Timber harvesting data are very essential for sustainable management of forest resources.These data are very scarce in developing countries.Therefore,we collected and analyzed data on the rate of timber production of ...Timber harvesting data are very essential for sustainable management of forest resources.These data are very scarce in developing countries.Therefore,we collected and analyzed data on the rate of timber production of the free areas and the forest reserves in Ondo State,Nigeria.The data collected from the State Department of Forestry＇s official records,annual reports and files were on the species,volume and number of different economic timbers exploited on monthly basis between 2003 and 2005.Analyses were done with the student t-test and one-way analysis of variance.Results reveal that the highest numbers of species,families and stems were exploited in the free areas when compared with what was exploited from the reserves for the three-year period.However,the total volume of trees removed from the reserves was significantly higher（p〈0.05） than what was removed from the free areas.A total 60 different indigenous hardwood species in 25 families were exploited from the free areas,and 57 in 23 families from the reserves.The total number of stems exploited from the forest ecosystem of Ondo state during the three-year period stood at 111377 with an estimated volume of 295089.67 m^3.While the mean number of stems and volume exploited per annum is 37125 and 98363.22 m^3,respectively.The monthly average number of stems and volume is 3094 and 8196 m^3,respectively.The t-test results show that there were significant differences（p〈0.05） in number of stems and volume removed from the free areas and the reserves.The ANOVA results reveal a significant increase（p〈0.05） in logging activities between the years of 2003 and 2004 but there was a decline in year 2005.This trend reveals that economic timber species were disappearing from the forests and the ecosystem was seriously disturbed during logging activities.Principles for achieving the goals of sustainable forest management（SFM） and urgent conservation measures to mitigate the consequences of forest degradation were suggested.展开更多
A four-party scheme is put forward for a sender to partition arbitrary single-qubit information among three receivers by utilizing a class of asymmetric four-qubit W state as quantum channels. In the scheme the sender...A four-party scheme is put forward for a sender to partition arbitrary single-qubit information among three receivers by utilizing a class of asymmetric four-qubit W state as quantum channels. In the scheme the sender＇s quantum information can be recovered by the three receivers if and only if they collaborate together. Specifically, they collaborate to perform first two different 2-qubit collective unitary operations and then a single-qubit unitary operation. The scheme is symmetric and （3, 3）-threshold with regard to the reconstruction, for any receiver can be assigned to conclusively recover the quantum information with the other two＇s assistances.展开更多
文摘Timber harvesting data are very essential for sustainable management of forest resources.These data are very scarce in developing countries.Therefore,we collected and analyzed data on the rate of timber production of the free areas and the forest reserves in Ondo State,Nigeria.The data collected from the State Department of Forestry＇s official records,annual reports and files were on the species,volume and number of different economic timbers exploited on monthly basis between 2003 and 2005.Analyses were done with the student t-test and one-way analysis of variance.Results reveal that the highest numbers of species,families and stems were exploited in the free areas when compared with what was exploited from the reserves for the three-year period.However,the total volume of trees removed from the reserves was significantly higher（p〈0.05） than what was removed from the free areas.A total 60 different indigenous hardwood species in 25 families were exploited from the free areas,and 57 in 23 families from the reserves.The total number of stems exploited from the forest ecosystem of Ondo state during the three-year period stood at 111377 with an estimated volume of 295089.67 m^3.While the mean number of stems and volume exploited per annum is 37125 and 98363.22 m^3,respectively.The monthly average number of stems and volume is 3094 and 8196 m^3,respectively.The t-test results show that there were significant differences（p〈0.05） in number of stems and volume removed from the free areas and the reserves.The ANOVA results reveal a significant increase（p〈0.05） in logging activities between the years of 2003 and 2004 but there was a decline in year 2005.This trend reveals that economic timber species were disappearing from the forests and the ecosystem was seriously disturbed during logging activities.Principles for achieving the goals of sustainable forest management（SFM） and urgent conservation measures to mitigate the consequences of forest degradation were suggested.
基金Supported by the Program for New Century Excellent Talents at the University of China under Grant No.NCET-06-0554the National Natural Science Foundation of China under Grant Nos.10975001,60677001,10747146,and 10874122+3 种基金the Science-Technology Fund of Anhui Province for Outstanding Youth under Grant No.06042087the Key Fund of the Ministry of Education of China under Grant No.206063the General Fund of the Educational Committee of Anhui Province under Grant No.2006KJ260Bthe Natural Science Foundation of Guangdong Province under Grant Nos.06300345 and 7007806
文摘A four-party scheme is put forward for a sender to partition arbitrary single-qubit information among three receivers by utilizing a class of asymmetric four-qubit W state as quantum channels. In the scheme the sender＇s quantum information can be recovered by the three receivers if and only if they collaborate together. Specifically, they collaborate to perform first two different 2-qubit collective unitary operations and then a single-qubit unitary operation. The scheme is symmetric and （3, 3）-threshold with regard to the reconstruction, for any receiver can be assigned to conclusively recover the quantum information with the other two＇s assistances.
