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

Abstract

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.

Woody species diversity and carbon stock potentials in homegarden agroforestry and other land use systems, northern Ethiopia

“…However, the AGC stock in the homegarden agroforestry was nine times higher than the previous report [ 37 ]. Similarly, the AGC stock of the HGAF of the study area was higher than that of the protected natural vegetation from northern Ethiopia [ 62 ], but similar to the findings from the agroforestry system in the Lowlands of Northern Ethiopia [ 67 ], as well as church forests [32.]. On the other hand, the biomass carbon stock values of the exclosure in the present study were lower than Jabitehnane district in Ethiopia [ 38 ].…”

“…The depth from 0 to 60 cm for SOC stocks of HGAF in the present study is lower than indigenous agroforestry systems on the south-eastern Rift Valley escarpment (173–373 Mg ha −1 ) [ 34 ]. However, it was higher than a report (mean: 109.75 ± 29.95 Mg ha −1 ) from Northern Ethiopia [ 67 , 74 ], as well as from India [ 74 ]. On the other hand, the surface layer (0–30 cm) SOC stocks of HGAF in the study area were lower than in previous reports [ 33 , 34 , 66 ].…”

“…Higher amount of SOC was stored on the surface than that on subsoil in the current study. Similarly, numerous scholars reported a decrease in SOC value with an increase in soil depth [ [33] , [34] , [35] , 62 , 67 , 72 ]. SOC is normally estimated to a depth of 0–30 cm(the top layer) where root activity is effective in this horizon [ 73 ].…”

Carbon Stock Assessment of Four Selected Agroforestry Systems in Owerri-West Local Government Area, Nigeria

“…Also extensive reviews were carried out by [8] for "West African countries (extending from Arid Sahara Desert to humid region Guinea) and they reported that biomass C stocks ranged from 22.2 to 70.8 t C ha −1" . "There are many similar studies conducted in various regions of the continents" [9]. "From global report, the total biomass C stock for agroforestry systems ranges between 12 and 228 t C ha −1" [1,10] also reported that "agroforestry practices stored C ranging from 0.29 to 15.21 t C ha −1 yr −1 in their aboveground biomass and can have from 30 to 300 t C ha −1 in their soil down to one-meter depth.…”

Assessing Carbon Pools of Three Indigenous Agroforestry Systems in the Southeastern Rift-Valley Landscapes, Ethiopia

“…Extensive reviews by [13] for West African Sahel countries (extending from arid Sahara Desert to humid region Guinea) reported biomass C stocks ranging from 22.2 to 70.8 t C ha −1 . There are many similar studies conducted in various regions of the continents [14][15][16][17]. As reports showed globally, the total biomass C stock for AF systems ranges between 12 and 228 t C ha −1 [10,18].…”