Year-end Sale % OFF 
Abstract
Raised bogs have accumulated more atmospheric carbon than any other terrestrial ecosystem on Earth. Climate-induced expansion of trees and shrubs may turn these ecosystems from net carbon sinks into sources when associated with reduced water tables. Increasing water loss through tree evapotranspiration could potentially deepen water tables, thus stimulating peat decomposition and carbon release. Bridging the gap between modelling and field studies, we conducted a three-year mesocosm experiment subjecting natural bog vegetation to three birch tree densities, and studied the changes in subsurface temperature, water balance components, leaf area index and vegetation composition. We found the deepest water table in mesocosms with low tree density. Mesocosms with high tree density remained wettest (i.e. highest water tables) whereas the control treatment without trees had intermediate water tables. These differences are attributed mostly to differences in evapotranspiration. Although our mesocosm results cannot be directly scaled up to ecosystem level, the systematic effect of tree density suggests that as bogs become colonized by trees, the effect of trees on ecosystem water loss changes with time, with tree transpiration effects of drying becoming increasingly offset by shading effects during the later phases of tree encroachment. These density-dependent effects of trees on water loss have important implications for the structure and functioning of peatbogs.
Highlights
Peatlands cover less than 3% of the Earth’s land surface but store almost 30% of all terrestrial soil carbon [1]
Tree Density Over the first summer, tree density affected mesocosm water loss leading to significant differences in the water table between experimental treatments (Fig. 1A)
The deepest water table was found in mesocosms with low tree density (LT), whereas mesocosms with high tree density (HT) remained wettest with the highest water tables
Summary
Peatlands cover less than 3% of the Earth’s land surface but store almost 30% of all terrestrial soil carbon [1]. Raised bogs are open peatlands, dominated by Sphagnum mosses, with anoxic, acidic and nutrient poor conditions that hamper the establishment and growth of vascular plants, trees [2]. Growing conditions for vascular plants could improve as the climate becomes drier and warmer. Drier and warmer conditions are known to improve vascular plant growth [4,5,6] as a result of reduced moss vitality [6,7], as well as by increased availability of nutrients [8]. Recent woody plant encroachment in pristine [9,10] and drained bogs [11,12] has been attributed to warmer and/or drier conditions, as well as to changes in fire frequencies associated with a drier climate
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
