Open AccessHow do forest landscapes respond to elevated CO 2 and ozone? Scaling Aspen‐FACE plot‐scale experimental results
Author(s) -
Gustafson Eric J.,
Miranda Brian R.,
Sturtevant Brian R.
Publication year - 2020
Publication title -
ecosphere
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.255
H-Index - 57
ISSN - 2150-8925
DOI - 10.1002/ecs2.3162
Subject(s) - environmental science , biomass (ecology) , ecological succession , disturbance (geology) , climate change , ecology , competition (biology) , ozone , atmospheric sciences , physical geography , geography , biology , paleontology , geology , meteorology
The Aspen‐FACE (Free‐Air Carbon Enrichment) experiment was an 11‐yr study of the effect of elevated CO 2 and ozone (alone and in combination) on the growth productivity of model aspen communities (pure aspen, aspen‐birch, and aspen‐maple) in the field in northern Wisconsin, USA. Uncertainty remains about how these short‐term plot‐level responses might play out at landscape scales where climate change, competition, succession, and disturbances interact with tree‐level responses. In this study, we used a recent physiology‐based approach (PnET‐Succession v3.1) within the forest landscape model LANDIS‐II to scale the site‐scale FACE results to landscape extents by mechanistically accounting for the globally changing drivers of CO 2 , ozone, temperature, and precipitation. We conducted a factorial simulation experiment to test five hypotheses about the effects of three treatments (CO 2 concentration, cumulative ozone exposure, and disturbance). CO 2 was clearly the dominant driver of landscape response, with disturbance also having a large effect. Ozone was not a dominant driver of landscape dynamics or total landscape biomass, but its negative effect on mean landscape biomass was nevertheless significant. We found that CO 2 mitigation of water stress may not have a major effect on species composition or biomass accumulation. We found that species diversity was somewhat decreased by elevated CO 2 as expected, but somewhat increased by O 3 , contrary to expectations. The spatial pattern of the landscape was minimally affected by the treatments. While rising CO 2 concentrations have some mitigating effect on the negative O 3 effect on the species studied, additional research is needed to confirm whether researchers and managers can be justified in disregarding O 3 as a primary driver of forest dynamics in other ecosystems. Our results also add more support to the growing consensus that projections of climate change effects must include robust, direct links between CO 2 and tree growth and competition; temperature effects (as demonstrated elsewhere) appear to be less by comparison.