In the restoration of degraded wetlands,fertilization can improve the vegetation-soil-microorganisms complex,thereby affecting the organic carbon content.However,it is currently unclear whether these effects are susta...In the restoration of degraded wetlands,fertilization can improve the vegetation-soil-microorganisms complex,thereby affecting the organic carbon content.However,it is currently unclear whether these effects are sustainable.This study employed Biolog-Eco surveys to investigate the changes in vegetation characteristics,soil physicochemical properties,and soil microbial functional diversity in degraded alpine wetlands of the source region of the Yellow River at 3 and 15 months after the application of nitrogen,phosphorus,and organic mixed fertilizer.The following results were obtained:The addition of nitrogen fertilizer and organic compost significantly affects the soil organic carbon content in degraded wetlands.Three months after fertilization,nitrogen addition increases soil organic carbon in both lightly and severely degraded wetlands,whereas after 15 months,organic compost enhanced the soil organic carbon level in severely degraded wetlands.Structural equation modeling indicates that fertilization decreases the soil pH and directly or indirectly influences the soil organic carbon levels through variations in the soil water content and the aboveground biomass of vegetation.Three months after fertilization,nitrogen fertilizer showed a direct positive effect on soil organic carbon.However,organic mixed fertilizer indirectly reduced soil organic carbon by increasing biomass and decreasing soil moisture.After 15 months,none of the fertilizers significantly affected the soil organic carbon level.In summary,it can be inferred that the addition of nitrogen fertilizer lacks sustainability in positively influencing the organic carbon content.展开更多
Soil respiration(Rs)is important for transport-ing or fixing carbon dioxide from the atmosphere,and even diminutive variations can profoundly influence the carbon cycle.However,the R_(s) dynamics in a loess alpine hil...Soil respiration(Rs)is important for transport-ing or fixing carbon dioxide from the atmosphere,and even diminutive variations can profoundly influence the carbon cycle.However,the R_(s) dynamics in a loess alpine hilly region with representative sensitivity to climate change and fragile ecology remains poorly understood.This study investigated the correlation and degree of control between R_(s) and its photosynthetic and environmental factors in five subalpine forest cover types.We examined the correlations between R_(s) and variables temperature(T_(10)) and soil moisture content at 10 cm depth(W_(10)),net photosynthetic rate(P_(n))and soil properties to establish multiple models,and the variables were measured for diurnal and monthly vari-ations from September 2018 to August 2019.The results showed that soil physical factors are not the main drivers of R_(s) dynamics at the diel scale;however,the trend in the monthly variation in R_(s) was consistent with that of T_(10)and P_(n).Further,R_(s) was significantly affected by pH,providing further evidence that coniferous forest leaves contribute to soil acidification,thus reducing R_(s).Significant exponential and linear correlations were established between R_(s) and T_(10)and W_(10),respectively,and R_(s) was positively correlated with P_(n).Accordingly,we established a two-factor model and a three-factor model,and the correlation coefficients(R_(2))was improved to different degrees compared with models based only on T_(10) and W_(10).Moreover,temperature sensitivity(Q_(10))was the highest in the secondary forest and lowest in the Larix principis-rupprechtii forest.Our findings suggest that the control of R_(s) by the environment(moisture and tempera-ture)and photosynthesis,which are interactive or comple-mentary effects,may influence spatial and temporal homeo-stasis in the region and showed that the models appropriately described the dynamic variation in R_(s) and the carbon cycle in different forest covers.In addition,total phosphorus(TP)and total potassium(TK)significantly affected the dynamic changes in R_(s).In summary,interannual and seasonal variations in forest R_(s) at multiple scales and the response forces of related ecophysiological factors,especially the interactive driving effects of soil temperature,soil moisture and photo-synthesis,were clarified,thus representing an important step in predicting the impact of climate change and formulating forest carbon management policies.展开更多
