Effects of Forest Disturbance on Vegetation Structure and Above-Ground Carbon in Three Isolated Forest Patches of Taita Hills

Abstract

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.

Investigation of tropical coastal forest regeneration after farming and livestock grazing exclusion

“…This difference is possible because many of the previous studies did not consider tree stand variables and diversity values, particularly from ADS and LGS seedlings and saplings. The variation in plant density recorded in this study area shows that forests subjected to different disturbances regenerate differently as supported by Wekesa et al (2015). ADS had more seedlings and saplings than in CFS, indicating that disturbances have some beneficial effects as found by others (Hessenmöller et al 2013;Kalaba et al 2013;Wekesa et al 2015 andLu et al 2017), though at small spatial scales (Duah-gyamfi et al 2014).…”

“…The variation in plant density recorded in this study area shows that forests subjected to different disturbances regenerate differently as supported by Wekesa et al (2015). ADS had more seedlings and saplings than in CFS, indicating that disturbances have some beneficial effects as found by others (Hessenmöller et al 2013;Kalaba et al 2013;Wekesa et al 2015 andLu et al 2017), though at small spatial scales (Duah-gyamfi et al 2014). Also, habitats modified by farming might also promote regeneration and are measurable after some years of human activities exclusion (Navroodi 2015).…”

Reconciling Community Livelihood Needs and Biodiversity Conservation in Taita Hills Forests for Improved Livelihoods and Transformational Management of the Landscape

“…Low to high levels of disturbance have been reported in the forest fragments. The forests of Mbololo and Ngangao, Chawia and Fururu, and Vuria have low, medium and high disturbance levels, respectively (Wekesa et al 2016). The disturbances have altered the forest structure and reduced tree species diversity (Wekesa et al 2016).…”

“…The forests of Mbololo and Ngangao, Chawia and Fururu, and Vuria have low, medium and high disturbance levels, respectively (Wekesa et al 2016). The disturbances have altered the forest structure and reduced tree species diversity (Wekesa et al 2016). Edge effects due to fragmentation of the forests have significantly affected the species diversity, distribution and abundance (Wekesa et al 2018(Wekesa et al , 2019.…”

Co2 Emission Trends and Risk Zone Mapping of Forest Fires in Subtropical and Moist Temperate Forests of Pakistan

“…Forest fires cause changes in the earth's biological and physical characteristics which over the years, affect carbon exchange (Harden et al, 2000;Vilen and Fernandes, 2011). According to Wekesa et al (2016), about 82-97% of released carbon dioxide (CO2) constitutes total carbon stock. Therefore, emission of greenhouse gases such as CO2 and methane (CH4) from forest fires directly affects climate (Simpson et al, 2006;Hansen et al, 2013) Forest fire risk zones are areas from where a fire is likely to have started and spreads to other areas (Leblon, 2005).…”