PROVENANCES OF JAUL (Alnus acuminata ssp. arguta (Schlect) Furlow IN COSTA RICA

by

Olman Murillo Gamboa &
Erika Rojas Cruz, Baulio Vilchez Alvarado
Instituto Tecnológico de Costa Rica
Departamento de Ingeniería Forestal
Apartado 159–7050
Cartago, Costa Rica

The genus Alnus is one of the most wide-spread and variable ones in the Americas, containing numerous species and sub-species occurring from North America to Chile and Argentina.

Alnus acuminata, Jaúl, is found from Costa Rica to South America; Furlow (1979a, 1979b) proposes splitting the species into three sub-species. The sub-species Alnus acuminata spp. arguta occurs naturally from 1 500 to 3 000 m a.s.l. in the areas of Cordillera Volcánica Central and Cerro de la Muerte of Costa Rica. The species needs ample humidity to thrive, and is especially demanding in regard to soil humidity; it is therefore rare in areas with prolonged drought, and generally does not occur in areas in which the hydrological deficit exceeds 30–60 days.

Jaúl is considered one of the most promising species available for reforestation in high-altitude areas of the country. Marketing possibilities for wood of Jaúl are on the increase, and experience is being accumulated on planting techniques and management using the species in combination with agricultural crops such as coffee, forage and fruit trees.

In order to lay a good foundation for future work in tree improvement and genetic conservation, some work has been undertaken over the past years to determine intra-specific variation in Jaúl in Costa Rica; this work was supported financially by the International Science Foundation based in Sweden and by the Instituto Tecnológico of Costa Rica.

As a first step in the work, the natural distribution area of Jaúl in Costa Rica was sub-divided in accordance with natural vegetation (Gómez 1986), and in altitudinal zones of 500 m each. Populations which were of sufficient size to be considered possible, genetically distinct and viable entities, were determined in each of these zones through field observations. Material from a number of small relict stands was not included in the present work; such stands were especially frequent in the region of Talamanca (Cerro de la Muerte), between an altitude of 1 500 and 2 000 m a.s.l.

In each of the areas demarcated, information was collected on soil horizons through sampling and subsequent analysis in the soil laboratory of Centro Agronómico Tropical de Investigación y Enseñanza, (CATIE). Climatic records were collected from climatic stations considered most representative for each of the collecting sites. Twenty adult leaves and 10 fruits were collected from 15 well-spaced trees at each site; these were collected half-way up the crown, for subsequent measurements of length and width. Wood samples were also taken from these trees for subsequent determination of specific weight, using a 12 mm increment borer. An analysis of variance was carried out for the characteristics measured, complemented by multi-variate analyses.

Results indicated that variation in the species can be sub-divided into two main regions of provenance: the Cordillera Central Volcánica on andosoles; and the Cerro de la Muerte/Talamanca region, on different types of soils. Among the provenances in the Cordillera Central Volcánica, one provenance (Bajos del Toro) seems to differ considerably from the rest, and will necessitate additional study. The provenance of Copey de Dota from the same region, is also of special, scientific interest because of its unusually high percentage of hermaphroditic flowers and some other, provenance-specific characteristics. Based on the size of the leaves and the fruits, clinal variation seems to be present in the species in the Talamanca area, with a clear trend of diminishing size with altitude and with higher humidity (Murillo et al. 1991).

Based on the above studies, it is proposed to sub-divide Alnus acuminata in Costa Rica into 15 provenances (see Table 1 and Figure 1).

In conclusion, it was found that Jaúl exhibits ample variation through its natural range in Costa Rica. The work described will be complemented in the future with replicated provenance trials to determine genetic variation and heritability, adaptability of the provenances to a range of plantation sites and to confirm the preliminary demarcation of provenances proposed. It is however felt that the movement of seed should already now be regulated, to avoid moving seed between low-altitude and high-altitude sites, from higher to lower humidity areas and, above all, to avoid moving any reproductive materials from one major region of provenance to another (Cordillera Volcánica Central/Talamanca).

Table 1. Altitude of provenances of Jaul (Alnus acuminata ssp. arguta) in Costa Rica.

Figure 1. Alnus acuminata spp. arguta provenances in Costa Rica.

References

Furlow, J.J. 1979a The systematics of the Americam species of Alnus (Betulaceae).
Part I. Rhodora 81: 1 – 121.

Furlow, J.J. 1979b The systematics of the Americam species of Alnus (Betulaceae).
Part II. Rhodora 81: 151 – 248.

Gomez, L.D. 1986 Vegetación de Costa Rica. Apuntes para una biogeografia costarricense. Vol. vegetacion y clima de Costa Rica. EUNED. San Jose, Costa Rica. pp. 327.

Murillo, O; & Vilchez, B. & Rojas, E. 1991 Variacion entre pobblaciones de Jaul (Alnus acuminata spp. arguta (Schlectendal) Furlow) en la region de El cerro de la Muerte, Costa Rica. En: Tercer Congreso nacional de Biologia. Dr. Douglas Robinson. Resumenes. 18–22 de noviembre. San Jose, Costa Rica.

Forest Genetic Resources Information no. 21. FAO, Rome (1993)
Manuscript received in November 1992.