A significant increase in forest floor Mgexch was also observed with ash loading, but its dominance on the exchange complex was expectedly much lower than Ca. In fact, Mgexch behaved more like Kexch in that it did not increase over time like Caexch, suggesting oxides are stable in this environment and acting as a small source of Mg2+.
The progressive adsorption of Ca+ on exchange sites in the forest floor was accompanied by the displacement of acidityexch ( i.e.H+)and in turn, an increase in pH. However,of changes in forest floor pH in response to ash loading occurred more rapidly (but also stabilized more quickly) than changes in Caexch acidityexch and base saturation. It is possible that initially changed in response to displacement by K and subsequently in response to replacement by Ca. Conversely,Reid and Watmough(2014) reported that base saturation is more susceptible to ash loading than pH, regardless of soil horizon. In our study, nonetheless, functional groups were deprotonated at high pH resulting in more negative charges and consequently high CECeff.
Eight years after ash application, forest base cation concentrations and saturation all increased linearly with ash loading.However, the relationships were less pronounced than five yeais after application The effects of ash on soil can be preserved for a long period (saalsa er 2012) and further study is required to determine its lasting effect in the context of the Canadian boreal forest.