Farming changes and the fate of Portugal's wild plants

Algarvian Toadflax (Linaria algarviana)

Right across the Mediterranean, farming methods are altering fast. Many of the traditionally farmed areas - for example the olive and fig groves, perhaps little changed since the dawn of civilisation - are being abandoned or replaced by more modern, intensive systems. But as these old farming methods go, the ancient balance between agriculture and plants is in danger of going with them. Using its study area as one case example, A Rocha Portugal is working to try to determine what threats this change in land use poses for the region's wild plants.

A rich variety of plants

Although on the Atlantic side of the Strait of Gibraltar, the Alvor Estuary - A Rocha Portugal's study area - is characteristic of Mediterranean coastal regions. The wide range of geology, soils and environments present in the area has given rise to a rich flora. Over 75 families and 300 genera of higher plants have been recorded and these plant groups show a wide range of growth forms and life strategies. Many are typical Mediterranean species adapted to the short rainy season and the long hot dry summers of the region. Some are specifically adapted to the challenges of surviving in particular habitats - for example, salt marsh or sand dunes.

Will Simonson undertook A Rocha's first survey of the flora of the Alvor between 1990 and 1992. During this systematic survey, almost 500 species were identified and records made of the preferred habitat, the phenology (the dates of flowering) and the abundance of each species on a standard DAFOR scale (a botanical scale running from "Dominant" to "Rare"). This survey was based on the study of over 15 plots of around a half-hectare to a hectare in size that were representative of different agricultural habitats on the Quinta da Rocha peninsula (for example, vineyards, orchards, pastures). Amongst the species identified were specialities such as the Bee and Tongue orchids of the genera Ophrys and Serapias and endemics (species restricted to Portugal) such as the Algarvian Toadflax Linaria algarviana, the Ox-tongue Picris algarbiensis and the Camphor Thyme Thymus camphoratus. Many other plants present were attractive species such as gladioli, asphodels, rockroses and broomrapes.

Since 1992, a small number of additions have been made to the original list. These additions do not simply show that there is always something new to discover, they also reflect the fact that, over time, the flora of any area will change. Now though, over ten years after the initial survey, a further systematic survey is being undertaken. The main reason for this is to chart the changes to the flora over this period and to see how these changes relate to the new patterns of land use in the area.

Changing farming, changing plants

The way in which the land has been used by human beings is a major factor in explaining why some plant species occur in an area and others do not. The richness of the flora of the Mediterranean region is widely recognised as being due to the way that plant communities here have, over centuries, adapted to traditional, low-intensity agricultural methods. Now though, these traditional agricultural methods are changing across the entire region. The effects are varied: good quality farmland comes under intensive agricultural production while elsewhere poorer quality areas are abandoned altogether. So, in the Alvor area, there has been a general decline in agricultural diversity with, for example, the loss of all the vineyards, and an increase in the extent of grazing pasture.

Such farming trends inevitably have an impact on plant communities: some species become threatened while other species seem to benefit by the return of semi-natural scrubland and woodland as fields are abandoned. Yet the facts on how these changes in farming practice are affecting plants are often elusive; few areas have had detailed botanical surveys done and often all that scientists have is anecdotal evidence of species change. Yet because of the earlier A Rocha survey, the Alvor Estuary area is different. Here, the existence of a systematic botanical study done before these agricultural changes means that the facts on plant change can be documented.

The survey revisited

Partly to look at the effects of these agricultural changes, Will is revisiting ten of the plots used in the 1990-92 survey and repeating the survey methods used then in order to look out for evidence of how these plant communities are reacting. He is seeking evidence of changes in the types and numbers of species present that cannot simply be due to year-to-year variations because of weather or some different sampling procedure. The first results already suggest some areas of concern, such as the deterioration of some fields formerly rich in orchids, and the fact that some species of formerly restricted occurrence are now absent.

The project will not just seek to reach scientific conclusions on what is happening to the region's plants, it will also propose management actions, and suggest how more detailed monitoring systems can be put in place. Over many thousands of years, Mediterranean farming practices achieved some sort of harmony with plants; it is vital that future farming practices and other uses of the land in the region do the same.

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Contact Will Simonson at A Rocha Portugal.