Ecology, Environment and Conservation Paper

DIVERSITY, VEGETATION STRUCTURE AND C STOCKS OF INUNDATED RIPARIAN FOREST PROTECTED FROM CONVERSION TO OIL PALM IN C. KALIMANTAN

Cahyo Prayogo, Risky Maulana Ishaq, Muhammad Khoirul Anwar, Didik Suprayogo, Choirul Anshori, Yudha Asmara, Bandung Sahari and Kurniatun Hairiah

Abstract

Riparian zone of conservation forests that buffer stream flow by periodic inundation deserve to be protected from conversion to plantation crops. In this study, C storage and tree diversity was quantified for 5 pools (above-ground tree biomass, understorey, necromass, root and soils) in inundated and non-inundated parts of conservation forest set aside by PT AMR (Anugerah Menara Rahmat), Central Kalimantan. We estimated C stock in the forest using RaCSA (Rapid Carbon Stock Appraisal) method in inundated and non-inundated forest sites in 4 replicates in 3 locations. Tree biomass of mixed deciduous forest trees was calculated using allometric equation. A specific allometric equation was developed for Pandanus sp. y= 0.002 x 4.023 (R2= 0.903). Total C stock in inundated forest was to be 325 ton ha-1, considerably higher than that in non-inundated conditions: 144 ton ha-1. Drainage of these riparian forests may thus cause substantial C emissions if it leads to a change in forest type. Trees with DBH > 30 cm were more frequent been found in the inundated ecosystem, but all C pools ecosystem (313 Mg C ha-1) were 50% higher compare to those non-inundated plots (143 Mg C ha-1). Bulk density in the inundated ecosystem was 0.5-0.8 g cm-3, significantly lower than that in non-inundated plots (0.8-1.3 g cm-3). The inundated forest was dominated by Shorea balangeran, Callicarpa havilandii, Baccaurea edulis and Polyalthia xanthopetala, while Schima wallichii, Hevea brasiliensis and Macaranga gigantean were frequently observed in non-inundated forest. In total 1017 species were recorded in the inundated forest and 1191 species in non-inundated forest. The diversity and similarity indices differed significantly (p<0.05) between inundated and non-inundated conditions, Indices Diversity H’<1.0 of inundated and 1.03.0 of non-inundated. Thus, differences in carbon stocks were not matched directly by differences in tree diversity, and conservation is needed of both inundated and non-inundated forest types.