Markku Kanninen

Modeling carbon sequestration in afforestation, agroforestry and forest management projects: the CO2FIX V.2 approach

Abstract The paper describes the Version 2 of the CO2FIX (CO2FIX V.2) model, a user-friendly tool for dynamically estimating the carbon sequestration potential of forest management, agroforesty and afforestation projects. CO2FIX V.2 is a multi-cohort ecosystem-level model based on carbon accounting of forest stands, including forest biomass, soils and products. Carbon stored in living biomass is estimated with a forest cohort model that allows for competition, natural mortality, logging, and mortality due to logging damage. Soil carbon is modeled using five stock pools, three for litter and two for humus. The dynamics of carbon stored in wood products is simulated with a set of pools for short-, medium- and long-lived products, and includes processing efficiency, re-use of by-products, recycling, and disposal forms. The CO2FIX V.2 model estimates total carbon balance of alternative management regimes in both even and uneven-aged forests, and thus has a wide applicability for both temperate and tropical conditions. Results for the model testing and validation in selected temperate and tropical forest management systems are presented and discussed.

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.

Environmental Services of Native Tree Plantations and Agroforestry Systems in Central America

SUMMARY Besides supplying the growing demand for wood, plantations and agroforestry systems provide environmental services such as carbon sequestration and recovery of biodiversity. Several countries of Central America have recently started incentive programs to encourage plantation and agroforestry development. In Costa Rica, Payment for Environmental Services (PES) provides subsidies to farmers for plantations and agroforestry systems. Funding for these subsidies comes from a special tax on gasoline, and from external sources sought by FONAFIFO (National Fund for Forestry Financing). These plantations and agroforestry systems are established on degraded land by farmers who are often advised by local NGOs (non-governmental organizations) or by research institutions that have practical experience in the region. Gathering information on species selection, plantation silviculture, and environmental services provided by plantations and agroforestry systems is important to the success of these systems. These incentive programs can also serve as a model for starting or modifying similar programs in other countries with comparable ecological and socioeconomic conditions. This paper presents experiences with native species plantations over the past twelve years in Costa Rica. Data on volume, biomass production and recuperation of biodiversity are presented. We recommend the establishment of government incentives for reforestation and agroforestry systems with native Species.

Foliage biomass - sapwood (area and volume) relationships of Tectona grandis L.F. and Gmelina arborea Roxb.: silvicultural implications

Abstract We developed foliage biomass to sapwood (area and volume) relationships for Tectona grandis L.F. and Gmelina arborea Roxb. growing in the Guanacaste province of Costa Rica. Strong linear relationships confirmed the applicability of Shinozakis pipe model theory to both of these fast-growing, tropical species. The linear models include data from 80 (40 per species) dominant, codominant, and suppressed trees that had been growing in un-, late and early thinned plantations and fence-row plantings. Results are applicable across a wide range of foliage biomass values. The relationships between foliage biomass and sapwood area and volume of the previous years growth ring were also analyzed and were found to be highly significant for T. grandis. Findings confirm that silvicultural regimes of these species must allow individual trees to augment foliage biomass from an early age if sustained rapid diameter growth is desired.

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.

PROVISIONAL EQUATIONS FOR ESTIMATING TOTAL AND MERCHANTABLE VOLUME OF TECTONA GRANDIS TREES IN COSTA RICA

ABSTRACT Although management practices for Tectona grandis in Central America have improved during the last decade, accurate volume equations are not yet available. The aim of this study was to develop equations which best predict individual-tree total volume and merchantable volume for T. grandis in Costa Rica. A total of 112 trees with ages between 2 and 47 years and breast height diameter (dbh) between 2.4 and 58.7 cm were felled for stem analysis. Linear and non-linear regression analyses were used to model the relationship of total volume with dbh, with dbh and total height, and with age. The study also included merchantable volume equations that estimate merchantable volume to any minimum top diameter or bole length. The equations tested in this study fitted the observed data well. Other models, developed elsewhere, tended to overestimate the stem volume, especially at dbh ≥ 30 cm. General geometric cylinder volume equations combined with a Stem Form Factor of 0.45 (widely used for T. grandis) were less precise than regression models when applied to this data set. Model validation with an independent data set suggested that the models should be calibrated with local data when great accuracy is required (error less than 10%).

