<p>Microtopographical heterogeneity is an important variable that drives biodiversity in forests, but current forest reclamation and restoration practices often do not incorporate site and soil heterogeneity into operations during site reconstruction. This research aims to understand whether and how increasing the variation of microtopographical features and substrate types has a positive impact on the establishment and early performance of planted and colonizing tree seedlings. We compared three treatments that varied microtopography and substrate availability on planted trembling aspen, jack pine and white spruce seedlings and on naturally colonizing aspen, hypothesizing that more variation would increase establishment success and with that early height growth. We also compared specific microsites within each treatment for more detailed seedling responses. Establishment of planted seedlings was successful across all treatments and species, but natural aspen colonization was only significant in treatments that had topographical and edaphic heterogeneity. After four growing seasons, tree height and root collar diameter increased with increasing microsite heterogeneity. Within these treatments, aspen grew tallest in microtopographic positions where initial belowground resource availability was the highest, likely driven by factors such soil water availability and temperatures, highlighting the fact that initial root development is crucial in the establishment of trees on reclamation sites. Overall, these results showcase the positive impact of heterogeneity on early forest establishment and growth and suggest that increasing topographical and soil variability can be extremely beneficial for forest reclamation practices and the subsequent success of forest restoration.</p>