Evaluation of trees indigenous to the montane forest of the Blue Mountains, Jamaica for reforestation and agroforestry

The shortage of forest products and unsustainability of current land use practices experienced by many hillside farmers in the Caribbean is associated with increasing rates of conversion and degradation of remaining natural forests. This pressure could be alleviated by the establishment of trees in community/farm forests or more integrated agroforestry systems. Indigenous tree species are largely untried for these applications and represent an underexploited resource that may offer a good combination of tolerance of local environmental conditions, together with potential to restore degraded environments. These needs were addressed in the Blue Mountains of Jamaica in a study that combined: eliciting local people’s knowledge about the utility of tree species for a wide range of products and services, assessment of the ecological characteristics of the tree species, and testing the establishment and growth of selected species over three and a half years in on-farm environments. Detailed interviews were conducted with 16 male and 11 female local respondents. Together they reported on the uses of 80 taxa of trees and shrubs, 43 of them indigenous (each respondent naming, on average, 19 taxa). All but one of the trees already present on farmland were exotic, but the majority of respondents were interested in planting more trees. The overall local valuations of each of the species were calculated for 10 uses. Timber and fruit were the highest rated individual uses but, for planting, multipurpose tree species were valued most highly. The respondents were familiar with most, but not all, of the indigenous species that have been recognised as having high commercial timber value. Farm environments on the southern slopes of the Blue Mountains are subject to significant drought as well as frequent disturbance from fire. Fifty-eight tree species indigenous to the montane forests were assessed for their potential suitability for growing in this environment by two indices of their distribution and three of their ecology. Their potential for timber production was also assessed in terms of their maximum size and wood density. Twenty-four of these species (together with one other indigenous timber species and the most highly valued exotic multipurpose tree species) were selected for a species elimination trial with a blocked structure replicated in two sites. After 42 months the species were strongly differentiated in terms of their rates of survival (from 0 to 48%), diameter growth (from 1.7 to 5.1 cm increment over the 42 months for the montane forest species), height growth (84–258 cm increment) and crown and stem form. Performance of most species in the trial could be explained post hoc by selective reference to their distribution and ecological traits in the natural montane forests. However, none of the traits taken alone provided accurate predictions of species’ performance in the trial. The best prediction was provided by a classification of species’ regeneration type with pioneer species tending to do better and shade-tolerant species worse, however there were many exceptions. No relationship was found between species’ performance in the trial and their altitudinal range, abundance in southern slope forest, in secondary forests or on landslides, or their growth rate or maximum stem density in mature forest stands. From the combination of local valuation and trial performance 10 species are recommended for more detailed testing. Of the undomesticated indigenous species, Juniperus lucayana and Clethra occidentalis are particularly recommended, and it is suggested that Turpinia occidentalis, Cinnamomum montanum, Viburnum alpinum, Dendropanax arboreus, Podocarpus urbanii and Prunus occidentalis also be considered because of their good combination of establishment and utility. In addition, from the analysis of ecological characteristics a further 19 species (11 already known to be valued for their utility) are recommended for an additional trial.