Stand growth scenarios for Bombacopsis quinata plantations in Costa Rica

In total 60 plots of approximately 80 trees each (including missing trees) were measured, with ages between 1 and 26 years. The main objective of this study was to develop intensive management scenarios for B. quinata plantations in Costa Rica to ensure high yielding of timber wood. The scenarios were based on a fitted curve for the relationship of DBH, and total height with age. A criterion of maximum basal area (18, 20, 22 and 24 m 2 ha � 1 ) was used to simulate different site qualities. Plantation density was modeled as a function of the crown area occupation of the standing trees. The scenarios consist of rotation periods between 23 and 30 years, final densities of 100–120 trees ha � 1 , mean DBH between 46 and 56 cm, and mean total heights of 30–35 m. The productivity at the end of the rotation varies between 9.6 and 11.3 m 3 ha � 1 per year, yielding a total volume at the end of the rotation of 220–340 m 3 ha � 1 . The scenarios presented here may provide farmers and private companies with useful and realistic growth projections for B. quinata plantations in Costa Rica. # 2002 Elsevier Science B.V. All rights reserved.

Above ground growth rate of a dwarf shrub community

The aim of the paper is to study the estimation of daily production of structural biomass by means of the height growth of plants. In particular, attention is paid to the relationship between dry matter production and self regulation of plants and the environment. A method for estimating the daily production of structural biomass based on these factors is presented for a dwarf shrub community of Vaccinium myrtillus (L.) and Vaccinium vitis-ida&a (L.). The amount of dry matter produced and the production ability of the plant community during different phases of the growing period is presented and discussed.

Vegetation structural characteristics and topographic factors in the remnant moist Afromontane forest of Wondo Genet, south central Ethiopia

For forest ecosystem management to be effective, knowledge of the horizontal and vertical structural diversity of a forest is essential. The moist Afromontane highlands of Wondo Genet in south-central Ethiopia present an opportunity to restore and rehabilitate and enhance the ecosystem services to be obtained from this forest sustainably. We focused on the forest structural characteristics to better understand the current forest conditions to assist in the sustainable management of this resource. A total of 75 (20 m × 20 m) quadrats were sampled and diameter at breast height (DBH) ≥ 2 cm and stem height ≥ 2 m were measured. Species identity and abundance, elevation, slope, and aspect were recorded for each plot. Structural characteristics were computed for each plot. Relationship of topographic factors with vegetation characteristics was conducted using R-Software. A total of 72 woody species was recorded. Whereas, the overall diameter distribution shows an inverted J-shaped curve, the basal area followed a bell-shaped pattern. Five types of population structures are revealed. The mean tree density and basal area was 397.3 stems·ha−1 and 31.4 m2·ha−1, respectively. Only 2.8% of the tree species have densities of >25 stems·ha−1 and the percentage distribution of trees show 56.2% in the DBH class 2–10 cm, indicating that the forest is dominated by medium-sized trees. Celtis africana (8.81 m2·ha−1) and Pouteria adolfi-friedericii (5.13 m2·ha−1) make the highest contribution to the basal area and species importance value index. The families/species with the highest importance value index are Ulmaceae, Fabacea and Sapotaceae. Species abundance (r2 =0.32, p <0.001) and species richness (r2 =0.50, p <0.001) are positively related with tree density. Tree density is negatively related with elevation (r2 =−0.36, p <0.001), slope (r2 =−0.15, p <0.001) and aspect (r2 =−0.07, p <0.05). While basal area is negatively related with elevation (r2 =−0.14, p <0.001), it has a positive relationship with tree density (r2 =0.28, p <0.001 and species richness (r2 =0.098). Species with poor population structure should be assisted by restoration tasks and further anthropogenic disturbance such as illegal logging and fuel wood extraction should be restricted.

Mahogany and Kadam Planting Farmers in South Kalimantan: The Link Between Silvicultural Activity and Stand Quality

This paper examines the relationship between farmers’ socio-economic characteristics, silvicultural activity and the quality of their mahogany and kadam plantation stands in two independent case study villages in South Kalimantan Province, Indonesia. Data on farmers’ socio-economic characteristics and silvicultural practices were collected and analysed by village using descriptive statistics, Mann–Whitney tests and Spearman correlations. Mahogany planters with larger areas planted carried out more silvicultural practices. Kadam planters who had joined the farmer’s group earliest, had favourable or highly favourable attitudes towards tree planting, and whose households included more members gaining income were more active in silvicultural management. Approximately half of the studied mahogany and kadam plantations were of high quality. Most of the farmers conducted the recommended silvicultural practices, but just conducting them did not of itself cause the variation in the quality of stands. Pruning timing and recovery time after pruning, however, had an effect on the volume of potentially merchantable wood on medium quality mahogany sites. Further research is required on timing, frequency and methods used for the silviculture in order to improve the quality of stands. The policy implications drawn from this research include that farmers need to be provided with: (a) incentives to plant species with identified markets with reasonable price; (b) motivated extension officers; (c) improved access to production inputs; and (d) structures and mechanisms to assist them to organize and to develop activities, such as joint marketing.