Ecophysiology of frailejones (Espeletia spp.), and its contribution to the hydrological functioning of páramo ecosystems

Autor: María Fernanda Cárdenas, Jorge I. del Valle, Conrado Tobón, Barret N. Rock
Rok vydání: 2017
Předmět:
Zdroj: Plant Ecology. 219:185-198
ISSN: 1573-5052
1385-0237
DOI: 10.1007/s11258-017-0787-x
Popis: Paramos are high elevation tropical ecosystems in northern Andes, with large water yield and water regulation. One of the main and representative species growing in these paramos is the genus Espeletia, known as frailejones. There is a lack of knowledge of Espeletia ecophysiology, maybe due to its unusual anatomical modifications and the specific climatic conditions of these ecosystems. Therefore, it is important to determine the relationships between the anatomical modifications of Espeletia, its physiological functioning, and its contribution to the ecohydrologic functioning of paramos. Consequently, we studied the physiology of frailejones in two Colombian paramos, focused on the identification of conductive tissues inside the stems, calculated the age, and measured sapflow, using the heat ratio method. Results show that Espeletia spp. have a central pith that increases with height, as the size of secondary xylem decreases. Frailejones respond quickly to the changing conditions of weather factors controlling transpiration such as solar radiation, temperature, and fog presence. However, although environmental factors favor transpiration, the sapflow tends to decrease—a particular behavior of the Espeletia transpiration processes—since this occurs chaotically over time, including sapflow at night. The transformation of sapflow velocity to depth of water in a basin shows that the water lost through their transpiration is very low, which contributes to the high runoff ratio of paramo ecosystems. For the first time, we determine by radiocarbon the real ages of three E. hartwegiana, and their mean growth rates to range between 3.8 and 6.9 cm year−1.
Databáze: OpenAIRE
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