Wild tree resins generate billions of dollars in revenue annually but many species face extinction. The lansan tree Protium attenuatum has disappeared across most of its range as a result of overexploitation for its valuable oleoresin, which is used as incense. This study in Saint Lucia aimed to determine whether lansan resin could be harvested sustainably. Over 34 months, 298 trees were tapped using 10 experimental methods, and compared with 74 controls. Significantly more resin was produced by tapping the same trees repeatedly, tapping trees with a wider girth, cutting the same part of the trunk repeatedly, and, in particular, spraying diluted sulphuric acid on the cut. Applying 5 and 30% sulphuric acid boosted yields by 58 and 134%, respectively, without negative impacts on tree growth, condition or mortality. In contrast, traditional methods used by local tappers were destructive, causing greater decay and infection, slower growth rates and increased mortality. Results show tappers can obtain more resin and maintain healthy populations by tapping mature trees of ≥ 20 cm diameter at breast height, using only one shallow cut per tree (refreshed every 2 weeks) and applying weak sulphuric acid solution. A blind survey found consumers could not distinguish between incense produced with or without this stimulant. A national management plan has been devised whereby tappers will be licensed and trained in the optimal method and granted their own forest coupes to manage under Forestry Department supervision. The methods and findings may guide the sustainable use and conservation of other resin-producing trees.

Three new species of braconid wasps from Costa Rica are described here: Allorhogas crinitus reared from leaf galls on Protium panamense (Burseraceae), Allorhogas lacuna reared from galls on Melastomataceae and Allorhogas triopsis reared from fruit galls on Psychotria (Rubiaceae). These new species are diagnosed and compared with other species in the genus. These are the first records of an Allorhogas species associated with the plant families Burseraceae and Rubiaceae. It is the third association of Allorhogas with the family Melastomaceae.

This study examined whether high nutrient concentrations associated with leaf-cutting ant nests influence plant growth and plant water relations in Amazon rain forests. Three nests of Atta cephalotes were selected along with 31 Amaioua guianensis and Protium sp. trees that were grouped into trees near and distant (>10 m) from nests. A 15N leaf-labelling experiment confirmed that trees located near nests accessed nutrients from nests. Trees near nests exhibited higher relative growth rates (based on stem diameter increases) on average compared with trees further away; however this was significant for A. guianensis (near nest 0.224 y−1 and far from nest 0.036 y−1) but not so for Protium sp. (0.146 y−1 and 0.114 y−1 respectively). Water relations were similarly species-specific; for A. guianensis, near-nest individuals showed significantly higher sap flow rates (16 vs. 5 cm h−1), higher predawn/midday water potentials (−0.66 vs. −0.98 MPa) and lower foliar δ13C than trees further away indicating greater water uptake in proximity to the nests while the Protium sp. showed no significant difference except for carbon isotopes. This study thus shows that plant response to high nutrient concentrations in an oligotrophic ecosystem varies with species. Lower seedling abundance and species richness on nests as compared with further away suggests that while adult plants access subterranean nutrient pools, the nest surfaces themselves do not encourage plant establishment and growth.

Despite the importance of treefall gaps in tropical forest dynamics, few studies have followed gap-phase processes for more than 2 y. We monitored, for five years, the growth and survival of many seedlings of Tetragastris panamensis (Engler) O. Kuntze, Protium panamense (Rose) I. M. Johnston, and Desmopsis panamensis (Rob.) Saff. (three common tree species of the Panamanian tropical moist forest) in artificially created treefall gaps and under intact-canopy control plots. On these same plots, we also monitored light levels using hemispherical photographs taken over an 8-y period. Seedling height growth was faster in gaps than under intact canopies during the first 42 mo of regrowth, then declined to rates similar to those under intact canopies. Light levels in gaps similarly rose and fell, returning to pre-gap levels by month 48. Only Tetragastris panamensis showed higher survival in gaps, contrary to the general assumption that seedling survival is enhanced by gap creation. Our results document important transition points that mark the conclusion of the gap phase, suggesting an estimate of 4y for the duration of the gap phase in this tropical forest.