Though aboveground biomass(AGB) has an important contribution to the global carbon cycle,the information about storage and climatic effects of AGB is scare in Three-River Source Region(TRSR)shrub ecosystems. This stud...Though aboveground biomass(AGB) has an important contribution to the global carbon cycle,the information about storage and climatic effects of AGB is scare in Three-River Source Region(TRSR)shrub ecosystems. This study investigated AGB storage and its climatic controls in the TRSR alpine shrub ecosystems using data collected from 23 sites on the Tibetan Plateau from 2011 to 2013. We estimated the AGB storage(both shrub layer biomass and grass layer biomass) in the alpine shrubs as 37.49 Tg, with an average density of 1447.31 g m^(-2). Biomass was primarily accumulated in the shrub layer, which accounted for 92% of AGB, while the grass layer accounted for only 8%. AGB significantly increased with the mean annual temperature(P < 0.05). The effects of the mean annual precipitation on AGB were not significant. These results suggest that temperature,rather than precipitation, has significantly effects on of aboveground vegetation growth in the TRSR alpine shrub ecosystems. The actual and potential increase in AGB density was different due to global warming varies among different regions of the TRSR. We conclude that long-term monitoring of dynamic changes is necessary to improve the accuracy estimations of potential AGB carbon sequestration across the TRSR alpine shrub ecosystems.展开更多
Three-River Headwaters(TRH) region involved in this paper refers to the source region of the Changjiang(Yangtze) River,the Huanghe(Yellow) River and the Lancang River in China.Taking the TRH region of the Qinghai-Tibe...Three-River Headwaters(TRH) region involved in this paper refers to the source region of the Changjiang(Yangtze) River,the Huanghe(Yellow) River and the Lancang River in China.Taking the TRH region of the Qinghai-Tibet Plateau as a case,the annual evapotranspiration(ET) model developed by Zhang et al.(2001) was applied to evaluate mean annual ET in the alpine area,and the response of annual ET to land use change was analyzed.The plant-available water coefficient(w) of Zhang's model was revised by using vegetation-temperature condition index(VTCI) before annual ET was calculated in alpine area.The future land use scenario,an input of ET model,was spatially simulated by using the conversion of land use and its effects at small regional extent(CLUE-S) to study the response of ET to land use change.Results show that the relative errors between the simulated ET and that calculated by using water balance equation were 3.81% and the index of agreement was 0.69.This indicates that Zhang's ET model based on revised plant-available water coefficient is a scientific and practical tool to estimate the annual ET in the alpine area.The annual ET in 2000 in the study area was 221.2 mm,11.6 mm more than that in 1980.Average annual ET decreased from southeast to northwest,but the change of annual ET between 1980 and 2000 increased from southeast to northwest.As a vast and sparsely populated area,the population in the TRH region was extremely unbalanced and land use change was concentrated in very small regions.Thus,land use change had little effect on total annual ET in the study area but a great impact on its spatial distribution,and the effect of land use change on ET decreased with increasing precipitation.ET was most sensitive to the interconversion between forest and unused land,and was least sensitive to the interconversion between cropland and low-covered grassland.展开更多
An underlying wetland surface comprises soil, water and vegetation and is sensitive to local climate change. Analysis of the degree of coupling between wetlands and the atmosphere and a quantitative assessment of how ...An underlying wetland surface comprises soil, water and vegetation and is sensitive to local climate change. Analysis of the degree of coupling between wetlands and the atmosphere and a quantitative assessment of how environmental factors influence latent heat flux have considerable scientific significance. Using data from observational tests of the Maduo Observatory of Climate and Environment of the Northwest Institute of Eco-Environment and Resource, CAS, from June 1 to August 31, 2014, this study analysed the time-varying characteristics and causes of the degree of coupling(Ω factor)between alpine wetlands underlying surface and the atmosphere and quantitatively calculated the influences of different environmental factors(solar radiation and vapour pressure deficit) on latent heat flux. The results were as follows:(1) Due to diurnal variations of solar radiation and wind speed, a trend developed where diurnal variations of the Ω factor were small in the morning and large in the evening. Due to the vegetation growing cycle, seasonal variations of the Ω factor present a reverse "U" trend. These trends are similar to the diurnal and seasonal variations of the absolute control exercised by solar radiation over latent heat flux. This conforms to the Omega Theory.(2) The values for average absolute atmospheric factor(surface factor or total) control exercised by solar radiation and water vapour pressure are 0.20(0.02 or 0.22) and 0.005(-0.07 or-0.06) W/(m2·Pa), respectively. Generally speaking, solar radiation and water vapour pressure deficit exert opposite forces on latent heat flux.(3) At the underlying alpine wetland surface, solar radiation primarily influences latent heat flux through its direct effects(atmospheric factor controls). Water vapour pressure deficit primarily influences latent heat flux through its indirect effects(surface factor controls) on changing the surface resistance.(4) The average Ω factor in the underlying alpine wetland surface is high during the vegetation growing season, with a value of 0.38, and the degree of coupling between alpine wetland surface and atmosphere system is low. The actual measurements agree with the Omega Theory. The latent heat flux is mainly influenced by solar radiation.展开更多
