5. Conclusions
The data presented in this study related to plantation
productivity, aboveground biomass and nutrient concentration
and C content by tree compartment, aboveground
biomass equations by tree compartment, soil nutrient
reserves stability indices, plus already published information
(e.a [13] and [1]), can be used as a reference for: a) selection of
tree species vs site characteristics, b) estimation of nutrient
export by stem þ bark harvesting, c) planning for a second
rotation, c) maintenance of site productivity and d) generate
better carbon sequestration estimations.
In light of the results of this study, the total lack of interest
in Costa Rica to plant Pinus caribae and other Pinus species
deserves future consideration for three main reasons: a) these
species competes very well on degraded or unfertile soils with
T. grandis and G. arborea with the advantage of having higher
carbon fixing capacity and better soil nutrient stability indices,
b) the silviculture and wood technological package for industrial
use of this species is well known, c) the timber from this
species is widely used and has a guaranteed market.
Surprisingly this species has been neglected in commercial
and small farmers’ reforestations projects because of its
ecological reputation. Further discussion on this issue must
take place between ecologists and foresters to recognize that
this species is a useful alternative for small landowners who
are willing to plant small plots, live fences or wind breaks on
degraded lands. These farmers will plant trees with the fair
expectation of an economical return and with minimum
management requirements to improve their livelihoods.We
agree that P. species is not one of the best choices for biological
conservation, but is an excellent choice for other ecological
services such as soil and water conservation, restoration of
degraded lands and carbon sequestrations, while undoughtily
supporting rural economy and land use diversification.