There are many different and even controversial results concerning the effects of Tamarisk on the physicochemical properties of soil. A year-round monitoring of soil salinity, p H and moisture is conducted beneath the...There are many different and even controversial results concerning the effects of Tamarisk on the physicochemical properties of soil. A year-round monitoring of soil salinity, p H and moisture is conducted beneath the Tamarisk shrub in a coastal wetland in the Bohai Sea in China, to ascertain the effects of Tamarisk on the physicochemical properties of soil in coastal wetland. Compared with the control area, the soil moisture content is lower around the area of the taproot when there is less precipitation in the growing season because of water consumption by Tamarisk shrub. However, the soil moisture content is higher around the taproot when there is more precipitation in the growing season or in the non-growing period because of water conservation by the rhizosphere. The absorption of salt by the Tamarisk shrub reduces the soil salinity temporarily, but eventually salt returns to the soil by the leaching of salt on leaves by rainfall or by fallen leaves. The annual average soil moisture content beneath the Tamarisk shrub is lower than the control area by only 6.4%, indicating that the Tamarisk shrub has little effect on drought or water conservation in soils in the temperate coastal wetland with moderate annual precipitation. The annual average salinity beneath the Tamarisk shrub is 18% greater than that of the control area, indicating that Tamarisk does have an effect of rising soil salinity around Tamarisk shrubs. The soil p H value is as low as 7.3 in summer and as high as 10.2 in winter. The p H of soil near the taproot of the Tamarisk shrubs is one p H unit lower than that in the control area during the growing season. The difference in p H is less different from the control area in the non-growing season, indicating that the Tamarisk shrub does have the effect of reducing the alkalinity of soil in coastal wetland.展开更多
The present review provides a compilation of the published data on the ecology and social behavior of tamarisk gerbils. Both field studies anddirect observations under semi-natural conditions provide evidence that the...The present review provides a compilation of the published data on the ecology and social behavior of tamarisk gerbils. Both field studies anddirect observations under semi-natural conditions provide evidence that the tamarisk gerbil is a nocturnal herbivorous rodent that lives in highlyseasonal habitats and displays seasonal fluctuations in reproduction and spatial organization. A typical feature of the tamarisk gerbils’ spatialorganization is higher mobility of males during the breeding season (as compared with the nonbreeding period) and formation of temporaryaggregations of males competing for access to receptive females;the composition of these aggregations was variable and depended on thereproductive condition of the females. Females tend to occupy exclusive home ranges irrespective of their reproductive condition. The matingsystem of the species can be defined as scramble competition polygyny with some features of polygynandry and promiscuity. The tamariskgerbil has distinct features of a solitary species and its social structure is primarily based on aggressive interactions or mutual avoidance ofconspecifics resulting in a dominance hierarchy among males and site-dependent dominance among females during the breeding season. Bythe end of the breeding season, males become less mobile and occupy nearly exclusive home ranges, consistent with solitary living. The mainfeatures of the spatial and social organization of this species, which distinguish it from other solitary rodents, are the higher mobility of malesand the formation of temporary multimale–multifemale aggregations during the breeding season. Overall, the data presented expand our understanding of socioecology of gerbils.展开更多
Chinese tamarisk(saltcedar)is a deciduous shrub that occurs widely across the Yellow River Delta in China.The spatial structure of Chinese tamarisk is believed to have an influence on the landscape and habitats of rar...Chinese tamarisk(saltcedar)is a deciduous shrub that occurs widely across the Yellow River Delta in China.The spatial structure of Chinese tamarisk is believed to have an influence on the landscape and habitats of rare birds.In this study,first,Chinese tamarisk is detected using Canny edge detector and mathematical morphological operators based on SPOT 5 fusion-ready imagery.Then the numbers,areas,locations,and patch spacing of Chinese tamarisk patches are calculated.The experiments show that the detection accuracy of Chinese tamarisk patches is about 93.4%after the disconnection of connected patches.The distribution orientation of about 70%of the patches is approximately south-north.About 91%of the minimum distances among the patches are between 12.5 and 57.5 m.The rose graph indicates that the main azimuth between patches is north--northwest,and the second is northeast and southeast.The present study indicates that the integrating Canny edge detector with the algorithms for extracting circular and elliptical objects based on mathematical morphology is simple and effective for detecting Chinese tamarisk patches and is easy to identify the spatial structure of Chinese tamarisk patches,which reduces the time and labor for the visual interpretation of Chinese tamarisk patches.展开更多