The Alpine region of Uvira District in South-Kivu Province faces low agricultural productivity challenges largely due to human population pressure on the natural resource base. During the dry season, conflicts between...The Alpine region of Uvira District in South-Kivu Province faces low agricultural productivity challenges largely due to human population pressure on the natural resource base. During the dry season, conflicts between crop farmers and livestock breeders are common. This region is located 2500 - 3020 m a.s.l. and is almost inaccessible due to poor road infrastructure. To understand the interactions between natural resources (forests, pastures, soils) and sedentary agriculture, and to propose solutions for sustainable natural resource management, Participatory Rural Appraisal (PRA) sessions covering three farmer group interviews were conducted in July 2010 in Marungu, Kitembe and Kahololo location. The livelihoods of the Banyamulenge have been transformed from pastoralism to a sedentary system with the introduction of crop cultivation after 1980. Maize, bush beans and Irish potatoes are cultivated with limited success because of late crop maturity under the prevailing climatic conditions. Livestock, mainly cattle, sheep and goats is managed under extensive system, relying on natural pasture far from the human settlements. Livestock plays an important role to define people’s wealth and is mainly managed by men. There is a real need of forages during the dry season;however, cultivation of forages is unknown. On the other hand, pastures appear to be degenerating due to overgrazing. Access by farmers to efficient and effective agricultural extension services is fundamental in order to promote locally adapted and profitable crop and livestock production while at the same time, sustaining the productive resource base and security.展开更多
Alpine-cold regions are characterized as hypoxia,strong wind,heavy rain,cold climate,huge temperature difference between day and night,and vertical climate. All these make it difficult for an emergency rescue when a n...Alpine-cold regions are characterized as hypoxia,strong wind,heavy rain,cold climate,huge temperature difference between day and night,and vertical climate. All these make it difficult for an emergency rescue when a natural disaster such as earthquake happens. Based on the characteristics of emergency rescue in alpinecold region,several multifunctional protective equipments have been developed by the Quartermaster Equipment Institute of General Logistics Departmen(tGLD)of the Chinese People's Liberation Army(CPLA). These equipments are lightweight,durable and environment adaptable.展开更多
Carex brunnescens(Pers.), a typical clonal species, is considered to be the only herb found to date that can develop on sand dunes in Maqu alpine region of northwestern China. However, the characteristics that C. br...Carex brunnescens(Pers.), a typical clonal species, is considered to be the only herb found to date that can develop on sand dunes in Maqu alpine region of northwestern China. However, the characteristics that C. brunnescens resists to harsh alpine environment have not been documented. In this study, we conducted a field investigation to determine the morphological, reproductive, and sand-fixing characteristics of C. brunnescens. Concomitantly, we transplanted the belowground rhizomes of C. brunnescens to sand dunes and compared the abilities to restore degraded alpine meadows among sand dunes that had no further treatment(SD+N), sand dunes that had straw checkerboard technique but no transplanted rhizomes of C. brunnescens(SD+SCT), and sand dunes that had both SCT and transplanted rhizomes of C. brunnescens(SD+SCT+P). We found that belowground vertical rhizomes and horizontal rhizomes(including branching rhizomes and main rhizomes) of C. brunnescens were highly developed and that population reproduction was dominated by horizontal rhizomes. C. brunnescens exhibited a significant sand-fixation effect under following conditions: population density was 145–156 ramets/m^2, vegetation cover was 31.2%–39.3%, total length of belowground rhizomes was 11,223 cm/m^2, total length of belowground first-order roots was 9161–10,524 cm/m^2, fresh weight of aboveground part was 198.5–212.6 g/m^2, and fresh weight of belowground part was 578.8–612.4 g/m^2. It should be particularly noted that SD+SCT+P treatment(sand dunes that had both straw