FOREST GENETIC RESOURCES IN BUENOS AIRES PROVINCE, ARGENTINA: CHARACTERIZATION, CONSERVATION AND PROPAGATION

by
M.C. Rivas, W.I. Abedini and S. Sharry³¹

BACKGROUND AND ISSUES

Argentina is situated in the Southern cone of the American continent, covers 3.761.274 km² and hosts approximately 35 million hectares of native forests (as by 1984 - Merenson, 1992). In 1915, the forest cover was more than 30 percent of the national territory (SAGP&A, 1998). Today, forest cover is estimated at 12.7% of the total land area (FAO, 2003).

The Province of Buenos Aires covers 308.000 km², at an average latitude of 37-38º L.S in the neo-tropical region, and hosts about 1500 native plant species. The number of extinct species due to overgrazing, intensive agriculture or urban settlements is not known. Thirty six percent of the Buenos Aires province area is used for agricultural purposes, 53 percent for livestock raising, while 11 percent has no use, although it practically does not harbor any remaining pristine forests.

The native forests of Buenos Aires province are strictly confined to the coastal strip of Rio de la Plata (marginal forests and “Talares” of Celtis tala Gill ex Planch) and to the Western region (Caldén forests) (Parodi, 1939) (see Figure 1). When the city of Buenos Aires was founded, in 1590, its surrounding areas hosted forests of Celtis tala and white algarrobo (Prosopis alba) (Cozzo, 1992). The exploitation of forests for firewood was so intensive that the resources were exhausted at the beginning of the 19^th century. Today, these relic woodlands are known as “Talares” and ”Monte Blanco”.

Figure 1: Location of natural forests (Talares) in Buenos Aires Province

DESCRIPTION OF THE TALARES AREA

The administrative district of Talares spans the slopes of the Parana river and the province’s coastal area up to the Samborombón Bay. (Figure 1). The climax vegetation was represented by white algarrobo (Prosopis alba), and tala (Celtis tala). Current tree species include Celtis tala (tala), Scutia buxifolia (coronillo), Jodina rhombifolia (sombra de toro), Schinus longifolius (molle), Sambucus australis (sauco), Phytolacca tetramera (ombusillo) and Sapium haematospermun (curupí). The Celtis tala forests underwent an intense degradation process due to the expansion of urban settlements, livestock raising and firewood exploitation (Parodi 1939). The current status of conservation shows that protection of Celtis tala forests is considered a priority due to their high biodiversity and fragility.

The unique characteristics of the Talares lead to the creation, in 1984, of the Biosphere Reserve “Parque Costero del Sur” (MAB-UNESCO), now considered a natural and cultural heritage site. This reserve consists of a group of natural interphases, with exceptionally rich flora and fauna. Its area stretches over 26.581 ha, of which 73% is covered by different grasslands, 9% by talares, 9% by scrublands and 1% by riparian forests. The remaining eight percent is covered by cultivated areas (Goya et al., 1992). Most of the area is privately owned and productive activities are not regulated. The area could be managed as a reserve if the administrators would balance economic and conservation interests (Arturi M., 1997).

There is little information on the biology of native tree species, the different purposes they could be used for and the genetic variation between and within the species. This lack of knowledge could lead to irreversible loss of genetic diversity even before any study on variability is made. The implementation of in situ and ex situ conservation strategies for native trees is considered absolutely necessary.

A NATIVE FOREST SPECIES GERMPLASM BANK IN BUENOS AIRES PROVINCE

The Faculty of Agricultural and Forestry Sciences of La Plata National University has proposed the creation of a Germplasm Bank for the conservation of native forest genetic resources. To implement this initiative, the active involvement of concerned agencies (including the Environmental Policy Secretariat of the Buenos Aires Province, and the Experimental Centre of Vegetative Propagation (C.E.Pro.Ve.) of the Faculty of Agricultural and Forestry Sciences) was obtained. The Centre has been working in plant propagation since 1983, mainly with forestry species, through conventional methods (macro propagation, seed technology) and biotechnology. The project was declared a provincial level project; it is supported by the Buenos Aires Province Chamber of the Senate, and the Secretariat of Natural Resources and Sustainable Development of the Presidency.

The objectives of the germplasm bank are to:

• increase the number of accessions per species

• increase the number of tree and shrub species

• carry out molecular characterization of selected individuals and populations

• join forces with government agencies to develop in situ conservation schemes in protected areas

• obtain additional reproductive material to establish field tests and exchange it with other scientists.

