Effects of fencing on threatened plant species conservation

Abstract

Excessive herbivory causes serious problems of erosion, desertification, and biodiversity loss. Protective fences have been widely used to control this problem, although it has been proven that these fences have both positive and negative and undesirable effects in the medium term. However, there are no studies evaluating their effectiveness in the medium or long-term. In this work we have selected 6 threatened plant species (located in the Sierras de Cazorla, Segura y las Villas and Sierra de Mágina) with both fenced and unfenced populations. In these populations, data on the threatened species and different habitat parameters were collected in the field.

It was found that fencing generally reduced the presence and activity of ungulates, but in some cases individuals in fenced populations pro- duced a lower number of flowers and fruits. Fenced areas experienced a significant increase in cover, increasing interspecific competition for threatened species as well. There were no drastic changes in the soil, although there was an increase in some parameters indicative of overgrazing. The clearest conclusion of this work is that the effect of fencing, positive or negative, is not uniform, but varies among species and among populations of the same species. Narcissus, Atropa and Glandora were benefited, while Aquilegia, Euonymus and Geranium did not receive a clear benefit. Also, we highlighted the need to periodically evaluate the effectiveness of fencing, as well as the necessity to test and evaluate alternative fencing methods (individual fencing, temporary fencing, etc.).