The structure and species composition of undisturbed natural forests serve as benchmarks for understanding forest carbon storage potential for reduced carbon emissions. Even though Kenya is seeking to stabilize forest...The structure and species composition of undisturbed natural forests serve as benchmarks for understanding forest carbon storage potential for reduced carbon emissions. Even though Kenya is seeking to stabilize forest cover, reverse degradation and increase forest cover through mechanisms such as REDD+, there is relatively little information on inherent forest carbon storage potential or its response to disturbance. Comparative studies were undertaken in three remnant fragments of indigenous forests in Taita Hills, Kenya to characterize the structure and forest carbon storage potential of undisturbed, moderately and heavily disturbed sites within these forests. The sensitivity of forest carbon storage estimates to different methods of tree biomass estimation were also examined, including estimates which used DBH, tree height and wood density from extracted tree cores. Disturbance altered the forest structure, reduced species diversity and decreased the capacity of the forests to sequester carbon. The forests’ capacity to sequester carbon reduced by between 9.2% and 70.7% depending on the site (forest fragment) and level of disturbance. Models with DBH and wood density gave higher quantities of carbon of between 0.9% and 44.4% for sites exhibiting different levels of disturbance. The present results suggest that disturbance had strong influence on forest structure, species diversity and carbon stocks and therefore maintaining the forests’ ecological integrity over the long-term may prove difficult if the frequency and intensity of disturbance increases. Moreover, development and implementation of effective mitigation strategies to reduce carbon emissions will require the use of local biomass models since they are accurate.展开更多
Landsat images were used to evaluate changes in forest cover of five forest fragments (Chawia, Fururu, Mbololo, Ngangao and Vuria) between 1973 and 2016. The forest fragments are part of the Eastern Arc Mountains, a g...Landsat images were used to evaluate changes in forest cover of five forest fragments (Chawia, Fururu, Mbololo, Ngangao and Vuria) between 1973 and 2016. The forest fragments are part of the Eastern Arc Mountains, a global biodiversity hotspot that boasts outstanding diversity of flora and fauna and a high level of endemism. Landsat imageries of 1973, 1987, 2001, 2012 and 2016 were analyzed using ArcGIS version 10.0 to provide information on forest cover change of the fragments between 1973 and 2016. Results showed that the annual rate of deforestation was 0.5% and was similar to global estimates. The forest fragments lost 23.2% of forest cover between 1973 and 2016. The forest area lost was higher in Vuria (43.0%) and Chawia (32.7%) which are non-gazetted forests managed by the County government of Taita Taveta but lower in Fururu (3.2%), Mbololo (13.7%) and Ngangao (16.8%) which are gazetted forests managed by Kenya Forest Service. Fururu and Mbololo forest fragments gazetted in early 1990s suffered less loss in forest cover compared to Ngangao, which was gazetted 12 years later. Gazettement of forests could preclude further forest degradation and loss by improving their management for effective provision of ecosystem services and conservation of biodiversity.展开更多
文摘The structure and species composition of undisturbed natural forests serve as benchmarks for understanding forest carbon storage potential for reduced carbon emissions. Even though Kenya is seeking to stabilize forest cover, reverse degradation and increase forest cover through mechanisms such as REDD+, there is relatively little information on inherent forest carbon storage potential or its response to disturbance. Comparative studies were undertaken in three remnant fragments of indigenous forests in Taita Hills, Kenya to characterize the structure and forest carbon storage potential of undisturbed, moderately and heavily disturbed sites within these forests. The sensitivity of forest carbon storage estimates to different methods of tree biomass estimation were also examined, including estimates which used DBH, tree height and wood density from extracted tree cores. Disturbance altered the forest structure, reduced species diversity and decreased the capacity of the forests to sequester carbon. The forests’ capacity to sequester carbon reduced by between 9.2% and 70.7% depending on the site (forest fragment) and level of disturbance. Models with DBH and wood density gave higher quantities of carbon of between 0.9% and 44.4% for sites exhibiting different levels of disturbance. The present results suggest that disturbance had strong influence on forest structure, species diversity and carbon stocks and therefore maintaining the forests’ ecological integrity over the long-term may prove difficult if the frequency and intensity of disturbance increases. Moreover, development and implementation of effective mitigation strategies to reduce carbon emissions will require the use of local biomass models since they are accurate.
文摘Landsat images were used to evaluate changes in forest cover of five forest fragments (Chawia, Fururu, Mbololo, Ngangao and Vuria) between 1973 and 2016. The forest fragments are part of the Eastern Arc Mountains, a global biodiversity hotspot that boasts outstanding diversity of flora and fauna and a high level of endemism. Landsat imageries of 1973, 1987, 2001, 2012 and 2016 were analyzed using ArcGIS version 10.0 to provide information on forest cover change of the fragments between 1973 and 2016. Results showed that the annual rate of deforestation was 0.5% and was similar to global estimates. The forest fragments lost 23.2% of forest cover between 1973 and 2016. The forest area lost was higher in Vuria (43.0%) and Chawia (32.7%) which are non-gazetted forests managed by the County government of Taita Taveta but lower in Fururu (3.2%), Mbololo (13.7%) and Ngangao (16.8%) which are gazetted forests managed by Kenya Forest Service. Fururu and Mbololo forest fragments gazetted in early 1990s suffered less loss in forest cover compared to Ngangao, which was gazetted 12 years later. Gazettement of forests could preclude further forest degradation and loss by improving their management for effective provision of ecosystem services and conservation of biodiversity.
