| dc.description.abstract | Peatlands contain 40 cm or more of partially-decomposed plant matter and sequester carbon and nutrients. The disturbance of peatlands alters these ecological functions. Seismic lines, long cutlines in the forest created for geologic exploration, represent an enormous area of disturbed peatlands in Canada. In Alberta, over 345,000 km of seismic lines intersect peatlands, meaning that the approximately 134,000 km2 of boreal peatlands in Alberta are covered with an estimated 1,900 km2 of seismic line disturbance. There is no definitive method on how to restore peatland seismic lines and little research on post-restoration ecosystem function. This thesis aims to better understand the effects of restoration on biogeochemical functioning, particularly the nutrient cycling of nitogen (N) and phosphoous (P), on legacy seismic lines in a Alberta fen. The major themes of this thesis examined (1) quantifying how the restoration of seismic lines using new mounding techniques affected decomposition rates, pore water nutrient concentrations, and net mineralization rates in a fen, and (2) assessing the interactions between restoration treatments and fertilization on pore water nutrient concentrations, net mineralization rates, and plant nutrient supply rates in-situ and controlled impacts of an NPK fertilizer on soil processes in preliminary applications.
To evaluate the implications of the different restoration techiques, of mounding and fertilizing, on the ecological functioning of the fen, field and laboratory studies were conducted in 2019 and 2020. The effects of mounding on hydrophysical peat properties were analyzed by peat surface samples. Decomposition was determinered using the Tea Bag Index (TBI) in the field and by the loss of mass in the laboratory experiment. Net mineralization rates of N and P were analyzed using the buried bag method, and pore water samples were collected (0-10 cm) and analyzed for N and P concentrations.
The results from this study suggest that microbial activity increases with the addition of microtopgraphy. However, nutrient cycling effects from mechanical restoration were not clearly seen within two years post-restoration. When examining the effect of NPK fertilizer on nutrient availability, net mineralization rates, and foliar concentrations, results suggest that the use of fertilizer can increase organic matter decomposition in mechanically restored treatments. The addition of fertilizer can increase nutrient availability; however, the fertilizer is more likely to become immobilized in unsaturated conditions. The use of fertilizer resulted in taller trees. However it also increased the cover of graminoids, which may provide increased competition for tree seedlings. More research is needed to confirm the direct effects of fertilizer on tree recovery on restored seismic lines over time, but results suggest fertilizer may assist in providing nutrients needed for faster tree growth over unfertilized lines.
This study provides background concentrations of decomposition rates, N and P pools, and net N and P mineralization rates, which can be used to monitor the progress of the restoration techniques as the peatland recovers. These results also imply that implementation of mechanical restoration techniques, that introduce hummock and hollow microtopography, will increase microbial activity and allow oxidation of N. Additionally, the use of NPK fertilizer will enhance peatland seismic line restoration, by increasing nutrient availability and aiding in tree growth. However, fertilizer should be applied in moderation, as the addition of fertilizer also resulted in increased graminoid cover. These results from this study provide valuable information for improving the success of future restoration projects leading to more reforestation of the seismic lines, which will not only benefit humanity, but will aid in the conservation of wildlife, such as the woodland caribou (Rangifer tarandus caribou). | en |
