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.
Highlights
Sustainable forest management can be defined in many ways, sustainability of forest harvesting is dependent on the availability of growth-limiting nutrients (Ågren, 1985; Sverdrup & Rosen, 1998)
This study suggests, that care must be taken when using old soil survey data to initialize nutrient budget models such as NBM-NS
This paper describes a geospatial, GIS-linked nutrient budget model (NBM-NS) that can be used to: predict long-term sustainability of forest harvesting regimes in relation to primary nutrient input and output estimates; estimate sustainable mean annual increment (SusMAI) values for individual stands or sites by determining limiting nutrient levels; and develop nutrient-based site quality assessments based on soil/substrate characteristics and atmospheric deposition data
Summary
Sustainable forest management can be defined in many ways, sustainability of forest harvesting is dependent on the availability of growth-limiting nutrients (Ågren, 1985; Sverdrup & Rosen, 1998). A sustainable balance is achieved when demand is less than or equal to supply in the context of a complete harvest rotation; i.e., all nutrients lost through harvesting and depletion need to be replenished before the rotation comes into effect. In this regard, forest nutrient budgets can vary widely across landscapes based on differences in climate, atmospheric deposition, soil type, and vegetation type (Ranger & Turpault, 1999)
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