This study was conducted to assess the current stock of soil organic carbon under different agricultural land uses, soil types and soil depths in the Noun plain in western Cameroon. Three sites were selected for the s...This study was conducted to assess the current stock of soil organic carbon under different agricultural land uses, soil types and soil depths in the Noun plain in western Cameroon. Three sites were selected for the study, namely Mangoum, Makeka and Fossang, representative of the three dominant soil types of the noun plain (Andosols, Acrisols and Ferralsols). Three land uses were selected per site including natural vegetation, agroforest and crop field. Soil was sampled at three depths;0 - 20 cm, 20 - 40 cm, and 40 - 60 cm. Analysis of variance showed that soil type did not significantly influence carbon storage, but rather land uses and soil depth. SOCS decreased significantly with depth in all the sites, with an average stock of 66.3 ± 15.8 tC/ha at 0 - 20 cm, compared to an average stock of 33.3 ± 7.4 tC/ha at 40 - 60 cm. SOCS was significantly highest in the natural formation with 57.2 ± 19.7 tC/ha, and lowest in cultivated fields, at 37.7 ± 10.6 tC/ha. Andosols, with their high content of coarse fragments, stored less organic carbon than Ferralsols and Acrisols.展开更多
A study was conducted to assess carbon stocks in various forms and land-use types and reliably estimate the impact of land use on C stocks in the Nam Yao sub-watershed (19°05′10″N, 100°37′02″E), Thaila...A study was conducted to assess carbon stocks in various forms and land-use types and reliably estimate the impact of land use on C stocks in the Nam Yao sub-watershed (19°05′10″N, 100°37′02″E), Thailand. The carbon stocks of aboveground, soil organic and fine root within primary forest, reforestation and agricultural land were estimated through field data collection. Results re- vealed that the amount of total carbon stock of forests (357.62 ± 28.51 Mg·ha^-1, simplified expression of Mg (carbon)·ha^-1) was significantly greater (P〈 0.05) than the reforestation (195.25 ± 14.38 Mg·ha^-1) and the agricultural land (103.10 ± 18.24 Mg·ha^-1). Soil organic carbon in the forests (196.24 ± 22.81 Mg·ha^-1) was also significantly greater (P〈 0.05) than the reforestation (146.83 ± 7.22 Mg·ha^-1) and the agricultural land (95.09± 14.18 Mg·ha^-1). The differences in carbon stocks across land-use types are the primary consequence of variations in the vegetation biomass and the soil organic matter. Fine root carbon was a small fraction of carbon stocks in all land-use types. Most of the soil organic carbon and fine root carbon content was found in the upper 40-cm layer and decreased with soil depth. The aboveground carbon:soil organic carbon: fine root carbon ratios (ABGC: SOC: FRC), was 5:8:1, 2:8:1, and 3:50:1 for the forest, reforestation and agricultural land, respectively. These results indicate that a relatively large proportion of the C loss is due to forest conversion to agricultural land. However, the C can be effectively recaptured through reforestation where high levels of C are stored in biomass as carbon sinks, facilitating carbon dioxide mitigation.展开更多
Understanding the effects of land cover changes on ecosystem carbon stocks is essential for ecosystem management and envi- ronmental protection, particularly in the transboundary region that has undergone marked chang...Understanding the effects of land cover changes on ecosystem carbon stocks is essential for ecosystem management and envi- ronmental protection, particularly in the transboundary region that has undergone marked changes. This study aimed to examine the impacts of land cover changes on ecosystem carbon stocks in the transboundary Tureen River Basin (TTRB). We extracted the spatial information from Landsat Thematic Imager (TM) and Operational Land Imager (OLI) images for the years 1990 and 2015 and obtained convincing estimates of terrestrial biomass and soil carbon stocks with the INVEST model. The results showed that forestland, cropland and built-up land increased by 57.5, 429.7 and 128.9 km2, respectively, while grassland, wetland and barren land declined by 24.9, 548.0 and 43.0 km2, respectively in the TTRB from 1990 to 2015. The total carbon stocks encompassing