Fire as a common agricultural tool in the tropics favours the growth of tropical bracken, an extremely aggressive weed
2 Geographie, Universität Marburg
O 1.8 in Ecosystem Function
15.04.2010, 11:00-11:15, H13
Fire is commonly used in the tropics for forest clearing and maintenance of agricultural areas. Bracken (Pteridium aquilinum agg.) is one of the world’s most aggressive weeds whose growth and spreading is promoted by repeated burning. In contrast to the well investigated bracken of the northern hemisphere, the ecology of the neotropical P. arachnoideum and caudatum is less well known. On undisturbed bracken areas a 1 : 1-ratio of leaf emergence and leaf dying was found suggesting growth control by nutrient shortage. After burning very high frond development rates were found, resulting in canopy closure after 4 months. In the laboratory the effect of fire was simulated by artificial heat shocks on bracken rhizomes at different temperatures. The leaf producing rhizome laterals, growing close to the soil surface showed heat tolerance of up to 80°C, whereas the main rhizome axes (long shoots) which are commonly found at deeper soil layers were less heat tolerant. Stimulation of bud break and frond production was significant up to 60°C which is in good agreement with the field observations. Therefore the invasive power of bracken as a postfire colonizer appears to rest with the short shoots. Fast canopy closure outcompetes all kinds of crops.
Export as iCal:
