Preprint - Edge Effects of Linear Disturbances on Plant Functional Traits in Boreal Fens of Northern Alberta, Canada

Global resource development has resulted in numerous disturbances that have a myriad of consequences on peatlands. We examined edge effects from one such linear disturbance, seismic lines, on plant community composition and select functional traits in Alberta, Canada. We tested the hypothesis that these disturbances influence community composition 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, phosphorus, potassium, and carbon content on the seismic lines and at various distances from the line edge. The influence of these disturbances was most evident on species 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. Leaf dry matter content did not show significant species-level changes. Plant height was significantly different across measured distances for B. glandulosa and C. aquatilis. Generally, tissue nitrogen, phosphorus, potassium, and carbon increased on the seismic line, consistent with a release of nutrients during disturbance. Carex aquatilis, M. trifoliata, and S. warnstorfii contained remarkably different levels of these nutrients in their tissues compared to our other study species. Connecting community composition to functional traits provided insight into why recovery is lacking on seismic lines. We show that functional trait variation in response to linear disturbances signals a pathway of stress resilience that must be considered in ongoing forest management practices.