aboveground, belowground, soil and litter layer carbon storage pools have declined from 831.48 Tg C in 1990 to 831.42 Tg C in 2015 due to land cover changes. In detail, the carbon stocks de- creased by 3.13 Tg C and 0.44 Tg C in Democratic People's Republic of Korea (North Korea) and Russia, respectively, while increased by 3.51 Tg C in China. Furthermore, economic development, and national policy accounted for most land cover changes in the TTRB. Our results imply that effective wetland and forestland protection policies among China, North Korea, and Russia are much needed for protecting the natural resources, promoting local ecosystem services and regional sustainable development in the transnational area.展开更多
【Title】【Author】This study was conducted to determine the changes in the soil carbon stocks as influenced by land use in a humid zone of Deylaman district (10,876 ha), a mountainous region of northern Iran. For t...【Title】【Author】This study was conducted to determine the changes in the soil carbon stocks as influenced by land use in a humid zone of Deylaman district (10,876 ha), a mountainous region of northern Iran. For this, land use maps were produced from TM and ETM+ images for 1985, 2000 and 2010 years; and this was supplemented by field measurement of soil carbon in 2010. The results showed that the mean soil organic carbon (SOC) density was 6.7±1.8 kg C m-2, 5.2±3.4 kg C m-2 and 3.2±1.8 kg C m-2 for 0-20 cm soil layer and 4.8±1.9 kg C m-2, 3.1±2 kg C m-2 and 2.7±1.8 kg C m-2 for 20-40 cm soil layer in forest, rangeland and cultivated land, respectively. During the past 25 years, 14.4% of the forest area had been converted to rangeland; and 28.4% of rangelands had been converted to cultivated land. According to the historical land use changes in the study area, the highest loss of SOC stocks resulted from the conversion of the forest to rangeland (0.45×104 Mg C in 0-40 cm depth layer); and the conversion of rangeland to cultivated land (0.37×104 Mg C in 0-40 cm), which typically led to the loss of soil carbon in the area studied. The knowledge on the historical land use changes and its influence on overall SOC stocks could be helpful for making management decision for farmers and policy managers in the future, for enhancing the potential of C sequestration in northern Iran.展开更多
Changes in land use cover, particularly from forest to agriculture, is a major contributing factor in increasing carbon dioxide(CO2) level in the atmosphere.Using satellite images of 1999 and 2011, land use and land...Changes in land use cover, particularly from forest to agriculture, is a major contributing factor in increasing carbon dioxide(CO2) level in the atmosphere.Using satellite images of 1999 and 2011, land use and land use changes in the Kumrat valley KPK, Pakistan, were determined: a net decrease of 11.56 and 7.46 % occurred in forest and rangeland, while 100 % increase occurred in agriculture land(AL). Biomass in different land uses,forest land(FL), AL, and range land(RL) was determined by field inventory. From the biomass data, the amount of carbon was calculated, considering 50 % of the biomass as carbon. Soil carbon was also determined to a depth of 0–15and 16–30 cm. The average carbon stocks(C stocks) in all land uses ranged from 28.62 ± 13.8 t ha-1in AL to486.6 ± 32.4 t ha-1in pure Cedrus deodara forest. The results of the study confirmed that forest soil and vegetation stored the maximum amount of carbon followed by RL. Conversion of FL and RL to AL not only leads to total loss of about 56 %(from FL conversion) and 37 %(RL conversion) of soil carbon in the last decades but also the loss of a valuable carbon sink. In order to meet the emissions reduction obligations of the Kyoto Protocol, Conservation of forest and RL in the mountainous regions of the Hindu Kush will help Pakistan to meet its emissions reduction goals under the Kyoto Protocol.展开更多
