Abstract:
The study determined the carbon stocks and litter
nutrient concentration in tropical forests along the ecological
gradient in Kenya. This could help understand the potential
of mitigating climate change using tropical forest ecosystems in diferent ecological zones, which are being afected
by climate change to a level that they are becoming carbon
sources instead of sinks. Stratifed sampling technique was
used to categorize tropical forests into rain, moist deciduous and dry zone forests depending on the average annual
rainfall received. Simple random sampling technique was
used to select three tropical forests in each category. Modifed consistent sampling technique was used to develop 10
main 20 m×100 m plots in each forest, with 20 2 m×50 m sub-plots in each plot. Systematic random sampling technique was used in selecting 10 sub-plots from each main
plot for inventory study. Non-destructive approach based on
allometric equations using trees’ diameter at breast height
(DBH), total height and species’ wood specific gravity
were used in estimating tree carbon stock in each forest.
Soil organic carbon (SOC) and litter nutrient concentration
(total phosphorus and nitrogen) were determined in each
forest based on standard laboratory procedures. The results
indicated that, whilst trees in rain forests recorded a signifcantly higher (p<0.001) DBH (20.36 cm) and total tree
height (12.1 m), trees in dry zone forests recorded a signifcantly higher (p<0.001) specifc gravity (0.67 kg m−3). Dry
zone tropical forests stored a signifcantly lower amount of
total tree carbon of 73 Mg ha−1, compared to tropical rain
forests (439.5 Mg ha−1) and moist deciduous tropical forests
(449 Mg ha−1). The SOC content was signifcantly higher
in tropical rainforests (3.9%), compared to soils from moist
deciduous (2.9%) and dry zone forests (1.8%). While litter from tropical rain forests recorded a signifcantly higher
amount of total nitrogen (3.4%), litter from dry zone forests
recorded a signifcantly higher concentration of total phosphorus (0.27%). In conclusion, ecological gradient that is
dictated by the prevailing temperatures and precipitation
afects the tropical forests carbon stock potential and litter nutrient concentration. This implies that, the changing
climate is having a serious implication on the ecosystem
services such as carbon stock and nutrients cycling in tropical forests.
