Forest Ecology and Management 190 (2004) 359–372 Pure and mixed forest plantations with native species of the dry tropics of Costa Rica: a comparison of growth and productivity Daniel Piottoa, Edgar Vı´quezb, Florencia Montagninic,*, Markku Kanninend aGeotec Consultoria, Rua Estado de Israel 30, Sa˜o Paulo, SP, CEP 04022-000, Brazil bCentro Agrono´mico Tropical de Investigacio´n y Ensen˜anza (CATIE), 7170 Turrialba, Costa Rica cYale University, School of Forestry and Environmental Studies, 370 Prospect Street, New Haven, CT 06511, USA dCenter for International Forestry Research (CIFOR), 16680 Bogor Barat, Indonesia Received 7 April 2003; received in revised form 7 June 2003; accepted 6 November 2003 Abstract In Costa Rica, most reforestation trials with native species were established in the tropical humid regions. In the dry tropics, research on the performance of native species in forest plantations is incipient and trials comparing pure and mixed designs are limited. This paper presents the results of two experimental plantations with native trees in pure and mixed plots in the dry tropics of Costa Rica. The growth and productivity of 13 native species in pure and mixed plantations was compared with Tectona grandis (L.f.) Lam., an exotic species broadly used in the region. In a plantation of relatively slower growing species, measurements taken at 68 months of age resulted in Samanea saman (Jacq.) Merril. and Dalbergia retusa Hemsl. demonstrating the best growth, followed by Astronium graveolens Jacq. and Swietenia macrophylla King. Measurements in a plantation of relatively faster growing species, at 68 months of age, showed that growth of Schizolobium parahyba (Vell.) Blake was greatest in the pure and mixed plots, followed by Terminalia oblonga (Ruiz & Pav.) Steud., Anarcadium excelsum (Bert. & Balb. ex Kunth) Skeels and Pseudosamanea guachapele (Kunth) Harms. The native species grew better in the mixed plots. The pure plots of T. grandis (L.f.) Lam. were the most productive, compared to all species and the mixture of species. Plantations of T. grandis (L.f.) Lam. seem to be well adapted to the region and are certainly a commercially interesting alternative. Nevertheless, mixed plantations with native species would contribute more to sustainable management, because while single-species plantations do not provide a great range of goods and services when compared to the natural forest, mixed plantations are likely to increase this range of benefits. # 2003 Elsevier B.V. All rights reserved. Keywords: Costa Rica; Native species; Mixed plantations 1. Introduction cies from timber production to other land uses, and increasing protection of remaining forest areas. Con- Supply of high value timbers worldwide is becom- sequently, over the last few years, interest in establish- ing more limited due to overexploitation of these ing reforestation projects with native species in forest resources, conversion of forests containing these spe- plantations as a means to supplement existing tropical wood markets and as a way to detain the overexploita- * Corresponding author. Tel.: þ1-203-436-4221; tion of natural resources has increased. fax: þ1-203-432-3929. In Costa Rica, most reforestation trials with native E-mail address: [email protected] (F. Montagnini). species began in the 1980s, the majority of which were 0378-1127/$ – see front matter # 2003 Elsevier B.V. All rights reserved. doi:10.1016/j.foreco.2003.11.005 360 D. Piotto et al. / Forest Ecology and Management 190 (2004) 359–372 established in the tropical humid regions (Butterfield, compared with Tectona grandis (L.f.) Lam., an exotic 1990; Butterfield and Espinoza, 1995; Gonza´lez and species broadly used in the region. The hypotheses Fisher, 1994; Nichols, 1994; Montagnini et al., 1995; tested were: there is variation in growth and survival Arguedas and Chaverri, 1997; Haggar et al., 1998). In among species; the growth and survival of native spe- the dry tropics, where the forest cover has been cies is higher in mixtures that in pure forest plantations. reduced to a small fraction of the original area (Janzen, 1988), research on the performance of native species in forest plantations is incipient. 