The drastic loss of Laurisilva forest after human arrival: A case study from Corvo Island

Abstract

Humans are a well-known threat to island biodiversity; however, the magnitude and dimension of flora loss is often not well understood. On Corvo island, in the Azores Archipelago and one of the most remote islands of the North Atlantic Ocean human land-use changes had a strong impact on the structure and function on its ecosystems. For instance, people removed the natural Laurisilva forest that dominated the island, resulting in the expansion of Sphagnumdominated environments. In this study we obtained a 2000-year long plant macrofossil record from asedimentary core in Lagoa do Caldeirão (400 m a.s.l.). We reconstructed the Laurisilva phytocenosis that surrounded the lake: Juniperus brevifolia and a rich epiphyte community of bryophytes and pteridophytes dominated a dense Laurisilva forest until the mid-12th century. A significant increase in the fragmented wood remains and charcoal particles between the mid-12th and 15th centuries signifies the onset of deforestation. In the second half of the 16th century, abrupt changes in vegetation occurred with the disappearance of the laurel forest. From the 17th century to the present day, pressure from livestock on the island led to a progressive increase in the abundance of Sphagnum and associated grassland species. The non-natural conditions of the present-day Sphagnum-dominated habitat illustrates a prime example of why the Habitats Directive of the EU requires a long-term perspective.