checkerboard technique and transplanted rhizomes of C. brunnescens) was the best and SD+N(sand dunes that had no further treatment) was the worst in terms of following biotic indicators: total number of reproductive ramets, total number of belowground rhizomes, and fresh weight of aboveground and belowground parts of C. brunnescens, contents of soil organic carbon, available nitrogen, microbial biomass carbon, and microbial biomass nitrogen. It implies that applying SCT in sand dunes and transplanting belowground rhizomes to sand dunes with SCT could improve both soil fertility and growth of C. brunnescens. These results suggest that the SCT-promoted high reproductive abilities of belowground rhizomes of C. brunnescens can successfully facilitate the establishment of ramets and can thus be an effective strategy to restore degraded vegetation in Maqu alpine region of northwestern China.展开更多
The source regions of the Yangtze and Yellow Rivers are important in the field of eco-environmental change research in China because of its distinct alpine ecosystem and cryosphere environment. At present, there are t...The source regions of the Yangtze and Yellow Rivers are important in the field of eco-environmental change research in China because of its distinct alpine ecosystem and cryosphere environment. At present, there are three different concepts on the extent of source areas of the Yangtze and Yellow Rivers: hydrological, geographical, and eco-environmental. Over the past decades, annual average air temperature has warmed significantly;moreover, the temperature rise rate increases notably with increase of time of the data series. Annual precipitation has no obvious increase or decrease trend, and the climate has become warm and dry in the source regions. As a result, the cryosphere in the regions has shrunk significantly since 1960 s. A warm and dry climate and changing cryosphere together induced a substantial declination of alpine wetlands, marked decrease in river runoff, significant degradation of alpine grassland, and a reduction of engineering stability.The ecological environment, however, has a tendency for restoration in the regions because the climate has become gradually warm and wet since 2000. Thus, studies on eco-environmental change is transforming from a single element to multidisciplinary integration. Climate change-cryopshere change-physical and socioeconomic impacts/risk-adaptation constitute a chain of multidisciplinary integration research.展开更多
Monitoring deformation in high undulating mountainous environments is critical for surface process research and disaster prevention studies. Although observations based on interferometric Synthetic Aperture Radar(InSA...Monitoring deformation in high undulating mountainous environments is critical for surface process research and disaster prevention studies. Although observations based on interferometric Synthetic Aperture Radar(InSAR) are an excellent tool for monitoring deformation, the shadow phenomena can limit its application. Based on a series of geomorphic parameters and limited InSAR observation data, surface deformations were reconstructed in areas with missing observations by constructing a random forest model to compensate for the shadow phenomenon at the grid-scale. The findings suggest that this method can be used to rebuild landscape variation characteristics in places where observation data is lacking. The dominant slope direction in the observation area corresponded to a more significant correlation between the reconstructed topography deformation characteristics and the observation. In addition, when building this model, consideration was given to the geomorphic parameter selection, elevation variation, hypsometric integral value, slope form, lithology, slope variation,and aspect variation;these parameters can significantly affect the surface deformation, which is closely related to their spatial autocorrelation. These findings are significant for eliminating the shadow phenomenon, which often occurs in In SAR observations taken over alpine canyon regions. The terrain and lithology of the underlying surface should be considered when reconstructing the surface deformation characteristics of the shadow region by using satellite observation data.展开更多
本文采用ECMWF(European Centre for Medium-Range Weather Forecasts)细网格和NCEP(National Centers for Environmental Prediction)模式数据、NCEP 1°×1°再分析资料、降雪加密观测和常规资料,对2022年初的5次降雪过...本文采用ECMWF(European Centre for Medium-Range Weather Forecasts)细网格和NCEP(National Centers for Environmental Prediction)模式数据、NCEP 1°×1°再分析资料、降雪加密观测和常规资料,对2022年初的5次降雪过程进行对比分析,发现5次降雪过程均为雨转雪过程,且持续时间相对较短,平原为雨夹雪或小雪到中雪,山区中到大雪,局部暴雪,数值模式预报的积雪深度与实况相差甚远;大尺度环流形势为500 hPa中低纬南支槽或弱波动配合700 hPa上的暖湿气流和中低层冷空气,造成边界层浅薄的冷垫上温度骤降而在短时间内形成降雪;相较于平原地区,高山区上空温度层结与最大上升运动中心的配置,有利于降雪粒子较长时间维持在有利于枝状雪花的形成区域,且高山区云底云水含量显著偏低、整层温度足够低,故高山区更利于暴雪的形成。展开更多
基金supported by the National Nature Science Foundations of China(32160269)the International Science and Technology Cooperation Project of Qinghai province of China(2022-HZ-817).
