Sky Islands

Name: Krislin Seepersad

I.D. No. : 812001658

BIOL 2462 – Caribbean Island Ecology

25th October 2014 – Sky Islands Lab Report

Abiotic and Biotic Characteristics of Tropical SKY ISLANDS

Evergreen Seasonal Forest in Arena Forest and Montane Forest on Morne Bleu

Introduction

Sky Islands are high altitude habitats that are surrounded by inhospitable lowland habitats such as plateaus, ridges and páramos. These lowlands act as a barrier to dispersal on sky islands which facilitates the divergence of isolated populations on sky islands. Montane forests can be considered sky islands because they are typically confined to the high altitudes of mountainous areas. Altitude brings a gradual reduction in overall temperature and often an increasing exposure to wind, the daily range in temperature is much more severe than that of lowlands and these conditions determine the growth form of trees, they rarely exceed 8m in height and the canopy is broken and open (Moore 2008). Moisture availability usually increases with a high altitude on tropical mountains and is highest where low clouds, fog or horizontal precipitation is common and thus vulnerable to increased rainfall and this high humidity than do lower forest not affected by fog (Bruijnzeel, Hamilton and Scatena 2010, 456).

Epiphytes are plants that grow entirely upon the support structures of other plants. Moore postulates that ferns, mosses and liverworts are more abundant in higher forests than in lowland forest because the cooler temperature reduces the rate of evaporation and favors these easily desiccated plants. He also states that flowering epiphytes such as orchids and bromeliads or more abundant in montane forests.

Temperature is a major factor which determines the rate of decomposition of leaf litter. Lower temperature would mean that there would be a decreased rate of decomposition in montane forest relative to lowland forests; however, slower rates of decomposition should allow larger pools of soil...