Unregulated commercial-scale exploitation of trees is an indication of the extent of threat to various tree species. The study examined the threat status of commercially exploited trees in the forest estates of South ...Unregulated commercial-scale exploitation of trees is an indication of the extent of threat to various tree species. The study examined the threat status of commercially exploited trees in the forest estates of South eastern Nigeria. Specifically, it identified tree species under threat, and categorized them into threat classes, as well as determined the rate at which exploited trees were slipping into extinction. The study utilized the IUCN’s threat categorization criteria, in determining the threat status of commercially exploited trees. This study combined both secondary and primary data sources generated through Forest Inventory records, Tree Felled Analysis records and Participatory Survey. Data such as population size and density of species, level of exploitation and threat sensitive social and ecological parameters were obtained and applied against the IUCN criteria. Twenty-eight (28) trees species representing Thirty-two percent (32%) of eighty-six (86) commercially exploited trees were identified as threatened, ranging from the Vulnerable to the Critically Endangered categories. The theory of small and declining population paradigms were found to be of relevance in explaining the processes. Nine tree species such as Triplochiton spp., Baillonella toxisperma, Pogaoleosa, Anopyxis spp. among others were considered to require urgent conservation attention. Recommendations are proposed to halt the process of decline in the biodiversity of exploited trees.展开更多
In order to evaluate all attack paths in a threat tree,based on threat modeling theory,a weight distribution algorithm of the root node in a threat tree is designed,which computes threat coefficients of leaf nodes in ...In order to evaluate all attack paths in a threat tree,based on threat modeling theory,a weight distribution algorithm of the root node in a threat tree is designed,which computes threat coefficients of leaf nodes in two ways including threat occurring possibility and the degree of damage.Besides,an algorithm of searching attack path was also obtained in accordence with its definition.Finally,an attack path evaluation system was implemented which can output the threat coefficients of the leaf nodes in a target threat tree,the weight distribution information,and the attack paths.An example threat tree is given to verify the effectiveness of the algorithms.展开更多
文摘Unregulated commercial-scale exploitation of trees is an indication of the extent of threat to various tree species. The study examined the threat status of commercially exploited trees in the forest estates of South eastern Nigeria. Specifically, it identified tree species under threat, and categorized them into threat classes, as well as determined the rate at which exploited trees were slipping into extinction. The study utilized the IUCN’s threat categorization criteria, in determining the threat status of commercially exploited trees. This study combined both secondary and primary data sources generated through Forest Inventory records, Tree Felled Analysis records and Participatory Survey. Data such as population size and density of species, level of exploitation and threat sensitive social and ecological parameters were obtained and applied against the IUCN criteria. Twenty-eight (28) trees species representing Thirty-two percent (32%) of eighty-six (86) commercially exploited trees were identified as threatened, ranging from the Vulnerable to the Critically Endangered categories. The theory of small and declining population paradigms were found to be of relevance in explaining the processes. Nine tree species such as Triplochiton spp., Baillonella toxisperma, Pogaoleosa, Anopyxis spp. among others were considered to require urgent conservation attention. Recommendations are proposed to halt the process of decline in the biodiversity of exploited trees.
基金Supported by National Natural Science Foundation of China (No.90718023)National High-Tech Research and Development Program of China (No.2007AA01Z130)
文摘In order to evaluate all attack paths in a threat tree,based on threat modeling theory,a weight distribution algorithm of the root node in a threat tree is designed,which computes threat coefficients of leaf nodes in two ways including threat occurring possibility and the degree of damage.Besides,an algorithm of searching attack path was also obtained in accordence with its definition.Finally,an attack path evaluation system was implemented which can output the threat coefficients of the leaf nodes in a target threat tree,the weight distribution information,and the attack paths.An example threat tree is given to verify the effectiveness of the algorithms.
