The Loess Plateau is one typical area of serious soil erosion in the world. China has implemented ′Grain for Green′(GFG) project to restore the eco-environment of the Loess Plateau since 1999. With the GFG project s...The Loess Plateau is one typical area of serious soil erosion in the world. China has implemented ′Grain for Green′(GFG) project to restore the eco-environment of the Loess Plateau since 1999. With the GFG project subsidy approaching the end, it is concerned that farmers of fewer subsidies may reclaim land again. Thus, ′Gully Land Consolidation Project′(GLCP) was initiated in 2010. The core of the GLCP was to create more land suitable for farming in gullies so as to reduce land reclamation on the slopes which are ecological vulnerable areas. This paper aims to assess the effect of the GLCP on soil erosion problems by studying Wangjiagou project region located in the central part of Anzi valley in the middle of the Loess Plateau, mainly using the revised universal soil loss equation(RUSLE) based on GIS. The findings show that the GLCP can help to reduce soil shipment by 9.87% and it creates more terraces and river-nearby land suitable for farming which account for 27.41% of the whole study area. Thus, it is feasible to implement the GLCP in places below gradient 15°, though the GLCP also intensifies soil erosion in certain places such as field ridge, village land, floodplain, natural grassland, and shrub land. In short, the GLCP develops new generation dam land and balances the short-term and long-term interests to ease the conflicts between economic development and environmental protection. Furthermore, the GLCP and the GFG could also be combined preferably. On the one hand, the GFG improves the ecological environment, which could offer certain safety to the GLCP, on the other hand, the GLCP creates more farmland favorable for farming in gullies instead of land reclamation on the slopes, which could indirectly protect the GFG project.展开更多
Aims A decrease in species diversity after fertilization is a common phenomenon in grasslands;however,the mechanism causing it remains highly controversial.The light competition hypothesis to explain loss of diversity...Aims A decrease in species diversity after fertilization is a common phenomenon in grasslands;however,the mechanism causing it remains highly controversial.The light competition hypothesis to explain loss of diversity has received much attention.The aim of the present paper was to test this hypothesis.Methods Fertilization was used to control above-and belowground resources simultaneously,while shade was used to control aboveground resource in an alpine meadow on the Tibetan Plateau.Univariate general linear models was used to estimate the effects of fertilization and shade on above-and belowground vegetation characteristics,including photosynthetically active radiation(PAR)in the understory,aboveground biomass,belowground biomass,R:S ratio,species richness and Simpson’s diversity index.Important findings PAR was similar in the understory of shaded and fertilized plots,but only fertilization reduced species richness and diversity,suggesting that light competition alone could not explain diversity loss after fertilization.The root biomass and R:S ratio had a significant increase in shaded plots,but the richness and diversity did not change,suggesting that root competition alone also could not explain diversity loss after fertilization in this community.Our results illustrated that the root–shoot competition interactions,investigated from a functional groups perspective,should be the most reasonable explanation leading to the diversity loss due to fertilization.展开更多
Fine-root decomposition is a critical process regulating ecosystem carbon cycles and affecting nutrient cycling and soil fertility.However,whether interaction between warming and grazing affects fine-root decompositio...Fine-root decomposition is a critical process regulating ecosystem carbon cycles and affecting nutrient cycling and soil fertility.However,whether interaction between warming and grazing affects fine-root decomposition is still under-researched in natural grasslands.A two-factorial experiment with asymmetric warming(i.e.daytime vs.nighttime and growing season vs.nongrowing season)and moderate grazing(i.e.about average 50%forage utilization rate)was conducted to explore whether warming and grazing affect fine-root decomposition and loss of nutrients during a 2-year decomposition period in an alpine meadow on the Tibetan Plateau.Both warming and grazing facilitated carbon cycling through increase in fine-root decomposition,and influenced element cycling which varies among elements.The effects of warming and grazing on fine-root decomposition and loss of nutrients were additive.Both warming and grazing significantly increased cumulative percentage mass loss and total organic carbon loss of fine roots during the 2-year experiment.Only warming with grazing treatment reduced percentage nitrogen loss,whereas warming,regardless of grazing,decreased percentage phosphorus loss.Warming and grazing alone increased percentage loss of potassium,sodium,calcium and magnesium compared with control.There were no interactions between warming and grazing on fine-root decomposition and loss of nutrients.There was greater temperature sensitivity of decreased phosphorus loss than that of decreased nitrogen loss.Different temperature sensitivities of percentage loss of nutrients from fine-root decomposition would alter ratios of the available nutrients in soils,and may further affect ecosystem structure and functions in future warming.展开更多
Loess Plateau is the most serious region of soil and water loss in China and the world. The sediment carried into the Yellow River amounts to 1.6 billion tons every year. This paper reviews the factors and reasons for...Loess Plateau is the most serious region of soil and water loss in China and the world. The sediment carried into the Yellow River amounts to 1.6 billion tons every year. This paper reviews the factors and reasons for erosion in this area, and puts forward a comprehensive controlling policy on the basis of the principles of ecology and practise of Chinese scientists for 40 years. In conformity with the policy, a number of technical measures for controlling soil and water loss are suggested.展开更多