文摘In the restoration of degraded wetlands,fertilization can improve the vegetation-soil-microorganisms complex,thereby affecting the organic carbon content.However,it is currently unclear whether these effects are sustainable.This study employed Biolog-Eco surveys to investigate the changes in vegetation characteristics,soil physicochemical properties,and soil microbial functional diversity in degraded alpine wetlands of the source region of the Yellow River at 3 and 15 months after the application of nitrogen,phosphorus,and organic mixed fertilizer.The following results were obtained:The addition of nitrogen fertilizer and organic compost significantly affects the soil organic carbon content in degraded wetlands.Three months after fertilization,nitrogen addition increases soil organic carbon in both lightly and severely degraded wetlands,whereas after 15 months,organic compost enhanced the soil organic carbon level in severely degraded wetlands.Structural equation modeling indicates that fertilization decreases the soil pH and directly or indirectly influences the soil organic carbon levels through variations in the soil water content and the aboveground biomass of vegetation.Three months after fertilization,nitrogen fertilizer showed a direct positive effect on soil organic carbon.However,organic mixed fertilizer indirectly reduced soil organic carbon by increasing biomass and decreasing soil moisture.After 15 months,none of the fertilizers significantly affected the soil organic carbon level.In summary,it can be inferred that the addition of nitrogen fertilizer lacks sustainability in positively influencing the organic carbon content.
基金This work was supported financially by the National Key Research and Development Plan Projects of China(2017YFC0504604).
文摘Soil respiration(Rs)is important for transport-ing or fixing carbon dioxide from the atmosphere,and even diminutive variations can profoundly influence the carbon cycle.However,the R_(s) dynamics in a loess alpine hilly region with representative sensitivity to climate change and fragile ecology remains poorly understood.This study investigated the correlation and degree of control between R_(s) and its photosynthetic and environmental factors in five subalpine forest cover types.We examined the correlations between R_(s) and variables temperature(T_(10)) and soil moisture content at 10 cm depth(W_(10)),net photosynthetic rate(P_(n))and soil properties to establish multiple models,and the variables were measured for diurnal and monthly vari-ations from September 2018 to August 2019.The results showed that soil physical factors are not the main drivers of R_(s) dynamics at the diel scale;however,the trend in the monthly variation in R_(s) was consistent with that of T_(10)and P_(n).Further,R_(s) was significantly affected by pH,providing further evidence that coniferous forest leaves contribute to soil acidification,thus reducing R_(s).Significant exponential and linear correlations were established between R_(s) and T_(10)and W_(10),respectively,and R_(s) was positively correlated with P_(n).Accordingly,we established a two-factor model and a three-factor model,and the correlation coefficients(R_(2))was improved to different degrees compared with models based only on T_(10) and W_(10).Moreover,temperature sensitivity(Q_(10))was the highest in the secondary forest and lowest in the Larix principis-rupprechtii forest.Our findings suggest that the control of R_(s) by the environment(moisture and tempera-ture)and photosynthesis,which are interactive or comple-mentary effects,may influence spatial and temporal homeo-stasis in the region and showed that the models appropriately described the dynamic variation in R_(s) and the carbon cycle in different forest covers.In addition,total phosphorus(TP)and total potassium(TK)significantly affected the dynamic changes in R_(s).In summary,interannual and seasonal variations in forest R_(s) at multiple scales and the response forces of related ecophysiological factors,especially the interactive driving effects of soil temperature,soil moisture and photo-synthesis,were clarified,thus representing an important step in predicting the impact of climate change and formulating forest carbon management policies.
