Efficiency of inventory plot patterns for the estimation of woody vegetation recruit density in a tropical dense forest in Benin

This study assessed the effectiveness of plot patterns for estimating recruit density of woody species in the dense forest of Lama Reserve (Benin). The experimental design consisted of thirty 0.04 ha plots randomly settled in the forest and each subdivided into four hundred 1-m(2) quadrats. Within each quadrat, recruits (dbh <= 10 cm) were counted and saplings (h >= 2 m and 2 cm <= dbh < 7 cm) and young trees (h >= 2 m and 7 cm <= dbh < 10 cm) were measured in dbh. In each 0.04 ha plot, seven different plot shapes and sizes were considered by grouping adjacent 1-m(2) quadrats. Relationship between mean square error of the estimation of the density of recruitments and the plot sizes was modelled using the Smith law. Results obtained showed an average value of density of recruitments of 10.7 plants/m(2) with Green index value of 0.01. Shape and size of plots highly influenced the estimation of the density of recruitments. Rectangular plots of length/width = 2 and size of 72 m(2) (12 m x 6 m) were most efficient for the estimation of the density of recruitments in tropical dense forest with standard error of 0.79 plants/m(2)