes can significantly change surface morphology of the Earth. Taking the Horqin Sandy Land as the research area and using Landsat series satellite remote sensing images, this study utilizes geomorphology and landscape ecology to monitor and analyze the aeolian geomorphology characteristics of the Horqin Sandy Land. Results show that the sand dunes of the Horqin Sandy Land are mainly distributed on alluvial plains along the banks of the mainstream and tributaries of the Western Liao River, and the sand dune types tend to simplify from west to east and from south to north. The aeolian geomorphology coverage tend to be decreasing in the past 40 years, with an average annual change rate of 0.31%. While the area of traveling dunes decreased, the area of fixed and semi-fixed dunes increased. The fractal dimensions of various types of sand dune have all remained relatively constant between 1.07 and 1.10, suggesting that they are experiencing a relatively stable evolutionary process. There is a complex interaction between fluvial and aeolian processes of the Horqin Sandy Land, which plays a central role in surface landscape molding. Sand dunes on both sides of different rivers on the Horqin Sandy Land present certain regularity and different characteristics in terms of morphology, developmental scale, and spatial pattern. There are six fluvial-aeolian interaction modes in this area: supply of sand sources by rivers for sand dune development, complete obstruction of dune migration by rivers, partial obstruction of dune migration by rivers, influence of river valleys on dune developmental types on both sides, influence of river valleys on dune developmental scale on both sides, and river diversion due to obstruction and forcing by sand dunes. This study deepens our understanding of the surface process mechanism of the interaction between fluvial and aeolian processes in semi-arid regions, and provides a basis for researches on regional landscape responses in the context of global environmental change.
基金funded by the Second Tibetan Plateau Scientific Expedition and Research Program(2019QZKK0902)the National Natural Science Foundation of China(91747207,41790434)。
文摘Large-scale rock-ice avalanches resulting from the interaction of tectonics and climate are characterized with high mobility,huge volumes of sediment,and rapid denudation,being a major agent of landscape evolution in high altitude mountainous regions.Specifically,the extreme glaciated slope failures often transform into extraordinarily large and mobile debris flows,resulting in disastrous consequences such as sedimentation and desertification.Due to a dearth of on-site observation data and experimental data collection,our comprehension of the geomorphic and kinematic characteristics of rock-ice avalanches remains poor.Here we report a cluster of ancient rock-ice avalanches spreading along the Chomolhari range of the China-Bhutan Himalayas.By integrating remote sensing image interpretation with detailed field investigations,we demonstrate the geomorphic and sedimentary characteristics of four events among the avalanches.The estimated volumes of the four are 23.73 Mm³,39.69 Mm³,38.43 Mm³,and 38.25 Mm³,respectively.The presence of pre-existing moraines or alluvial fans constrained their movement,resulting in deposition features such as marginal digitated lobes at higher elevations and large depressed areas in the interior.Applying the Savage-Hutter theory,we calculate the basal friction angle and travel angle of these ancient rock-ice avalanches that are both less than 10°,affirming the similarity of these avalanches in the study area to those occurring in other regions.Our study significantly contributes to understanding the geomorphic and kinematic characteristics of rock-ice avalanches in high-altitude mountainous regions,providing valuable insights into their response to the disproportionate growth of Himalayan peaks.
