Rapid litter production and accumulation in Bornean mangrove forests

Abstract

Litter fall and accumulation were measured weekly for one year (January–December 2007) at five mangrove forests within the Apar‐Adang Nature Reserve, East Kalimantan, Indonesia. Three forests were located near the sea edge, each co‐dominated by combinations of Sonnertia alba, Rhizophora apiculata, and Bruguiera parviflora; two forests were co‐dominated by Ceriops decandra, Exocoecaria agallocha, and Bruguiera sexangula (site IV), and by B. parviflora and B. sexangula (site V) and located further inland but subjected to intermittant freshwater inputs. Mean rates of annual litter production at forests I to V were 20.3, 19.7, 27.2, 24.2 and 27.6 Mg DW ha−1 yr−1 (mean of all forests = 23.7 Mg DW ha−1 yr−1) and rates of litter accumulation were 44.4, 50.2, 45.9, 61.3 and 66.2 Mg DW ha−1 yr−1 (mean of all forests = 57.8 Mg DW ha−1 yr−1), respectively, exhibiting peaks in the wet and dry seasons. Litter accumulation was greater than litter fall due to tidal advection of litter from forests closer to the sea edge coupled with slow decay rates. These rates of aboveground litter production and accumulation are the highest recorded for mangroves and higher than rates measured in tropical humid evergreen forests, suggesting that large expanses of equatorial mangrove forest, such as those on Borneo, may constitute an immense sink for coastal carbon.