We introduce and analyze operating mechanism of three major rural land joint-stock cooperative systems in China,including community type(Nanhai model),collective leasing type(Ningxia Pingluo model) and joint operating...We introduce and analyze operating mechanism of three major rural land joint-stock cooperative systems in China,including community type(Nanhai model),collective leasing type(Ningxia Pingluo model) and joint operating type(Zhejiang Jiande model).Current rural land joint-stock cooperative system has following characteristics.Firstly,adhere to the collective ownership and household contract responsibility system in rural areas.Secondly,safeguard farmers' land contractual rights and interests.Thirdly,implement large-scale agricultural production and operation.Fourthly,carry out normative operation of farmers' cooperatives.On the basis of these,we point out such problems as backward technology and short of funds in development of rural land joint-stock cooperative system.Finally,we conclude that the development of rural land joint-stock cooperative system should fully draw lessons from foreign advanced experience,actively try new model like securitization of rural land,to explore a road suitable for current national conditions.展开更多
Land use change activities have greatly affected the total ecosystem carbon stock (TECS) and also contribute to global change through emission of greenhouse gases. The present study assessed the change in vegetation b...Land use change activities have greatly affected the total ecosystem carbon stock (TECS) and also contribute to global change through emission of greenhouse gases. The present study assessed the change in vegetation biomass carbon stock (VBCS) and soil organic carbon stock (SOCS) following conversion in major land use sectors (agriculture, agroforestry, forest and plantation) in Mizoram, Northeast India. SOCS was the highest in agroforestry (50.85 Mg C ha-1) and the lowest in agriculture (33.99 Mg C ha-1). VBCS was the highest in plantation (131.66 Mg C ha-1) and the lowest in agriculture (7.44 Mg C ha-1). The highest positive TECS change rate was observed when agriculture was converted to plantation (6.61 Mg C ha-1·yr-1), while negative rate of change in carbon stock was observed following the establishment of agriculture from other land use. A positive rate of change was observed in both VBCS and SOCS with TECS rate of 3.58 Mg C ha-1·yr-1 when agriculture got converted to agroforestry. The absolute carbon stock change rates were higher in VBCS than SOCS signifying the importance to maintain tree based vegetation cover.展开更多
Land use effect of tropical Andosol, with two from crop lands (Site 1 and Site 2) and one from Agroforestry coffee plantation (Site 3) was explored under laboratory conditions to understand their physical, chemical an...Land use effect of tropical Andosol, with two from crop lands (Site 1 and Site 2) and one from Agroforestry coffee plantation (Site 3) was explored under laboratory conditions to understand their physical, chemical and biological properties and soil organic carbon (SOC) stocks from the rift valley of Ethiopia. Site 3 that acquired less cultivation than others exhibited better aggregate size fraction (AF, 55%), higher aggregate stability (AS, 91%), and greater active microbial biomass (AMB), reflecting better soil structure development. Comparatively, higher total carbon (TC), organic carbon (OC) and total nitrogen (TN) concentrations were recorded in bulk soils and microaggregate fractions of Site 2 and Site 3 than in intensively cultivated Site 1. As expected, microaggregate fractions displayed greater OC and TN than bulk soils across all land uses. Site 1 revealed higher metabolic quotient (qCO2) and lower SOC stock (2.1 Mg·ha-1), suggesting microbial stress, while micro nutrients deficiencies were observed with the alkaline soil (Site 2). Conversely, the highest SOC stock was exhibited with Site 3 (4.2 Mg·ha-1), indicating the importance of coffee land use in C sequestration. Crop lands, depleted much of their native carbon stocks had significant CO2 sink capacity. Hence, management practices that increase the input of organic resources should be adopted to build SOM and enhance soil fertility.展开更多
