Distribution of thornless Mimosa tenuiflora, Piptadenia stipulacea and Cnidoscolus quercifolius in a seasonally dry tropical forest remnant

Abstract

ABSTRACT The density and distribution of three tree species of local economic importance with, but sometimes without, thorns (Mimosa tenuiflora, Piptadenia stipulacea) or urticating hairs (Cnidoscolus quercifolius) thriving in native seasonally dry tropical forests, were assessed in a 43.5-hectare cattle-grazed caatinga remnant, located in Patos/Paraíba, Brazil. We recorded and georeferenced all the thorny and thornless regenerant plants (≥50 cm high and circumference at breast height (CBH) < 6 cm). We also recorded and georeferenced all the mature thorny and thornless trees (CBH ≥ 6 cm); in addition all the thornless mature trees and their respective nearest thorny mature plant were measured. Thornless M. tenuiflora, P. stipulacea and C. quercifolius totaled 560, 9 and 13 plants, respectively. The thornless plants formed groups and the mature ones showed height and CBH similar to their respective nearest mature thorny neighbor. Based on our data and on published data, we suggest management practices aiming at replacing thorny trees by thornless trees, including among others: the planting of 15 groups/ha of, respectively, 7, 2 and 2 thornless M. tenuiflora, P. stipulacea and C. quercifolius seedlings. Such a progressive replacement of the thorny trees by thornless trees would facilitate grazing and the management of the forest.