Northern Peatland Vegetation Unfazed by Atmospheric Drought

Abstract

While the prevailing narrative in most studies highlights global vegetation suppression due to increasing atmospheric drought, our investigation challenges this perspective, specifically in the case of northern peatlands. Through site-level manipulation experiments and a comprehensive multi-dataset synthesis, our study unveils the distinctive effects of increased vapor pressure deficit (VPD) on vegetation growth in northern peatlands, where the positive effects of VPD dominate. In northern peatlands under climate change, soil water availability and plant water use strategies emerge as key factors in these diverse impacts. Plants in these ecosystems thrive in moist soil-air environments, adopting an "open" water-use strategy characterized by relaxed stomatal regulation to optimize carbon uptake. Regional analysis confirms that the distinctive VPD effect is widespread in most northern peatlands, in contrast to global non-peatland areas where simultaneous warming and declining relative humidity result in vegetation suppression. This study contributes to reconcile the unique responses of northern peatlands to rising VPD, thereby enhancing our ability to accurately model and mitigate the impacts of climate change on these ecologically critical ecosystems.