Soil pH Effects on Selected Species of Boreal Plants

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Oil sands mining causes disturbance to boreal ecosystems as it involves complete removal and reconstruction of landforms. The impacts of this development on the environment are mitigated through reclamation, reforestation and soils closure activities. In many of the oil sands reclamation areas, soil pH is more alkaline than soil pH measured in comparable soil horizons found in undisturbed boreal forests in the region . Potential differences in pH between reclamation soils compared with that of undisturbed forest soils can profoundly affect forest productivity. These differences in the initial soil pH on reclamation sites may be particularly significant for some of the acid-loving forest understory plant species. Understanding the effects of high soil pH on plants is essential before undertaking steps aimed at addressing these concerns in reclaimed soils. In the proposed project, we will examine the effects of root zone pH on the physiology, growth and survival of plant species native to the boreal forest of northeastern Alberta. In the controlled-environment experiments, we will examine growth and physiological responses of pH-tolerant and pH-sensitive plants to understand their limits and mechanisms of pH tolerance. We will examine the hypotheses that: 1) Boreal plants vary in their sensitivity to high soil pH, ) Negative effects of high pH on plants are aggravated by high calcium concentrations, 3) Alkalinity tolerance of plants is related to their ability to control Ca uptake, 4) Increasing soil P and Fe availability alleviates effects of alkalinity, and 5) Resistance of plants to high soil pH increases with age. The proposed study will generate knowledge required to develop protocols for the reclamation of oil sand areas that are affected by high soil pH.