Biomasa Karbon Mikroba dan Aktivitas Enzim Selulolitik di Cagar Biosfer Giam Siak Kecil-Bukit Batu: Status Hara Karbon

Abstract

Giam Siak Kecil-Bukit Batu Biosphere Reserve is a peatland ecosystem consisting higher biodiversity of flora, fauna and soil microbes. Most of this areas have been converted into industrial forest plantation, oil palm plantation, agricultural activities, and settlement. This activity will decrease vegetation number and influence microbial population and activities at the end. Changing of the microbial at those population and activities will affect rate the impact of C cycle in peatland. This research aim was to analyze the impact of land use changes to microbial carbon biomass, cellulolytic bacterial cells number, and rate of cellulolytic enzymes activity (celllulase and β-glucosidase). Soil samples were taken from six different locations in Giam Siak Kecil-Bukit Batu Biosphere Reserve, namely primary forest (as a control), secondary forest, fourteen years old rubber plantation, fourty to sixty years old rubber plantation, twelve years old oil palm plantation, and three years old oil palm plantation. Soil physical and chemical characteristics varied in every location ranging from 28.25-31.25 ( o C) for soil temperature, dry weight 14.35-33.10 (%); water content 72.07-83.30 (%); bulk density 0.06-0.33 (g/cm 1 3 ) and 3.5 for soil pH. The lowest number of microbial carbon biomass was shown in the twelve years old oil palm plantation (240.29 µg C/hour/g soil) and the highest was in the primary forest (963.95 µg C/hour/g soil). The lowest number of cellulolytic bacterial cells number was shown in the primary forest (2.4·10 3 CFU/g soil) and the highest was in the fourty to sixty years old rubber plantation (1.3·10 4 CFU/g soil). The lowest number of cellulase activity was shown in the primary forest (0.67 µg/hour/g soil) and the highest was in the fourty to sixty years old rubber plantation (4.17 µg/jam/g tanah). The lowest number of β-glucosidase activity was shown in the 3 years old oil palm plantation (5.92 µmol PNP/hour/g soil) and the highest was in the fourty to sixty years old rubber plantation (27.45 µmol PNP/hour/g soil). Generally, land use changes govern the biomass microbial carbon biomass, cellulolytic bacterial number, and rate of cellulolytic enzymes activity in Giam Siak Kecil-Bukit Batu Biosphere Reserve.