Natural regeneration of tree species is important to the sustainability of native forest ecosystems in the temperate zone of north- east China. This study compared the densities and heights of seedlings and the divers...Natural regeneration of tree species is important to the sustainability of native forest ecosystems in the temperate zone of north- east China. This study compared the densities and heights of seedlings and the diversities of shrubs and herbs on three sites of logging op- erations: log-skidding trails (LST), logging gaps (LG) and log landing sites (LLS). Sites undisturbed by logging gaps operations were sam- pled as control. The species, counts and height of tree seedlings and the species, counts, height and percentage coverage of shrubs and herbs were recorded in the field. The highest density and greatest height of regeneration trees were observed at LG and LST. The effects of LST on the densities of broadleaved trees were greater than those of coniferous trees. The difference in seedling density between LLS and control was significant (p=0.05). There was no significant difference in average seedling height for all the tree species between the disturbed sites and control. There were more shrub and herb species at the disturbed sites than at control. The diversity of understory plants at LG was the highest among all the sites. LST and LLS were different in shrub diversity, so were LLS and control. Both LG and LLS were different from control in herb diversity. Active measures need to be taken on the operation sites to protect the coniferous trees and the diversities of under- story plants for sustaining the structure and composition of the broadleaved-Korean pine mixed forest on Changbai Mountain of China. Since different operation sites have different effects on different tree species, site-dependent actions must be taken to assure the regeneration of ecologically important tree species.展开更多
The problem of routing logical links (lightpaths) on a physical topology of WDM networks in a way that the logical topology remains connected in the event of single physical link failure is called survivable routing. ...The problem of routing logical links (lightpaths) on a physical topology of WDM networks in a way that the logical topology remains connected in the event of single physical link failure is called survivable routing. This paper addresses the survivable routing problem with and without wavelength-continuity constraints by proposing a new Integer Linear Programming (ILP) algorithm, which is based on a simplified necessary and sufficient condition. Numerical results are given and discussed to show that survivable routing solutions of most logical topologies can be found by the algorithm of the authors. Furthermore, comparing with other similar methods, the above algorithm can find out a survivable solution in much shorter time, and it works especially well with sparse-connected logical topologies. The impact of wavelength-continuity constraints and the other factors that influence the probability to find out a survivable solution are also discussed in the paper.展开更多
This paper analyzes the role of Tongren Citys ecological forest ranger policy in consolidating and expanding the achievements of poverty alleviation and rural revitalization, points out the existing problems in welfar...This paper analyzes the role of Tongren Citys ecological forest ranger policy in consolidating and expanding the achievements of poverty alleviation and rural revitalization, points out the existing problems in welfare benefits, equipment allocation, personnel quality, education and training, and indicators, and puts forward suggestions on improving subsidy standards, implementing supporting policies, adjusting personnel structure, strengthening education and training, and innovating management and protection methods.展开更多
At present, China's urbanization process is further accelerated, people also have more and more requirements for landscape architecture projects, in such a situation, it is necessary to do a more effective job in ...At present, China's urbanization process is further accelerated, people also have more and more requirements for landscape architecture projects, in such a situation, it is necessary to do a more effective job in landscape architecture construction, for the construction of various management work in the process of project construction should also be effectively strengthened, in the on-site construction link to further improve the management level, and then for the effective improvement of the quality of landscape architecture construction to provide the necessary guarantee. Combined with this situation, this paper explores the relevant contents of on-site management measures in the construction process of landscape architecture, hoping that the analysis of this paper can provide certain enlightenment for relevant practitioners, and then promote the quality of urbanization development to be more effectively improved.展开更多
文摘Natural regeneration of tree species is important to the sustainability of native forest ecosystems in the temperate zone of north- east China. This study compared the densities and heights of seedlings and the diversities of shrubs and herbs on three sites of logging op- erations: log-skidding trails (LST), logging gaps (LG) and log landing sites (LLS). Sites undisturbed by logging gaps operations were sam- pled as control. The species, counts and height of tree seedlings and the species, counts, height and percentage coverage of shrubs and herbs were recorded in the field. The highest density and greatest height of regeneration trees were observed at LG and LST. The effects of LST on the densities of broadleaved trees were greater than those of coniferous trees. The difference in seedling density between LLS and control was significant (p=0.05). There was no significant difference in average seedling height for all the tree species between the disturbed sites and control. There were more shrub and herb species at the disturbed sites than at control. The diversity of understory plants at LG was the highest among all the sites. LST and LLS were different in shrub diversity, so were LLS and control. Both LG and LLS were different from control in herb diversity. Active measures need to be taken on the operation sites to protect the coniferous trees and the diversities of under- story plants for sustaining the structure and composition of the broadleaved-Korean pine mixed forest on Changbai Mountain of China. Since different operation sites have different effects on different tree species, site-dependent actions must be taken to assure the regeneration of ecologically important tree species.
文摘The problem of routing logical links (lightpaths) on a physical topology of WDM networks in a way that the logical topology remains connected in the event of single physical link failure is called survivable routing. This paper addresses the survivable routing problem with and without wavelength-continuity constraints by proposing a new Integer Linear Programming (ILP) algorithm, which is based on a simplified necessary and sufficient condition. Numerical results are given and discussed to show that survivable routing solutions of most logical topologies can be found by the algorithm of the authors. Furthermore, comparing with other similar methods, the above algorithm can find out a survivable solution in much shorter time, and it works especially well with sparse-connected logical topologies. The impact of wavelength-continuity constraints and the other factors that influence the probability to find out a survivable solution are also discussed in the paper.
文摘This paper analyzes the role of Tongren Citys ecological forest ranger policy in consolidating and expanding the achievements of poverty alleviation and rural revitalization, points out the existing problems in welfare benefits, equipment allocation, personnel quality, education and training, and indicators, and puts forward suggestions on improving subsidy standards, implementing supporting policies, adjusting personnel structure, strengthening education and training, and innovating management and protection methods.
文摘At present, China's urbanization process is further accelerated, people also have more and more requirements for landscape architecture projects, in such a situation, it is necessary to do a more effective job in landscape architecture construction, for the construction of various management work in the process of project construction should also be effectively strengthened, in the on-site construction link to further improve the management level, and then for the effective improvement of the quality of landscape architecture construction to provide the necessary guarantee. Combined with this situation, this paper explores the relevant contents of on-site management measures in the construction process of landscape architecture, hoping that the analysis of this paper can provide certain enlightenment for relevant practitioners, and then promote the quality of urbanization development to be more effectively improved.
