The upper valley of Min River (102° 59′ –104° 14′ E, 31° 26′ – 33° 16′ N), which is consisted of the counties Wenchuan, Maoxian, Lixian, Heishui, and Songpan, refers to the part up to Dujiang...The upper valley of Min River (102° 59′ –104° 14′ E, 31° 26′ – 33° 16′ N), which is consisted of the counties Wenchuan, Maoxian, Lixian, Heishui, and Songpan, refers to the part up to Dujiangyan City, and locates on the transition zone from the Tibetan Plateau to the Si- chuan Basin. It is one of the most important forest areas in China, especially in Sichuan Province. Over past two decades, the landscape changed remarkably in the region. The 3S techniques (Remote Sensing (RS), Geographic Information System (GIS) and Global Position System (GPS)) were used to classify the images and analyze the landscape change. The remotely sensed data of Landsat TM 1986 and Landsat ETM+ 2000 were used to analyze the landscape change of the region. The landscape were classified into 10 types of cropland, for- est, shrub land, economic forest, grassland, build up land, river, lake, swamp, and unused land. The results showed that: 1) the woodland and grassland were dominating landscape types in the upper valley of Min River, which is more than 91% of the study area; 2) the alteration of the landscape was mainly happened among forest, shrub land, grassland, economic forest, cropland, and build up land, where forest de- creased from 51.17% to 47.56%; 3) the landscape fragmentation in the upper valley of Min River was aggravated from 1986 to 2000.展开更多
HabRat richness influences and even determines biological diversity. Plant habitat suitability assessment can provide technical guidance and information support for ecological restoration. Thirteen factors in three ca...HabRat richness influences and even determines biological diversity. Plant habitat suitability assessment can provide technical guidance and information support for ecological restoration. Thirteen factors in three categories of terrain, meteorology and soil were chosen to build a habitat suitability assessment index framework in the Upper Reaches of the Min River, based on the local natural environment and the actual influencing factors of vegetative growth. Combined with the Analytic Hierarchy Process （AHP） and entropy method, which were used to calculate weights of indexes, habitat suitability was studied by using a multi-objective linear weighting model and geographic information systems （GIS） spatial analysis techniques. The assessment results are as follows： Altitude, soil stability, aspect and slope have more important effects on plant habitat suitability in the Upper Reaches of the Min River, and their weights are o.311, 0.260, o.198 and o.125, respectively. Suitable and sub-suitable habitats cover 4431.8o km2 and 6171.12 km2, respectively; most of which are distributed along both sides of rivers and have higher suitability. Unsuitable habitats cover the largest area （6679.76 km2）, accounting for 29.83% of the whole area; and the worst unsuitable habitats are 5107.23 km2 （22.81%）; they account for more than half of the study area. These results indicate that the plant habitat in the Upper Reaches of the Min River is poor and ecological restoration is both urgent and difficult. Therefore, based on the principle of taking measures suitable to the habitat in ecological restoration projects, ecological and engineering measures should be combined to have better effects, while increasing the strength of ecological protection.展开更多
On the basis of the ecological footprint (EF) model, this paper studied theecological security in the Upper Min River Basin ecosystem. The result shows that with 2. 038 2 hm^2per capita ecological capacity (0. 422 2 h...On the basis of the ecological footprint (EF) model, this paper studied theecological security in the Upper Min River Basin ecosystem. The result shows that with 2. 038 2 hm^2per capita ecological capacity (0. 422 2 hm^2 higher than per capita EF) ,and 165 825 hm^2 ecologysurplus , the ecosystem in Upper Min River is generally secure at present. But the arable land isoverweighed and omens an eco-security crisis. Meanwhile, problems such as low forest coverage rate,severe loss of water and soil,enlargement of arid-valley area, frequent occurrence of mountainhazards and degradation of pastures have been major threats to the eco-security of this region. Thecalculation result of ten-thousand-yuan ( RMB) GDP shows that the use of natural resources isextensive, and there will be a rapid increase tendency of EF in the future. In order to maintain thepresent eco-security, the ways of use natural resources must be improved in the Upper Min RiverBasin.展开更多
Coseismic landslides and subsequent mobilization of sediment greatly aggravated the landscape evolution and river sedimentation after the Wenchuan earthquake.The debris-flow alluvial fan and river morphological index ...Coseismic landslides and subsequent mobilization of sediment greatly aggravated the landscape evolution and river sedimentation after the Wenchuan earthquake.The debris-flow alluvial fan and river morphological index was combined to describe quantitatively the effects of debris-flow sediment on the river characteristics in Longmen Mountains.The section of the Min River from the urban area of the Wenchuan county to the epicenter,the Yingxiu town in this county,was selected as the study area.We identified 27 river-blocking debrisflows(5 partial-,7 semi-,7 over semi-,and 5 fullyblocking degrees)in the study area via remote sensing interpretation and field survey.Based on this,the response of river longitudinal profile and curvature to debris-flow sediment was qualitatively and quantitatively analyzed.The results show that the channel gradient has decreased due to debris-flow aggradation,while two marked peaks in the river steepness index(ksn,represents the relative steepness degree of the channel)changed from 585 m0.9 to 732 m0.9 in zone 1,from 362 m0.9 to 513 m0.9 in zone 2.Moreover,the main channel has undergone substantial lateral migration with channel width decreased and river curvature increased.The temporal and spatial variation between river morphological characteristics and debris-flow sediments in short-term provides insights into the internal dynamic role of mass wasting processes in river morphology,which could be served as useful information for natural hazards management to prevent the river from being blocked by episodically debris flows after the earthquake.展开更多
