Daniel Piotto

Growth and effects of thinning of mixed and pure plantations with native trees in humid tropical Costa Rica

Abstract Reforestation efforts are being promoted throughout the humid tropics in response to increased areas of deforested and abandoned or degraded lands. Farmers need technical information on species performance, plantation design and management in order to make appropriate choices of species and silvicultural techniques to achieve high productivity. In Costa Rica, government incentives have promoted the planting of native tree species, but information is still scarce on species performance and silvicultural management. The present study examines the growth and responses to thinning of native species in mixed and pure-species plantations in the Caribbean Lowlands of Costa Rica. At 9–10 years of age, the species with best growth in diameter and volume were Vochysia guatemalensis Donn. Sm., Terminalia amazonia (J. Gmell) Excell, Jacaranda copaia (Aubl) D. Don, Virola koschnyi Warb. and Vochysia ferruginea Mart. Most species had better growth in mixed than in pure-species plantations. The slower growing species Calophyllum brasiliense Cambess and Genipa americana L. grew better in pure than in mixed stands. Mixed plantations (combinations of 3–4 species) ranked among the most productive in terms of volume. Trees responded to thinning with increased diameter growth, while height was not generally influenced by thinning. Tight initial spacing and thinning with high extraction of stems can improve growth and timber quality of stands. Results of the present research are useful to improve species choices for reforestation and plantation management in the humid lowlands of Costa Rica and in other regions with similar ecological characteristics.

Forest plantations in Costa Rica and Nicaragua: performance of species and preferences of farmers

Abstract The area of forest plantations in the tropics worldwide is increasing as a response to the expansion of degraded lands. Rural farmers of many regions of the dry and humid areas are responding to government and other incentives, dedicating portions of their land to native and exotic tree plantations with varied uses and objectives. We evaluated the success of reforestation efforts in a dry region of Nicaragua and in a humid region of Costa Rica where reforestation has been promoted by the governments with local assistance of technical personnel and non-governmental organizations. In all farms, the survival, diameter at breast height (dbh), height, form, and health of the tree plantations were evaluated. In addition, information regarding the farmers preferences and characteristics of the farms and the farmers was gathered through a survey including socioeconomic and silvicultural aspects. In both countries farmers used more native than exotic species for reforestation. Farmers are willing to continue reforesting as long as they continue to receive government incentives. In Costa Rica the plantations had better silvicultural management than in Nicaragua. In Nicaragua the species preferred by farmers for their growth were Azadirachta indica, Caesalpinia eriostachys, Eucalyptus spp., Gliricidia sepium, Leucaena leucocephala, and Tectona grandis. In Costa Rica the preferred species for their growth were Cordia alliodora, Gmelina arborea, Terminalia amazonia, Tectona grandis, Vochysia guatemalensis, and Virola koschnyi. The implementation of incentive programs for reforestation was a key factor in encouraging the participation of small and medium farmers.

Guidelines for documenting and reporting tree allometric equations

1 IntroductionGiven the pressing need to quantify carbon fluxes associatedwith terrestrial vegetation dynamics, an increasing number ofresearchers have sought to improve estimates of tree volume,biomass, and carbon stocks. Tree allometric equations arecritical tools for such purpose and have the potential toimprove our understanding about carbon sequestration inwoody vegetation, to support the implementation of policiesand mechanisms designed to mitigate climate change (e.g.CDM and REDD+; Agrawal et al. 2011), to calculate costsand benefits associated with forest carbon projects, and toimprove bioenergy systems and sustainable forest manage-ment (Henry et al. 2013).

An overview of existing and promising technologies for national forest monitoring

The main goal of national forest programs is to lead and steer forest policy development and implementation processes in an inter-sectoral way (FAO 2006). National forest monitoring systems contribute to forest programs through monitoring forest changes and forest services over time (FAO 2013). To do so, they generally collect and analyze forest-related data and provide knowledge and recommendations at regular intervals. The collection of forest-related data and their analyses have continually evolved with technological and computational advances (Kleinn 2002).

Diversity-dependent temporal divergence of ecosystem functioning in experimental ecosystems.

The effects of biodiversity on ecosystem functioning generally increase over time, but the underlying processes remain unclear. Using 26 long-term grassland and forest experimental ecosystems, we demonstrate that biodiversity–ecosystem functioning relationships strengthen mainly by greater increases in functioning in high-diversity communities in grasslands and forests. In grasslands, biodiversity effects also strengthen due to decreases in functioning in low-diversity communities. Contrasting trends across grasslands are associated with differences in soil characteristics.Long-term grassland and forest experiments reveal that temporal strengthening in biodiversity functioning relationships is mainly driven by increases in functioning in high-diversity communities.

