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
Black locust （Robinia pseudoacacia） is widely planted throughout the semi-arid Loess Plateau of China. The spatial distribution of this species at different ages is highly heterogeneous due to restoration and manage...Black locust （Robinia pseudoacacia） is widely planted throughout the semi-arid Loess Plateau of China. The spatial distribution of this species at different ages is highly heterogeneous due to restoration and management practices. In this study, we aimed to compare the transpiration levels between different aged black locusts at the tree and stand scales, clarifying the physiological status of this species with different ages. Black locust trees with two representative age classes （12 and 28 years） were selected in the Yangjuangou catchment on the semi-arid Loess Plateau. Sap flux density （Fd） and environmental variables （solar radiation, air temperature, relative humidity and soil water content） were simultaneously monitored throughout the growing season of 2014. Tree transpiration （Et） was the product of Fd and sapwood area （As）, and stand transpiration （Ec） was calculated basing on the stand sap flux density （Js） and stand total sapwood area （AsT）. Stomatal conductance （gs） was measured in a controlled environment and hydraulic conductance was estimated using the relationship between transpiration rate and vapor pressure deficit （VPD）. Our results showed that Et and Ec were higher in the 28-year-old stand than in the 12-year-old stand. The gs and hydraulic conductance of 28-year-old trees were also higher than those of 12-year-old trees, and the two parameters were thus the causes of variations in transpiration between different age classes. After rainfall, mean Fd increased by 9% in 28-year-old trees and by 5% in 12-year-old trees. This study thus suggests that stand age should be considered for estimating transpiration at the catchment and region scales in this area. These results provide ecophysiological evidences that the older black locust trees had more active physiological status than the younger ones in this area. These findings also provide basic information for the management of water resources and forests on the semi-arid Loess Plateau.展开更多
The Beijing-Tianjin Sand Source Control Project(BTSSCP), a national ecological restoration project, was launched to construct an ecological protection system in the Beijing-Tianjin sand source areas to reduce dust haz...The Beijing-Tianjin Sand Source Control Project(BTSSCP), a national ecological restoration project, was launched to construct an ecological protection system in the Beijing-Tianjin sand source areas to reduce dust hazards. The carbon sequestration dynamics can be used to assess the ecological effects of an ecological restoration project. Here, we conducted vegetation and soil study to assess the carbon sequestration in the plantations with 10 years old stands in Beijing-Tianjin sand source areas. The results at the site scales indicated that the average net increase of plantation ecosystem carbon stock was 33.8 Mg C ha^(-1), with an annual increase rate of 3.38 Mg C ha^(-1) yr^(-1). The average net increase of carbon varied among regions, vegetation types, and forest management activities. Soil bulk density in the top soil decreased slightly after 10-year implementation of the project. Coniferous forests and shrubs are suitable plant species for sand source areas.Natural restoration in the plantations is a practical and feasible and promising approach for enhancing ecosystem carbon sequestration potential.展开更多
Background Three-North Afforestation Program(TNAP)in China is the largest ecological restoration project on Earth(ongoing from 1978 to 2050),harboring a huge area of newly planted forests,which provides a wealth of go...Background Three-North Afforestation Program(TNAP)in China is the largest ecological restoration project on Earth(ongoing from 1978 to 2050),harboring a huge area of newly planted forests,which provides a wealth of goods and ecosystem services that benefit society at levels ranging from region to East Asia.This project-induced carbon(C)sink has been expected to be large,but its size and location remain uncertain.Results In this study,we investigated the changes in the C stocks of biomass,soil C and the C accumulation ben-efited from the ecological effects in the project areas from 1978 to 2017 within the Three-North regions(4.069×10^(6)km^(2)),and evaluated its project-induced C sequestration.Using a combination of remote sensing images,field obser-vations and national forest inventory data,we estimated a total ecosystem sink of 47.06 Tg C per year(1 Tg=10^(12)g)increased by the TNAP implementation.Importantly,we first found that the C sink via the ecological effects of this project could contribute to a high proportion up to 15.94%,indicating a critical role of ecological effects in shaping the distribution of C stocks in the protective forests.This finding suggests that it is necessary to explicitly consider carbon sequestration benefited from the ecological effects when estimating C sink and parameterizing C models of the restoration projects in China and globally.Conclusions Our results update the estimates of C pools in the world’s largest ecological restoration project area,demonstrating that this project has substantially contributed to mitigating the climate change.展开更多
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.