Human settlements are the place where human beings live,among which the rural settlements can be regarded as a reflection of human-land relationship in mountain areas because their vertical distribution is greatly inf...Human settlements are the place where human beings live,among which the rural settlements can be regarded as a reflection of human-land relationship in mountain areas because their vertical distribution is greatly influenced by the specific geographical environment and ecological conditions of mountains.Based on field investigation,this paper uses physical,geographical,and ecological theories to make a comprehensive study of rural settlements and mountain disasters in the upper Min River,which is an ecologically fragile area with high-frequency disasters(collapse,landslide,debris flow,etc.) and a minority inhabit district.By applying these modern scientific theories,this paper attempts to shed some light on the relationship between rural settlements and mountain disasters.Consequently,an in-depth understanding of this relationship was achieved as follows:(1) Rural settlements and mountain disasters are mainly distributed in the intercepted flows of water and soil; and both quantity and quality of arable lands in mountains are important indicators of these flows.(2) The Small Watershed Management Project is a complex system of rural settlements and mountain disasters that interacts with and constrains the ecological system.By this project,the human survival will be better guaranteed.Being fundamental for the ecological reconstruction,the coupling mechanism of rural settlements and mountain disasters is not only an engine to promote harmonious development between human and nature,but also a bridge to link them.展开更多
Although estuarine tidal marshes are important contributors to the emission of greenhouse gases into the atmosphere, the relationship between carbon dioxide（CO2）, methane（CH4）emission, and environmental factors, w...Although estuarine tidal marshes are important contributors to the emission of greenhouse gases into the atmosphere, the relationship between carbon dioxide（CO2）, methane（CH4）emission, and environmental factors, with respect to estuarine marshes, has not been clarified thoroughly. This study investigated the crucial factors controlling the emission of CO2 and CH4from a freshwater marsh and a brackish marsh located in a subtropical estuary in southeastern China, as well as their magnitude. The duration of the study period was November 2013 to October 2014. Relevant to both the field and incubation experiments, the CO2 and CH4emissions from the two marshes showed pronounced seasonal variations. The CO2 and CH4emissions from both marshes demonstrated significant positive correlations with the air/soil temperature（p 〈 0.01）, but negative correlations with the soil electrical conductivity and the pore water/tide water Cl-and SO42- （p 〈 0.01）. The results indicate no significant difference in the CO2 emissions between the freshwater and brackish marshes in the subtropical estuary, whereas there was a difference in the CH4 emissions between the two sites（p 〈 0.01）. Although future sea-level rise and saltwater intrusion could reduce the CH4 emissions from the estuarine freshwater marshes, these factors had little effect on the CO2 emissions with respect to an increase in salinity of less than 5‰. The findings of this study could have important implications for estimating the global warming contributions of estuarine marshes along differing salinity gradients.展开更多
文摘The upper valley of Min River (102° 59′ –104° 14′ E, 31° 26′ – 33° 16′ N), which is consisted of the counties Wenchuan, Maoxian, Lixian, Heishui, and Songpan, refers to the part up to Dujiangyan City, and locates on the transition zone from the Tibetan Plateau to the Si- chuan Basin. It is one of the most important forest areas in China, especially in Sichuan Province. Over past two decades, the landscape changed remarkably in the region. The 3S techniques (Remote Sensing (RS), Geographic Information System (GIS) and Global Position System (GPS)) were used to classify the images and analyze the landscape change. The remotely sensed data of Landsat TM 1986 and Landsat ETM+ 2000 were used to analyze the landscape change of the region. The landscape were classified into 10 types of cropland, for- est, shrub land, economic forest, grassland, build up land, river, lake, swamp, and unused land. The results showed that: 1) the woodland and grassland were dominating landscape types in the upper valley of Min River, which is more than 91% of the study area; 2) the alteration of the landscape was mainly happened among forest, shrub land, grassland, economic forest, cropland, and build up land, where forest de- creased from 51.17% to 47.56%; 3) the landscape fragmentation in the upper valley of Min River was aggravated from 1986 to 2000.
