Subjects: Geosciences >> Geography submitted time 2024-07-04 Cooperative journals: 《干旱区研究》
Abstract： Net Ecosystem Productivity (NEP) is a crucial indicator for assessing the arbon sequestration capacity of terrestrial ecosystems, and Land Use/Cover Change (LUCC) is a key factor influencing regional differences in carbon uptake. Analyzing the trends of LUCC and NEP is essential for achieving regional carbon peaking and carbon neutrality goals. Based on the LUCC and MODIS remote sensing data from 2000 to 2020 in the Aksu River Basin, the annual average carbon sequestration rate of each land use/cover type in the region was estimated. The LUCC for the next 40 years was simulated by the PLUS model, and the spatial and temporal trend of NEP for the next 40 years in the river basin was predicted. The results show that: (1) the total NEP in the basin has shown an increasing trend in the past 20 years, with an uptake rate of 0.136 Mt C·(10a)-1, and the average carbon sequestration rate of forest area is the highest; (2) the total carbon uptake in the Aksu River Basin will continue to increase in the future 40 years. The increase in forest area is the main way of increasing carbon uptake in the Aksu River Basin, and the positive role of ecological protection projects plays a key role in this process.
Subjects: Geosciences >> Geography submitted time 2024-07-04 Cooperative journals: 《干旱区研究》
Abstract： Lakes, as integral components of terrestrial ecosystems, are vital for regional economic growth and ecological security. Previous studies have primarily focused on typical or large lakes in the Xinjiang region, with comparatively less attention given to smaller lakes. This study analyzed the areal dynamics of 74 small and medium-sized lakes in Xinjiang from 1991 to 2020, conducting a comprehensive analysis of lakes at varying altitudes and with diverse geographical characteristics. The research uncovered that during 1991-2020, the total area of lakes in Xinjiang expanded from 167.98 km² to 400.51 km², with the most significant growth observed in mountainous lakes. Monthly scale analysis revealed pronounced seasonal characteristics in the areal changes of these mountainous lakes. Statistical analysis indicated divergent responses of lakes at different altitudes to climatic changes. The substantial enlargement of lakes in Xinjiang’s mountainous regions is primarily attributed to climate change, particularly the rise in average annual temperatures. In the plains, human activities, especially irrigation, were identified as the primary drivers of lake area changes, while the impact of climatic factors was relatively minor.
Subjects: Geosciences >> Geography submitted time 2024-07-04 Cooperative journals: 《干旱区研究》
Abstract： Soil nitrogen mineralization is a key process of soil nitrogen cycle, and temperature is one of the most important factors affecting soil nitrogen mineralization. Studying the effect of temperature on soil nitrogen mineralization characteristics in different successional stages is of great significance for understanding soil nitrogen cycle in terrestrial ecosystems. In this study, the communities in different successional stages of Xinglong Mountain in Gansu Province were taken as the research object. The indoor constant temperature aerobic culture method was used to study the soil nitrogen mineralization characteristics of five successional stages (grassland, shrub forest, Betula platyphylla forest, Picea wilsonii-Betula platyphylla forest and Picea wilsonii forest) under different temperatures (15 ℃, 25 ℃, 35 ℃). The results showed that: (1) Except for the 0~20 cm soil depth of grassland, the soil nitrogen mineralization rate of the other successional stages increased with the increase of temperature (15~35 ℃), and the cumulative mineralization of soil nitrogen in different successional stages increased with the increase of temperature. (2) With the positive advancement of succession, the soil nitrogen mineralization rate and cumulative mineralization amount of different successional stages showed a trend of increasing first and then decreasing. The soil nitrogen mineralization rate of Betula platyphylla forest was the highest, which was 1.63 times, 1.61 times, 1.25 times and 1.47 times that of grassland, shrub forest, Picea wilsonii-Betula platyphylla forest and Picea wilsonii forest, respectively. The soil nitrogen mineralization rate and cumulative mineralization amount of Picea wilsonii-Betula platyphylla forest were the highest, which were 0.68 times, 0.72 times, 0.84 times and 0.97 times of those of grassland, shrub forest, Betula platyphylla forest and Picea wilsonii forest, respectively. (3) With the increase of soil depth, the soil nitrogen mineralization rate and cumulative mineralization showed a decreasing trend, with the maximum in the 0~20 cm soil depth. (4) There were significant differences in the temperature sensitivity coefficient Q10 at 15 ℃ and 25 ℃ in different successional stages (P<0.05). With the positive succession, the temperature sensitivity coefficient Q10 decreased first and then increased. There was no significant difference in the temperature sensitivity coefficient Q10 between the communities at different succession stages at 25 ℃ and 35 ℃ (P>0.05). The results of this study will provide a theoretical basis for the evolution of soil quality and the dynamic change of soil nitrogen supply capacity in the community.