基金supported by the Doctoral INPh INIT Retaining Fellowship(LCF/BQ/DR22/11950023)from la Caixa Foundation(ID 100010434,Barcelona,Spain)with additional funding through grant PID2021127241OB I00 from the Spanish Ministry of Science and Innovation/Agen-cia Estatal de Investigación(MCIN/AEI/10.13039/501100011033)co funded by the European Regional Development Fund(ERDF)under the A Way of Making Europe。
文摘Land use/land cover(LULC)change monitoring is critical for understanding environmental and socioeconomic processes and to identify patterns that may affect current and future land management.Forest cover evolution in the Mediterranean region has been studied to better understand forest succession,wildfires potential,and carbon stock assessment for climate change mitigation,among other reasons.However,though multiple sources of current LULC exist,data from last century's forest cover are less common,and are normally still reliant on locally orthophoto-interpreted data,making continuous maps of historical forest cover relatively uncommon.In this work,a pipeline based on image segmentation and random forest LULC modeling was developed to process three high resolution orthophotos(1956,1989,and 2021)into LULC continuous land cover maps of Spain's island of Ibiza.Next,they were combined to quantify forest evolution of Mediterranean Aleppo pine(Pinus halepensis Mill.)and to generate a continuous map of forest age classes.Our models were able to differentiate forestland with an accuracy higher than 80%in all cases,and were able to approximate forestland cover change since the mid-twentieth century,estimating 21,165±252 ha(37.0±0.4%)in 1956,27,099±472 ha(46.8±0.8%)in 1989,and 30,195±302 ha(52.8±0.5%)in 2021,with a mean increase of 139±6 ha(0.46±0.02%,calculated from current forest cover estimate)per year.The most important variables for the identification of the forestland were the terrain slope and the image gray level or color information in all orthophotos.When combining the information from the three periods,the analysis of forest evolution revealed that a significant portion of current forest cover,approximately 15,776 ha,fell within the 75-120 year age range,while 5388 ha fell within the range of 42-74 years,and 9022 ha within the 10-41 years forest age class.Younger forests,except when mapped after known wildfires,were not considered due to the limitations of the methodology.When compared to forest age data based on ground measurements,significant differences were found among each of the remotely sensed forest age classes,with a mean difference of 13 years between the theoretical age class central value and the real observed plot average age.Overall,63%of the forest inventory plots were assigned with the correct forest age class.This work will allow a better understanding of long-term Mediterranean forest dynamics and will help landowners and policymakers to better respond to new landscape planning challenges and achieve sustainable development goals.
基金supported by the National Natural Science Foundation of China(Grant Nos.42030305,W2411033)the National Key Research and Development Project(Grant No.2024ZD1001105)the State Key Laboratory of Earthquake Dynamics and Earthquake Prediction(Grant No.LED2022A03)。
文摘The Tibetan Plateau is bounded by the Altyn Tagh left-lateral strike-slip fault system in the northwest,unlike the common thrust fault-bounded margins in the south or east.Quantifying surface denudation rate along this enigmatic margin is important for understanding tectonic-geomorphic evolution and deep dynamic processes at margins of the Tibetan Plateau.In this study,we collected modern river sand samples from 29 drainage basins along the eastern section of the Altyn Tagh fault zone and analyzed the concentrations of terrestrial in-situ cosmogenic nuclides26Al and10Be.The26Al-10Be paired-nuclide method is effective in verifying the assumptions of steady-state denudation and short-term sediment transportation time in these basins,thereby ensuring the reliability of derived denudation rates.We found that10Be-derived basin-wide denudation rates range from15 to 610 mm kyr^(-1).Denudation rates are notably enhanced in locations with structural complexities that allow enhanced vertical uplift along this strike-slip fault system,such as restraining double bends and kinematic transition zones of fault junctions,and that the local topography becomes significantly steeper.This finding indicates that local tectonic uplift is the dominant factor governing topographic relief,as well as the intensity and spatial distribution of surface denudation.Basin-wide denudation rates exhibit a non-linear positive correlation with slope gradient,topographic relief,and channel steepness index(k_(sn)),suggesting that topographic indexes constitute robust proxies for estimating denudation rates in this region.Conversely,no discernible correlation was detected between denudation rates and rainfall or vegetation indices.Moreover,the spatial heterogeneity in rock type and thus erodibility exert non-negligible effects on surface denudation and landscape evolution,particularly in areas where tectonic uplift is less dominant.Our study provides for the first time millennial basin-wide denudation rates and their spatial distribution patterns along the northwestern margin of the Tibetan Plateau,and reveals the interplay between surface denudation and tectonic deformation along the Altyn Tagh fault.The results thereby fill an important knowledge gap in understanding surface processes across the poorly-understood plateau's northwestern margin.
