High altitude Alpine forests. Physiognomy - ecology and possible dynamics
2001
Anfodillo, T. | Urbinati, C. (Padua Univ. (Italy). Dipartimento del Territorio e Sistemi Agroforestali)
Upper treelines are ecotones located between the uppermost borders of closed forests and the isolated trees. The AA review the main ecological factors affecting current and past structure and functioning of treelines and the possible implications caused in such ecotones by environmental changes. Low temperatures and short growing seasons are commonly considered the main driving forces, which nonetheless do not explain the physiological mechanisms involved. A recent hypothesis (growth limitation hypothesis) would attribute the treeline occurrence to the inhibited photosynthates accumulation rather than to their production: a sort of incapability of carbon investment of high altitude trees due to low temperatures. However, the present features of the treelines in the Alps are mainly the results of millenary anthropogenic disturbances, that have changed their structure, composition and altitude distribution. Nonetheless, since treelines are environments highly sensitive to temperature increase, they act as reliable indicators of global changes and of their possible effects on vegetation. Responses to current changes (CO2 and temperature increase) seem different around the world and therefore dependent on regional conditions, which modulate their effects. The outcome is a very complex picture of this specific issue
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