Subjects: Geosciences >> Geography submitted time 2024-07-04 Cooperative journals: 《干旱区研究》
Abstract： In order to study the characteristics of hydrochemistry and groundwater recharge in Hotan River Basin, this study analyzed the characteristics of water chemical composition, main recharge sources and mutual transformation of water bodies (well, pond and river) in different geomorphic units by using SPSS statistical analysis, Piper diagram, Gibbs diagram and isotope tracing methods(D, 18O and 14C). The results showed that: (1) The water bodies mainly originated from the ice and snow meltwater and atmospheric precipitation in the middle and high mountainous areas above 2000m in the south. From the mountains to the desert, the groundwater chemical type and salinity had obvious zonal characteristics. The pH value of different water bodies were weakly alkaline, and the ion composition and TDS value were different, with the overall order of pond > well > river. The NO3- content of some groundwater samples were significantly abnormal. (2) The groundwater in the gravel plain area mainly received vertical and disconnected recharge from surface river water. The groundwater had a fast renewal rate, low salinity and main water-rock interaction, mostly SO4•Cl–Ca•Mg type. (3) The TDS value of groundwater in the fine soil plain area had a large range, mostly as the Cl•SO4–Na type. In the inter-river block, the groundwater near the upstream received surface water and lateral runoff from adjacent areas, and the 14C age was small. “Drift Oxygen” of δD and δ18O isotope in the groundwater of the middle and lower reaches was generally appeared. The 14C age of groundwater in the watershed was large, and the age was small near the riverbank. The relation between the groundwater and river was close. On both sides of the inter-river block, the groundwater runoff flowed along the northeast and northwest directions respectively, and finally discharged into the peripheral desert area.The research results can provide theoretical basis for reasonable development and utilization of water resources and ecological environment protection in Hotan River Basin.
Subjects: Geosciences >> Geography submitted time 2024-07-04 Cooperative journals: 《干旱区研究》
Abstract： Ningxia is an important region in Northwest China. Thus, it is imperative to study land use change and its impact on ecosystem services to improve the ecological environment of Ningxia and put forward environmental protection measures for the future. However, previous studies have primarily focused on the changes in the ecosystem services during historical periods but lacked a prediction of the ecosystem services and their trade-offs and synergistic relationships under future scenarios. Therefore, this study simulated the land use status under three future scenarios, quantified the four ecosystem services of carbon storage, soil conservation, water yield, and grain yield under the different land use types, an d ascertained their trade-offs and synergies at various spatial scales. The main conclusions are as follows: in the future, the water yield of the three scenarios was lower than that of the current year, and the soil conservation and carbon storage were th e largest in the ecological protection scenario, reaching 7.98×107and 4.72×107tons, respectively. In contrast, the grain yield was the largest in the farmland protection scenario, reaching 1.52×107tons. The trade-off relationship between ecosystem services mainly occurred between the regulating and supplying services and the synergy relationship between the regulating services. At the provincial scale, only carbon storage and soil conservation services demonstrated a high synergistic relationship; at the regional and county scales, the synergy between water yield and carbon storage services was also remarkable.
Subjects: Geosciences >> Geography submitted time 2024-07-04 Cooperative journals: 《干旱区研究》
Abstract： Established leaf nitrogen concentration (LNC) is the response of crop photosynthesis, an important index of nutrition and growth. To accurately and efficiently estimate different growth period of winter wheat LNC, with the new winter 22 as the research object, using the (UAVs) Pika L hyperspectral cameras for four key growth period of winter wheat canopy reflectance data. The LNC-sensitive spectral index was screened based on the band optimization algorithm and correlation analysis. Stepwise regression, multiple linear regression, and partial least squares regression were combined to establish the estimation model of winter wheat LNC in each key growth stage, which was compared with the single variable estimation model. The results showed that (1) the correlation between the combined spectral index screened using the band optimization algorithm and LNC was stronger than that obtained using the traditional vegetation index and was extremely significant; (2) the combined spectral index in the single variable LNC estimation model allowed to obtain a more accurate model compared with the traditional vegetation index, including Yang flowering DSI(R940, R968) estimate model is set up, best R²of 0.789. The multi-variable estimation models were more accurate than the single variable estimation models and, among them, the LNC estimation model based on partial least squares regression was the best, and the fitting effect of the booting and flowering stages was better. This model had a coefficient of determination of 0.923 and rootmean-square errors of 0.082 and 0.084. The results of this study provide a theoretical basis and technical support to estimate the LNC of winter wheat and monitor its growth.
Subjects: Geosciences >> Geography submitted time 2024-07-04 Cooperative journals: 《干旱区研究》
Abstract： In order to explore the spatial-temporal dynamic change characteristics and driving factors of ecological environment in Yanchi County. Taking remote sensing images from 1990 to 2020 as data source, on the basis of the SA-RSEI. Combined with Theil-Sen Median analysis, Mann-Kendall significance test and Hurst index, the spatial-temporal variation pattern and change trend of ecological environment quality in Yanchi County were analyzed. The driving factors of ecological environment quality in Yanchi County were explored by using Geography Detector. The results showed that: (1) SA-RSEI in Yanchi County decreased first and then increased from 2000 to 2020. (2) The ecological environment quality of Yanchi County showed an evolution process of degradation first and then recovery in 21 years. The spatial distribution pattern gradually changed from poor in the south and good in the north to good in the southeast and poor in the northwest. (3) During the 21 years, the ecological environment quality of Yanchi County generally showed a slow degradation trend, but the degree of degradation gradually decreased, and the degree of ecological environment improvement will gradually increase after 2020. (4) DI, precipitation, elevation, and GDP are the main factors influencing the spatial variation in regional ecological quality. (5) The interaction between DI, temperature, precipitation and elevation and other detection factors plays a leading role, the influence of economic factors on SA-RSEI gradually increases.
Subjects: Geosciences >> Geography submitted time 2024-07-04 Cooperative journals: 《干旱区研究》
Abstract： It is of great significance for scientific management and efficient utilization of water resources in the basin to deeply explore the information of internal conversion process of land use types, measure the impact of land use change intensity on evapotranspiration, and accurately evaluate the temporal and spatial variation of ET. Based on the intensity analysis model, the intensity change characteristics of land use types at different levels in the Aksu River Basin from 2000 to 2020 and their impact on the actual evapotranspiration of the basin were revealed. The results showed that : ( 1 ) At the time interval level, the intensity of land use change in the basin increased first and then decreased, and the change was the most active from 2000 to 2005. At the land type level, the increase and decrease of cultivated land, construction land, water area and forest land area are more active. The increase of cultivated land area at the transfer level mainly comes from grassland ( 54.31% ) and unused land ( 26.26% ). ( 2 ) The average annual evapotranspiration of the basin is 166.56 mm. The interannual fluctuation is large, and the overall trend is increasing, with an annual growth rate of 3.68 mm·a-1. Evapotranspiration from April to October accounted for 71.76% of the annual evapotranspiration. The high value of actual evapotranspiration is distributed in mountainous forest land and cultivated land in plain area, and the low value area is distributed in piedmont desert area and oasis and desert transition zone. ( 3 ) The results of principal component analysis show that the driving force of ETa change in Aksu River Basin is the conversion intensity of grassland, cultivated land and unused land. The correlation coefficient between land use change intensity and actual evapotranspiration is 0.87, and there is a strong correlation between the two.
Subjects: Geosciences >> Geography submitted time 2024-07-04 Cooperative journals: 《干旱区研究》
Abstract： Based on the measured annual and monthly runoff data of Huining, Guochengyi and Jingyuan stations in the main stream of Zuli River from 1957 to 2021, the variation characteristics and driving factors of runoff at different time scales in Zuli River Basin were analyzed by linear tendency estimation, Mann-Kendall test and wavelet analysis. The results showed that: which are mainly influenced by human activities and climatic factors. (1) The runoff of the main stream of the Zuli River showed a decreasing trend from 1957 to 2021, and the runoff has decreased by 52.9% over the past 30 years. (2) The measured annual runoff of the three hydrological stations of Huining, Guochengyi, and Jingyuan underwent abrupt changes in 1992, 1984, and 1994, respectively. (3)Runoff and precipitation showed similar cycles of abundant and low state at the three stations of the main stream of Zuli River. The analysis results show that the reduction of measured annual runoff in the main stream of the Zuli River is mainly affected by human activities such as soil and water conservation measures, followed by climatic factors such as the reduction of precipitation, of which human activities and climate change contribute to the reduction of runoff by 74.47% and 25.53%, respectively.
Subjects: Geosciences >> Geography submitted time 2024-07-04 Cooperative journals: 《干旱区研究》
Abstract： High-resolution time-series remote sensing plays a vital role in monitoring glacier changes. In this paper, Sentinel-2 multitemporal satellite images from 2016-2022 were used along with the D-UNet semantic segmentation model to extract the glacier change information of Yilian Habirga. These results were compared with the Landsat remote sensing data of the similar temporal phase to ascertain any differences in the accuracies of Sentinel-2 and Landsat for glacier mapping. Based on these findings, 75 typical glaciers were selected to analyze the change- related characteristics of the total glacier area and glacier end in the recent study area. The results show that (1) The overall accuracy of Sentinel-2 glacier mapping was 95.0%,which is 5%-10% higher than Landsat-8 under the same conditions. (2) The average area retreat rate of glaciers in the study area from 2016 to 2022 was 0.75%±0.69%·a-1, in which the region<4600 m above sea level was that of glacier area reduction; the lower the altitude, the greater the area retreat rate. (3) In the last 6 years, the average heights of the 75 typical glacier ends rose by 17.75 m, and the average lengths reduced by 11.39 ± 2.36 m·a-1. Among these, the retreats in the west, northeast, and south were the most significant, which were 15.49 ± 2.36 m·a- 1, 13.95 ± 2.36 m·a- 1 , and 13.14 ± 2.36 m·a-1, respectively; the rate of the glacier end retreated with an increase in the elevation and the decreased.
Subjects: Geosciences >> Geography submitted time 2024-07-04 Cooperative journals: 《干旱区研究》
Abstract： Severe freezing injury has a significant impact on the growth and development of walnuts (Juglans regia), even leading to plant death in some cases. This study employed the sample method to examine the freezing injury to J. regia in the Wild Walnut Nature Reserve located in the West Tianshan valley in Xinjiang. The distribution characteristics of freezing injury among J. regia were analyzed, and the influence of tree height, crown width, and slope position on the extent of freezing injury was investigated. The results indicated that (1) the total freezing injury rate of J. regia was 87.1%. Among these, the proportion of plants with grade 2 freezing injury was the largest (43.4% ), followed by grade 1 (22.5% ), grade 3 (17.5% ), and grade 4 (3.7% ). (2) the proportion of freezing injury in J. regia plants was the largest in the middle of slope (46.5%), followed by the bottom (35.9%), and the top (4.7%); the proportion of uninjured plants was the maximum at the top of slope (7.4%), followed by the bottom (3.3%), and the middle (2.2%). (3) the proportion of freezing injured plants in the six height classes (H) was most prominent in H1 (43.4% ), followed by H4 (19.5% ), H6 (17.0% ), H5 (15.7% ), H3 (4.3% ), and H2 (0.1%). (4) the proportion of freezing injured plants in the six crown width classes (CW) was most extensive in CW1 (43.4%), followed by CW4 (22.1%), CW3 (20.3%), CW5 (9.5%), CW2 (2.9%), and CW6 (1.8%). (5) the proportion of freezing injured plants in different H and CW classes at the same slope position differed significantly (P<0.05). Plants with grade 1 and 2 freezing injuries were mainly restricted to the middle and bottom of the slope, and those with grade 3 and 4 injuries to the middle. (6) freezing injury in plants was markedly correlated with diameter at breast height (P<0.05) and extremely negatively correlated with CW (P<0.01). Most J. regia plants in the Reserve suffered from freezing injury, and the proportions of freezing injury grades varied conspicuously among the different slope positions，and different H and CW classes. The results of this study provide a scientific reference for the management of the Wild Walnut Nature Reserve and the prevention of freezing injury in J. regia.