基金supported by the National Natural Science Foundation of China (NSFC)(Grant No.41071115)the National Science and Technology Support Program of the Ministry of Science and Technology "Twelfth Five-Year" of China (Grant No.2011BAK12B04)
文摘HabRat richness influences and even determines biological diversity. Plant habitat suitability assessment can provide technical guidance and information support for ecological restoration. Thirteen factors in three categories of terrain, meteorology and soil were chosen to build a habitat suitability assessment index framework in the Upper Reaches of the Min River, based on the local natural environment and the actual influencing factors of vegetative growth. Combined with the Analytic Hierarchy Process （AHP） and entropy method, which were used to calculate weights of indexes, habitat suitability was studied by using a multi-objective linear weighting model and geographic information systems （GIS） spatial analysis techniques. The assessment results are as follows： Altitude, soil stability, aspect and slope have more important effects on plant habitat suitability in the Upper Reaches of the Min River, and their weights are o.311, 0.260, o.198 and o.125, respectively. Suitable and sub-suitable habitats cover 4431.8o km2 and 6171.12 km2, respectively; most of which are distributed along both sides of rivers and have higher suitability. Unsuitable habitats cover the largest area （6679.76 km2）, accounting for 29.83% of the whole area; and the worst unsuitable habitats are 5107.23 km2 （22.81%）; they account for more than half of the study area. These results indicate that the plant habitat in the Upper Reaches of the Min River is poor and ecological restoration is both urgent and difficult. Therefore, based on the principle of taking measures suitable to the habitat in ecological restoration projects, ecological and engineering measures should be combined to have better effects, while increasing the strength of ecological protection.
文摘On the basis of the ecological footprint (EF) model, this paper studied theecological security in the Upper Min River Basin ecosystem. The result shows that with 2. 038 2 hm^2per capita ecological capacity (0. 422 2 hm^2 higher than per capita EF) ,and 165 825 hm^2 ecologysurplus , the ecosystem in Upper Min River is generally secure at present. But the arable land isoverweighed and omens an eco-security crisis. Meanwhile, problems such as low forest coverage rate,severe loss of water and soil,enlargement of arid-valley area, frequent occurrence of mountainhazards and degradation of pastures have been major threats to the eco-security of this region. Thecalculation result of ten-thousand-yuan ( RMB) GDP shows that the use of natural resources isextensive, and there will be a rapid increase tendency of EF in the future. In order to maintain thepresent eco-security, the ways of use natural resources must be improved in the Upper Min RiverBasin.
