“Evolution Canyon”is a typical Mediterranean-basin canyon with a summer dry stream at the bottom and large differences in vegetation cover and solar radiation between the north-facing slope(NFS)and the south-facing ...“Evolution Canyon”is a typical Mediterranean-basin canyon with a summer dry stream at the bottom and large differences in vegetation cover and solar radiation between the north-facing slope(NFS)and the south-facing slope(SFS).It is known to act as an abiotic mediator influencing the community structure of soil fauna.The aim of this study was to determine the spatial dispersion of soil microbial and free-living nematode communities in the open sites(between shrubs)in the upper(0-10 cm)soil layer at four altitudes on both slopes.The combination of relative soil moisture availability and temperature,known to be one of the main triggers for soil biota activity,was explained by slope orientation.The above-mentioned differences were found to significantly affect microbial biomass and CO_(2)evolution resulting in temporary stress,corresponding to higher values in metabolic quotient(qCO_(2))values.These differences may represent microbial investment in energy in order to overcome stress resulting from the microclimatic differences between the two slopes.Moreover,the degree of substrate limitation(primary production due to the differences in plant cover)of microbial activity was explained by the difference in microbial functional groups.The total abundance of soil free-living nematodes was found to be 2-fold higher on the SFS than on the NFS.Thirty-nine genera,including 12 bacteria-feeders,5 fungifeeders,12 plant-parasites,and 10 omnivore-predators,were found at the study site,with 34 genera on the NFS and 29 on the SFS.The generic diversity of the bacteriafeeding nematodes was higher on the SFS than on the NFS.This study elucidates the importance of slope orientation and its effect on the structural levels of soil microbial and nematode communities.展开更多
This paper presents a new 3D edge operator based on Legendre orthogonal moments. This operator can be used to extract the edge of 3D object in any window size,with more accurate surface orientation and more precise su...This paper presents a new 3D edge operator based on Legendre orthogonal moments. This operator can be used to extract the edge of 3D object in any window size,with more accurate surface orientation and more precise surface location. It also has full geometry meaning. Process of calculation is considered in the moment based method.We can greatly speed up the computation by calculating out the masks in advance. We integrate this operator into our rendering of medical image data based on ray casting algorithm. Experimental results show that it is an effective 3D edge operator that is more accurate in position and orientation.展开更多
文摘“Evolution Canyon”is a typical Mediterranean-basin canyon with a summer dry stream at the bottom and large differences in vegetation cover and solar radiation between the north-facing slope(NFS)and the south-facing slope(SFS).It is known to act as an abiotic mediator influencing the community structure of soil fauna.The aim of this study was to determine the spatial dispersion of soil microbial and free-living nematode communities in the open sites(between shrubs)in the upper(0-10 cm)soil layer at four altitudes on both slopes.The combination of relative soil moisture availability and temperature,known to be one of the main triggers for soil biota activity,was explained by slope orientation.The above-mentioned differences were found to significantly affect microbial biomass and CO_(2)evolution resulting in temporary stress,corresponding to higher values in metabolic quotient(qCO_(2))values.These differences may represent microbial investment in energy in order to overcome stress resulting from the microclimatic differences between the two slopes.Moreover,the degree of substrate limitation(primary production due to the differences in plant cover)of microbial activity was explained by the difference in microbial functional groups.The total abundance of soil free-living nematodes was found to be 2-fold higher on the SFS than on the NFS.Thirty-nine genera,including 12 bacteria-feeders,5 fungifeeders,12 plant-parasites,and 10 omnivore-predators,were found at the study site,with 34 genera on the NFS and 29 on the SFS.The generic diversity of the bacteriafeeding nematodes was higher on the SFS than on the NFS.This study elucidates the importance of slope orientation and its effect on the structural levels of soil microbial and nematode communities.
基金This work was supported by the National Natural Science Foundation of China(Grant No.60272045)the National Basic Research Program of China(Grant No.2003CB716102).
文摘This paper presents a new 3D edge operator based on Legendre orthogonal moments. This operator can be used to extract the edge of 3D object in any window size,with more accurate surface orientation and more precise surface location. It also has full geometry meaning. Process of calculation is considered in the moment based method.We can greatly speed up the computation by calculating out the masks in advance. We integrate this operator into our rendering of medical image data based on ray casting algorithm. Experimental results show that it is an effective 3D edge operator that is more accurate in position and orientation.
