Carbon storage potential of grassland ecosystems in the Eastern Arc mountains: a case study of Udzungwa mountains, Tanzania

Abstract

Grasslands are believed to store carbon in below and above ground. However, little is known on the actual proportion amount of carbon stored in the different carbon pools in the grassland ecosystems. This study aimed at quantifying below and above ground carbon stocks of floodplain and upland grasslands. Quadrants measuring 1 m2 were established systematically along transects in the floodplain and upland grasslands. Above ground vegetation and litter were sampled in 1 m x 1 m plots and below ground roots and soils were sampled in pits of 0.5 m x 0.5 m x 0.6 m. Soil samples were taken from 0 – 15 cm, 15 – 30 cm, 30 – 45 cm and 45 – 60 cm depth. Carbon in shoots, litter and roots was determined by Loss on Ignition method. Carbon in soils was determined by Walkley Black method. Data were analyzed using descriptive statistics and ANOVA. The above ground carbon in upland grassland was 12.60 } 0.50 t ha-1 and 3.09 } 0.11 t ha-1 for vegetation and litter respectively. Below ground carbon was 7.82 } 0.57 t ha-1 for roots and 40.26 } 1.17 t ha-1 for soils. In the floodplain grasslands above ground carbon was 33.04 } 1.18 t ha-1 for vegetation and 1.89 } 0.08 t ha-1 for litter. On the other hand below ground carbon was 6.22 } 0.25 t ha-1 and 24.63 } 0.88 t ha-1 for roots and soil respectively. In total upland grasslands has potential to store 63.77 } 2.35 t ha-1 of carbon while the floodplain grasslands storage was 65.78 } 2.39 t C ha-1. With exception of roots all other pools showed a significant difference in carbon storage between floodplain and upland grasslands (P = 0.000). Both upland and floodplain grasslands have high potential for carbon storage and emission mitigation.