Conservation – Calcium depletion/acidification

An Overview of the “Depleted Soil” Issue as it relates to the forests (left) & aquatic systems (centre);   and ways it is being addressed (right).  Click on image for larger version. Graphic from a  presentation to the 2022 Nature NS Celebration of Nature. Adjusting harvests according to nutrient budgets in the EM (Ecological Matrix) is likely not sufficient on its own to reverse soil acidification on the most depleted soils  where liming may be required to “jump start” the process.**

An inconvenient truth:  sketch shows prominence of highly acidic, calcium-deficient/high aluminum forest soils in Nova Scotia.  Sketch after Keys et al. (2016), Fig 3.

On Salmon and Soils, An Update

Post by David Patriquin on NSFN, Feb 15, 2022; last edit June 10, 2022

SUMMARY As a result of the inherently poorly buffered soils that cover more than 60% of our landscape and acid rain, exacerbated by intensive logging and climate warming, Nova Scotia has some of the most acidic, high aluminum & low calcium surface waters and some of the poorest soils for forestry in North America.

Recovery of surface waters and soils following reductions in the acidifying components in fossil fuel emissions has been much slower than expected, but we are beginning to understand the mechanisms, thanks largely to aquatic scientists.

Impacts on aquatic life, particularly salmon, are well recognized and efforts are being made to address them, e.g. by raising salmon fry separately and releasing them into the acidified waters, and by liming.

We have been slower to recognize the impacts on our forest ecosystems, and have not taken the precautionary measures we could have 11 years ago or even earlier. However, some really good science has been conducted in the interim and finally the Forest Nutrient Budget Model published in 2016 has been incorporated into manuals guiding forestry practices on Crown lands and should be come functional in 2023.

Some significant concerns remain, in particular that we will still push the forests too hard, especially in the Ecological Matrix of Crown lands and on many private lands.

Nutrient Budgeting for AP068499 Beals Meadow
Page on NSFN. posted Jun 9, 2022, last edits Jun 20, 2022. Examines a critical question: will application of the NBM-NS to highly depleted soils within the Ecological Matrix reverse the depleted state of the soil. Answer: Likely NO, unless lime is also applied**.
In relation to Beal’s meadow, also view:
AP068499 Beals Meadow Soil Type
Poor Recovery after a Clearcut

** See Helicopter Liming to Help Restore Acidified Forest Soil Productivity
McCavour, Caitlin ; Sterling, Shannon ; Keys, Kevin ; Halfyard, Edmund
Publication date 2021/4; Journal EGU General Assembly Conference Abstracts Pages EGU21-13660
Decades of acid deposition across northeastern North America has caused excess leaching of soil base cations (Ca2+, Mg2+, K+) and increases in bioavailable aluminum (Al3+) that, in combination, have resulted in widespread decreases in potential forest productivity. Despite major reductions in SO2 and NOx emissions since the 1990s, forest soils across the region have shown few signs of recovery from acid deposition impacts and it could take decades or centuries for natural recovery to occur. As a result, affected forests are stressed, less productive, and more prone to climate change-induced damage. Helicopter liming of upland forests may be an effective way to jump-start the soil recovery process. Here we report on early results (one-year) from a helicopter liming trial in Nova Scotia, Canada where 10 tonnes/ha of dolomitic limestone was applied to approximately 8 ha of mature red spruce (Picea rubens …

A Nutrient-Sustainable Harvest Assessment Tool for Nova Scotia Acadian Forests
Kevi Keys & Jana Bockstette. NS Natural Resources and Renewables Biodiversity Conservation and Forestry Technical Report Series. Forestry Tech Report 2023-04 | October 2023 “Abstract
Nova Scotia forest soils have been severely impacted by acidic deposition and base cation depletion to the point where mean percent base saturation levels for many dominant soil series are below 10%. Given these conditions, it is critical that nutrient budget assessments be integrated into timber harvest planning to ensure site-specific harvest removals are nutrient sustainable. The Nova Scotia Department of Natural Resources and Renewables has partnered with researchers in the Faculty of Forestry and Environmental Management at the University of New Brunswick to develop a locally calibrated forest nutrient budget model (NBM-NS) that can be used to assess the nutrient sustainability of proposed harvest prescriptions before operations begin. Using model inputs derived from ecosystem-based vegetation and soil classification units, a series of sustainable mean annual increment (SusMAI) tables have been generated that list current nutrient-sustainable growth rates (equals potential harvest rates) based on estimated tree species nutrient demands and local soil/site supply rates. These SusMAI tables can be used to assess the nutrient sustainability of any proposed harvest removal on upland Acadian forest sites where stand-level vegetation type, soil type, merchantable volume, and age data are known.” Document discusses appropriate uses of the NBM-NS, limitations. Imp. to note: “Given that forest ecosystems tend to naturally acidify over time, and that Ca2+ concentrations in base-poor soils in Nova Scotia were probably already decreasing before the accelerated losses from acidic deposition (as suggested by Leys et al., 2016), Nova Scotia forest soils will likely never return to “pre-acid rain” base cation levels without the use of remedial amendments (e.g., dolomitic lime). In addition, any natural recovery will be slow as discussed by Lawrence et al. (2015) and supported by a 20-year soil reassessment study in Kejimkujik National Park (Keys, 2018). It is therefore critical that timber harvest operations do not exacerbate the lingering impacts of acid deposition on soil base cation levels. To this end, the default %BS value for all NBM-NS calculations was set to 30%. This approach allows for some level of timber harvesting while theoretically [italic inserted] allowing soil base cation levels to gradually rebuild to more healthy levels over time.”

Addition of Alkalinity to Rivers: a new CO2 Removal Strategy
Shannon Sterling et al., 2023 “Addition of alkalinity to rivers is a previously unexplored but promising new tool to aid our global mission to reduce serious risks from climate change while restoring aquatic habitats.”

See Shannon Sterling on Google Scholar for related papers

Sit Back Seminar: Healthy Soils – Healthy Woodlands