Effects of three site preparation treatments on mortality and growth of four early-successional species on degraded sites

Abstract

Three site preparation treatments, straw (S), Meri-Crusher (MC), and coarse woody debris (CWD) in a 2x2x2 factorial testing four early-successional species for land restoration: Betula papyrifera, B. populifolia, Alnus viridis ssp. crispa, and A. incana ssp. rugosa were examined for mortality and growth. The study was conducted on three 25- year barren sites. Chapter 1 assessed summer 2021, winter, and spring frost heaved mortality Greatest causes of mortality were frost heaved followed by summer drought. Overall, S reduced mortality by 27%, CWD by 19%, and MC increased by ~4%. When treatments were combined in any way, mortality dropped significantly indicative of an additive effect. Chapter 2 focused on growth measurements, in 2022, alders and birches had on average 3 and 1 stems, respectively. Alders averaged 11x more dry mass than birches. When site preparation treatments were combined alders stem mass mostly experienced synergistic while birches were largely additive growth.