基金supported by the National Natural Science Foundation of China(41390462,41201182,31300402)the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry
文摘Black locust （Robinia pseudoacacia） is widely planted throughout the semi-arid Loess Plateau of China. The spatial distribution of this species at different ages is highly heterogeneous due to restoration and management practices. In this study, we aimed to compare the transpiration levels between different aged black locusts at the tree and stand scales, clarifying the physiological status of this species with different ages. Black locust trees with two representative age classes （12 and 28 years） were selected in the Yangjuangou catchment on the semi-arid Loess Plateau. Sap flux density （Fd） and environmental variables （solar radiation, air temperature, relative humidity and soil water content） were simultaneously monitored throughout the growing season of 2014. Tree transpiration （Et） was the product of Fd and sapwood area （As）, and stand transpiration （Ec） was calculated basing on the stand sap flux density （Js） and stand total sapwood area （AsT）. Stomatal conductance （gs） was measured in a controlled environment and hydraulic conductance was estimated using the relationship between transpiration rate and vapor pressure deficit （VPD）. Our results showed that Et and Ec were higher in the 28-year-old stand than in the 12-year-old stand. The gs and hydraulic conductance of 28-year-old trees were also higher than those of 12-year-old trees, and the two parameters were thus the causes of variations in transpiration between different age classes. After rainfall, mean Fd increased by 9% in 28-year-old trees and by 5% in 12-year-old trees. This study thus suggests that stand age should be considered for estimating transpiration at the catchment and region scales in this area. These results provide ecophysiological evidences that the older black locust trees had more active physiological status than the younger ones in this area. These findings also provide basic information for the management of water resources and forests on the semi-arid Loess Plateau.
基金supported by the National Key Research and Development Program of China(2016YFC0500802)the "Strategic Priority Research Program" of the Chinese Academy of Sciences(XDA05060600)+1 种基金Visiting Scholars Program of ported by Chinese Academy of SciencesYouth Innovation Promotion Association,CAS(2014083)
文摘The Beijing-Tianjin Sand Source Control Project(BTSSCP), a national ecological restoration project, was launched to construct an ecological protection system in the Beijing-Tianjin sand source areas to reduce dust hazards. The carbon sequestration dynamics can be used to assess the ecological effects of an ecological restoration project. Here, we conducted vegetation and soil study to assess the carbon sequestration in the plantations with 10 years old stands in Beijing-Tianjin sand source areas. The results at the site scales indicated that the average net increase of plantation ecosystem carbon stock was 33.8 Mg C ha^(-1), with an annual increase rate of 3.38 Mg C ha^(-1) yr^(-1). The average net increase of carbon varied among regions, vegetation types, and forest management activities. Soil bulk density in the top soil decreased slightly after 10-year implementation of the project. Coniferous forests and shrubs are suitable plant species for sand source areas.Natural restoration in the plantations is a practical and feasible and promising approach for enhancing ecosystem carbon sequestration potential.
基金supported by grants from National Key R&D Program of China(2020YFA0608100)CAS Key Research Program of Frontier Sciences(QYZDJ-SSW-DQC027)+2 种基金National Natural Science Foundation of China(31025007)the Knowledge Innovation Program of Chinese Academy of Sciences(KZCX1-YW-08-02)the Consultation Project supported by Divisions of the Chinese Academy of Sciences(2019-ZW09-A-032).
文摘Background Three-North Afforestation Program(TNAP)in China is the largest ecological restoration project on Earth(ongoing from 1978 to 2050),harboring a huge area of newly planted forests,which provides a wealth of goods and ecosystem services that benefit society at levels ranging from region to East Asia.This project-induced carbon(C)sink has been expected to be large,but its size and location remain uncertain.Results In this study,we investigated the changes in the C stocks of biomass,soil C and the C accumulation ben-efited from the ecological effects in the project areas from 1978 to 2017 within the Three-North regions(4.069×10^(6)km^(2)),and evaluated its project-induced C sequestration.Using a combination of remote sensing images,field obser-vations and national forest inventory data,we estimated a total ecosystem sink of 47.06 Tg C per year(1 Tg=10^(12)g)increased by the TNAP implementation.Importantly,we first found that the C sink via the ecological effects of this project could contribute to a high proportion up to 15.94%,indicating a critical role of ecological effects in shaping the distribution of C stocks in the protective forests.This finding suggests that it is necessary to explicitly consider carbon sequestration benefited from the ecological effects when estimating C sink and parameterizing C models of the restoration projects in China and globally.Conclusions Our results update the estimates of C pools in the world’s largest ecological restoration project area,demonstrating that this project has substantially contributed to mitigating the climate change.