Understanding the interaction between canopy structure and the parameters of interception loss is essential in predicting the variations in partitioning rainfall and water resources as affected by changes in canopy st...Understanding the interaction between canopy structure and the parameters of interception loss is essential in predicting the variations in partitioning rainfall and water resources as affected by changes in canopy structure and in implementing water-based management in semiarid forest plantations.In this study,seasonal variations in rainfall interception loss and canopy storage capacity as driven by canopy structure were predicted and the linkages were tested using seasonal filed measurements.The study was conducted in nine 50 m×50 m Robinia pseudoacacia plots in the semiarid region of China’s Loess Plateau.Gross rain-fall,throughfall and stemflow were measured in seasons with and without leaves in 2015 and 2016.Results show that measured average interception loss for the nine plots were 17.9% and 9.4% of gross rainfall during periods with leaves (the growing season) and without leaves, respectively. Average canopy storage capacity estimated using an indirect method was 1.3 mm in the growing season and 0.2 mm in the leafless season. Correlations of relative interception loss and canopy storage capacity to canopy variables were highest for leaf/wood area index (LAI/WAI) and canopy cover, fol-lowed by bark area, basal area, tree height and stand density. Combined canopy cover, leaf/wood area index and bark area multiple regression models of interception loss and canopy storage capacity were established for the growing season and in the leafless season in 2015. It explained 97% and 96% of the variations in relative interception loss during seasons with and without leaves, respectively. It also explained 98% and 99% of the variations in canopy storage capacity during seasons with and without leaves, respectively. The empiri-cal regression models were validated using field data col-lected in 2016. The models satisfactorily predicted relative interception loss and canopy storage capacity during seasons with and without leaves. This study provides greater under-standing about the effects of changes in tree canopy st展开更多
基金Under the auspices of National Natural Science Foundation of China(No.41130748,41471143)
文摘The Loess Plateau is one typical area of serious soil erosion in the world. China has implemented ′Grain for Green′(GFG) project to restore the eco-environment of the Loess Plateau since 1999. With the GFG project subsidy approaching the end, it is concerned that farmers of fewer subsidies may reclaim land again. Thus, ′Gully Land Consolidation Project′(GLCP) was initiated in 2010. The core of the GLCP was to create more land suitable for farming in gullies so as to reduce land reclamation on the slopes which are ecological vulnerable areas. This paper aims to assess the effect of the GLCP on soil erosion problems by studying Wangjiagou project region located in the central part of Anzi valley in the middle of the Loess Plateau, mainly using the revised universal soil loss equation(RUSLE) based on GIS. The findings show that the GLCP can help to reduce soil shipment by 9.87% and it creates more terraces and river-nearby land suitable for farming which account for 27.41% of the whole study area. Thus, it is feasible to implement the GLCP in places below gradient 15°, though the GLCP also intensifies soil erosion in certain places such as field ridge, village land, floodplain, natural grassland, and shrub land. In short, the GLCP develops new generation dam land and balances the short-term and long-term interests to ease the conflicts between economic development and environmental protection. Furthermore, the GLCP and the GFG could also be combined preferably. On the one hand, the GFG improves the ecological environment, which could offer certain safety to the GLCP, on the other hand, the GLCP creates more farmland favorable for farming in gullies instead of land reclamation on the slopes, which could indirectly protect the GFG project.
基金Key Program of National Natural Science Foundation of China(No.40930533).
文摘Aims A decrease in species diversity after fertilization is a common phenomenon in grasslands;however,the mechanism causing it remains highly controversial.The light competition hypothesis to explain loss of diversity has received much attention.The aim of the present paper was to test this hypothesis.Methods Fertilization was used to control above-and belowground resources simultaneously,while shade was used to control aboveground resource in an alpine meadow on the Tibetan Plateau.Univariate general linear models was used to estimate the effects of fertilization and shade on above-and belowground vegetation characteristics,including photosynthetically active radiation(PAR)in the understory,aboveground biomass,belowground biomass,R:S ratio,species richness and Simpson’s diversity index.Important findings PAR was similar in the understory of shaded and fertilized plots,but only fertilization reduced species richness and diversity,suggesting that light competition alone could not explain diversity loss after fertilization.The root biomass and R:S ratio had a significant increase in shaded plots,but the richness and diversity did not change,suggesting that root competition alone also could not explain diversity loss after fertilization in this community.Our results illustrated that the root–shoot competition interactions,investigated from a functional groups perspective,should be the most reasonable explanation leading to the diversity loss due to fertilization.
