Distribution of Soil Organic Carbon in Riparian Forest Soils Affected by Frequent Floods (Southern Québec, Canada)

Abstract

Abstract:Measuring soil organic carbon (SOC) in riparian forest soils affected by floods is crucial for evaluating their concentration and distribution along hydrological gradients (longitudinal and transversal). Hydromorphological factors (e.g., sedimentation vs. erosion, size of floodplain, flood recurrence) may be the cause of major variations in the concentration of organic matter and SOC in soils and could have a direct impact on C levels in soil profiles. For this study, SOC concentrations were assessed in riparian soils collected along transects perpendicular to the riverbanks which cross through inundated and non-inundated zones. Other soil properties (e.g., acidity, nitrogen, texture, bulk density) that may affect the concentration of SOC were also considered. The main purpose of this study was to assess SOC concentrations in soils subjected to flooding with those outside the flood zones, and also measure various soil properties (in surface soils and at various depths ranging from 0 to 100 cm) for each selected area. Across the various areas, SOC shows marked differences in concentration and spatial distribution, with the lowest values found in mineral soils affected by successive floods (recurrence of 0-20 years). SOC at 0-20 cm in depth was significantly lower in active floodplains (Tukey HSD test), with average values of 2.29 ± 1.64% compared to non-inundated soils (3.83 ± 2.22%). The proportion of C stocks calculated in soils (inundated vs. non-inundated zones) was significantly different, with average values of 38.22 ± 10.40 and 79.75 ± 29.47 t·ha −1 , respectively. Flood frequency appears to be a key factor in understanding the low SOC concentrations in floodplain soils subjected to high flood recurrence (0-20 years).

How geomorphic context governs the influence of wildfire on floodplain organic carbon in fire‐prone environments of the western United States

“…The latter factor is important because analyses of floodplain soil OC from diverse river networks suggest that autochthonous floodplain production is a more important source of soil OC than riverine transport and deposition of organic material (e.g. Van Cleve et al, 1993;Omengo et al, 2016;Saint-Laurent et al, 2017;Lininger et al, 2018;Scott and Wohl, 2018a). Older floodplain forests represent older and more stable floodplain surfaces with uninterrupted accumulation of autochthonous OC.…”

Land capability classification of Vernazza catchment, Cinque Terre National Park, Italy

“…Moreover, the protection of soil and the conservation of mixed wood in this area have two important implications: (i) from a hydrogeological point of view, natural vegetation reduce impact of rain drops on soils, intercept hidden precipitations (mist and fog), allowing the conservation of water in soils; (ii) from an ecological point of view, soils are one of the most significant reservoirs of soil organic carbon and have the capacity to store carbon over very long periods of time (Saint-Laurent et al, 2017), in particular soil organic carbon increases under conifer and broadleaved woodlands (Rodríguez-Murillo, 2011).…”

Japanese knotweed increases soil erosion on riverbanks

“…This additional erosion of nearly 3 cm is equivalent to a soil loss of 25–45 kg m −2 per spring flooding episode given the bulk density of sandy loams and loamy sands, which varies from 0.9 (Saint‐Laurent, Gervais‐Beaulac, Paradis, Arsenault‐Boucher, & Demers, 2017) to 1.6 tons m −3 (Alberta Agriculture and Rural Development, 2010). In comparison, purple jewelweed ( Impatiens glandulifera ), another riverside invasive species, may occasionally cause soil losses of 3–17 kg m −2 per winter (6 months) along Swiss and English rivers (Greenwood et al, 2018).…”