Horqin Sandy Land is a fragile, seriously desertified region located in Inner Mongolia of China. Over- grazing is one of the primary drivers of desertification in this region. We investigated whether the establishment...Horqin Sandy Land is a fragile, seriously desertified region located in Inner Mongolia of China. Over- grazing is one of the primary drivers of desertification in this region. We investigated whether the establishment of grazing exclosures in areas with active sand dunes enhances soil carbon （C） sequestration and benefits soil re- covery. The results showed that soil organic C storage was 1.4, 1.9, and 3.5 times, and light fraction C storage was 2.3, 3.2, and 4.4 times in the 100-cm topsoil after 7, 12, and 25 years of grazing exclusion, respectively, compared to the case in active sand dunes. The light fraction of soil played an important role in soil C sequestration, although it might not change rapidly to provide an early indication of how soil C is increasing in response to grazing exclusion. The results indicated that soils could potentially sequester up to 13.8 Mt C in 25 years if active sand dunes in the study area were to be protected by exclosures. This corresponds to 12.8% of the estimated carbon loss （107.53 Mt） that has been associated with desertification over the past century in the Horqin Sandy Land. Our results suggested that exclosures have the capacity to increase soil C sequestration; however, decades will be required for soil C to recover to historical grassland levels observed prior to desertification.展开更多
During the period of September 12, 1999 to September 24, 2000, we measured sap flow ofeucalyptus (Euca/yptus urophylla S.T. Blake) plantations using heat pulse technique, and the relevantenvironmental vaiables, such a...During the period of September 12, 1999 to September 24, 2000, we measured sap flow ofeucalyptus (Euca/yptus urophylla S.T. Blake) plantations using heat pulse technique, and the relevantenvironmental vaiables, such as soil evaporation and canopy interception, etc, at Hetou and Jijia sites,Leizhou Peninsula, Guangdong Province. Based on the measurements of sap flow and estimates ofevapotranspiration, the following can be concluded: (1) the maximum of diurnal xylem sap flux density (SFD)at Hetou, where covered with coarse-textured soils formed on Quaternary sediments, was almost twice ofthat at Jijia, where located on clay-rich soils derived from basalt; (2) SFD was highly correlated to watervapor pressure deficit (VPD) of ambient air near the canopy layer, (3) the correlation between SFD and airtemperature also depends on soil properties and soil water potential; (4) the relative differences betweenmeasured and modeled evapotranspiration were small, being 5.26% at Hetou and 6.14% at Jijia; (5) theplantation transpiration accounted for 62.2% and 51.3% of the evapotranspiration at Hetou and Jijia,respectively; and (6) the averaged SFD per unit leaf area (ASPULA) was a good index to estimate theamount of water consumption of tree species.展开更多
[Objectives] Within a research area on basin scale, soil nutrient distribution characteristics and main causes were analyzed, to provide a basis for soil nutrient management on basin scale.[Methods] With the Nandu Riv...[Objectives] Within a research area on basin scale, soil nutrient distribution characteristics and main causes were analyzed, to provide a basis for soil nutrient management on basin scale.[Methods] With the Nandu River Basin of Hainan Island as the research area, by means of geostatistics and spatial analysis methods, the distribution available of soil pH, organic matter, alkali-hydrolyzale nitrogen, available phosphorus, available potassium and available trace elements were studied.[Results] The cultivated land in the Nandu River Basin of Hainan Province is overall acidic, with an average pH of 5.2. The soil organic matter content is overall lower, and its spatial differences are also significant. Soil alkali-hydrolyzable nitrogen, exchangeable calcium and exchangeable magnesium content are at a medium level, but the soil lacks available phosphorus and available potassium.[Conclusions] The differences in pH within the research area might be related to parent materials distribution and fertilizer applications. The main reasons for the low soil organic matter content are inadequate and uneven input of organic fertilizer and high-temperate rainy climate. The lack of soil phosphorus and potassium is mainly caused by unreasonable fertilizer application and climatic and terrain factors.展开更多
This paper sets out to determine the link between socio-economic attributes of smallholders, silvicultural activity and the stand quality of Acacia mangium and Eucalyptus urophylla plantations in two unrelated commune...This paper sets out to determine the link between socio-economic attributes of smallholders, silvicultural activity and the stand quality of Acacia mangium and Eucalyptus urophylla plantations in two unrelated communes in Phu Tho province, Vietnam. The necessary data was collected by interviewing the smallholders and conducting inventory of the stands. The data was analyzed with descriptive statistics, Mann-Whitney tests and Spearman correlations. More silvicultural practices were conducted by A. mangium planters with larger areas. Most of the smallholders practiced the suggested silvicultural activities. Productivity was affected by pruning in medium quality sites. This research recommends that smallholders were supported with incentives for the plantation establishment, education for smallholders in silvicultural techniques, organization and development activities for the wider market.展开更多
