A Simple Geospatial Nutrient Budget Model for Assessing Forest Harvest Sustainability across Nova Scotia, Canada

Abstract

A geospatial GIS-linked spreadsheet model (Nutrient Budget Model-Nova Scotia: NBM-NS) was developed for Nova Scotia to assess the long-term sustainability of forest harvest scenarios as constrained by primary nutrient inputs and outputs due to atmospheric deposition, soil weathering, and leaching. Harvest scenarios refer to user-defined stand-specific removal rates of bole wood, bark, branches, and foliage, based on current or projected forest inventories. These scenarios are evaluated within the context of existing data layers for current climate (mean annual precipitation and air temperatures), atmospheric deposition (N, S, Ca, Mg, K), and soil/substrate types, supplemented by species-specific look-up tables containing expected biomass fractions and nutrient concentrations. This article introduces this model to assess relative site quality and limiting nutrients for red spruce and sugar maple across Nova Scotia. This is followed by an output comparison involving 25 spruce plantations whereby NBM-NS determinations derived using "default" soil survey data are compared with those derived using plantation-specific soil data. Model output shows that (i) Ca and N are the main growth-limiting nutrients across Nova Scotia, (ii) currently projected plantation yields are generally not sustainable on sites underlain by slowly weathering soils, (iii) current soil base cation contents are generally lower than what is reported in historic soil survey reports, and (iv) model results are expected to vary within the context of changing climate, acid deposition levels, and data accuracy.

Kejimkujik calibrated catchments: A benchmark dataset for long‐term impacts of terrestrial and freshwater acidification

“…Despite reductions in acid deposition at KNP that strongly decreased in eastern Canada around 2000 (Sterling et al, 2020), acid deposition rates around 2008 still exceeded critical loads (Clair et al, 2011; Keys et al, 2016). Forest soil resampling in 1995 and 2017 showed that most forest soils in the area have seen little to no recovery from acid deposition, with base saturation values often below 10% (Keys, 2018; Keys et al, 2016), leading to nutrient limitation stresses for the affected forests.…”

“…Despite reductions in acid deposition at KNP that strongly decreased in eastern Canada around 2000 (Sterling et al, 2020), acid deposition rates around 2008 still exceeded critical loads (Clair et al, 2011; Keys et al, 2016). Forest soil resampling in 1995 and 2017 showed that most forest soils in the area have seen little to no recovery from acid deposition, with base saturation values often below 10% (Keys, 2018; Keys et al, 2016), leading to nutrient limitation stresses for the affected forests. Because of evidence suggesting lack of freshwater and soil recovery from acidification (Keys, 2018; Sterling et al, 2020), data collected at KCC are needed now as much as ever to understand the impacts of delays in acidification recovery in ecosystems in a warming climate.…”

Assessing Soil-Related Black Spruce and White Spruce Plantation Productivity

“…Doing this requires further in-depth studies and model calibrations. v) For generalization purposes, the evaluations need to be placed into the context of regionally varying climate and atmospheric deposition conditions (Keys et al, 2016). In addition to the above plot-based evaluations, one could use LiDAR-generated forest metrics for stem counts, tree height, basal and total wood volume at the tree-by-tree level, with, e.g., 20 × 20 or 25 × 25 m 2 summations (Strunk et al 2008;Woods et al, 2011;Treitz et al, 2012;Wulder et al, 2012;Latifi et al, 2015).…”

“…Likely soil-related growth and yield affecting differences refer to rooting depth, organic matter and coarse fragment content, and nutrient availabilities as modified by rate of soil weathering, litter decomposition, soil moisture regime and climate. Climate related factors refer to length of growing season, the extent of atmospheric deposition in the form of precipitation (rain, snow, and nutrients such as N, S, Ca, Mg and K), and actual evapotranspiration as dictated by monthly precipitation and air temperature patterns (Keys et al, 2016).…”

Increasing biomass demand enlarges negative forest nutrient budget areas in wood export regions

“…The medium- to long-term pool is represented by geogenic supply of nutrients from weathering and from atmospheric deposition 24 . In some cases, slow weathering nutrient allocation may limit the biomass yield 20 .…”