INTRODUCTION

The whole of Central America lies in a region where five tectonic plates converge. The tectonic movement and volcanism that formed Central America began 15-25 million years ago during the Miocene period and produced the land bridge between North and South America, which had previously been separate. This bridge allowed the movement of plant and animal species and contributed to the amazing biodiversity seen today.Arenal volcano The turbulent creation of the region means that Costa Rica has 112 volcanoes, five of which are classified as still active, and three major mountain ranges with the highest peak (Mount Chirripo) at 3819 m. Costa Rica occupies a narrow strip of land (50660 sq km) between Nicaragua in the north and Panama in the south and has coastlines on the Pacific ocean and the Carribean. The current population of Costa Rica is ca. 4.5 million with a large proportion living in the capital San Jose and the surrounding Central Valley region. Large parts of the country therefore have relatively low population densities. The topography of the country means that there is an enormous habitat range from mangrove swamps, through lowland rain forest, to cloud forest and seasonal dry forest to Paramo (wet grassland situated above the forest tree line at ca. 3000 m) and sub-alpine regions with dwarf vegetation.Epiphytes This range of different environments means that Costa Rica has more than 9000 identified species of vascular plants, including >900 tree species, >1500 orchid species and a wide range of epiphytic species including bromeliads. The animal species show a similarly high biodiversity with >850 birds, >200 mammals and >3500 insects.