Stability or change? Understanding sub Andean forest ecosystems - fragile environments facing disturbance

Fragile environments facing disturbance in the semi-arid regions of northern Peru will be analysed by use of aerial photo interpretation, vegetation mapping, GIS, direct gradient analysis (ordination), dendrochronology, analysis of key species densities a nd analysis of land use. Long term and recent stability and change in vegetation will be compared with occasional, but extreme weather situations (El Niño) and with land use (e.g. forest harvesting and livestock grazing). The aim is to identify effects of climate extremes and effects of land use on forest ecosystems, and to identify ways to sustainable management of fragile lands. The study will be presented in four interrelated parts plus a synthesis. The first three parts emphasise changes in vegetatio n structure and biodiversity as a response to El Niño and human disturbance in forest ecosystems; part four deals with relationships between man and nature: 1. Forest function and stratigraphy – an analysis of adaptation to changing environments and huma n disturbance, using direct gradient analysis (ordination) 2. Changes in key species concentration – retreat, stability or expansion of subtropical forest frontiers 3. Dendrochronlogy – an analysis of past and present forest pulsation and dynamics in fore st ecosystems facing disturbance 4. Changing land use – changing environments? An analysis of forest harvesting and forest distribution at local and regional scales during the last 30 years The districts of Piura and Frias (northern Peru) will be used as study areas. The first is situated in the arid lowlands, the latter in the more moist highlands. Differences in altitude, temperatures, and precipitation may cause distinct differences in the effects of El Niño, land use and human influence, and the lowl and/highland transect will be used to investigate possible regional adaptations, vulnerabilities and persistence to disturbance.