We review the current status of experimental studies in India to understand the linkages between afforestation and hydrology. This discipline deals with the use and management of water, social awareness of environment...We review the current status of experimental studies in India to understand the linkages between afforestation and hydrology. This discipline deals with the use and management of water, social awareness of environmental problems, and ecosystem limitations on provision of watershed services by river basins in the mountain regions of India. Our review begins with examination of experimental works in tropical countries and proceeds to discussion of initiatives of Indian research institutes and Government organizations towards establishing experimental watersheds to understand the impacts of land cover changes on hydrologic regimes in the Indian sub-continent. This is followed by the review of the experimental work carried out by various authors to assess the impact of land cover changes on major water balance components such as, runoff, groundwater, evapotranspiration and sediment yield. The spatial scales of these experiments have been limited to small watersheds or field plots. This paper also describes impacts of human interventions （such as planta- tions of exotic forest species to restore degraded landscapes） on the water balance components in diverse hydro-geo-environmental conditions in the Indian sub-continent. We focus on identifying the research areas which require immediate attention to develop tools to assist planners and policy makers in assessing and managing the water resources in these complex environments. The review is largely based on research results reported during the last 20 to 30 years.展开更多
In slopes of Mediterranean mid-mountain areas,land use and land cover changes linked to the aban-donment of cropland activity affect soil quality and degradation and soil redistribution;however,limited attention has b...In slopes of Mediterranean mid-mountain areas,land use and land cover changes linked to the aban-donment of cropland activity affect soil quality and degradation and soil redistribution;however,limited attention has been paid to this issue at catchment scale.This paper evaluates the effects of cropland abandonment and post-land abandonment management(through natural revegetation and afforesta-tion)on soil redistribution rates using fallout ^(137)Cs measurements in the Araguás catchment(0.45 km^(2),Central Spanish Pyrenees).A total of 52 soil core samples,distributed in a regular grid,from the first 30-40 cm and 9 sectioned reference samples were collected across the catchment and soil properties were analysed.Fallout ^(137)Cs was measured in a 5 cm sectioned references samples and in bulk grid samples.^(137)Cs inventories were used to estimate soil erosion and deposition rates across the catchment.Results show that the highest erosion rates were recorded under sparsely vegetated sites in the badland area,while the lowest rates were found in the afforested area,but no significant differences were observed between the different uses and covers in soil redistribution rates likely due to a long history of human intervention through cultivation in steep slopes and afforestation practices.However,the recovery of the soil organic matter in afforested areas suggest that afforestation can reduce soil degradation at long-term scale.The information gained achieve a better understanding of soil redistribution dynamics and provide knowledge for effective land management after cropland abandonment of agroecosystems in Mediter-ranean mountain areas.展开更多
In the past 50 years, large areas of the Horqin sandy land were afforested to prevent desertification. Although the afforestation policy appears successful, many people now doubt whether it is suitable to plant trees ...In the past 50 years, large areas of the Horqin sandy land were afforested to prevent desertification. Although the afforestation policy appears successful, many people now doubt whether it is suitable to plant trees with high density on the poor soils in semiarid regions. Little is known about the impacts of afforestation on the sandy soil properties, although the evaluation of these impacts is fundamental to judge the rationality of afforestation policy. Soil phosphorus （P） fractions, acid phosphomonoesterase activities, and other soil chemical properties were compared among five adjoining typical ecosystems on poor sandy soils in southeastern Horqin sandy land. The ecosystems studied are natural elm savanna, degraded grassland, Mongolian pine （Pinus sylvestris var. mongolica） plantation, Chinese pine （Pinus tabulaeformis） plantation, and mixed plantation of Mongolian pine and poplar （Populus simonii）. The results showed that organic P dominated soil P （47%-65%） was the principal source of available P. The degradation of elm savanna to grassland significantly reduced soil pH and resulted in an overall reduction in soil fertility, although slightly increased labile inorganic P. Grassland afforestation had no significant influence on soil pH, organic carbon, and total N but significantly reduced total P. Impacts of grassland afforestation on soil P fractions depended on tree species. Natural elm savanna had higher soil P conserving ability than artificial plantations. Therefore, with the aim of developing a sustainable ecosystem, we suggested that vegetations with low nutrient demand （particularly P） and efficient nutrient cycling would be more suitable for ecosystem restoration in the semiarid region.展开更多
Soil moisture is an important resource for plant growth on the arid and semi-arid Loess Plateau of China where the‘‘Grain for Green’’project was launched in 1999,but there has been no systematic evaluation of soil...Soil moisture is an important resource for plant growth on the arid and semi-arid Loess Plateau of China where the‘‘Grain for Green’’project was launched in 1999,but there has been no systematic evaluation of soil moisture from the effects of ecological restoration at a regional scale.We systematically assessed 63 published studies during 2000-2015,including 2050 observations at 68 sites on the Loess Plateau with the aim of determining soil moisture changes and the factors influencing those changes.We found that,after land use conversion,soil moisture decreased by 17%in the upper 100 cm soil layer and that tree plantations and shrub lands appeared to cause soil moisture depletion which became increasingly serious with soil depth.The decrease of soil moisture was significantly influenced by the planting species in all restoration types(tree plantations,shrub lands,and grasslands).We also found that tree plantations and grasslands converted from farmlands consumed more soil moisture than from wasteland(including bare land,abandoned land and wild grasslands).Artificial restoration led to significant soil moisture reduction,but natural restoration had little effect on soil moisture.Therefore,natural restoration should be an alternative restoration practice on the Loess Plateau.These results will provide helpful information for artificial afforestation and planning ecological restoration campaigns for policy makers on water-limited regions.展开更多