基金The Public Science and Technology Research Funds Projects of Ocean under contract No.201205008
文摘There are many different and even controversial results concerning the effects of Tamarisk on the physicochemical properties of soil. A year-round monitoring of soil salinity, p H and moisture is conducted beneath the Tamarisk shrub in a coastal wetland in the Bohai Sea in China, to ascertain the effects of Tamarisk on the physicochemical properties of soil in coastal wetland. Compared with the control area, the soil moisture content is lower around the area of the taproot when there is less precipitation in the growing season because of water consumption by Tamarisk shrub. However, the soil moisture content is higher around the taproot when there is more precipitation in the growing season or in the non-growing period because of water conservation by the rhizosphere. The absorption of salt by the Tamarisk shrub reduces the soil salinity temporarily, but eventually salt returns to the soil by the leaching of salt on leaves by rainfall or by fallen leaves. The annual average soil moisture content beneath the Tamarisk shrub is lower than the control area by only 6.4%, indicating that the Tamarisk shrub has little effect on drought or water conservation in soils in the temperate coastal wetland with moderate annual precipitation. The annual average salinity beneath the Tamarisk shrub is 18% greater than that of the control area, indicating that Tamarisk does have an effect of rising soil salinity around Tamarisk shrubs. The soil p H value is as low as 7.3 in summer and as high as 10.2 in winter. The p H of soil near the taproot of the Tamarisk shrubs is one p H unit lower than that in the control area during the growing season. The difference in p H is less different from the control area in the non-growing season, indicating that the Tamarisk shrub does have the effect of reducing the alkalinity of soil in coastal wetland.
文摘The present review provides a compilation of the published data on the ecology and social behavior of tamarisk gerbils. Both field studies anddirect observations under semi-natural conditions provide evidence that the tamarisk gerbil is a nocturnal herbivorous rodent that lives in highlyseasonal habitats and displays seasonal fluctuations in reproduction and spatial organization. A typical feature of the tamarisk gerbils’ spatialorganization is higher mobility of males during the breeding season (as compared with the nonbreeding period) and formation of temporaryaggregations of males competing for access to receptive females;the composition of these aggregations was variable and depended on thereproductive condition of the females. Females tend to occupy exclusive home ranges irrespective of their reproductive condition. The matingsystem of the species can be defined as scramble competition polygyny with some features of polygynandry and promiscuity. The tamariskgerbil has distinct features of a solitary species and its social structure is primarily based on aggressive interactions or mutual avoidance ofconspecifics resulting in a dominance hierarchy among males and site-dependent dominance among females during the breeding season. Bythe end of the breeding season, males become less mobile and occupy nearly exclusive home ranges, consistent with solitary living. The mainfeatures of the spatial and social organization of this species, which distinguish it from other solitary rodents, are the higher mobility of malesand the formation of temporary multimale–multifemale aggregations during the breeding season. Overall, the data presented expand our understanding of socioecology of gerbils.
基金supported by a grant from the National Natural Science Foundation of China(Project No.41023010)a grant from the Strategic Priority Research Program of Chinese Academy of Sciences(Project No.XDA05050601).
文摘Chinese tamarisk(saltcedar)is a deciduous shrub that occurs widely across the Yellow River Delta in China.The spatial structure of Chinese tamarisk is believed to have an influence on the landscape and habitats of rare birds.In this study,first,Chinese tamarisk is detected using Canny edge detector and mathematical morphological operators based on SPOT 5 fusion-ready imagery.Then the numbers,areas,locations,and patch spacing of Chinese tamarisk patches are calculated.The experiments show that the detection accuracy of Chinese tamarisk patches is about 93.4%after the disconnection of connected patches.The distribution orientation of about 70%of the patches is approximately south-north.About 91%of the minimum distances among the patches are between 12.5 and 57.5 m.The rose graph indicates that the main azimuth between patches is north--northwest,and the second is northeast and southeast.The present study indicates that the integrating Canny edge detector with the algorithms for extracting circular and elliptical objects based on mathematical morphology is simple and effective for detecting Chinese tamarisk patches and is easy to identify the spatial structure of Chinese tamarisk patches,which reduces the time and labor for the visual interpretation of Chinese tamarisk patches.