基金funded by the National Science and Technology Support Project (Grant No.2014BAC05B01)National Program on Basic Work Project of China (Grant No.2015FY11030001)+1 种基金Strategic Priority Research Program of CAS (Grant No.XDA0505030304)National Natural Science Foundation of China (Grant No.40801076)
文摘Though aboveground biomass(AGB) has an important contribution to the global carbon cycle,the information about storage and climatic effects of AGB is scare in Three-River Source Region(TRSR)shrub ecosystems. This study investigated AGB storage and its climatic controls in the TRSR alpine shrub ecosystems using data collected from 23 sites on the Tibetan Plateau from 2011 to 2013. We estimated the AGB storage(both shrub layer biomass and grass layer biomass) in the alpine shrubs as 37.49 Tg, with an average density of 1447.31 g m^(-2). Biomass was primarily accumulated in the shrub layer, which accounted for 92% of AGB, while the grass layer accounted for only 8%. AGB significantly increased with the mean annual temperature(P < 0.05). The effects of the mean annual precipitation on AGB were not significant. These results suggest that temperature,rather than precipitation, has significantly effects on of aboveground vegetation growth in the TRSR alpine shrub ecosystems. The actual and potential increase in AGB density was different due to global warming varies among different regions of the TRSR. We conclude that long-term monitoring of dynamic changes is necessary to improve the accuracy estimations of potential AGB carbon sequestration across the TRSR alpine shrub ecosystems.
基金Under the auspices of Supporting Program of the 'Eleventh Five-year Plan' for Science and Technology Research of China (No. 2009BAC61B02)China Postdoctoral Science Foundation Funded Project (No. 20100470561)
文摘Three-River Headwaters(TRH) region involved in this paper refers to the source region of the Changjiang(Yangtze) River,the Huanghe(Yellow) River and the Lancang River in China.Taking the TRH region of the Qinghai-Tibet Plateau as a case,the annual evapotranspiration(ET) model developed by Zhang et al.(2001) was applied to evaluate mean annual ET in the alpine area,and the response of annual ET to land use change was analyzed.The plant-available water coefficient(w) of Zhang's model was revised by using vegetation-temperature condition index(VTCI) before annual ET was calculated in alpine area.The future land use scenario,an input of ET model,was spatially simulated by using the conversion of land use and its effects at small regional extent(CLUE-S) to study the response of ET to land use change.Results show that the relative errors between the simulated ET and that calculated by using water balance equation were 3.81% and the index of agreement was 0.69.This indicates that Zhang's ET model based on revised plant-available water coefficient is a scientific and practical tool to estimate the annual ET in the alpine area.The annual ET in 2000 in the study area was 221.2 mm,11.6 mm more than that in 1980.Average annual ET decreased from southeast to northwest,but the change of annual ET between 1980 and 2000 increased from southeast to northwest.As a vast and sparsely populated area,the population in the TRH region was extremely unbalanced and land use change was concentrated in very small regions.Thus,land use change had little effect on total annual ET in the study area but a great impact on its spatial distribution,and the effect of land use change on ET decreased with increasing precipitation.ET was most sensitive to the interconversion between forest and unused land,and was least sensitive to the interconversion between cropland and low-covered grassland.
基金supported by funding from the National Natural Science Foundation of China(Grant Nos.41530529 and 91737103)
文摘An underlying wetland surface comprises soil, water and vegetation and is sensitive to local climate change. Analysis of the degree of coupling between wetlands and the atmosphere and a quantitative assessment of how environmental factors influence latent heat flux have considerable scientific significance. Using data from observational tests of the Maduo Observatory of Climate and Environment of the Northwest Institute of Eco-Environment and Resource, CAS, from June 1 to August 31, 2014, this study analysed the time-varying characteristics and causes of the degree of coupling(Ω factor)between alpine wetlands underlying surface and the atmosphere and quantitatively calculated the influences of different environmental factors(solar radiation and vapour pressure deficit) on latent heat flux. The results were as follows:(1) Due to diurnal variations of solar radiation and wind speed, a trend developed where diurnal variations of the Ω factor were small in the morning and large in the evening. Due to the vegetation growing cycle, seasonal variations of the Ω factor present a reverse "U" trend. These trends are similar to the diurnal and seasonal variations of the absolute control exercised by solar radiation over latent heat flux. This conforms to the Omega Theory.(2) The values for average absolute atmospheric factor(surface factor or total) control exercised by solar radiation and water vapour pressure are 0.20(0.02 or 0.22) and 0.005(-0.07 or-0.06) W/(m2·Pa), respectively. Generally speaking, solar radiation and water vapour pressure deficit exert opposite forces on latent heat flux.(3) At the underlying alpine wetland surface, solar radiation primarily influences latent heat flux through its direct effects(atmospheric factor controls). Water vapour pressure deficit primarily influences latent heat flux through its indirect effects(surface factor controls) on changing the surface resistance.(4) The average Ω factor in the underlying alpine wetland surface is high during the vegetation growing season, with a value of 0.38, and the degree of coupling between alpine wetland surface and atmosphere system is low. The actual measurements agree with the Omega Theory. The latent heat flux is mainly influenced by solar radiation.
