Assessment of vegetation and peat soil characteristics of a fire-impacted tropical peatland in Costa Rica

Abstract

Tropical peatlands are highly vulnerable to anthropogenic alterations. In Costa Rica, riverine peatlands are understudied, and most are excluded from the protected areas. Aiming to assess the anthropogenic pressure in the Los Robles sector (LRS) of Medio Queso Wetland (MQW), this study evaluates its changes in vegetation cover, productivity, the topsoil, and soil profile. Fires have prevented the LRS from accumulating carbon (C) in the upper layers. Higher density and ash content; and lower C:N ratio in the dark black layers than the lower peat profile without carbonization, point to recurrent fires with a low water table (WT) for many years. To reduce the damage by fires to C accumulation, urgent measures to prevent prescribed fires, avoiding them specially until the beginning of the rainy season when the WT rise to near soil surface level. The species Eleocharis interstincta promotes higher C stability during the dry season, has a foliage with lower C:N ratio which make it more palatable for livestock and a more recalcitrant composition of the root system that favors peat formation than the temporally dominant Scleria melaleuca. Therefore, conserving E. interstincta could promote the recovery of the peatland functionality in the LRS.