Land-use conversion and unsustainable farming practices are degrading native forest ecosystems of Ghana’s humid savannah agro-ecological zone. This study assessed the impact of land-use change on soil C and N stocks ...Land-use conversion and unsustainable farming practices are degrading native forest ecosystems of Ghana’s humid savannah agro-ecological zone. This study assessed the impact of land-use change on soil C and N stocks in different land-use systems and soil types. A total of eighty (80) composite soil samples at two depths (0 - 20 cm and 20 - 50 cm) were sampled from five land use types (Forest, Woodland savannah, Grassland, Fallow and Cropland) for laboratory analyses. Particle size distribution, bulk density, pH, SOC and TN were determined using standard procedures. Results of the study indicated that C and N stocks were significantly lower in croplands (p < 0.05) compared to other land-use systems. There were significant interactions (p < 0.05) within land-use systems, soil types, and soil depth for soil C and N stocks. Acrisol and associated soils had the highest C and N stocks. A strong positive significant correlation (p < 0.05) was observed between C and N stocks with an R<sup>2</sup> value of 0.85 and 0.93 for the 0 - 20 and 20 - 50 cm depth, respectively. Soil C and N stocks in the study area were estimated to be 34.56 kg/m<sup>2</sup> and 4.63 kg/m<sup>2</sup> for soil types and 26.89 kg/m<sup>2</sup> and 3.39 kg/m2 for land use types, respectively for the 0 to 50 cm soil depth. Our findings indicated that the conversion of native forest to arable land has significantly reduced soil C and N stocks in the top 50 cm (0.50 m) soil layer by 50.77% and 47.77%, respectively. Therefore, we conclude that land-use change, soil type, and soil depth influenced soil C and N stocks of land-use systems in the humid savannah agro-ecological zone of Ghana.展开更多
文摘This study was conducted to assess the current stock of soil organic carbon under different agricultural land uses, soil types and soil depths in the Noun plain in western Cameroon. Three sites were selected for the study, namely Mangoum, Makeka and Fossang, representative of the three dominant soil types of the noun plain (Andosols, Acrisols and Ferralsols). Three land uses were selected per site including natural vegetation, agroforest and crop field. Soil was sampled at three depths;0 - 20 cm, 20 - 40 cm, and 40 - 60 cm. Analysis of variance showed that soil type did not significantly influence carbon storage, but rather land uses and soil depth. SOCS decreased significantly with depth in all the sites, with an average stock of 66.3 ± 15.8 tC/ha at 0 - 20 cm, compared to an average stock of 33.3 ± 7.4 tC/ha at 40 - 60 cm. SOCS was significantly highest in the natural formation with 57.2 ± 19.7 tC/ha, and lowest in cultivated fields, at 37.7 ± 10.6 tC/ha. Andosols, with their high content of coarse fragments, stored less organic carbon than Ferralsols and Acrisols.
文摘A study was conducted to assess carbon stocks in various forms and land-use types and reliably estimate the impact of land use on C stocks in the Nam Yao sub-watershed (19°05′10″N, 100°37′02″E), Thailand. The carbon stocks of aboveground, soil organic and fine root within primary forest, reforestation and agricultural land were estimated through field data collection. Results re- vealed that the amount of total carbon stock of forests (357.62 ± 28.51 Mg·ha^-1, simplified expression of Mg (carbon)·ha^-1) was significantly greater (P〈 0.05) than the reforestation (195.25 ± 14.38 Mg·ha^-1) and the agricultural land (103.10 ± 18.24 Mg·ha^-1). Soil organic carbon in the forests (196.24 ± 22.81 Mg·ha^-1) was also significantly greater (P〈 0.05) than the reforestation (146.83 ± 7.22 Mg·ha^-1) and the agricultural land (95.09± 14.18 Mg·ha^-1). The differences in carbon stocks across land-use types are the primary consequence of variations in the vegetation biomass and the soil organic matter. Fine root carbon was a small fraction of carbon stocks in all land-use types. Most of the soil organic carbon and fine root carbon content was found in the upper 40-cm layer and decreased with soil depth. The aboveground carbon:soil organic carbon: fine root carbon ratios (ABGC: SOC: FRC), was 5:8:1, 2:8:1, and 3:50:1 for the forest, reforestation and agricultural land, respectively. These results indicate that a relatively large proportion of the C loss is due to forest conversion to agricultural land. However, the C can be effectively recaptured through reforestation where high levels of C are stored in biomass as carbon sinks, facilitating carbon dioxide mitigation.
