7.01.07 - Multiple stressors on ecosystems


Mikhail Kozlov, Finland

About Unit

The intention of the Working Party "Impacts of air pollution and climate change - multiple stressors" is to raise awareness on the multiple, interactive effects of air pollution (ozone, nitrogen oxides, excess nitrogen deposition) and climate change (increase in CO2, temperature, extreme climatic events) on forest ecosystems and the services they provide. By forest ecosystem services, we refer to those functions that are valued by humans (e.g., water quality/quantity, clean air, carbon sequestration, habitat protection), but which are taken for granted and/or are difficult to quantify (see Fig. 1).

The interrelationship between physical, biological, and social systems are intimately influenced by one another: their concurrent consideration will allow us to gain insights that would not otherwise be available from a traditional, single disciplinary approach to research. To this end, we will encourage interdisciplinary research (atmospheric science, forest ecology, plant physiology and biochemistry, biodiversity and invasives, soil science, ecohydrology, geochemistry, fire science, land management), multi-trophic level studies, and integrative approaches (monitoring, research, modelling). This will not only improve knowledge, but will also help identify unknowns, and improve visibility of our research. This is a critical next-step to understand the consequences of air pollution and climate change on global forest ecosystems and refine our research agenda.

State of Knowledge

The importance of studying the effect of concurrent, multiple environmental stressors (elevated ozone, excess nitrogen deposition, drought, increased temperature) or enhancers (elevated CO2 or nitrogen deposition) on forest ecosystems is increasingly highlighted (Bytnerowicz et al., 2007; Paoletti et al., 2007). Anthropogenically driven gradients in pollution exposure and deposition have been used historically to elucidate long term effects of concurrent stressors on forest ecosystems (overview in Arbaugh et al., 2003). Long term, chronic to acute (in the mid 1970s and 1980s) O3 exposure increased mortality of sensitive species and altered forest stand composition (Miller et al., 1989). Recent studies of this pollution gradient demonstrated a link between high air pollution exposure, tree susceptibility to bark beetle, and higher tree mortality (Grulke et al., 2008).  Read full article.