Thu, Aug 18, 2022: 5:00 PM-6:30 PM
ESA Exhibit Hall
Background/Question/Methods: Low productivity open lichen (Cladonia spp.) woodlands have been rapidly expanding in the closed-crown boreal forest in eastern Canada. Open lichen woodlands have been described as an alternative stable state to closed-crown feather moss (Pleurozium schreberi (Brid.) Mitt.) forests. Lichen, moss, as two common ground covers in boreal forests could be a driver of forest productivity. However, more research is needed to elucidate the mechanisms by which they affect soil properties and forest growth. Our experiment was implemented in a poor growing jack pine stand with a lichen ground cover. In September 2011, the ground cover surrounding 30 focal trees was treated as follows: 1) lichen cover removed (No Lichen), 2) lichen cover removed and addition of a feather moss (Pleurozium schreberi) cover (Added Moss) and 3) lichen control (no treatment) (Lichen Control) over a 160 m2 area around each focal tree. In June 2021, we selected a nearby productive Jack pine site (Moss Control) which had a continuous feather moss cover composed mostly of Pleurozium schreberi to serve as a natural benchmark. During June-October 2021, we extracted tree stem increment cores and collected needles and soil samples (forest floor and mineral soil) for nutrient analyses.
Results/Conclusions: We found significant differences in the Jack pine growth between the treatments. Growth of the jack pine stand with a lichen ground cover (Lichen Control) has been declining over time, while that of the natural-productive-moss stand (Moss Control) was relatively stable. After the 2011 treatments, there was a rapid decline in Jack pine growth in the lichen removal treatment (No Lichen) that has been maintained to date. In contrast, no such decline was found in the Added Moss treatment. Also, this treatment enhanced foliar nutrition, especially for Ca, Mg, Zn and Na. It also showed soil conditions that were closer to that of the Moss Control. Our results indicate that feather moss cover favors Jack pine growth and has the potential to modify or promote poor-growing stands. Overall, our findings suggest that manipulating the ground cover of boreal forest directly or indirectly through the establishment of conditions conducive to the survival of feather moss, could represent a new tool to maintain forest productivity in boreal forests.
Results/Conclusions: We found significant differences in the Jack pine growth between the treatments. Growth of the jack pine stand with a lichen ground cover (Lichen Control) has been declining over time, while that of the natural-productive-moss stand (Moss Control) was relatively stable. After the 2011 treatments, there was a rapid decline in Jack pine growth in the lichen removal treatment (No Lichen) that has been maintained to date. In contrast, no such decline was found in the Added Moss treatment. Also, this treatment enhanced foliar nutrition, especially for Ca, Mg, Zn and Na. It also showed soil conditions that were closer to that of the Moss Control. Our results indicate that feather moss cover favors Jack pine growth and has the potential to modify or promote poor-growing stands. Overall, our findings suggest that manipulating the ground cover of boreal forest directly or indirectly through the establishment of conditions conducive to the survival of feather moss, could represent a new tool to maintain forest productivity in boreal forests.