ACTIVITIES

Since 1999, data on target species have been collected in a number of natural areas, including the restricted Natural Reserve Otamendi, the provincial Park Pereyra Iraola, the Punta Lara reserve and the Biosphere Reserve “Parque Costero del Sur” (Fig. 1), following a methodology proposed by Painting et al. (1993). Trees and seed-producing stands have been selected and marked, while material has been collected (Table 1) for the herbarium.

Most of the samplings are used to develop propagation protocols and seed analysis tests. The on-going project first phase studies the following species:

Acacia caven (espinillo)

Parkinsonia aculeata L. (cina-cina)

Erythrina crista galli L. (seibo)

Celtis tala Gill. ex Planch(tala)

Scutia buxifolia (coronillo)

Sesbania punicea (Cav.) Benth (acacia mansa)

Caesalpinia gilliesii (Hook.) Benth (barba de chivo)

Gleditsia triacanthos L. (acacia negra)

The following multiplication techniques are used:

• macro propagation (rooting of branches, roots, grafts)

• micro propagation (organogenesis, micro-grafts, embryogenesis somatic and meristem cultivation).

Complete plants have been obtained using these techniques. Cloned individuals are conserved in ex situ banks.

Seeds are being collected for conservation, after physiology studies have been carried out (feasibility and germination tests) out according to FAO/IPGRI gene bank methodologies. The facilities and the experienced personnel allow the Centre to operate as a Certifying Centre of Forestry Species Seeds, thus facilitating seed exchange with other institutions.

In addition, woody indigenous species including tala (Celtis tala), espinillo (Acacia caven) and cina cina (Parkinsonia aculeata) originating from Pereyra Iraola and Punta Lara Parks have been planted in the Ecological Park of La Plata Municipality (Buenos Aires) with the aim of evaluating growth and behavior.

Table 1: General information on forest tree accessions collected in the Talares (from 1999 to 2002)

CONCLUSIONS AND FUTURE PROSPECTS

As mentioned above, the forest resources of the Northeastern region of Buenos Aires province are under significant threat and require urgent action to halt the perceived loss of genetic diversity. In spite of the on-going destruction of the native forests, the National University of La Plata and the provincial government of Buenos Aires have started a unique ex situ germplasm conservation programme of native forest species. Similar projects exist in other provinces of Argentina, i.e. the Prosopis Bank in Cordoba province, but, considering the size of the country, such efforts are still scattered and limited. It is hoped that in the near future more resources will be devoted to protecting and sustainably managing the unique genetic heritage of native Argentinean forest trees.

REFERENCES

Arturi, M. 1997.Regeneración de Celtis tala Gill ex Planch en el NO de la Provincia de Buenos Aires. Doctorate thesis. Fac. de Cs. Agrarias y Forestales. UNLP.

Cozzo, D. 1992. Las pérdidas del primitivo paisaje de bosques, montes y arbustiformes de la Argentina con especial referencia a sus territorios áridos y húnedos. Acad. Nac. de Ciencias Miscelánea Nro.90. Córdoba.

Goya, J., Placci, G., Arturi, M. & Brown, A. 1992. Distribución y características estructurales de Los Talares de la Reserva de la Biosfera ”Parque Costero Sur”. Rev. de la Facultad de Agronomía, Tomo 68 : 53-64.

FAO. 2003. State of the World’s Forest. FAO, Rome, Italy

Liotta, J. 1999. Pautas generales para un sistema de áreas protegidas del NE bonaerense. Convenio Secretaría de Política Ambiental-UNLP.

Painting, K., Perry, M., Denning, R. & Ayad W. 1993. Guía para la documentación de recursos genéticos. Consejo Internacional de Recursos Fitogenéticos, Rome.

Parodi, L. 1939. Los bosques naturales de la Provincia de Buenos Aires. Ac. Nac. de Ciencias Exactas y Naturales de Buenos Aires. Argentina.

SAGP&A. 1998. Primer Inventario Nacional de Bosques Nativos-Sumario-Argentina.

³¹ Experimental Centre for Vegetative propagation, Faculty of Agricultural and Forestry Sciences, La Plata National University, CC 31 , La Plata (1900), Buenos Aires, Argentina