The Tarim River Basin, located in the typical arid region, is one of the key regions of LUCC research in China and plays an important role in maintaining the sustainable development of the western China. In recent yea...The Tarim River Basin, located in the typical arid region, is one of the key regions of LUCC research in China and plays an important role in maintaining the sustainable development of the western China. In recent years,the ecological environment of the Tarim River Basin has degraded greatly. In the lower reaches, in particular, the riverbed has been dried up for more than 20 years, which accelerated the desertification and has been a great threat to people′s lives. Taking the section of the Tarim River between Qiala Lake and Taitema Lake as a typical region, an investigation on land cover changes was carried out with the support of remote sensing information of 1988 and 2000 respectively. The changes of land cover in this region were obtained: 1) Cropland tended to increase. 2) Urban or Built-up Area in 2000 was 324.4ha more than that in 1988. 3) Waters expanded by 3476.51ha. 4) Woodland and Grassland decreased, while Barren Land increased by 3824.9ha. The total amount of land use/land cover change between 1988 and 2000 is small,which is only 0.355% of the total area. It shows that the developmental pace of the lower reaches of the Tarim River is relative slow. Based on these results, the authors assessed the landscape dynamics of this region and pointed out that the degree of desertification was strengthened and the landscape dominated by sand land was further characterized by salt desert.展开更多
Understanding of the habitat range of threatened Himalayan medicinal plants which are declining in their abundance due to high anthropogenic disturbances is essential for developing conservation strategies and agrotec...Understanding of the habitat range of threatened Himalayan medicinal plants which are declining in their abundance due to high anthropogenic disturbances is essential for developing conservation strategies and agrotechnologies for cultivation. In this communication, we have discussed the habitat range of two alpine medicinal plants, Aconitum naviculare （Bruehl） Stapf and Neopicrorhiza scrophulariiflora （Pennel） Hong in a trans-Himalayan dry valley of central Nepal, Manang district. They are the most prioritized medicinal plants of the study area in terms of ethnomedicinal uses. A. naviculare occurs on warm and dry south facing slopes between 4090-4650 m asl along with sclerophyllous and thorny alpine scrubs, while N. scrophulariiflora is exclusively found on cool and moist north facing slope between 4000 and 4400 m asl where adequate water is available from snow melt to create a suitable habitat for this wetland dependent species. The soil in rooting zone of the two plants differs significantly in organic carbon （OC）, organic matter （OM）, total nitrogen （N） and carbon to nitrogen （C/N） ratio. Due to cool and moist condition of N. scrophulariiflora habitat, accumulation of soil OC is higher, but soil N content is lower probably due to slow release from litter, higher leaching loss and greater retention in perennial live biomass of the plant. The C/N ratio of soil is more suitable in A. navuculare habitat than that of N scrophulariiflora for N supply. Warm and sunny site with N rich soil can be suitable for cultivation ofA. naviculare, while moist and cool site with organic soil for N. scrophulariiflora. The populations of both the plants are fragmented and small. Due to collection by human and trampling damage by livestock, the population of A. naviculare was found absent in open areas in five of the six sampling sites and it was confined only within the bushes of alpine scrubs. For N. serophulariiflora, high probability of complete receding of small glaeiers may be a new threat in future to its habitat. The information about habitat conditions, together with the information from other areas, ean be useful to identify potential habitats and plan for cultivation or domestication of the two medieinal plants.展开更多
The effective and efficient management of agricultural water use is crucial to enhance agricultural production to meet the demand of a rapidly growing population. The performance assessment studies are successfully us...The effective and efficient management of agricultural water use is crucial to enhance agricultural production to meet the demand of a rapidly growing population. The performance assessment studies are successfully used to describe the irrigation problems and provide remedial measures. In this study, the performance assessment of the twin main canals of the Gezira Scheme were examined and evaluated using a set of performance indicators. The analysis was made using 3 Landsat and 8 Modis data of 2001-2002, and results showed that the seasonal average values of water productivity, relative water supply, overall consumed ratio, depleted fraction and relative evapotranspiration were respectively 0.47, 0.72, 1.41, 0.75 and 0.57 kg·m^-3 for Gezira main canal, whereas the values for Managil main canal were 0.43, 0.54, 1.68, 0.71 and 0.50 kg·m^-3, respectively. The monthly average values of crop water deficit for Gezira and Managil were respectively 71 and 78 mm-month^-1. Considering the spatial variation in some indicators, the irrigation uniformity is deemed as poor according to Molden and Gates （1990）. The analysis also showed that the gap between water demand and supply during winter season was glaringly high （46%）.展开更多
The drumstick tree(Moringa oleifera Lam.) is a perennial crop that has gained popularity in certain developing countries for its high-nutrition content and adaptability to arid and semi-arid environments. Here we repo...The drumstick tree(Moringa oleifera Lam.) is a perennial crop that has gained popularity in certain developing countries for its high-nutrition content and adaptability to arid and semi-arid environments. Here we report a high-quality draft genome sequence of M. oleifera. This assembly represents 91.78% of the estimated genome size and contains 19,465 protein-coding genes. Comparative genomic analysis between M. oleifera and related woody plant genomes helps clarify the general evolution of this species, while the identification of several species-specific gene families and positively selected genes in M. oleifera may help identify genes related to M. oleifera's high protein content, fast-growth, heat and stress tolerance. This reference genome greatly extends the basic research on M. oleifera, and may further promote applying genomics to enhanced breeding and improvement of M. oleifera.展开更多
基金Under the auspices of Special Science Foundation for Doctoral Subject of Universities,Ministry of Education(No.20020001019)
文摘The Tarim River Basin, located in the typical arid region, is one of the key regions of LUCC research in China and plays an important role in maintaining the sustainable development of the western China. In recent years,the ecological environment of the Tarim River Basin has degraded greatly. In the lower reaches, in particular, the riverbed has been dried up for more than 20 years, which accelerated the desertification and has been a great threat to people′s lives. Taking the section of the Tarim River between Qiala Lake and Taitema Lake as a typical region, an investigation on land cover changes was carried out with the support of remote sensing information of 1988 and 2000 respectively. The changes of land cover in this region were obtained: 1) Cropland tended to increase. 2) Urban or Built-up Area in 2000 was 324.4ha more than that in 1988. 3) Waters expanded by 3476.51ha. 4) Woodland and Grassland decreased, while Barren Land increased by 3824.9ha. The total amount of land use/land cover change between 1988 and 2000 is small,which is only 0.355% of the total area. It shows that the developmental pace of the lower reaches of the Tarim River is relative slow. Based on these results, the authors assessed the landscape dynamics of this region and pointed out that the degree of desertification was strengthened and the landscape dominated by sand land was further characterized by salt desert.
