Speaker: Dr Yude Pan; USDA Forest Service Northern Research Station
Abstract: An empirical model depicting the relationship between changes in leaf area index (LAI) and aboveground net primary productivity (ANPP) of terrestrial ecosystems provides an opportunity exploring these changes at a global scale. As LAI can be an effective indicator for ANPP, it also facilitates observations of larger scaled disturbances on terrestrial ecosystems and evaluating consequences in ANPP. These disturbances were originated from both human activities and natural forces. Human disturbances such as deforestation around tropical rainforests evidenced losses in LAI. Natural disturbances related to changing climate are recognisable from intensified wildfires and droughts, which left marks in fire-prone regions and extremely dry lands. Although elevated atmospheric CO2 appeared to have enhanced global ANPP, disturbances and relevant tree mortality caused 30% of vegetated lands with reduced LAI and 14% with decreased ANPP.