ASSESSMENT OF WOODY SPECIES DIVERSITY, BIOMASS AND CARBON STOCK POTENTIAL OF DZALANYAMA FOREST RESERVE, MALAWI

Abstract

Deforestation and forest degradation affect livelihoods variously including diminished ability of forests for climate mitigation. This study aimed to estimate vegetation structures, species diversity and carbon stocks potential of Dzalanyama Forest reserve in Malawi. A forest inventory was conducted in 31 concentric cluster sample plots. Trees ≥ 5cm Diameter at Breast Height (DBH) were recorded and identified to species level. Floristic composition and diversity were evaluated. Soil samples were taken from 0-30cm depths to determine the potential for carbon stock. To analyze the total woodland carbon stock, local allometric equations were used. The results were subjected to statistical analysis using independent t test. A total of 388 individuals belonging to 57 species and 23 families were recorded. Fabacea was the dominant family with 11 species in subfamily caesalpinioidae. Species diversity was found to be H’ = 3.31 (Shannon index) signifying high diversity of trees in the reserve. Significance difference (P≤0.05) between Shannon wiener diversity and level of disturbance was observed. Diameter and density in the distribution of the population in the area exhibited a reverse J shape, which indicated a stable woodland. Significant difference (P≤0.05) was observed between diameter classes and the level of disturbance. There was significant difference (p< 0.05) between DBH classes, with the DBH class of 5-14.9 cm having the highest number of stems per hectare implying more regenerants in the sampled plots, which is good for future carbon storage with good forest management. The undisturbed forests exhibited a higher basal area compared to disturbed forests with a significant difference of (P≤0.05).The above ground biomass (44.275±30.824), above ground carbon stock (22.140±15.41),below ground biomass (21.813±14.946) and below ground carbon stock (10.906±7.472) were significantly higher (P≤0.05) in the least disturbed forests than disturbed forests. The disturbed forests also showed significance (P≤0.05) with the level of disturbance, above ground biomass (7.341±7.244), above ground carbon (3.671±3.622), below ground biomass (3.803±3.337) and below ground carbon stock as (1.901±1.669). The overall carbon stock was higher in least- disturbed as compared to disturbed forest. Generally, least-disturbed forest had better total carbon and species. However high level of illegal human intervention with poor security and law enforcement actions beside ecological variation resulted in relatively poor total Carbon and species diversity. Therefore, better ecological, policy and socioeconomic concerns should be adopted in the area especially in disturbed areas. Dzalanyama Forest Reserve may be considered a potential area for investment in REDD+ in Malawi