The Use of Homegarden Agroforestry Systems for Climate Change Mitigation in Lowlands of Southern Tigray, Northern Ethiopia

Mitigation of climate change is one of the major environmental challenges facing the globe. In this context, homegarden agroforestry systems (HGAFs) have large potential for climate change mitigation. Therefore, this study was initiated to estimate the biomass and soil carbon stocks of HGAFs in relation to adjacent Natural Forest (NF). It also analyzed the relationship between woody species diversity, evenness and richness with biomass and soil carbon stocks. Three sites were purposely selected on the basis of the presence of HGAFs and NF adjacent to each other. Random sampling was used to select representative homegardens from the study population. In NF, a systematic sampling technique was employed. A total of 60 plots with a size of 10 m x 20 m were used to collect vegetation and soil data in both land uses. Soil samples were collected from each plot of the samples laid for vegetation sampling. Accordingly, 120 composite and 120 undisturbed soil samples from 0-30 cm and 30-60 cm soil depths were collected for soil organic carbon (SOC) and bulk density analysis respectively. Biomass estimation for each woody species was analyzed by using appropriate allometric equations. The result showed that the total amount of carbon stocks was 148.32±35.76 tons ha-1 and 157.27±51.61 tons ha-1 in HGAFs and adjacent NF respectively which did not vary significantly between the two studied land uses (P > 0.05). The finding also shows a positive but non-significant (P>0.05) relationship between carbon stocks and woody species diversity, richness, and evenness. Specifically, in NF lands, woody species diversity with SOC (r=0.36) and in HGAFs species richness with biomass carbon (r=0.39) was correlated positively and significantly (P=0.05). We concluded that HGAFs have the same potential as the NF for carbon stock accumulation and to counteract the loss of biomass.