Potential influence of nutrient availability along a hillslope: Peatland gradient on aspen recovery following fire

Abstract

The Boreal Plains (BP) of Western Canada have been exposed to increasing disturbance by wildfire and host a mixture of upland‐wetland‐pond complexes with substantial quantities of trembling aspen (Populus tremuloides Michx.) throughout the terrestrial areas. The ability of these tree species to regenerate within both upland and wetland areas of the BP following wildfire is unclear. The purpose of this study was to investigate the influence of fire on nutrient dynamics in soil and water in peatlands and forested landscapes in the BP and relate this to aspen regeneration. Nutrient concentrations, nutrient supply rates, and net nutrient mineralization rates were determined in burned and unburned sections of a peatland and forest and compared with the regeneration of aspen. NO3−, NH4+, and P varied spatially throughout the landscape, and differences were observed between peatland and upland areas. In general, differences in nutrient dynamics were not observed between burned and unburned areas, with the exception of P. Nutrient and growth data suggest that aspen do not require nutrient‐rich conditions for regeneration and instead relied on forest litter to satisfy nutrient demands. Although the peatlands contained high nutrients, aspen did not flourish in the combination of anoxic and aerobic organic‐rich soils present in this area. Although aspen may use peat water and nutrients through their rooting zones, peatlands are unsuitable for aspen re‐establishment in the long‐term. However, the combination of abundant nutrients in surface mineral soils in peat margins may indicate the vulnerability of margins to upland transformations in later successional stages.

Deeper burning in a boreal fen peatland 1‐year post‐wildfire accelerates recovery trajectory of carbon dioxide uptake

“…Ecohydrological and edaphic conditions present in post‐fire peatlands may determine the magnitude and direction of modification to C cycling in these sites. For instance, the limited fluctuation in water table and increased availability of nutrients following the loss of upper peat layers (Certini, 2005; Galang, Markewitz, & Morris, 2010) in post‐fire peatlands supports the quick initiation of secondary succession (Depante et al, 2018; van Beest, Petrone, Nwaishi, Waddington, & Macrae, 2019). Given that nutrient dynamics in peatlands play an important role in determining plant productivity and decomposition rates (Wood et al, 2016), the response of post‐fire vegetation to increased nutrient and moisture availability could be a key determinant of C cycling and storage rates.…”

Postfire Soil Carbon Accumulation Does Not Recover Boreal Peatland Combustion Loss in Some Hydrogeological Settings

“…Acting as the interface between the peatland proper and the adjacent forestland, peatland margins experience large water table fluctuation (Devito et al, ). At the peatland margin, the WTD often decreases in comparison to the peatland interior due to a hydraulic gradient from the peatland to the adjacent forestland (Dimitrov et al, ) caused by a smaller storage deficit in the peatland, as well as uplift via aspen root networks, which transfer water from the peatland to be used by forestland vegetation (Depante et al, ; Devito et al, ; Petrone et al, ). Hydrogeological setting directly influences the amount of water table fluctuation at the margin, as it controls the degree of connection to local and regional groundwater flow systems, thus influencing the amount of groundwater received by the peatland (Devito et al, ; Hokanson et al, ).…”

Plant community type is an indicator of the seasonal moisture deficit in a disturbed raised bog

“…The loss of the surface peat may result in denser and more humified (i.e., catotelmic) peat being exposed at the surface (Sherwood et al, 2013), as well as near‐surface water repellency due to the production of hydrophobic compounds (Moore et al, 2017; Wilkinson, Verkaik, Moore, & Waddington, 2019). Fire may also increase nutrient supply in bogs (Depante et al, 2018). Due to these effects, significant changes to bog vegetation can occur after a fire, such as a reduction of Sphagnum cover and an increase in ericaceous shrubs and Cladonia species (Damman, 1977).…”