2. Materials and methods At the global level, single-species or ‘‘pure’’ plan- tations prevail in the tropics (Evans, 1999). Most forest 2.1. Site description projects use a small group of exotic species that are easy to manage through a variety of propagation The study plots were established in July 1995 in the methods, and are known for easy establishment, fast Peninsula of Nicoya, in the northern pacific region of initial growth and production of multiple products for Costa Rica (coordinates 108010North and established markets (Keenan et al., 1999). It should be 858420West). The land occupied by the study sites noted that many native tropical tree species are also was previously used for cattle ranching and is owned potentially valuable commercially, and that using such by Precious Woods of Costa Rica, a private company species, aside from satisfying economic objectives, that has reforested the majority of their properties with could be more acceptable ecologically and socially pure plantations of T. grandis and Bombacopsis qui- (Ball et al., 1995). nata (Jacq.) Dugand. The planting material was pro- For native species, mixed plantation systems seem duced in the company’s nursery, under a conventional to be the most appropriate for providing a broader black polyethylene nursery bag system. Seeds were range of options, such as production, protection, bio- collected from selected trees in the region. Weeding diversity conservation, and restoration of degraded was the main maintenance activity after field planting areas (Montagnini et al., 1995; Keenan et al., 1995; of trees, and a pruning of secondary apical shoots was Guariguata et al., 1995; Parrotta and Knowles, 1999). conducted in the first year. Mixed plantations can produce more biomass per unit The experimental area is located at an elevation of area because competition among individuals is 10–100 m above sea level and has an annual average reduced and the site is used integrally (Montagnini temperature of 27.5 8C. The mean annual rainfall is et al., 1995). The roots of different species may occupy 2350 mm per year with a 5-month dry period (less than different soil strata allowing more complete utilization 100 mm of precipitation per month). The trial replica- of soil and water resources (Lamb and Lawrence, tions were located in different slope and soil condi- 1993). More solar energy can be captured because tions (Table 1). In general Typic Haplustalf soils different species have different light requirements and prevail in the region, with medium to high fertility. crowns are broadly distributed in the vertical plane (Guariguata et al., 1995). 2.2. Methodology However, the success of the establishment of mixed forest plantations depends on plantation design and an Seven local species well known for slow growth and appropriate definition of the species to be used, taking seven species with relatively faster growth were into consideration ecological and silvicultural aspects planted in single-species plots and in a mixed-planting (Wormald, 1992). There exists very little information design. Table 2 includes the list of species, families, on the growth of tree species native to the dry tropics and range of natural distribution. Species choice was and information on experiences comparing pure and based on growth rate, timber value and availability of mixed forest plantations is limited. planting material. This paper presents the results of two experimental The growth and planting design combinations plantations with native trees in pure and mixed plots in resulted in four different species trials. Each trial the dry tropics of Costa Rica. Thegrowth and survival of has a complete randomized block design, with four 13 native species in pure and mixed plantations was replications, and species as treatments. D. Piotto et al. / Forest Ecology and Management 190 (2004) 359–372 361 Table 1 Soil characteristics at 0–20 cm depth in the experimental forest plantations at 68 months of age, in the Garza and Ostional Farms, Nicoya, Costa Rica Replication 1234 Farm Garza Ostional Ostional Ostional Slope (%) 15 0 45 70 Rockinessa Low Low High Medium Organic matter (%) 5.4 8.1 7.4 4.3 pH (water) 6.4 5.9 7.3 6.6 Total nitrogen (%) 0.28 0.41 0.37 0.24 Phosphorus (mg/l) 3.1 3.5 1.9 1.6 Calcium (cmol/l) 24.51 19.90 35.89 28.27 Potassium (cmol/l) 0.48 0.22 0.20 0.40 Magnesium (cmol/l) 6.09 8.14 2.99 8.60 a Low (1–10%), medium (11–30%), high (>30%). Every single-species plot trial (fast and slow growth In each plot, diameter at breast height (dbh) and group of species), has 25 trees per plot; while the total height were measured for each tree, including mixed planting design trials have 20 trees per species, border trees, at 16, 46 and 68 months. The averages of randomly distributed within the replication. T. grandis total height, dbh, basal area, volume index and survi- (L.f.) Lam. was only included in a single-species plot val were calculated for each plot. Variance analysis trial. was carried out for all variables for comparison Replications one and two in all of the four trials between species. For the volume index calculation a were established in a terrain with less than 15% slope, form factor of 0.5 was used, as suggested by New- in replication three the slope was 45% and in replica- bould (1967). For productivity variables (basal area tion four 70%. Planting distance was 3 m  3m. and volume index) it was necessary to carry out Table 2 Names, family and natural distribution of the 14 species used in mixed and pure plantations in the Garza and Ostional Farms, Nicoya, Costa Ricaa Species Family Natural distribution Slow growth species P.