Article

The impacts of railroad engineering on the alpine grassland ecosystem in Qinghai-Tibet plateau

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... The degradation of alpine ecosystems is manifested in changes of ecosystem structure and composition as well as a reduction in vegetative cover (Li and Zhou, 1998;Wang et al., 2001a,b). It can be described by three indexes: vegetative cover, ecosystem variability, and dominant species standing (Zhou, 2001;Wang et al., 2005), of which the latter is the integration of original plant species number and their frequency (Wang et al., 2005): ...
... The degradation of alpine ecosystems is manifested in changes of ecosystem structure and composition as well as a reduction in vegetative cover (Li and Zhou, 1998;Wang et al., 2001a,b). It can be described by three indexes: vegetative cover, ecosystem variability, and dominant species standing (Zhou, 2001;Wang et al., 2005), of which the latter is the integration of original plant species number and their frequency (Wang et al., 2005): ...
... When the S L dropped below 20%, water storage in meadow and steppe topsoils was similar. Overall, degraded steppes showed a greater potential for restoration than degraded meadows (Wang et al., 2005), the difference in the response of their soil physical properties to ecosystem changes being the main cause. ...
... The degradation of alpine ecosystems is manifested in changes of ecosystem structure and composition as well as a reduction in vegetative cover (Li and Zhou, 1998;Wang et al., 2001a,b). It can be described by three indexes: vegetative cover, ecosystem variability, and dominant species standing (Zhou, 2001;Wang et al., 2005), of which the latter is the integration of original plant species number and their frequency (Wang et al., 2005): ...
... The degradation of alpine ecosystems is manifested in changes of ecosystem structure and composition as well as a reduction in vegetative cover (Li and Zhou, 1998;Wang et al., 2001a,b). It can be described by three indexes: vegetative cover, ecosystem variability, and dominant species standing (Zhou, 2001;Wang et al., 2005), of which the latter is the integration of original plant species number and their frequency (Wang et al., 2005): ...
... When the S L dropped below 20%, water storage in meadow and steppe topsoils was similar. Overall, degraded steppes showed a greater potential for restoration than degraded meadows (Wang et al., 2005), the difference in the response of their soil physical properties to ecosystem changes being the main cause. ...
Article
Alpine ecosystems are quite sensitive to global climatic changes. Drawing from two sets of remote sensing data (1986 and 2000) and field investigations, the ecological index method was used to document ecosystem changes in the Yangtze and Yellow River source regions of central Qinghai–Tibet. Although crucial to understanding alpine ecosystem responses to global climatic changes, and in assessing the potential for their rehabilitation, the impact of such changes on alpine soil characteristics, including structure, composition, water retention, as well as chemical and nutrient contents, is poorly understood. Over a 15-year period (1986–2000), climatic changes led to considerable degradation of alpine meadows and steppes. In the meadows, the surface layers of the soil became coarser, bulk density, porosity and saturated hydraulic conductivity rose, while water-holding capacity decreased. In comparison, steppe soils showed little changes in soil physical properties. Degradation of alpine ecosystems led to large losses in soil available Fe, Mn and Zn. Important losses in soil organic matter (SOM) and total nitrogen (TN) occurred in badly degraded ecosystems. Climate warming in the Qinghai–Tibet Plateau, caused by the impact of greenhouse gas, has resulted in changes of cold alpine ecosystem such as the significant alteration of the soil C and N cycles.
... The degradation of alpine ecosystems is manifested in changes of ecosystem structure and composition as well as a reduction in vegetative cover (Li and Zhou, 1998; Wang et al., 2001a,b). It can be described by three indexes: vegetative cover, ecosystem variability, and dominant species standing (Zhou, 2001; Wang et al., 2005), of which the latter is the integration of original plant species number and their frequency (Wang et al., 2005): ...
... The degradation of alpine ecosystems is manifested in changes of ecosystem structure and composition as well as a reduction in vegetative cover (Li and Zhou, 1998; Wang et al., 2001a,b). It can be described by three indexes: vegetative cover, ecosystem variability, and dominant species standing (Zhou, 2001; Wang et al., 2005), of which the latter is the integration of original plant species number and their frequency (Wang et al., 2005): ...