基金supported by the National Natural Science Foundation of China(Grant No.42001002)the Key Laboratory of Mountain Hazards and Earth Surface Processes+3 种基金Chinese Academy of Sciences(Grant No.KLMHESP-20-02)the Key Programs of Science and Technology Research PlanHubei Provincial Department of Education(Grant NoD20201205)Power China Science and Technology Projects(Grant No.DJ-ZDXM-2016-04)。
文摘Coseismic landslides and subsequent mobilization of sediment greatly aggravated the landscape evolution and river sedimentation after the Wenchuan earthquake.The debris-flow alluvial fan and river morphological index was combined to describe quantitatively the effects of debris-flow sediment on the river characteristics in Longmen Mountains.The section of the Min River from the urban area of the Wenchuan county to the epicenter,the Yingxiu town in this county,was selected as the study area.We identified 27 river-blocking debrisflows(5 partial-,7 semi-,7 over semi-,and 5 fullyblocking degrees)in the study area via remote sensing interpretation and field survey.Based on this,the response of river longitudinal profile and curvature to debris-flow sediment was qualitatively and quantitatively analyzed.The results show that the channel gradient has decreased due to debris-flow aggradation,while two marked peaks in the river steepness index(ksn,represents the relative steepness degree of the channel)changed from 585 m0.9 to 732 m0.9 in zone 1,from 362 m0.9 to 513 m0.9 in zone 2.Moreover,the main channel has undergone substantial lateral migration with channel width decreased and river curvature increased.The temporal and spatial variation between river morphological characteristics and debris-flow sediments in short-term provides insights into the internal dynamic role of mass wasting processes in river morphology,which could be served as useful information for natural hazards management to prevent the river from being blocked by episodically debris flows after the earthquake.
基金financially supported by the National Natural Science Foundation of China(Grant No.41101164 and 41371185)Directional Project of Institute of Mountain Hazards and Environment of Chinese Academy of Sciences(Grant No.SDS-135-1204-01)the key project of Education Department of Sichuan Province(Grant No.13ZA0160)
文摘Human settlements are the place where human beings live,among which the rural settlements can be regarded as a reflection of human-land relationship in mountain areas because their vertical distribution is greatly influenced by the specific geographical environment and ecological conditions of mountains.Based on field investigation,this paper uses physical,geographical,and ecological theories to make a comprehensive study of rural settlements and mountain disasters in the upper Min River,which is an ecologically fragile area with high-frequency disasters(collapse,landslide,debris flow,etc.) and a minority inhabit district.By applying these modern scientific theories,this paper attempts to shed some light on the relationship between rural settlements and mountain disasters.Consequently,an in-depth understanding of this relationship was achieved as follows:(1) Rural settlements and mountain disasters are mainly distributed in the intercepted flows of water and soil; and both quantity and quality of arable lands in mountains are important indicators of these flows.(2) The Small Watershed Management Project is a complex system of rural settlements and mountain disasters that interacts with and constrains the ecological system.By this project,the human survival will be better guaranteed.Being fundamental for the ecological reconstruction,the coupling mechanism of rural settlements and mountain disasters is not only an engine to promote harmonious development between human and nature,but also a bridge to link them.
基金was supported by the National Natural Science Foundation of China(No.41371127)the Program for Innovative Research Teams of Fujian Normal University(No.IRTL1205)+1 种基金the Key Sciences and Technology Project of Fujian Province(No.2014R1034-1)the Graduate Innovation Project of the School of Geographical Sciences of Fujian Normal University(No.GY201501)
文摘Although estuarine tidal marshes are important contributors to the emission of greenhouse gases into the atmosphere, the relationship between carbon dioxide（CO2）, methane（CH4）emission, and environmental factors, with respect to estuarine marshes, has not been clarified thoroughly. This study investigated the crucial factors controlling the emission of CO2 and CH4from a freshwater marsh and a brackish marsh located in a subtropical estuary in southeastern China, as well as their magnitude. The duration of the study period was November 2013 to October 2014. Relevant to both the field and incubation experiments, the CO2 and CH4emissions from the two marshes showed pronounced seasonal variations. The CO2 and CH4emissions from both marshes demonstrated significant positive correlations with the air/soil temperature（p 〈 0.01）, but negative correlations with the soil electrical conductivity and the pore water/tide water Cl-and SO42- （p 〈 0.01）. The results indicate no significant difference in the CO2 emissions between the freshwater and brackish marshes in the subtropical estuary, whereas there was a difference in the CH4 emissions between the two sites（p 〈 0.01）. Although future sea-level rise and saltwater intrusion could reduce the CH4 emissions from the estuarine freshwater marshes, these factors had little effect on the CO2 emissions with respect to an increase in salinity of less than 5‰. The findings of this study could have important implications for estimating the global warming contributions of estuarine marshes along differing salinity gradients.
