Identifying Dicymbe corymbosa Monodominant Forests in Guyana Using Satellite Imagery

Abstract

ABSTRACTThe ectomycorrhizal (EM) canopy tree Dicymbe corymbosa (Fabaceae subfam. Caesalpinioideae) forms monodominant forests in the Pakaraima Mountains of western Guyana. Like other tropical monodominants, D. corymbosa has several life‐history traits that promote conspecific clumping, in contrast to density‐dependent recruitment limitations characterizing most tropical trees. Dicymbe corymbosa forests, occurring in Guyana as patches within a largely non‐EM mixed‐species forest matrix, are important habitats for a diverse assemblage of EM fungi. Ground‐based studies have not adequately determined the regional extent of D. corymbosa forests, nor are they practical due to the rugged, remote nature of the Pakaraima Mountains. We assessed the suitability of Landsat satellite imagery for mapping regional distribution of D. corymbosa forests in Guyana's Upper Potaro River Basin. Supervised image classification was performed on images from August 1989 (Landsat‐5 TM) and October 1999 (Landsat‐7 ETM+). In situ forest reference data were used to quantitatively assess accuracy of output classification maps. Classification performed well in distinguishing monodominant from mixed‐species forests. For both images, D. corymbosa forest class accuracy was good (1989 user's accuracy = 89.8%, Khat= 0.74; 1999 user's accuracy = 80.7%, Khat= 0.59). The resulting output classification maps will be useful for planning fungal surveys and ecological studies in forests of the Pakaraima region. Classification of Landsat images may be effective for identifying monodominant forests in other remote regions of the tropics.