Surprisingly, both aspen and spruce grew on sites with very high salinity and pH deeper in the soil profile (i.e., 40-100cm), so long as surface soils were not highly saline and had adequate moisture and nutrients.
However, aspen growth was reduced by 50% in highly saline stands compared to non-saline sites and growth rate slowed substantially in all stands once trees were over 15 years old. This suggests that salinity impacted aspen growth more strongly over time. The researchers also found that the majority of roots were distributed in the forest floor organic layer (LFH) and top 20cm of mineral soil with minimal root biomass found in the deeper highly saline soils (i.e., depths of 40-100cm). Thus, it seemed that once aspen roots outgrew their ‘favorable’ rooting zone, growth rates slowed considerably.
White spruce seemed to be unaffected by the salinity gradient and had steady growth rates over time. However, these growth rates were still lower than non-saline sites and would not be considered commercially viable. The tendency for white spruce to have a shallow rooting system and slow growth rates resulted in it being more tolerant to salinity than aspen