... When the S L dropped below 20%, water storage in meadow and steppe topsoils was similar. Overall, degraded steppes showed a greater potential for restoration than degraded meadows (Wang et al., 2005), the difference in the response of their soil physical properties to ecosystem changes being the main cause. The changes of soil physical and chemical features implicated serious soil erosion occurred in the permafrost area of Qinghai–Tibet Plateau. ...
Article
CO2 emission fluxes of two types of ecosystem, swamp meadow and alpine meadow, in the Fenghuoshan region of the Qinghai-Tibet Plateau were studied by the static chamber-portable infrared chromatographic method. The results showed that there was large difference in the CO2 emission fluxes between the two ecosystems and in the same ecosystem of different degradation degrees. CO2 emission flux of the swamp meadow gradually decreased with increasing degradation degree, while that of the alpine meadow gradually increased with increasing degradation degree except in May. The CO2 emission flux of undegraded swamp meadow was 65.1%–80.3% higher than that of undegraded alpine meadow; and the CO2 emission flux of moderately degraded swamp meadow was 22.1%–67.5% higher than that of alpine meadow; but the CO2 emission flux of severely degraded alpine meadow was 14.3%–29.5% higher than that of swamp meadow. The soil moisture content and temperature in the upper 5 cm soil layer and above-ground biomass were significantly correlated with the CO2 emission fluxes and regarded as the main environment factors to control the CO2 emission.
... Although railway planners and builders did all they could do to minimize the negative impacts of the construction and try to make it an environmentally friendly railway, for example vegetation removed during construction was then restored after the work was complete the potential long-term QTR environmental impacts should not be underestimated (Zhang et al. 2008). Wang et al. (2005) estimated that at its worst, the construction exerted a 'middle' degree of degradation on alpine meadow ecosystems, and a 'middle to light' degree on alpine steppe ecosystems. Based on a large body of fieldwork (Jin et al. 2008;Shen et al. 2004), it appears that alpine grasslands in which the vegetation and soils were severely damaged will take 20-30 years to recover, whereas for the alpine meadows it will be 45-60 years. ...
Article
Full-text available
Large-scale engineering projects such as mines and dams cause ecological damage that can persist after construction is complete. The Qinghai-Tibet Railway (QTR) from Golmud to Lhasa was constructed entirely during the Landsat era and began operating in 2006. Therefore, it presents an opportunity for determining both the extent of ecological damage and the time required for some level of natural restoration after a major construction project. We have studied the effect of the QTR construction on vegetation abundance measured using multi-endmember spectral mixture analysis (MESMA) of a time series of Landsat TM/ETM+ images (2001, 2007, 2010) covering the 231 km stretch of the railway from south of Kaixinling Station to north of Chumaerhe Station. We found that the effect of QTR construction on vegetation abundance was limited to within 5.0 km of the tracks, the largest decrease, 2.9%, occurring within 0.125 km of the tracks from 2001 to 2007. There was only 0.4% further decrease in vegetation abundance from 2007 to 2010. We attributed the decrease in vegetation abundance within 0.125 km of the tracks mostly to the accumulation of drifting sand resulting from the barrier of the railway and the measures adopted to keep the sand away from the railway under the prevailing west or northwest winds. It appears that in this sensitive cold desert, vegetation damage was limited to the period of railway construction.
... The development of wetland is based on the existence of frozen soils, so the degradation of permafrost will inevitably lead to the shrink or loss of alpine wetlands. Wang et al. (2005) also presented that the degradation of frozen soils was an important reason of the degradation of the alpine marsh wetlands in the Qinghai-Tibet Plateau. ...
Article
Zoige Plateau wetlands are located in the northeastern corner of the Qinghai-Tibet Plateau. The landscape pattern evolution processes in the Zoige Plateau and their driving factors were identified by analyzing the dynamic changes in landscape modification and conversion and their dynamic rates of alpine wetlands over the past four decades. The results showed that the landscape conversion between wetlands and non-wetlands mainly occurred during the period from 1966 to 1986. The marsh wetland area converted from lake and river wetlands was larger because of swamping compared to other wetland landscapes. Meanwhile, the larger area of marsh wetlands was also converted to lake wetlands more than other types of wetlands. The modification processes mainly occurred among natural wetland landscapes in the first three periods. Obvious conversions were observed between wetland and non-wetland landscapes (i.e., forestland, grassland, and other landscapes) in the Zoige Plateau. These natural wetland landscapes such as river, lake and marsh wetlands showed a net loss over the past four decades, whereas artificial wetland landscapes (i.e., paddy field and reservoir and pond wetlands) showed a net decrease. The annual dynamic rate of the whole wetland landscape was 0.72%, in which the annual dynamic rate of river wetlands was the highest, followed by lake wetlands, while marsh wetlands had the lowest dynamic rate. The integrated landscape dynamic rate showed a decreasing trend in the first three periods. The changes in wetland landscape patterns were comprehensively controlled by natural factors and human activities, especially human activities play an important role in changing wetland landscape patterns.
