Maarten Kappelle

Successional age and forest structure in a Costa Rican upper montane Quercus forest

Changes in structure of a Costa Rican upper montane Quercus forest were studied in twelve 0.1 ha plots along a chronosequence including 8- to 20-year-old Early Secondary Forest (ESF), 25- to 32-year-old Late Secondary Forest (LSF) and mature Primary Forest (PF). In 1.2 ha 2854 stems ≥ 3.0 cm dbh belonging to 42 tree species were recorded. Tree species richness per 0.1 ha ranged from 15 to 30. Diversity indices did not change significantly during succession. Stem density did not differ significantly among successional phases, while basal area was significantly higher in PF than in ESF and LSF. Maximum canopy height and basal area increased linearly during the first three decades of recovery. Height and dbh showed a significant, logarithmic regression for all forest phases. A period of 84 y was estimated as the theoretically minimum time needed for structural recovery. The maximum canopy height and basal area recovered two to five times slower in upper montane than in lower montane or lowland Neotropical forests.

Changes in diversity along a successional gradient in a Costa Rican upper montane Quercus forest

Changes in terrestrial vascular plant diversity along a successional gradient were studied in a Costa Rican upper montane Quercus forest. In 1991 and 1992 species presence and cover were recorded in 12 successional 0.1 ha forest plots. A total of 176 species in 122 genera and 75 families were found. Asteraceae was the most speciose family. With the help of TWINSPAN three successional phases were classified: (i) Early Secondary Forest (ESF, 145 spp.), (ii) Late Secondary Forest (LSF, 130 spp.) and (iii) Primary Forest (PF, 96 spp.). Detrended Correspondence Analysis (DCA) species ordination using DECORANA illustrates that different ecological species groups can be distinguished along the time sequence. Alpha diversity (Shannon-Wiener index, among others) in ESF and LSF was significantly greater than in PF. This is probably explained by downslope migration of numerous sub(alpine) species to cleared and recently abandoned montane sites. Beta diversity applying Sørensens similarity coefficients declined during succession. Using linear regression, the minimum time required for floristic recovery following disturbance and abandonment was calculated at 65.9 years. A comparison with other studies shows that secondary forests in upper montane Costa Rica can be as diverse as in neotropical lowlands.

Changes in leaf characteristics along a successional gradient in upper montane Quercus forest, Costa Rica

Morphology and mineral levels of leaves of 19 secondary and 22 primary tree species were studied in Quercusdominated upper montane 10-year-old Early Secondary Forest (ESF), 30-year-old Late Secondary Forest (LSF) and undisturbed Primary Forest (PF) in the Costa Rican Cordillera de Talamanca. In general, the predominant leaf is simple, elliptic, entire, and pinnately veined. Notophyllous and microphyllous-sized leaves dominate all spectra. During secondary succession the mean leaf area of secondary species tends to reduce 30 to 65 percent, while the average leaf area of primary species doubles. Primary species exhibit a greater mean leaf dry weight per unit area than secondary species. As succession proceeds, the mean leaf water content drops among secondary species and rises among primary species. During forest recovery levels of foliar nitrogen, phosphorus, and potassium decline significantly. In leaves of species in ESF nitrogen, phosphorus, and potassium are significantly correlated. Values for leaf characteristics recorded in Costa Rican montane ESF, LSF, and PF fall mainly within the ranges known from other tropical montane forests.

Useful Plants Within a Campesino Community in a Costa Rican Montane Cloud Forest

Abstract An ethnobotanical survey was carried out among a campesino community in a Costa Rican montane cloud forest. Campesino families were interviewed about how they used indigenous and introduced vascular plants along an altitudinal gradient (2000–3000 m). From a total of 590 species known in the area, 23.8% of 189 useful plant species were used for medicinal purposes, 39.7% for food, and 24.3% for construction (timber) or as combustibles (fuelwood, charcoal). Less important uses included dye, ornament (ecotourism), fodder, gum, oil, and poison. A total of 61.9 % of the plants were used for one purpose only. The introduced and exotic woody species Cupressus lusitanica and Eucalyptus globulus showed the highest diversity in types of use (7), together with the native Alnus acuminata. Trunks (53%) and fruits (47%) were the main plant organs used, followed by leaves (33%) and branches (30%). Over 27.5% of all plants were used on a daily basis, while 34.9% were used occasionally. About 11.6% of the species were rarely used. At present, use of indigenous species is becoming less common; the trend is to favor introduced and economically important species. In the short or medium term, local knowledge of medicinal plants will probably disappear in this rural community that is undergoing modernization, with a focus on new undertakings such as fruticultural export, rainbow trout hatcheries, and ecotourism.