Vegetation of Las Yungas (Serranías de Zapla, Jujuy, Argentina): Subtropical Mountain Forest

Vegetation is the most easily recognisable component of the ecosystem, and is the result of the joint action of environmental factors: it reflects climate, the nature of the soil, the availability of water and nutrients, and biotic and anthropic factors. It therefore acts as an indicator of the characteristics and status of ecosystems (Whittaker 1975; Matteucci and Colma 1982). The study of vegetation is of exceptional importance as it is a vital part of the ecological system: it captures, transforms and stores solar energy, protects the soil, regulates the local climate and serves as sustenance and refuge for fauna; it is the origin of raw materials for humans and a source of spiritual and cultural well-being thanks to its aesthetic, recreational and educational value. It is the essential basis for obtaining information on the composition, structure, dynamic and distribution of plant communities within a specific plant formation (Braun-Blanquet 1964; Whittaker 1975; Matteucci and Colma 1982). Vegetation studies serve numerous purposes, basically for research and development, and are closely linked to the conservation of the environment. The information obtained from these studies can be used to assess the vegetation for the purposes of conservation and to reach a diagnosis on its current state, with a view to designing strategies and programmes for conservation, ordination and territorial management and for planning the use of the territory (Whittaker 1973; Mueller-Dombois and Ellenberg 1974; Meaza Rodriguez 2000). These studies serve as the basis for creating maps of vegetation distribution within a given area, delimiting homogeneous ecological units and determining the degree of priority of its conservation. They also provide indicators on the environment, the effects of management (livestock, forestry production and so on) and different treatments (fertilisation, irrigation, reforestation and others), and supply valuable information for studies on environmental impact and the sustainable management of natural resources (forestry, management of wild fauna, etc.), among others. The detailed study of the composition, structure, dynamic and distribution of vegetation is therefore the cornerstone of a greater understanding and a balanced management of ecosystems, of which humans also form part. The increasing anthropic pressure to which natural ecosystems are subject today makes this type of study absolutely essential (Matteucci and Colma 1982; Barbour et al. 1998).