Tree diversity and timber productivity in planted forests: Pinus patula versus mixed cloud forest species

Abstract

Planted forests contribute to maximizing timber production but their role as valuable habitat for diversity is of increasing concern, particularly in tropical montane cloud forest (TMCF) landscapes, which present extremely high diversity and endemism. We compared tree diversity, potential timber productivity and estimated net revenues in planted forests of Pinus patula and mixed TMCF species in southern Mexico. These planted forests were 21 years-old and established under similar environmental conditions in abandoned pastures previously occupied by TMCF. Adult tree height and density were similar between planted forests, but sapling and seedling density were reduced in P. patula in comparison to the mixed forest (0.05 and 0.28 sapling m−2 and 0.08 and 0.56 seedling m−2, respectively). The diversity of adults was similar, but that of saplings and seedlings was lower in P. patula than in the mixed forest (saplings: 3.39 and 9.14 effective species; seedlings: 2.85 and 9.59, respectively). Timber volume was similar between planted forests; however, due to higher establishment costs and lower market price, the net present value (NPV) of the mixed forest was considerably lower than that of P. patula. The mixed forest only achieved a positive NPV with subsidies and an interest rate < 5% under a 30% harvesting intensity. To ameliorate biobiodiversity loss, TMCF landscapes require alternative measures; e.g., a supply of a diverse mix of native seedlings, stimulation of the market for native species, compensatory mechanisms for mixed plantations of native species and landscape approaches that combine economically profitable and ecologically desirable species.