基金supported by the National Natural Science Foundation of China(4090104931060060)+1 种基金the Major State Basic Research Development Program of China(2009CB 421303)the 'Qing Lan' Talent Engineering Funds of Lanzhou Jiaotong University(QL-08-14A)
文摘Horqin Sandy Land is a fragile, seriously desertified region located in Inner Mongolia of China. Over- grazing is one of the primary drivers of desertification in this region. We investigated whether the establishment of grazing exclosures in areas with active sand dunes enhances soil carbon （C） sequestration and benefits soil re- covery. The results showed that soil organic C storage was 1.4, 1.9, and 3.5 times, and light fraction C storage was 2.3, 3.2, and 4.4 times in the 100-cm topsoil after 7, 12, and 25 years of grazing exclusion, respectively, compared to the case in active sand dunes. The light fraction of soil played an important role in soil C sequestration, although it might not change rapidly to provide an early indication of how soil C is increasing in response to grazing exclusion. The results indicated that soils could potentially sequester up to 13.8 Mt C in 25 years if active sand dunes in the study area were to be protected by exclosures. This corresponds to 12.8% of the estimated carbon loss （107.53 Mt） that has been associated with desertification over the past century in the Horqin Sandy Land. Our results suggested that exclosures have the capacity to increase soil C sequestration; however, decades will be required for soil C to recover to historical grassland levels observed prior to desertification.
文摘During the period of September 12, 1999 to September 24, 2000, we measured sap flow ofeucalyptus (Euca/yptus urophylla S.T. Blake) plantations using heat pulse technique, and the relevantenvironmental vaiables, such as soil evaporation and canopy interception, etc, at Hetou and Jijia sites,Leizhou Peninsula, Guangdong Province. Based on the measurements of sap flow and estimates ofevapotranspiration, the following can be concluded: (1) the maximum of diurnal xylem sap flux density (SFD)at Hetou, where covered with coarse-textured soils formed on Quaternary sediments, was almost twice ofthat at Jijia, where located on clay-rich soils derived from basalt; (2) SFD was highly correlated to watervapor pressure deficit (VPD) of ambient air near the canopy layer, (3) the correlation between SFD and airtemperature also depends on soil properties and soil water potential; (4) the relative differences betweenmeasured and modeled evapotranspiration were small, being 5.26% at Hetou and 6.14% at Jijia; (5) theplantation transpiration accounted for 62.2% and 51.3% of the evapotranspiration at Hetou and Jijia,respectively; and (6) the averaged SFD per unit leaf area (ASPULA) was a good index to estimate theamount of water consumption of tree species.
基金Supported by Fund for Basal Scientific Research of Chinese Academy of Tropical Agricultural Sciences （1630032017042）.
文摘[Objectives] Within a research area on basin scale, soil nutrient distribution characteristics and main causes were analyzed, to provide a basis for soil nutrient management on basin scale.[Methods] With the Nandu River Basin of Hainan Island as the research area, by means of geostatistics and spatial analysis methods, the distribution available of soil pH, organic matter, alkali-hydrolyzale nitrogen, available phosphorus, available potassium and available trace elements were studied.[Results] The cultivated land in the Nandu River Basin of Hainan Province is overall acidic, with an average pH of 5.2. The soil organic matter content is overall lower, and its spatial differences are also significant. Soil alkali-hydrolyzable nitrogen, exchangeable calcium and exchangeable magnesium content are at a medium level, but the soil lacks available phosphorus and available potassium.[Conclusions] The differences in pH within the research area might be related to parent materials distribution and fertilizer applications. The main reasons for the low soil organic matter content are inadequate and uneven input of organic fertilizer and high-temperate rainy climate. The lack of soil phosphorus and potassium is mainly caused by unreasonable fertilizer application and climatic and terrain factors.
文摘This paper sets out to determine the link between socio-economic attributes of smallholders, silvicultural activity and the stand quality of Acacia mangium and Eucalyptus urophylla plantations in two unrelated communes in Phu Tho province, Vietnam. The necessary data was collected by interviewing the smallholders and conducting inventory of the stands. The data was analyzed with descriptive statistics, Mann-Whitney tests and Spearman correlations. More silvicultural practices were conducted by A. mangium planters with larger areas. Most of the smallholders practiced the suggested silvicultural activities. Productivity was affected by pruning in medium quality sites. This research recommends that smallholders were supported with incentives for the plantation establishment, education for smallholders in silvicultural techniques, organization and development activities for the wider market.