Subjects: Geosciences >> Geography submitted time 2024-07-04 Cooperative journals: 《干旱区研究》
Abstract： Human activity is an important factor in the intensification of regional ecological risk, so it is urgent to discuss the impact of human activity intensity on landscape ecological risk. This paper takes the Tarim River basin as the research object, and based on the data of land use, population spatial distribution and night light in five periods from 2000 to 2020, introduces the comprehensive index of land use degree to improve the evaluation system of human activity intensity (HAI), and quantitatively evaluates the temporal and spatial changes of landscape ecological risk (LER) in the basin under strong human activity. Combined with Copula function and bivariate local spatial autocorrelation model, the spatio-temporal correlation between LER and HAI is revealed. The results showed that: (1) The HAI in the Tarim River Basin increased significantly in the past 20 years, and strong human activities were mainly distributed in the oasis areas with rich water resources. The intensity of human activities in the basin showed an increasing trend, with the proportion of low intensity area decreasing by 17.88% and the proportion of medium-high intensity area increasing by 3.57%. (2) The overall LER in the Tarim River Basin was characterized by high surrounding area and low central area, and the high-risk area was mainly distributed in the oasis areas with more frequent human activities. The LER in the basin showed an intensifying trend before 2015, but the intensifying trend slowed down after 2010, and the improvement trend gradually emerged after 2015. (3) The HAI and LER were positively correlated in the past 20 years, and the positive effect of human activities on LER was increasing. After 2010, the increasing trend of the relationship between the two tended to be flat, and the positive effect appeared in a transition stage from increasing to decreasing. The H-H cluster area showed an increasing trend in space, and the distribution pattern changed from dispersion to concentration. After 2015, the L-L and H-L cluster areas slowly increased, and the L-H cluster area slowly decreased. The results can provide scientific reference for the rational use of land resources and landscape ecological protection in the Tarim River Basin.
Subjects: Geosciences >> Geography submitted time 2024-07-04 Cooperative journals: 《干旱区研究》
Abstract： This study aimed to clarify the carbon sequestration capacity and its change mechanisms in the dry- lands of China. The study used the AI index to delineate the extent of drylands. Based on the MODIS Vegetation Gross Primary Productivity (GPP) dataset, the temporal and spatial characteristics of vegetation carbon sequestra- tion capacity in China’s drylands from 2001 to 2020 were investigated. This investigation considered meteorolog- ical data, including temperature, precipitation, vapor pressure deficit (VPD), soil water content, and human activi- ties such as land use. The results reveal the following: (1) Over the 20-year period, GPP in China’s drylands ele- vated significantly in 64.72% of the regions. (2) Temperature had the lowest impact on GPP, with a relative contri- bution rate of 21.7%. Precipitation and soil water content emerged as the dominant factors driving GPP growth, with their combined contribution rate exceeding 55%. As drought intensified, the effect of water stress gradually strengthened. In different vegetation types, except for mixed forests and alpine vegetation, precipitation was the most critical climate factor influencing GPP changes. (3) Differences in soil and landform types were the domi- nant factors influencing the spatial variation of GPP. Moisture and land use type factors also played important roles, with the explanatory power of the interaction between any two factors exceeding that of a single factor. The interaction between soil type and the other factors was particularly remarkable. The study’s findings hold essen- tial theoretical implications for a deeper understanding of the evolution characteristics of carbon sinks in arid eco- systems in China and their response mechanisms to external environmental factors.