基金financially supported by the Key Program of National Natural Science Foundation of China(No:42230107)the Strategic Science and Technology Talent Cultivation Special Project of Hubei Province(2024DJA012)
文摘Background Ecological land evolution is pivotal in shaping regional landscapes and ecosystem functions.However,existing metrics are limited in quantifying patch-scale dynamics of connectivity and fragmentation during the processes of ecological land degradation and restoration.This study introduces the Ecological Land Evolution Index(ELEI),a novel framework integrating spatial proximity and connectivity to evaluate spatiotemporal complexities of ecological land changes at the patch level.By incorporating adjacency rules and continuous value systems,ELEI offers a granular analysis of connectivity-fragmentation tradeoffs,addressing limitations in traditional landscape metrics.Results Using four temporal land use datasets(1990–2020)from the urban agglomeration in the middle reaches of the Yangtze River(UAMRYR)in China,we applied ELEI to characterize ecological land restoration(ELR)and degradation(ELD).Sensitivity analysis confirmed ELEI’s robustness,identifying connected patch area and spatial proximity as primary drivers.Monte Carlo simulations validated formula stability,highlighting symmetrical responses to connectivity changes but residual uncertainties in extreme scenarios(|ELEI|>60).Additionally,the results demonstrate significant spatiotemporal heterogeneity in ecological land evolution.Degradation of ecological land initially intensified from 2000 to 2010,but then decelerated from 2010 to 2020,while the restoration process first weakened and subsequently strengthened.Notably,the area of degraded ecological land steadily expanded throughout the study period,reaching 17,684.20 km^(2) between 1990 and 2020,while the restored area totaled 12,025.56 km^(2).Fragmentation dominated degradation processes,while connection patterns drove restoration.Urban centers like Wuhan and Changsha experienced severe fragmentation aligned with rapid urbanization,whereas cities such as Yichang,Hengyang,and Jiujiang achieved significant restoration via infilling and connection.Conclusions ELEI provides a nuanced understanding of ecological land dynamics in rapidly urbanizing regions by identifying restoration successes and ongoing degradation hotspots.Additionally,the integration of ELEI variants(arithmetic mean ELEI(MELEI)and area-weighted mean ELEI(AWMELEI))highlights their value in tracking long-term connectivity trends and degradation processes.This framework offers actionable insights for balancing urban development and conservation,underscoring its value in regional planning and sustainable landscape management.
基金supported jointly by National Science Foundation of China (Grant Nos. 40702028, 41030317)State Key Laboratory of Earthquake Dynamics (Grant Nos. LED2009A06,LED2008A02)Zhang Huiping was also supported as a visiting professor to CU by China Scholarship Council (Grant No. 2007106279)
文摘Initiation and recession of the knickpoints are significant boundary condition for processes of fluvial system. The distribution and recession rates of knickpoints contain information that provides a fundamental understanding of geomorphic processes. In the Yalu River-Wangtian＇e volcanic region of northeastern China, broadly distributed fiat lava terrain provides an ideal site to study the recession of fluvial knickpoints because knickpoints and waterfalls are well preserved here. Here we describe the distribution of knickpoints in the Yalu River-Wangtian＇e volcanic region by combining DEM analysis and numerical modeling Furthermore, we present a knickpoint celerity model, derived from stream-power incision model, to relate knickpoint recession rate to drainage area. We calibrate important empirical coefficients with our knickpoint celerity model; the best fit erosion coefficient （K） is 1.32×10^-8, and the best fit drainage area exponent （m） is 0.69. Error analysis indicates a close correspondence between synthetic and real knickpoints. Finally, we show that knickpoint recession rates in the Yalu River-Wangtian＇e volcanic region are -1-10 mm/a during the early stages of transient incision, and that the present rates are -1-6 mm/a. Our recession rate results are in good agreement with previous findings from the Aso Volcano and volcanoes near Boso Peninsula （Japan）, which have a similar geologic history to the Yalu River-Wangtian＇e volcanic region. Our present effort provides new insight into landscape evolution in the Yalu River-Wangtian＇e volcanic region in northeastern China.
