The study of tree mortality and recruitment contributes to the understanding of forest dynamics and, at the same time, supplies a baseline to evaluate the impact of human activities. The study site is a moist semi-dec...The study of tree mortality and recruitment contributes to the understanding of forest dynamics and, at the same time, supplies a baseline to evaluate the impact of human activities. The study site is a moist semi-deciduous forest located in the Caparo Forest Reserve, Venezuela. Tree data were obtained from permanent plots established in unlogged and logged stands. Successive measurements were taken during a 15 yr period. Tree species mortality and recruitment was analyzed for individuals with diameter at breast height （d）〉-- 10 cm. The species were classified according to their shade tolerance （low or intolerant, intermediate and high or tolerant） and the maximum height （hmax） （small〈15 m, medium： 15-30 m and large 〉30 m）. Palms were considered as a separate group. In the unlogged stands 307 and 274 trees ha-1 were found at the beginning and final time of the monitoring period, respectively. These trees were classified into 55 and 48 species, respectively. Among them predominate species from the shade intermediate tolerant and large size group and palms. Similarly, in the logged forest 155 and 207 trees ha^-1 were found, whereas 59 and 60 tree species were recorded. Only four species were found with 〉10 individuals had, the majority of these species belong to the functional group of shade intolerant medium size species, which may be partly explained by forest recovering after selective logging. In the unlogged stands the mean annual rate of tree mortality is 2.61% and the highest values corresponded to shade intermediate tolerant and intolerant small size species. Tree density was not significantly correlated to tree mortality in both forest conditions （logged and unlogged）. The recruitment rate in the unlogged forest was 1.33%, with the lowest values obtained for the same groups with highest mortality; whereas in the logged stands reached 2.58%, with the highest value for the shade tolerant small size species, followed by shade intermediate tolerant large size species. A significant difference was found between forest conditions for tree recruitment rates （H=0.0649）. In contrast, the correlation between tree mortality and recruitment was higher for logged （r=0.5988） than unlogged stands （r=0.4904） but not significant.展开更多
文摘The study of tree mortality and recruitment contributes to the understanding of forest dynamics and, at the same time, supplies a baseline to evaluate the impact of human activities. The study site is a moist semi-deciduous forest located in the Caparo Forest Reserve, Venezuela. Tree data were obtained from permanent plots established in unlogged and logged stands. Successive measurements were taken during a 15 yr period. Tree species mortality and recruitment was analyzed for individuals with diameter at breast height （d）〉-- 10 cm. The species were classified according to their shade tolerance （low or intolerant, intermediate and high or tolerant） and the maximum height （hmax） （small〈15 m, medium： 15-30 m and large 〉30 m）. Palms were considered as a separate group. In the unlogged stands 307 and 274 trees ha-1 were found at the beginning and final time of the monitoring period, respectively. These trees were classified into 55 and 48 species, respectively. Among them predominate species from the shade intermediate tolerant and large size group and palms. Similarly, in the logged forest 155 and 207 trees ha^-1 were found, whereas 59 and 60 tree species were recorded. Only four species were found with 〉10 individuals had, the majority of these species belong to the functional group of shade intolerant medium size species, which may be partly explained by forest recovering after selective logging. In the unlogged stands the mean annual rate of tree mortality is 2.61% and the highest values corresponded to shade intermediate tolerant and intolerant small size species. Tree density was not significantly correlated to tree mortality in both forest conditions （logged and unlogged）. The recruitment rate in the unlogged forest was 1.33%, with the lowest values obtained for the same groups with highest mortality; whereas in the logged stands reached 2.58%, with the highest value for the shade tolerant small size species, followed by shade intermediate tolerant large size species. A significant difference was found between forest conditions for tree recruitment rates （H=0.0649）. In contrast, the correlation between tree mortality and recruitment was higher for logged （r=0.5988） than unlogged stands （r=0.4904） but not significant.