The presence of increasing quantities of greenhouse gases is fostering climate change. This review chronicles the emerging research addressing the role of soil to sequester carbon across biomes, understand the soil me...The presence of increasing quantities of greenhouse gases is fostering climate change. This review chronicles the emerging research addressing the role of soil to sequester carbon across biomes, understand the soil mechanisms responsible for soil carbon preservation and indicate the need to estimate the intensity for site-specific carbon sequestration. To negate the continuing increase of atmospheric greenhouse gases requires using well-documented soil pathways to sequester carbon. For deciduous forests, emerging concepts center around two approaches: 1) increasing the ecosystem’s net primary productivity coupled with increasing the carbon supply into soil using appropriate land management practices, and 2) supporting soil processes that increase soil carbon retention. New perspectives suggest that soil carbon may be preferentially preserved because organic materials are adsorbed onto phyllosilicates and oxyhydroxides and subsequently protected from microbial degradation because of soil structure improvement. Thus, augmenting soil structure may promote soil organic matter persistence. Each soil has a soil carbon carrying capacity;however, soil survey databases infer that soil organic matter concentrations have a significant variance at the soil series level. The need exists for more precise estimates of the soil’s carbon carrying capacity at the pedon level to support land management practices that encourage land management options designed to preserve soil carbon. However, the complexity of the soil system may limit its usefulness for routine soil management decisions. Our modern understanding of soil carbon preservation processes and emerging soil carbon saturation deficit concepts may potentially improve decision support tools for managing soils for carbon sequestration.展开更多
文摘We review the current status of experimental studies in India to understand the linkages between afforestation and hydrology. This discipline deals with the use and management of water, social awareness of environmental problems, and ecosystem limitations on provision of watershed services by river basins in the mountain regions of India. Our review begins with examination of experimental works in tropical countries and proceeds to discussion of initiatives of Indian research institutes and Government organizations towards establishing experimental watersheds to understand the impacts of land cover changes on hydrologic regimes in the Indian sub-continent. This is followed by the review of the experimental work carried out by various authors to assess the impact of land cover changes on major water balance components such as, runoff, groundwater, evapotranspiration and sediment yield. The spatial scales of these experiments have been limited to small watersheds or field plots. This paper also describes impacts of human interventions （such as planta- tions of exotic forest species to restore degraded landscapes） on the water balance components in diverse hydro-geo-environmental conditions in the Indian sub-continent. We focus on identifying the research areas which require immediate attention to develop tools to assist planners and policy makers in assessing and managing the water resources in these complex environments. The review is largely based on research results reported during the last 20 to 30 years.
基金supported by the ESPAS and MANMOUNT projects(CGL2015-65569-R and PID2019-105983RB-100/AEI/10.13039/501100011033)the MINEC0-FEDER and MICINN-FEDER)and the RednutSOIL project(PID2019-104857RBI00/AEI/10.13039/501100011033)+1 种基金the MICINN-FEDERThe“Geoenvironmental Processes and Global Change"(E02_17E)research group is financed by the Aragon Government and the European Social Fund(ESF-FSE).
文摘In slopes of Mediterranean mid-mountain areas,land use and land cover changes linked to the aban-donment of cropland activity affect soil quality and degradation and soil redistribution;however,limited attention has been paid to this issue at catchment scale.This paper evaluates the effects of cropland abandonment and post-land abandonment management(through natural revegetation and afforesta-tion)on soil redistribution rates using fallout ^(137)Cs measurements in the Araguás catchment(0.45 km^(2),Central Spanish Pyrenees).A total of 52 soil core samples,distributed in a regular grid,from the first 30-40 cm and 9 sectioned reference samples were collected across the catchment and soil properties were analysed.Fallout ^(137)Cs was measured in a 5 cm sectioned references samples and in bulk grid samples.^(137)Cs inventories were used to estimate soil erosion and deposition rates across the catchment.Results show that the highest erosion rates were recorded under sparsely vegetated sites in the badland area,while the lowest rates were found in the afforested area,but no significant differences were observed between the different uses and covers in soil redistribution rates likely due to a long history of human intervention through cultivation in steep slopes and afforestation practices.However,the recovery of the soil organic matter in afforested areas suggest that afforestation can reduce soil degradation at long-term scale.The information gained achieve a better understanding of soil redistribution dynamics and provide knowledge for effective land management after cropland abandonment of agroecosystems in Mediter-ranean mountain areas.