基金This research was supported by grants from the National Natural Science Foundation of China(41731175,31770524 and 31872994)the Strategic Priority Research Program A of the Chinese Academy of Sciences(XDA20050101)+1 种基金the Joint Key Research Fund(U20A2005)under cooperative agreement between the National Natural Science Foundation of China(NSFC)and Tibet Autonomous Region(TAR)he Second Tibetan Plateau Scientific Expedition and Research(STEP)program(2019QZKK0302 and 2019QZKK0608).
文摘Fine-root decomposition is a critical process regulating ecosystem carbon cycles and affecting nutrient cycling and soil fertility.However,whether interaction between warming and grazing affects fine-root decomposition is still under-researched in natural grasslands.A two-factorial experiment with asymmetric warming(i.e.daytime vs.nighttime and growing season vs.nongrowing season)and moderate grazing(i.e.about average 50%forage utilization rate)was conducted to explore whether warming and grazing affect fine-root decomposition and loss of nutrients during a 2-year decomposition period in an alpine meadow on the Tibetan Plateau.Both warming and grazing facilitated carbon cycling through increase in fine-root decomposition,and influenced element cycling which varies among elements.The effects of warming and grazing on fine-root decomposition and loss of nutrients were additive.Both warming and grazing significantly increased cumulative percentage mass loss and total organic carbon loss of fine roots during the 2-year experiment.Only warming with grazing treatment reduced percentage nitrogen loss,whereas warming,regardless of grazing,decreased percentage phosphorus loss.Warming and grazing alone increased percentage loss of potassium,sodium,calcium and magnesium compared with control.There were no interactions between warming and grazing on fine-root decomposition and loss of nutrients.There was greater temperature sensitivity of decreased phosphorus loss than that of decreased nitrogen loss.Different temperature sensitivities of percentage loss of nutrients from fine-root decomposition would alter ratios of the available nutrients in soils,and may further affect ecosystem structure and functions in future warming.
文摘Loess Plateau is the most serious region of soil and water loss in China and the world. The sediment carried into the Yellow River amounts to 1.6 billion tons every year. This paper reviews the factors and reasons for erosion in this area, and puts forward a comprehensive controlling policy on the basis of the principles of ecology and practise of Chinese scientists for 40 years. In conformity with the policy, a number of technical measures for controlling soil and water loss are suggested.
基金This study is supported by National Key Research and Development Program(2016YFC0501603).
文摘Understanding the interaction between canopy structure and the parameters of interception loss is essential in predicting the variations in partitioning rainfall and water resources as affected by changes in canopy structure and in implementing water-based management in semiarid forest plantations.In this study,seasonal variations in rainfall interception loss and canopy storage capacity as driven by canopy structure were predicted and the linkages were tested using seasonal filed measurements.The study was conducted in nine 50 m×50 m Robinia pseudoacacia plots in the semiarid region of China’s Loess Plateau.Gross rain-fall,throughfall and stemflow were measured in seasons with and without leaves in 2015 and 2016.Results show that measured average interception loss for the nine plots were 17.9% and 9.4% of gross rainfall during periods with leaves (the growing season) and without leaves, respectively. Average canopy storage capacity estimated using an indirect method was 1.3 mm in the growing season and 0.2 mm in the leafless season. Correlations of relative interception loss and canopy storage capacity to canopy variables were highest for leaf/wood area index (LAI/WAI) and canopy cover, fol-lowed by bark area, basal area, tree height and stand density. Combined canopy cover, leaf/wood area index and bark area multiple regression models of interception loss and canopy storage capacity were established for the growing season and in the leafless season in 2015. It explained 97% and 96% of the variations in relative interception loss during seasons with and without leaves, respectively. It also explained 98% and 99% of the variations in canopy storage capacity during seasons with and without leaves, respectively. The empiri-cal regression models were validated using field data col-lected in 2016. The models satisfactorily predicted relative interception loss and canopy storage capacity during seasons with and without leaves. This study provides greater under-standing about the effects of changes in tree canopy st
