EFFECTS OF FARMLAND AND FOREST PRACTICES ON BIODIVERSITY CONSERVATION IN NORTH-WEST SPAIN

Abstract

The main changes in land use during the last 50 years have been agricultural intensification and forestry plantations with exotic species, and North-West Spain is not an exception. Traditionally, local people used to give value to native forests and sustainable agriculture, but several generations of rural abandonment and changes on the rural economy have led to a system in which farmers feel that they have to intensify their production. At the same time, they seem to have forgotten the values and services that native deciduous forests have always given to their ancestors. Nowadays, both fertile agricultural lands and mature native forests are rapidly being replaced by Eucalyptus plantations, which in less than 15 years can be cut down for paper production. It is known that Eucalyptus plantations affect biodiversity, but there are surprisingly few studies that analyse how these plantations affect biodiversity. In addition, during the last 18 years, there has been a 33% increase of organic farming in the area. This change has been mainly produced due to economical constraints in conventional farming, and most local farmers thought of it as the only way to continue living from farming. Many studies have documented how organic farming can counteract farmland intensification regarding the conservation of biodiversity, but few studies have considered how the effect of organic farming works in a heterogeneous landscape and how it varies between seasons. North-West Spain is an important wintering and breeding ground for many bird species, therefore, it is important to understand whether organic farming can enhance agricultural biodiversity conservation, as its effect in this area can affect biodiversity not only locally, but in a bigger scale. We analysed the effect of both farming and forest practices on biodiversity during an entire year by means of transects in paired organic and conventional farms and native and Eucalyptus patches. Bird, flying insect and plant species richness and abundance were compared. Bird species richness was higher in winter in organic than conventional farms. Bird abundance increased in organic squares with increasing surrounding native forest. Both species richness and abundance of plants and flying insects were higher in organic than conventional farms. Regarding forest and Eucalyptus patches, all species richness and abundance of birds, plants and flying insects were higher in native forests. Therefore, our results suggest that both organic agriculture and native forests have a key role in biodiversity conservation in the area, and that policies enhancing these two approaches will have positive effects on biodiversity conservation. Conserving traditional forest uses, such as chestnut production, or oak and chestnut wood use, at the same time as promoting an organic agriculture, will have a positive effect on biodiversity. Biodiversity conservation in the area cannot be separated from conservation of traditional land uses.