文摘The Alpine region of Uvira District in South-Kivu Province faces low agricultural productivity challenges largely due to human population pressure on the natural resource base. During the dry season, conflicts between crop farmers and livestock breeders are common. This region is located 2500 - 3020 m a.s.l. and is almost inaccessible due to poor road infrastructure. To understand the interactions between natural resources (forests, pastures, soils) and sedentary agriculture, and to propose solutions for sustainable natural resource management, Participatory Rural Appraisal (PRA) sessions covering three farmer group interviews were conducted in July 2010 in Marungu, Kitembe and Kahololo location. The livelihoods of the Banyamulenge have been transformed from pastoralism to a sedentary system with the introduction of crop cultivation after 1980. Maize, bush beans and Irish potatoes are cultivated with limited success because of late crop maturity under the prevailing climatic conditions. Livestock, mainly cattle, sheep and goats is managed under extensive system, relying on natural pasture far from the human settlements. Livestock plays an important role to define people’s wealth and is mainly managed by men. There is a real need of forages during the dry season;however, cultivation of forages is unknown. On the other hand, pastures appear to be degenerating due to overgrazing. Access by farmers to efficient and effective agricultural extension services is fundamental in order to promote locally adapted and profitable crop and livestock production while at the same time, sustaining the productive resource base and security.
文摘Alpine-cold regions are characterized as hypoxia,strong wind,heavy rain,cold climate,huge temperature difference between day and night,and vertical climate. All these make it difficult for an emergency rescue when a natural disaster such as earthquake happens. Based on the characteristics of emergency rescue in alpinecold region,several multifunctional protective equipments have been developed by the Quartermaster Equipment Institute of General Logistics Departmen(tGLD)of the Chinese People's Liberation Army(CPLA). These equipments are lightweight,durable and environment adaptable.
基金supported by the National Natural Science Foundation of China (31360087, 31360086)
文摘Carex brunnescens(Pers.), a typical clonal species, is considered to be the only herb found to date that can develop on sand dunes in Maqu alpine region of northwestern China. However, the characteristics that C. brunnescens resists to harsh alpine environment have not been documented. In this study, we conducted a field investigation to determine the morphological, reproductive, and sand-fixing characteristics of C. brunnescens. Concomitantly, we transplanted the belowground rhizomes of C. brunnescens to sand dunes and compared the abilities to restore degraded alpine meadows among sand dunes that had no further treatment(SD+N), sand dunes that had straw checkerboard technique but no transplanted rhizomes of C. brunnescens(SD+SCT), and sand dunes that had both SCT and transplanted rhizomes of C. brunnescens(SD+SCT+P). We found that belowground vertical rhizomes and horizontal rhizomes(including branching rhizomes and main rhizomes) of C. brunnescens were highly developed and that population reproduction was dominated by horizontal rhizomes. C. brunnescens exhibited a significant sand-fixation effect under following conditions: population density was 145–156 ramets/m^2, vegetation cover was 31.2%–39.3%, total length of belowground rhizomes was 11,223 cm/m^2, total length of belowground first-order roots was 9161–10,524 cm/m^2, fresh weight of aboveground part was 198.5–212.6 g/m^2, and fresh weight of belowground part was 578.8–612.4 g/m^2. It should be particularly noted that SD+SCT+P treatment(sand dunes that had both straw checkerboard technique and transplanted rhizomes of C. brunnescens) was the best and SD+N(sand dunes that had no further treatment) was the worst in terms of following biotic indicators: total number of reproductive ramets, total number of belowground rhizomes, and fresh weight of aboveground and belowground parts of C. brunnescens, contents of soil organic carbon, available nitrogen, microbial biomass carbon, and microbial biomass nitrogen. It implies that applying SCT in sand dunes and transplanting belowground rhizomes to sand dunes with SCT could improve both soil fertility and growth of C. brunnescens. These results suggest that the SCT-promoted high reproductive abilities of belowground rhizomes of C. brunnescens can successfully facilitate the establishment of ramets and can thus be an effective strategy to restore degraded vegetation in Maqu alpine region of northwestern China.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences,Grant No.XDA23060704