基金Under the auspices of the National Key Research and Development Project(No.2016YFA0602301)National Natural Science Foundation of China(No.41730643,41671219,41771109,31500400)
文摘Understanding the effects of land cover changes on ecosystem carbon stocks is essential for ecosystem management and envi- ronmental protection, particularly in the transboundary region that has undergone marked changes. This study aimed to examine the impacts of land cover changes on ecosystem carbon stocks in the transboundary Tureen River Basin (TTRB). We extracted the spatial information from Landsat Thematic Imager (TM) and Operational Land Imager (OLI) images for the years 1990 and 2015 and obtained convincing estimates of terrestrial biomass and soil carbon stocks with the INVEST model. The results showed that forestland, cropland and built-up land increased by 57.5, 429.7 and 128.9 km2, respectively, while grassland, wetland and barren land declined by 24.9, 548.0 and 43.0 km2, respectively in the TTRB from 1990 to 2015. The total carbon stocks encompassing aboveground, belowground, soil and litter layer carbon storage pools have declined from 831.48 Tg C in 1990 to 831.42 Tg C in 2015 due to land cover changes. In detail, the carbon stocks de- creased by 3.13 Tg C and 0.44 Tg C in Democratic People's Republic of Korea (North Korea) and Russia, respectively, while increased by 3.51 Tg C in China. Furthermore, economic development, and national policy accounted for most land cover changes in the TTRB. Our results imply that effective wetland and forestland protection policies among China, North Korea, and Russia are much needed for protecting the natural resources, promoting local ecosystem services and regional sustainable development in the transnational area.
文摘【Title】【Author】This study was conducted to determine the changes in the soil carbon stocks as influenced by land use in a humid zone of Deylaman district (10,876 ha), a mountainous region of northern Iran. For this, land use maps were produced from TM and ETM+ images for 1985, 2000 and 2010 years; and this was supplemented by field measurement of soil carbon in 2010. The results showed that the mean soil organic carbon (SOC) density was 6.7±1.8 kg C m-2, 5.2±3.4 kg C m-2 and 3.2±1.8 kg C m-2 for 0-20 cm soil layer and 4.8±1.9 kg C m-2, 3.1±2 kg C m-2 and 2.7±1.8 kg C m-2 for 20-40 cm soil layer in forest, rangeland and cultivated land, respectively. During the past 25 years, 14.4% of the forest area had been converted to rangeland; and 28.4% of rangelands had been converted to cultivated land. According to the historical land use changes in the study area, the highest loss of SOC stocks resulted from the conversion of the forest to rangeland (0.45×104 Mg C in 0-40 cm depth layer); and the conversion of rangeland to cultivated land (0.37×104 Mg C in 0-40 cm), which typically led to the loss of soil carbon in the area studied. The knowledge on the historical land use changes and its influence on overall SOC stocks could be helpful for making management decision for farmers and policy managers in the future, for enhancing the potential of C sequestration in northern Iran.
文摘Changes in land use cover, particularly from forest to agriculture, is a major contributing factor in increasing carbon dioxide(CO2) level in the atmosphere.Using satellite images of 1999 and 2011, land use and land use changes in the Kumrat valley KPK, Pakistan, were determined: a net decrease of 11.56 and 7.46 % occurred in forest and rangeland, while 100 % increase occurred in agriculture land(AL). Biomass in different land uses,forest land(FL), AL, and range land(RL) was determined by field inventory. From the biomass data, the amount of carbon was calculated, considering 50 % of the biomass as carbon. Soil carbon was also determined to a depth of 0–15and 16–30 cm. The average carbon stocks(C stocks) in all land uses ranged from 28.62 ± 13.8 t ha-1in AL to486.6 ± 32.4 t ha-1in pure Cedrus deodara forest. The results of the study confirmed that forest soil and vegetation stored the maximum amount of carbon followed by RL. Conversion of FL and RL to AL not only leads to total loss of about 56 %(from FL conversion) and 37 %(RL conversion) of soil carbon in the last decades but also the loss of a valuable carbon sink. In order to meet the emissions reduction obligations of the Kyoto Protocol, Conservation of forest and RL in the mountainous regions of the Hindu Kush will help Pakistan to meet its emissions reduction goals under the Kyoto Protocol.
文摘We introduce and analyze operating mechanism of three major rural land joint-stock cooperative systems in China,including community type(Nanhai model),collective leasing type(Ningxia Pingluo model) and joint operating type(Zhejiang Jiande model).Current rural land joint-stock cooperative system has following characteristics.Firstly,adhere to the collective ownership and household contract responsibility system in rural areas.Secondly,safeguard farmers' land contractual rights and interests.Thirdly,implement large-scale agricultural production and operation.Fourthly,carry out normative operation of farmers' cooperatives.On the basis of these,we point out such problems as backward technology and short of funds in development of rural land joint-stock cooperative system.Finally,we conclude that the development of rural land joint-stock cooperative system should fully draw lessons from foreign advanced experience,actively try new model like securitization of rural land,to explore a road suitable for current national conditions.