Article
The research was carried out in warm steppe along the Qinghai-Tibet Railway near Haiyan in Qinghai Province. The population density and community structure of rodents were determined by daily trapping at different distances from the railway, the relationship between the rodent community characteristics and the plants was analyzed, and the effect of traffic of the Qinghai-Tibet Railway on the community structure of rodents was discussed. Ochotona cansus, Allactaga sibirica, Cricetulus longicaudatus and Cricetulus migratorius all were captured in the research area. There were no exotic species encountered in research area from the beginning of the Railway activity in 1984 to now. The population density, number of species, and diversity index of rodents near the Railway were significantly higher than those in places 0.5 km and 1 km away from the Railway, but the evenness index of the rodents was lowest near the Railway. The community characteristics of the plants were the same at different distances from the Railway. A relationship between the community characteristics of the rodents and plants was not found. The activity of the Qinghai-Tibet Railway did not result in exotic species in the research area and suitable habitat and excessive food supplied by train travelers may have been factors causing the increase in population density and the changes in community structure of the rodents near the Railway. Thus, the construction and activity of the Railway affects the community structure of rodents in the research area.
Article
The serious negative impacts on local ecosystem alongside caused by expressway construction activities were analyzed. Based on theory of ecosystem services value and CBA(cost benefit analysis), the influence on and the damage to the ecosystem alongside by expressways construction are discussed and calculated in currency. Combined with comprehensive consideration of engineering cost, a scheme of minimum total cost was searched out through mathematical model to obtain the optimal scheme. The real purpose is to offer explicit economic information to management decision making during expressway construction, and make people realize that economic benefit brought by expressway construction have to be paid out by immense environmental cost and social cost. Which can help decision maker consider environmental cost and select right route.
Article
The area that the railway will cross is a region with the main physiognomies of desert and Gobi, with a most fragile ecological environment. It is also a region that is highly susceptible to man-made disturbance. The construction of railway will intensify soil erosion along the railway line to a certain degree. The map of soil erosion conditions in the section from Liugou to Dunhuang City in the range of 10 km each side along the line was compiled by using the techniques of remote sensing and geographic information system (GIS). Based on analysis of the status of desertification and the influence of the railway construction projects, the changes of the types, intensities and the total amount of the soil erosion caused by the construction were predicted.
Article
Bearing a total organic carbon (TOC) content of 9.3–10.7 kg C/m2, alpine grassland soils of the Qinghai–Tibet plateau's permafrost region bear a greater organic carbon pool than do grassland soils in other regions of China or than tropical savannah soils. The easily released light fraction organic carbon (LFOC) accounts for 34–54% of the TOC and is particularly enriched in the topsoil (0–0.10 m). The LFOC in the organic carbon pool of alpine cold meadow and alpine cold steppe soils decreased at exponential and quadratic rates, respectively, as the vegetative cover decreased. When the vegetative cover of alpine cold meadows decreased from > 80 dm2/m2 to 60 dm2/m2, the topsoil TOC and LFOC dropped by 20.4% and 38.4%, respectively. Similarly, when the vegetative cover of alpine cold meadow decreased from 50 dm2/m2 to 30 dm2/m2 and < 15 dm2/m2, the topsoil LFOC content dropped by 60% and 86.7%, respectively. Under climatic warming, the degradation of permafrost and vegetation have resulted in serious soil organic carbon (SOC) loss from the carbon pool. Land cover changes that occurred between 1986 and 2000 are estimated to have resulted in a 1.8 Gg C (120 Mg C/yr) loss in SOC, and a concomitant 65% decrease in the LFOC, in the 0–0.30 m soil layer in the Qinghai–Tibet plateau's permafrost regions. Since the region's ecosystems are quite sensitive to global climate changes, if global warming persists, alpine cold grassland ecosystems are expected to further degrade. Hence, the influence of global climatic change on soil carbon emissions from alpine grasslands should receive more attention.
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