基金the National Natural Science Foundation of China (No.30471377)the Science and Engi-neering Foundation of Korea, and the National Key Technologies R&D Programs of China (Nos.2005BA517A03 and2006BAC01A12)
文摘In the past 50 years, large areas of the Horqin sandy land were afforested to prevent desertification. Although the afforestation policy appears successful, many people now doubt whether it is suitable to plant trees with high density on the poor soils in semiarid regions. Little is known about the impacts of afforestation on the sandy soil properties, although the evaluation of these impacts is fundamental to judge the rationality of afforestation policy. Soil phosphorus （P） fractions, acid phosphomonoesterase activities, and other soil chemical properties were compared among five adjoining typical ecosystems on poor sandy soils in southeastern Horqin sandy land. The ecosystems studied are natural elm savanna, degraded grassland, Mongolian pine （Pinus sylvestris var. mongolica） plantation, Chinese pine （Pinus tabulaeformis） plantation, and mixed plantation of Mongolian pine and poplar （Populus simonii）. The results showed that organic P dominated soil P （47%-65%） was the principal source of available P. The degradation of elm savanna to grassland significantly reduced soil pH and resulted in an overall reduction in soil fertility, although slightly increased labile inorganic P. Grassland afforestation had no significant influence on soil pH, organic carbon, and total N but significantly reduced total P. Impacts of grassland afforestation on soil P fractions depended on tree species. Natural elm savanna had higher soil P conserving ability than artificial plantations. Therefore, with the aim of developing a sustainable ecosystem, we suggested that vegetations with low nutrient demand （particularly P） and efficient nutrient cycling would be more suitable for ecosystem restoration in the semiarid region.
文摘Soil moisture is an important resource for plant growth on the arid and semi-arid Loess Plateau of China where the‘‘Grain for Green’’project was launched in 1999,but there has been no systematic evaluation of soil moisture from the effects of ecological restoration at a regional scale.We systematically assessed 63 published studies during 2000-2015,including 2050 observations at 68 sites on the Loess Plateau with the aim of determining soil moisture changes and the factors influencing those changes.We found that,after land use conversion,soil moisture decreased by 17%in the upper 100 cm soil layer and that tree plantations and shrub lands appeared to cause soil moisture depletion which became increasingly serious with soil depth.The decrease of soil moisture was significantly influenced by the planting species in all restoration types(tree plantations,shrub lands,and grasslands).We also found that tree plantations and grasslands converted from farmlands consumed more soil moisture than from wasteland(including bare land,abandoned land and wild grasslands).Artificial restoration led to significant soil moisture reduction,but natural restoration had little effect on soil moisture.Therefore,natural restoration should be an alternative restoration practice on the Loess Plateau.These results will provide helpful information for artificial afforestation and planning ecological restoration campaigns for policy makers on water-limited regions.
文摘The presence of increasing quantities of greenhouse gases is fostering climate change. This review chronicles the emerging research addressing the role of soil to sequester carbon across biomes, understand the soil mechanisms responsible for soil carbon preservation and indicate the need to estimate the intensity for site-specific carbon sequestration. To negate the continuing increase of atmospheric greenhouse gases requires using well-documented soil pathways to sequester carbon. For deciduous forests, emerging concepts center around two approaches: 1) increasing the ecosystem’s net primary productivity coupled with increasing the carbon supply into soil using appropriate land management practices, and 2) supporting soil processes that increase soil carbon retention. New perspectives suggest that soil carbon may be preferentially preserved because organic materials are adsorbed onto phyllosilicates and oxyhydroxides and subsequently protected from microbial degradation because of soil structure improvement. Thus, augmenting soil structure may promote soil organic matter persistence. Each soil has a soil carbon carrying capacity;however, soil survey databases infer that soil organic matter concentrations have a significant variance at the soil series level. The need exists for more precise estimates of the soil’s carbon carrying capacity at the pedon level to support land management practices that encourage land management options designed to preserve soil carbon. However, the complexity of the soil system may limit its usefulness for routine soil management decisions. Our modern understanding of soil carbon preservation processes and emerging soil carbon saturation deficit concepts may potentially improve decision support tools for managing soils for carbon sequestration.