文摘The source regions of the Yangtze and Yellow Rivers are important in the field of eco-environmental change research in China because of its distinct alpine ecosystem and cryosphere environment. At present, there are three different concepts on the extent of source areas of the Yangtze and Yellow Rivers: hydrological, geographical, and eco-environmental. Over the past decades, annual average air temperature has warmed significantly;moreover, the temperature rise rate increases notably with increase of time of the data series. Annual precipitation has no obvious increase or decrease trend, and the climate has become warm and dry in the source regions. As a result, the cryosphere in the regions has shrunk significantly since 1960 s. A warm and dry climate and changing cryosphere together induced a substantial declination of alpine wetlands, marked decrease in river runoff, significant degradation of alpine grassland, and a reduction of engineering stability.The ecological environment, however, has a tendency for restoration in the regions because the climate has become gradually warm and wet since 2000. Thus, studies on eco-environmental change is transforming from a single element to multidisciplinary integration. Climate change-cryopshere change-physical and socioeconomic impacts/risk-adaptation constitute a chain of multidisciplinary integration research.
基金financially supported by the National Natural Science Foundation of China (42107218)China Geology Survey Project (DD20221738)+1 种基金China Three Gorges Corporation (YMJ(XLD) (19) 110)the National Key Research and Development Program of China (2018YFC1505002)。
文摘Monitoring deformation in high undulating mountainous environments is critical for surface process research and disaster prevention studies. Although observations based on interferometric Synthetic Aperture Radar(InSAR) are an excellent tool for monitoring deformation, the shadow phenomena can limit its application. Based on a series of geomorphic parameters and limited InSAR observation data, surface deformations were reconstructed in areas with missing observations by constructing a random forest model to compensate for the shadow phenomenon at the grid-scale. The findings suggest that this method can be used to rebuild landscape variation characteristics in places where observation data is lacking. The dominant slope direction in the observation area corresponded to a more significant correlation between the reconstructed topography deformation characteristics and the observation. In addition, when building this model, consideration was given to the geomorphic parameter selection, elevation variation, hypsometric integral value, slope form, lithology, slope variation,and aspect variation;these parameters can significantly affect the surface deformation, which is closely related to their spatial autocorrelation. These findings are significant for eliminating the shadow phenomenon, which often occurs in In SAR observations taken over alpine canyon regions. The terrain and lithology of the underlying surface should be considered when reconstructing the surface deformation characteristics of the shadow region by using satellite observation data.
文摘本文采用ECMWF(European Centre for Medium-Range Weather Forecasts)细网格和NCEP(National Centers for Environmental Prediction)模式数据、NCEP 1°×1°再分析资料、降雪加密观测和常规资料,对2022年初的5次降雪过程进行对比分析,发现5次降雪过程均为雨转雪过程,且持续时间相对较短,平原为雨夹雪或小雪到中雪,山区中到大雪,局部暴雪,数值模式预报的积雪深度与实况相差甚远;大尺度环流形势为500 hPa中低纬南支槽或弱波动配合700 hPa上的暖湿气流和中低层冷空气,造成边界层浅薄的冷垫上温度骤降而在短时间内形成降雪;相较于平原地区,高山区上空温度层结与最大上升运动中心的配置,有利于降雪粒子较长时间维持在有利于枝状雪花的形成区域,且高山区云底云水含量显著偏低、整层温度足够低,故高山区更利于暴雪的形成。