Subjects: Geosciences >> Geography submitted time 2024-07-04 Cooperative journals: 《干旱区研究》
Abstract： Net Primary Productivity (NPP) is an essential indicator of the terrestrial carbon (C) cycle, which can reflect the carbon sink capacity of terrestrial ecosystems. In the face of China’s“double carbon”goal of“carbon peak”and“carbon neutrality,”improving the carbon sequestration capacity of the terrestrial ecosystems is one of the crucial ways. Due to its vast geographical area and considerable vegetation restoration potential, it is of great practical significance to evaluate the current situation of carbon sequestration in Xinjiang and explore the potential of carbon sequestration so as to respond positively and realize the national“double carbon”goal. This study combined the Carnegie Ames Stanford Approach (CASA) model with the land use, remote sensing, and meteorological (temperature, precipitation, and solar radiation) data, and NPP in Xinjiang from 2001 to 2020 for the simulation. The Sen-MK method was used to analyze the trend in NPP changes. Pearson correlation analysis was used to identify the relationship between NPP variations and climatic factors. Further, different land use and vegetation scenarios from 2001 to 2020, as well as the pattern of NPP variations under pure climate scenarios simulated by the Miami model, were used to derive the final maximum potential of NPP and the maximum increment of NPP in Xinjiang. The results showed that: (1) The NPP in Xinjiang showed an upward trend with fluctuations from 2001 to 2020; (2) Among the climatic factors, precipitation had the maximal impact on NPP in Xinjiang; (3)Among the primary land use types in Xinjiang, cultivated land had a large NPP which showed an increasing trend; (4) The increment potential of NPP in Xinjiang was 79.43 g C·m−2. This study can provide a reference for Xinjiang to respond to the national call for“carbon peak”and“carbon neutrality”and to implement ecological restoration and cultivated land protection measures.
Subjects: Geosciences >> Geography submitted time 2024-07-04 Cooperative journals: 《干旱区研究》
Abstract： Change in land use profoundly impacts ecological development, posing a consequential threat to the sustainable progress of society, civilization, economy, and the environment. Based on high-precision land use data from 2000 to 2020, this study delves into the spatiotemporal evolution of land use and ecosystem service value (ESV) in the Lha sa River Basin. By employing PLUS models and geographic detectors, the driving factors of land use alterations and the spatial differentiatio n of ESV were explored. The findings reveal that (1) The predominant land use in the Lhasa River Basin was grasslan d from 2000 to 2020, constituting 85.23% of the total basin area, indicating a trend of grassland reduction and expansion of other l and types; specifically, the grasslands decreased by 2.45%, while construction land, water area, and forest land expanded by 199.72%, 44.64%, and 21.97%, respectively. (2) The change in land use within the watershed was intricately influenced by factors such as altitude, annual average ground temperature, and distance from lakes and reservoirs. Altitude, in particular, exhibited a substantial contribution to the expansion of water bodies and cultivated, forest, and construction lands, with respective values of 0.28, 0.18, 0.11, and 0.13. Slope and annual average ground temperature contributed significantly to changes in grass and unused lands, registering values of 0.14 and 0.15, respectively. (3) From 2000 to 2020, the overall ESV of the watershed increased by 1.14% (1.496 billion yuan). Grassland and climate regulation were the land use and ecosystem service types with the most prominent respective contributions of 87.13% and 25.50% to the ESV. (4) Furthermore, the ESV within the watershed exhibited substantial spatial differentiation, influenced by factors including NDVI, altitude, annual average wind speed, and annual average temperature. The explanatory power of NDVI reached a notable 0.46, and the interaction between any two factors accentuated ESV differentiation. These research outcomes provide valuable scientific insights for guiding the spatial planning and ecological and civilizational development of the Lhasa River Basin and analogous regions.