Recommendations for the use of tree models to estimate national forest biomass and assess their uncertainty

Key messageThree options are proposed to improve the accuracy of national forest biomass estimates and decrease the uncertainty related to tree model selection depending on available data and national contexts.IntroductionDifferent tree volume and biomass equations result in different estimates. At national scale, differences of estimates can be important while they constitute the basis to guide policies and measures, particularly in the context of climate change mitigation.MethodFew countries have developed national tree volume and biomass equation databases and have explored its potential to decrease uncertainty of volume and biomasttags estimates. With the launch of the GlobAllomeTree webplatform, most countries in the world could have access to country-specific databases. The aim of this article is to recommend approaches for assessing tree and forest volume and biomass at national level with the lowest uncertainty. The article highlights the crucial need to link allometric equation development with national forest inventory planning efforts.ResultsModels must represent the tree population considered. Data availability; technical, financial, and human capacities; and biophysical context, among other factors, will influence the calculation process.ConclusionThree options are proposed to improve accuracy of national forest assessment depending on identified contexts. Further improvements could be obtained through improved forest stratification and additional non-destructive field campaigns.

Mixed Plantations of Native Trees on Abandoned Pastures: Restoring Productivity, Ecosystem Properties, and Services on a Humid Tropical Site

Twelve native tree species grown in mixed and pure plantations on degraded pasturelands at La Selva Biological Station in the Caribbean Lowlands of Costa Rica were evaluated at 15–16 years of age. Mixed plantations performed considerably better than pure plantations. The best performing species under both conditions were Vochysia guatemalensis, Virola koschnyi, Jacaranda copaia, Terminalia amazonia, and Hieronyma alchorneoides. Mixed plantations were among the most productive in terms of volume and carbon sequestered, performing as well as pure plots of fast-growing species. Thinning and pruning improved growth, quality, and stability. At 2–4 years of age, three species suffered less pest damage in mixed than pure stands, while other species suffered no damage or similar damage under both conditions. At 6–8 years, four species suffered total mortality in pure plots and limited survival in mixed plots due to pest damage. Mixed plantations sometimes improved soil conditions such as higher organic matter, and had intermediate values for the soil nutrients examined. Both pure and mixed plantations facilitated tree regeneration by attracting seed-dispersing birds and bats. Income from thinnings and final timber harvest seem to strongly exceed establishment and management costs, providing an economic incentive for similar plantations. These systems are productive options for restoring degraded agriculture or pasturelands of the region.

Legume abundance along successional and rainfall gradients in Neotropical forests

The nutrient demands of regrowing tropical forests are partly satisfied by nitrogen-fixing legume trees, but our understanding of the abundance of those species is biased towards wet tropical regions. Here we show how the abundance of Leguminosae is affected by both recovery from disturbance and large-scale rainfall gradients through a synthesis of forest inventory plots from a network of 42 Neotropical forest chronosequences. During the first three decades of natural forest regeneration, legume basal area is twice as high in dry compared with wet secondary forests. The tremendous ecological success of legumes in recently disturbed, water-limited forests is likely to be related to both their reduced leaflet size and ability to fix N2, which together enhance legume drought tolerance and water-use efficiency. Earth system models should incorporate these large-scale successional and climatic patterns of legume dominance to provide more accurate estimates of the maximum potential for natural nitrogen fixation across tropical forests.Data from 42 chronosequence sites show a geater abundance of legumes in seasonally dry forests than in wet forests, particularly during early secondary succession, probably owing to legumes’ nitrogen-fixing ability and reduced leaflet size.

Overcoming obstacles to sharing data on tree allometric equations

Miguel Cifuentes Jara & Matieu Henry & Maxime Rejou Mechain & Omar R. Lopez & Craig Wayson & Jose Maria Michel Fuentes & Edwin Castellanos & Mauricio Zapata-Cuartas & Daniel Piotto & Federico Alice Guier & Hector Castaneda Lombis & Ruby Cuenca Lara & Kelvin Cueva Rojas & Jhon del Aguila Pasquel & Alvaro Duque Montoya & Javier Fernandez Vega & Abner Jimenez Galo & Lars Gunnar Marklund & Fabian Milla & Jose de Jesus Navar Chaidez & Edgar Ortiz Malavassi & Johnny Perez & Carla Ramirez Zea & Luis Rangel Garcia & Rafael Rubilar Pons & Laurent Saint-Andre & Carlos Sanquetta & Charles Scott & James Westfall