Pattern and structure of microtopography implies autogenic origins in forested wetlands

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dc.contributor.authorDiamond, Jacob S.en
dc.contributor.authorMcLaughlin, Daniel L.en
dc.contributor.authorSlesak, Robert A.en
dc.contributor.authorStovall, Atticusen
dc.contributor.departmentForest Resources and Environmental Conservationen
dc.date.accessioned2020-01-14T18:37:55Zen
dc.date.available2020-01-14T18:37:55Zen
dc.date.issued2019-12-16en
dc.description.abstractWetland microtopography is a visually striking feature, but also critically influences biogeochemical processes at both the scale of its observation (10(-2)-10(2)m(2)) and at aggregate scales (10(2)-10(4) m(2)). However, relatively little is known about how wetland microtopography develops or the factors influencing its structure and pattern. Growing research across different ecosystems suggests that reinforcing processes may be common between plants and their environment, resulting in self-organized patch features, like hummocks. Here, we used landscape ecology metrics and diagnostics to evaluate the plausibility of plant-environment feedback mechanisms in the maintenance of wetland microtopography. We used terrestrial laser scanning (TLS) to quantify the sizing and spatial distribution of hummocks in 10 black ash (Fraxinus nigra Marshall) wetlands in northern Minnesota, USA. We observed clear elevation bimodality in our wettest sites, indicating microsite divergence into two states: elevated hummocks and low elevation hollows. We coupled the TLS dataset to a 3-year water level record and soil-depth measurements, and showed that hummock height (mean = 0.31 +/- 0.06 m) variability is largely predicted by mean water level depth (R-2 = 0.8 at the site scale, R-2 = 0.12-0.56 at the hummock scale), with little influence of subsurface microtopography on surface microtopography. Hummocks at wetter sites exhibited regular spatial patterning (i.e., regular spacing of ca. 1.5 m, 25 %-30 % further apart than expected by chance) in contrast to the more random spatial arrangements of hummocks at drier sites Hummock size distributions (perimeters, areas, and volumes) were lognormal, with a characteristic patch area of approximately 1 m(2) across sites. Hummocks increase the effective soil surface area for redox gradients and exchange interfaces in black ash wetlands by up to 32 %, and influence surface water dynamics through modulation of specific yield by up to 30 %. Taken together, the data support the hypothesis that vegetation develops and maintains hummocks in response to anaerobic stresses from saturated soils, with a potential for a micro-topographic signature of life.en
dc.description.notesThis project was funded by the Minnesota Environmental and Natural Resources Trust Fund, the USDA Forest Service Northern Research Station, and the Minnesota Forest Resources Council. Additional funding was provided by the Virginia Tech Forest Resources and Environmental Conservation department, the Virginia Tech Institute for Critical Technology and Applied Science, and the Virginia TechWilliam J. Dann Fellowship. Jacob S. Diamond is supported by POI FEDER Loire no. 2017-EX001784, the Water Agency of Loire Catchment AELB, and the University of Tours.en
dc.description.sponsorshipMinnesota Environmental and Natural Resources Trust Fund; USDA Forest Service Northern Research StationUnited States Department of Agriculture (USDA)United States Forest Service; Minnesota Forest Resources Council; Virginia Tech Forest Resources and Environmental Conservation department; Virginia Tech Institute for Critical Technology and Applied Science; Virginia TechWilliam J. Dann Fellowship; POI FEDER Loire [2017-EX001784]; Water Agency of Loire Catchment AELB; University of Toursen
dc.format.mimetypeapplication/pdfen
dc.identifier.doihttps://doi.org/10.5194/hess-23-5069-2019en
dc.identifier.eissn1607-7938en
dc.identifier.issn1027-5606en
dc.identifier.issue12en
dc.identifier.urihttp://hdl.handle.net/10919/96432en
dc.identifier.volume23en
dc.language.isoenen
dc.publisherEuropean Geosciences Unionen
dc.rightsCreative Commons Attribution 4.0 Internationalen
dc.rights.urihttp://creativecommons.org/licenses/by/4.0/en
dc.titlePattern and structure of microtopography implies autogenic origins in forested wetlandsen
dc.title.serialHydrology and Earth System Sciencesen
dc.typeArticle - Refereeden
dc.type.dcmitypeTexten
dc.type.dcmitypeStillImageen

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