The Ecological Approach to the Conservation of Plants in Botanic Gardens - The Experience of the Botanic Garden in Valdivia, Chile
Volume 2 Number 10 - June 1998
C. San Martín Padovani
Traditionally, botanic gardens have conserved individual plant species ex situ in isolation, that is to say, without reference to other plants in the plant's natural environment. Nowadays there is an ecological approach that attempts to group together in the same area of a garden those species that belong to the same geographic region. The Valdivia Botanic Garden proposes to use this approach to reconstruct the principal plant formations that make up the landscape of the surrounding region in the Garden, grouping together species traditionally grown in isolation.
The Valdivia Botanic Garden was established in 1955 at the same time as the Southern University of Chile (Universidad Austral de Chile),. It is administered by the central services of the University and its scientific policy is formulated by the Botany Institute of the University. It is one of the most southerly botanic gardens in the world and is situated in the temperate rain forest region of Chile.
The Garden is located in the city of Valdivia, in the South-Central zone of Chile, 800 km to the south of the capital Santiago. It has an area of 10 ha and is situated on an island of the largest river system of the region (the basin of the Valdivia river). A large part of the terrace facing the Cau-Cau River suffered a collapse of some two metres in the earthquakes of May 1960 which devastated the south-central part of Chile. The collapsed part of the terrace was flooded by the river and now forms a swamp.
The main objectives of the Valdivia Botanic Garden are:
- To show the region's indigenous plants, especially those with conservation problems;
- To make people realise that it is not enough to conserve species without also conserving the environments in which they grow;
- To show the range of growth forms of plants;
- To demonstrate the adaptions of plants to their surroundings;
- To show the main ways in which flowering plants have evolved.
To achieve these objectives, the Botanic Garden is organized in sections that correspond to the various types of landscape and plant formations in the Central Chile region between the cities of Valparaíso and Puerto Montt. Thus, we have forest areas, scrubland, swamps and prairies, amongst others, which emphasize the interaction between plants and the environment. Visitors can also appreciate the different adaptions which enable plants to colonize different environments or niches that the soil and the climate provide, and also those created by the plants themselves. One can observe lianas that climb tree-trunks, bromeliads that live as epiphytes in the base of branches, the shrubs of the understorey and weeds and mosses on the forest floor.
The plants in the Garden are arranged according to the plant formations in which they occur. The diversity of the plant kingdom is demonstrated in these units, showing different life and growth forms. There are paths that give the visitor the opportunity of looking at the whole of the plant world represented in the forest such as trees, shrubs, weeds, herbaceous plants, ferns, mosses, epiphytes, climbers etc. This enables us to appreciate species as integral parts of the landscape and not simply as a mere curiosities that are cultivated in the garden, and that they need other organisms to survive in nature.
One of the best-developed sections of the Garden is that of the Valdivian forest; this is a plant formation that was abundant in the region, characterized by the presence of endemic species of trees and evergreen shrubs. This forest shows several layers which are joined by climbers, and is known as temperate rain forest. It represents an unique ecosystem in the world, with vicariants in New Zealand which are floristically similar, and in the Pacific coast region of the United States and Canada, which are ecologically but not floristically similar.
Although this forest is popularly regarded as very homogeneous and without large internal floristic differences, eight different plant associations have been described in it; they occupy distinct areas, amongst which we can highlight the forests of Olivillo, Coigue-Ulmo, Tepa-Tineo, Coigue, Array n, Coigue de Cilo‚ Coigue de Magallanes and Alerce.
The Valdivian rain forest occurs on the Coastal and Andean mountain ranges. To the south of Puerto Montt, it is present on all the islands in the centre of the Patagonian Channel region. A large project is being currently set up in Chile which will attempt to establish exactly how much native forest still remains and will map the location of its stands. Meanwhile, our Garden will try to make known what our native forests are and of what they consist, confident that people will protect and appreciate what they know about and what they feel is theirs. Thus we are helping to secure the objectives of the Montreal Protocol, leading to the conservation and sustainable management of the temperate and boreal forests. To this end, Australia, Canada, Chile, China, the United States, the Russian Federation, Japan, Mexico, New Zealand and the Republic of Korea joined together in 1995 to issue the Declaration of Santiago (Chile) 1995, which endorsed this initiative.
The principal genus of this temperate rain forest is Nothofagus, which is represented by three dominant species in different communities of this plant formation. Evergreen species are: N. dombeyi (Coigue), N. nitida (Coigue de Chilo‚) and N. betuloides (Coigue de Magallanes), all with a small leaf surface, which indicates some problems of water uptake, certainly due to a slowing of physiological processes caused by the cold.
In other sections of the Valdivia Botanic Garden there are also representative stands of the sclerophyllous and deciduous forests of central Chile and of the magellanic evergreen and deciduous magellanic forests that are located in the extreme south of our long territory. Their survival in their natural habitats is threatened by the existence of huge forestry projects, either to exploit the indigenous forest or plantations of exotic species - mainly the pine Pinus radiata and the eucalypt Eucalyptus globulus.