Subjects: Geosciences >> Geography Subjects: Biology >> Ecology Subjects: Law >> Civil and Commercial Law Subjects: Management Science >> Business Management of Department Subjects: Other Disciplines >> Synthetic discipline submitted time 2024-06-19
Abstract： Purpose/significance South Africa is a world famous tourist paradise . A thematic study on how South Africa is developing its tourism industry can provide a useful reference for China. Method/process This paper summarizes South Africa’s experience in tourism development, based mainly on foreign research data and using literature review methods. Result/conclusion In the development of tourism, South Africa has five major successful experiences: first, it has attached great importance to tourism and taken a number of initiatives, including the enactment of the Tourism Act, the introduction of a number of tourism development strategies and plans, and the establishment of the Department of Tourism of South Africa and the South African Tourism; second, it has actively upgraded its hardware and software facilities; third, it has endeavored to diversify its tourism products; fourth, it has put the concept of responsible tourism into practice; and fifth, it has made great efforts to develop its domestic tourism industry.
Subjects: Geosciences >> Geography submitted time 2024-06-12 Cooperative journals: 《干旱区研究》
Abstract： Landscape ecological risk evaluation is an essential tool for measuring the safety of ecosystems within a certain range. Taking the Yarkant River Basin as the study area, we synthesized the Markov-PLUS model and the landscape ecological risk assessment index to analyze and predict the evolution characteristics of land use and landscape ecological risk and the change trends under multiple future scenarios and to delineate the risk focus management regions. The results were as follows: (1) Cultivated land, water, and impervious surface in the Yar-kant River Basin increased, and woodland, grassland, and unused land decreased from 2005 to 2020. In 2035, land use under Scenario I followed the historical development pattern of change. In comparison with Scenario I, cultivated land increased and other land types decreased in Scenario II; woodland, grassland, and water increased and cultivated land, impervious surface, and unused land decreased in Scenario III. (2) From 2005 to 2035, the landscape ecological risk of the Yarkant River Basin as a whole showed an upward trend, and the spatial distribution was characterized by "low in the southwest and high in the northeast." The risk deterioration area was mainly concentrated in the alluvial plains at lower altitudes, and the risk maintenance area was mainly distributed in the mountains and glaciers at higher altitudes. (3) In comparison with Scenarios I and II, Scenario III had a smaller average value of the landscape ecological risk index, and it was the optimal future scenario to achieve a win-win situation for both ecological protection and economic development in the Yarkant River Basin. (4) The alluvial plain in the northeastern part of the Yarkant River Basin was a stable high-risk region, the edges of the alluvial plain and the mountains in the west were risk-prone regions, and the mountains and glaciers in the south were in-creasing-risk lagging regions. The results of this study can provide a reference for the optimization of local landscape ecological security patterns and ecological risk prevention or reduction.
Subjects: Geosciences >> Geography submitted time 2024-06-12 Cooperative journals: 《干旱区研究》
Abstract： There are a large number of rodent mounds in the alpine grassland rodent activity area of the Yellow River source, and soil wind erosion is easy to occur under the influence of dry and windy climate. In order to clarify the characteristics and laws of soil wind erosion in rodent mounds, this study took the Ochotona curzoniae and Myospalax baileyi mounds in 14 test areas at different altitudes and vegetation coverage in the Yellow River source basin as the research objects. The field simulated wind erosion test device was used to analyze and discuss the soil loss and nutrient loss law of rodent mounds in different regions under different wind speeds. results showed: (1)There was a significant difference in the amount of soil wind erosion between different regions ( P<0.05 ). When the wind speed is small, there is no significant difference in soil loss between the two different mounds. When the wind speed increased to 12 m·s-1, the soil loss of plateau pika mound was greater than that of plateau zokor mound ( P<0.05 ). When the wind speed increased from 3 m·s-1 to 12 m·s-1, the average increase of soil loss in the two kinds of mounds was 238.16% and 146.31%, respectively. (2) The wind erosion rate of the mound soil in each test area generally showed a decreasing trend from fast to slow. Vegetation coverage was a significant factor affecting the soil loss of the mound under low wind speed and was related to altitude. (3)With the aggravation of grassland degradation, soil total nitrogen content, available nitrogen, available potassium and organic matter content decreased significantly, while total phosphorus, total potassium and available phosphorus showed an upward trend. This study shows that the difference of soil wind erosion in different regions of the Yellow River source is closely related to soil moisture content, particle size and wind speed.
