Facilitation differentially affects competitive responses of aspen and subalpine fir through stages of stand development

Spatial interactions between trees influence forest community succession. The objective of this study was to investigate how shifts in composition and proximity tree species affect stand development over time mixed systems. At six locations across the Fishlake National Forest, Utah, USA, stands where facilitation has been documented previously, tree-ring samples were collected from aspen subalpine fir trees. Basal area increment calculated characterize effects overstory on multidecadal growth responses aspen-dominant aspen–conifer stands. Subalpine seedlings established next (within 10 cm) when 15 120 years old with a mean age 60 years. Aspen rates reduced increasing conifer abundance. growing proximate had slower than independently. Growth aspen-dominated similar independently or near However, conifer-dominated maintained higher an data suggest that as competition increases abundance, competitive exclusion while having beneficial effect fir. These results underscore importance maintaining natural fire regimes systems keep balance.