Forest recovery by root suckers and above-ground sprouts after slash-and-burn agriculture, fire and logging in Paraguay and Venezuela

Abstract

Vegetative regeneration is an important component of forest recovery after disturbance. This study focused on the role of resprouting, both as root suckers and above-ground sprouts in comparison to seed regeneration (plants 30–130 cm tall), under different disturbance regimes, pattern with successional age and importance in mature forest. Differently aged forest fallows, a fire-degraded stand (Paraguay), differently aged logged stands (Venezuela) and mature forest in both sites were selected. In Paraguay, the percentage of resprouts declined from 76% in the young forest fallows (2–5-y old) to 48 and 14%, respectively, in the older forest fallows (10 and 15-y old) and mature forest. In Venezuela, by contrast, the proportion of resprouts from the youngest logged stand (5-y old) to the oldest logged stand (19-y old) and mature forest slightly increased from 10 to 16% and 17%, respectively. Root suckers were more common than above-ground sprouts in any of the sampled stands. In forest fallows, 38% of all species possessed both modes of regeneration, while 20 and 18%, respectively, were either found with above-ground sprouts or root suckers. In the fire-degraded stand, most resprouting species were observed with root suckers (28%), whereas species represented with either above-ground sprouts or both modes of vegetative regeneration were less common (7 and 14%, respectively). In logged stands, species reproducing by both means of vegetative regeneration were more frequent (20%) than the other groups (14 and 8%, respectively). In the mature stands in Paraguay and Venezuela, 42 and 14% of the species, respectively, were found with either or both modes of vegetative regeneration. In both sites, significant differences in the ability to resprout between growth forms were found. Of 301 resprouting individuals in Paraguay, 114 were found to be uncut stems, of these 108 produced root suckers andsix above-ground sprouts.