Subjects: Geosciences >> Geography submitted time 2024-06-12 Cooperative journals: 《干旱区研究》
Abstract： This study analyzed the land use structure, dynamics, intensity, and land use conversion of the agro-pastoral ecotone of Gansu Province from 2000 to 2020 using remote sensing (RS), geographic information system (GIS), and Geodetector in combination with social and economic data. (1) From 2000 to 2020, cultivated land, forest land, and grassland were the main land use types in the agro-pastoral ecotone of Gansu Province, and the total proportion of the three was more than 95%. The difference degree of land use structure was less than 0.01, and the structure was generally stable. The overall land use change initially increased and subsequently slowed down over time. (2) The conversion of cultivated land, forest land, and grassland accounted for more than 96% of the total conversion area in the agro-pastoral ecotone of Gansu Province. Land use conversion was observed among all land use types. Converted cultivated lands were mainly converted to forest land and grassland, whereas other land use types were converted to construction land. Land use type changes were mainly concentrated in the Loess hills in central Gansu and the Loess Plateau gully region in eastern Gansu. (3) In the context of l ong term land use changes, Geodetector demonstrated good applicability. The driving factors for land use changes in the farming–pastoral ecotone of Gansu varied during different periods. These changes were driven by a combination of socioeconomic factors and natural geographic factors, with the former having stronger explanatory power for land use change. Interactions among these factors exhibited either two-factor enhancement or nonlinear enhancement. Two-factor interactions had stronger explanatory power for land use changes than single-factor explanations.
Subjects: Geosciences >> Geography submitted time 2024-06-12 Cooperative journals: 《干旱区研究》
Abstract： In the present study, clay sand barrier–artificial Haloxylon ammodendron plantations and a mobile sand site (control) in the Minqin desert area were used to investigate the plant species composition, species importance value, dominan t species characteristics, species diversity, and soil moisture content. This study explored the long term effects of clay sand barrier–artificial Haloxylon ammodendron plantation construction on regional plant community structure, species diversity, and soil moisture. In total, 12 species belonging to 12 genera and 6 families were recorded in the c lay sand barrier–artificial Haloxylon ammodendron plantations in the Minqin desert area, with Chenopodiaceae and Zygophyllaceae being the dominant families. The construction of the artificial sand control system significantly increased the number of plant species in the region (from 4 species to 5–8 species). With an increase in the installation period, the vegetation structure gradually evolved from Agriophyllum squarrosum and Haloxylon ammodendrine (dominant species) to Grubovia dasyphylla, Kali collinum,Limonium aureum, and Haloxylon ammodendrine (dominant species). The life forms also shifted from a single type dominated by annual herbaceous plants to a composite type consisting of annual herbaceous plants, perennial herbaceous plants, and shrubs. Regarding alpha diversity, species richness index, Shannon–Wiener index, Simpson index, Pielou index, and Alatalo index showed an overall unimodal trend, with the highest species number and most even species distribution observed in the 20-year installation site and the lowest species number and most uneven species distribution observed in the control sand site. The Jaccard index of plant community similarity between neighboring sites with various installation periods showed the following order: control sand site > 1-year installation site > 20-year and 40-year installation sites > 1-year and 5-year installation sites > 10-year and 20-year installation sites > 40-year and 60-year installation sites > 5-year and 10-year installation sites. The dissimilarity index and Cody index showed the opposite trend. The fluctuation pattern of the regional soil moisture content was consistent with the trend of plant community succession. Compared with deeper soil layers (40 –60 cm), the role of shallow soil layers (10–30 cm) in the natural succession process of regional plants was more pronounced.
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