文摘Land use change activities have greatly affected the total ecosystem carbon stock (TECS) and also contribute to global change through emission of greenhouse gases. The present study assessed the change in vegetation biomass carbon stock (VBCS) and soil organic carbon stock (SOCS) following conversion in major land use sectors (agriculture, agroforestry, forest and plantation) in Mizoram, Northeast India. SOCS was the highest in agroforestry (50.85 Mg C ha-1) and the lowest in agriculture (33.99 Mg C ha-1). VBCS was the highest in plantation (131.66 Mg C ha-1) and the lowest in agriculture (7.44 Mg C ha-1). The highest positive TECS change rate was observed when agriculture was converted to plantation (6.61 Mg C ha-1·yr-1), while negative rate of change in carbon stock was observed following the establishment of agriculture from other land use. A positive rate of change was observed in both VBCS and SOCS with TECS rate of 3.58 Mg C ha-1·yr-1 when agriculture got converted to agroforestry. The absolute carbon stock change rates were higher in VBCS than SOCS signifying the importance to maintain tree based vegetation cover.
文摘Land use effect of tropical Andosol, with two from crop lands (Site 1 and Site 2) and one from Agroforestry coffee plantation (Site 3) was explored under laboratory conditions to understand their physical, chemical and biological properties and soil organic carbon (SOC) stocks from the rift valley of Ethiopia. Site 3 that acquired less cultivation than others exhibited better aggregate size fraction (AF, 55%), higher aggregate stability (AS, 91%), and greater active microbial biomass (AMB), reflecting better soil structure development. Comparatively, higher total carbon (TC), organic carbon (OC) and total nitrogen (TN) concentrations were recorded in bulk soils and microaggregate fractions of Site 2 and Site 3 than in intensively cultivated Site 1. As expected, microaggregate fractions displayed greater OC and TN than bulk soils across all land uses. Site 1 revealed higher metabolic quotient (qCO2) and lower SOC stock (2.1 Mg·ha-1), suggesting microbial stress, while micro nutrients deficiencies were observed with the alkaline soil (Site 2). Conversely, the highest SOC stock was exhibited with Site 3 (4.2 Mg·ha-1), indicating the importance of coffee land use in C sequestration. Crop lands, depleted much of their native carbon stocks had significant CO2 sink capacity. Hence, management practices that increase the input of organic resources should be adopted to build SOM and enhance soil fertility.
文摘Land-use conversion and unsustainable farming practices are degrading native forest ecosystems of Ghana’s humid savannah agro-ecological zone. This study assessed the impact of land-use change on soil C and N stocks in different land-use systems and soil types. A total of eighty (80) composite soil samples at two depths (0 - 20 cm and 20 - 50 cm) were sampled from five land use types (Forest, Woodland savannah, Grassland, Fallow and Cropland) for laboratory analyses. Particle size distribution, bulk density, pH, SOC and TN were determined using standard procedures. Results of the study indicated that C and N stocks were significantly lower in croplands (p < 0.05) compared to other land-use systems. There were significant interactions (p < 0.05) within land-use systems, soil types, and soil depth for soil C and N stocks. Acrisol and associated soils had the highest C and N stocks. A strong positive significant correlation (p < 0.05) was observed between C and N stocks with an R<sup>2</sup> value of 0.85 and 0.93 for the 0 - 20 and 20 - 50 cm depth, respectively. Soil C and N stocks in the study area were estimated to be 34.56 kg/m<sup>2</sup> and 4.63 kg/m<sup>2</sup> for soil types and 26.89 kg/m<sup>2</sup> and 3.39 kg/m2 for land use types, respectively for the 0 to 50 cm soil depth. Our findings indicated that the conversion of native forest to arable land has significantly reduced soil C and N stocks in the top 50 cm (0.50 m) soil layer by 50.77% and 47.77%, respectively. Therefore, we conclude that land-use change, soil type, and soil depth influenced soil C and N stocks of land-use systems in the humid savannah agro-ecological zone of Ghana.