Edge effects of linear disturbances on plant functional traits in boreal fens of northern Alberta, Canada

Abstract

Global resource development has resulted in numerous disturbances that have a myriad of consequences on peatlands. We examined edge effects from one such disturbance, seismic lines, on plant species percent cover and select functional traits in Alberta, Canada. We tested various hypotheses that seismic lines and their edge effects influence percent cover and functional traits for eight dominant fen plant species: Larix laricina, Picea mariana, Betula glandulosa, Salix pedicellaris, Andromeda polifolia, Menyanthes trifoliata, Carex aquatilis, and Sphagnum warnstorfii. We analyzed species percent cover, plant height, leaf dry matter content, and tissue nitrogen (N), phosphorus (P), potassium (K), and carbon (C) content on the seismic lines and at various distances from the seismic line edge. Our findings suggest plant stress resilience to environmental variation through functional trait expression. This was most evident on species percent cover; P. mariana, M. trifoliata, C. aquatilis, and S. warnstorfii showed significant and unique responses across measured distances, with generally decreased plant cover on seismic lines. Plant height was significantly different across measured distances for B. glandulosa and C. aquatilis. Generally, tissue N, P, K, and C increased on the seismic line, consistent with a lasting release of nutrients during and following the disturbance. Connecting plant species abundance to functional traits provided insight into why recovery is lacking on seismic lines, even close to 30 years after the initial disturbance. We show that functional trait variation signals a pathway of plant stress resilience to disturbance that must be considered in ongoing forest management practices.