Polylepis - Ecology

Ecology

Mountain forest ecosystems have drastically changed due to human disruption such as cutting, burning and grazing, which causes fragmentation of the forest landscape. Polylepis contains some unique forms of autoecological (population ecology) and synecological relationships. Since they are located at high altitudes, they are equipped with specializations that help them withstand the harsh conditions. They are semiarid with an mean annual rainfall average between 200 and 500 mm. Tropical habitats found above 3600 m are subject to extreme diurnal changes. In midday, the temperatures may reach somewhere around 10-12°C (or higher). This causes the soil lower than the top 30 cms to maintain a constant temperature of about 2-5 °C (or lower) all year. Thus plants must stay active throughout the year and do not become dormant. Given these harsh circumstances, the growth of trees in such areas should be impossible. The reasons for Polylepis’ ability to inhabit such conditions have been studied by many. Carl Troll, for example, considered Polylepis to be a distinct type of vegetation and he claimed one of the reasons for their survival is the presence of microclimatic phenomena such as the formation of cloud layers on slopes and along low drainage areas, prevented nighttime freezes and producing what he called "lower elevation" conditions. Another study was done by Hoch and Korner which provided that Polylepis has slow growth making it a weak competitor. Therefore, if the temperatures become warmer and more humid, Polylepis tends to lose out to the species that are more vigorous.