Disturbance Impacts on Thermal Hot Spots and Hot Moments at the Peatland‐Atmosphere Interface. Issue 1 (13th January 2018)

• Record Type: Journal Article
• Authors: Leonard, R. M.; Kettridge, N.; Devito, K. J.; Petrone, R. M.; Mendoza, C. A.; Waddington, J. M.; Krause, S.
• Is Part Of: Geophysical research letters. Volume 45:Issue 1(2018)
• Page Start: 185
• Page End: 193
• Publication Date: 2018-01-13
• Subjects: soil temperature -- thermal hot spots/hot moments -- ecosystem structure -- ecosystem functioning; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1002/2017GL075974
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: Soil‐surface temperature acts as a master variable driving nonlinear terrestrial ecohydrological, biogeochemical, and micrometeorological processes, inducing short‐lived or spatially isolated extremes across heterogeneous landscape surfaces. However, subcanopy soil‐surface temperatures have been, to date, characterized through isolated, spatially discrete measurements. Using spatially complex forested northern peatlands as an exemplar ecosystem, we explore the high‐resolution spatiotemporal thermal behavior of this critical interface and its response to disturbances by using Fiber‐Optic Distributed Temperature Sensing. Soil‐surface thermal patterning was identified from 1.9 million temperature measurements under undisturbed, trees removed and vascular subcanopy removed conditions. Removing layers of the structurally diverse vegetation canopy not only increased mean temperatures but it shifted the spatial and temporal distribution, range, and longevity of thermal hot spots and hot moments. We argue that linking hot spots and/or hot moments with spatially variable ecosystem processes and feedbacks is key for predicting ecosystem function and resilience. Plain Language Summary: Peatlands cover 3% of the Earth's surface but hold more carbon than the world's forests. Surface temperatures are a key control over many important peatland processes such as carbon storage and release. While peatland function and their response to disturbances has traditionally been examined as uniform, spatially isolated systems, peatland processes occur in a spatially complex and interconnected manner. New technology enables us to explore these fine‐scale behaviors, examining near‐surface temperatures spatially across a peatland. Temperatures were measured high spatial and temporal resolution in an undisturbed ecosystem, and subsequently repeated after the trees canopy was removed, and after the shrubs and grasses were cut and removed. We effectively removed layers of the ecosystem, reducing the complexity of the system. Results showed that average temperatures increased with removal of vegetation layers as expected. However, importantly, this temperature increase was uneven across the peatland surface and did not reflect predisturbance temperature patterns. We relate this system response to ecosystem layers and system complexity. As more layers are removed (e.g., shrub layer, and tree layer), the intensity of thermal hot spots increases. This has important implications for understanding ecosystem resilience and for predicting carbon storage ability of soils. Key Points: Temporal shifts in environmental stressors cause spatially explicit system feedbacks that define ecosystem resilience to change Layers of peatland ecosystem complexity reduce thermal hot spot intensity Novel application of Fiber‐Optic Distributed Temperature Sensing gives soil‐surface temperatures at unprecedented spatiotemporal resolution