Change in tree growth before and after rewetting of drained peatlands

Sammanfattning

Peatlands are important ecosystems that have been extensively drained for forestry, increasing CO₂ emissions and altering ecosystem functions. Rewetting is now being used as a restoration strategy to reduce emissions and restore peatland ecosystems and biodiversity. However, this could negatively impact tree growth by altering site hydrology and soil conditions. This study investigates changes in tree growth in Pinus sylvestris before and after peatland rewetting across eight pairs of peatlands in Sweden in a Before-After-Control-Impact (BACI) design. Tree-ring widths from tree cores collected at varying distances from ditches were measured and converted into area increase and analyzed using linear mixed-effects models. While a negative trend in growth was observed after rewetting and with increasing distance from ditches, the effect could not be detected statistically. The lack of strong effects may be explained by site-specific differences in drainage and rewetting effectiveness and variable water-table changes. Overall, this study indicates that pine tree growth is influenced by peatland drainage and rewetting, but that responses are likely variable and site-specific.