文摘Understanding of the habitat range of threatened Himalayan medicinal plants which are declining in their abundance due to high anthropogenic disturbances is essential for developing conservation strategies and agrotechnologies for cultivation. In this communication, we have discussed the habitat range of two alpine medicinal plants, Aconitum naviculare （Bruehl） Stapf and Neopicrorhiza scrophulariiflora （Pennel） Hong in a trans-Himalayan dry valley of central Nepal, Manang district. They are the most prioritized medicinal plants of the study area in terms of ethnomedicinal uses. A. naviculare occurs on warm and dry south facing slopes between 4090-4650 m asl along with sclerophyllous and thorny alpine scrubs, while N. scrophulariiflora is exclusively found on cool and moist north facing slope between 4000 and 4400 m asl where adequate water is available from snow melt to create a suitable habitat for this wetland dependent species. The soil in rooting zone of the two plants differs significantly in organic carbon （OC）, organic matter （OM）, total nitrogen （N） and carbon to nitrogen （C/N） ratio. Due to cool and moist condition of N. scrophulariiflora habitat, accumulation of soil OC is higher, but soil N content is lower probably due to slow release from litter, higher leaching loss and greater retention in perennial live biomass of the plant. The C/N ratio of soil is more suitable in A. navuculare habitat than that of N scrophulariiflora for N supply. Warm and sunny site with N rich soil can be suitable for cultivation ofA. naviculare, while moist and cool site with organic soil for N. scrophulariiflora. The populations of both the plants are fragmented and small. Due to collection by human and trampling damage by livestock, the population of A. naviculare was found absent in open areas in five of the six sampling sites and it was confined only within the bushes of alpine scrubs. For N. serophulariiflora, high probability of complete receding of small glaeiers may be a new threat in future to its habitat. The information about habitat conditions, together with the information from other areas, ean be useful to identify potential habitats and plan for cultivation or domestication of the two medieinal plants.
文摘The effective and efficient management of agricultural water use is crucial to enhance agricultural production to meet the demand of a rapidly growing population. The performance assessment studies are successfully used to describe the irrigation problems and provide remedial measures. In this study, the performance assessment of the twin main canals of the Gezira Scheme were examined and evaluated using a set of performance indicators. The analysis was made using 3 Landsat and 8 Modis data of 2001-2002, and results showed that the seasonal average values of water productivity, relative water supply, overall consumed ratio, depleted fraction and relative evapotranspiration were respectively 0.47, 0.72, 1.41, 0.75 and 0.57 kg·m^-3 for Gezira main canal, whereas the values for Managil main canal were 0.43, 0.54, 1.68, 0.71 and 0.50 kg·m^-3, respectively. The monthly average values of crop water deficit for Gezira and Managil were respectively 71 and 78 mm-month^-1. Considering the spatial variation in some indicators, the irrigation uniformity is deemed as poor according to Molden and Gates （1990）. The analysis also showed that the gap between water demand and supply during winter season was glaringly high （46%）.
文摘The drumstick tree(Moringa oleifera Lam.) is a perennial crop that has gained popularity in certain developing countries for its high-nutrition content and adaptability to arid and semi-arid environments. Here we report a high-quality draft genome sequence of M. oleifera. This assembly represents 91.78% of the estimated genome size and contains 19,465 protein-coding genes. Comparative genomic analysis between M. oleifera and related woody plant genomes helps clarify the general evolution of this species, while the identification of several species-specific gene families and positively selected genes in M. oleifera may help identify genes related to M. oleifera's high protein content, fast-growth, heat and stress tolerance. This reference genome greatly extends the basic research on M. oleifera, and may further promote applying genomics to enhanced breeding and improvement of M. oleifera.
