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Responsible forest management requires accounting for adverse environmental effects, such as increased nutrient export to water courses. We constructed a spatially-distributed nutrient balance model NutSpaFHy that extends the hydrological model SpaFHy by introducing a grid-based nutrient balance sub-model and a conceptual solute transport routine to approximate total nitrogen (N) and phosphorus (P) export to streams. NutSpaFHy uses openly-available Multi-Source National Forest Inventory data, soil maps, topographic databases, location of water bodies, and meteorological variables as input, and computes nutrient processes in monthly time-steps. NutSpaFHy contains two calibrated parameters both for N and P, which were optimized against measured N and P concentrations in runoff from twelve forested catchments distributed across Finland. NutSpaFHy was independently tested against six catchments. The model produced realistic nutrient exports. For one catchment, we simulated 25 scenarios, where clear-cuts were located differently with respect to distance to water body, location on mineral or peat soil, and on sites with different fertility. Results indicate that NutSpaFHy can be used to identify current and future nutrient export hot spots, allowing comparison of logging scenarios with variable harvesting area, location and harvest techniques, and to identify acceptable scenarios that preserve the wood supply whilst maintaining acceptable level of nutrient export.

We quantified the response of peatland water table level (WTL) and energy fluxes to harvesting of a drained peatland forest. Two alternative harvests (clear-cut and partial harvest) were carried out in a mixed-species ditch-drained peatland forest in southern Finland, where water and energy balance components were monitored for six pre-treatment and three post-treatment growing seasons. To explore the responses caused by harvestings, we applied a mechanistic multi-layer soil-plant-atmosphere transfer model. At the clear-cut site, the mean growing season WTL rose by 0.18 +/- 0.02 m (error estimate based on measurement uncertainty), while net radiation, and sensible and latent heat fluxes decreased after harvest. On the contrary, we observed only minor changes in energy fluxes and mean WTL (0.05 +/- 0.03 m increase) at the partial harvest site, although as much as 70% of the stand basal area was removed and leaf-area index was reduced to half. The small changes were mainly explained by increased water use of spruce undergrowth and field layer vegetation, as well as increased forest floor evaporation. The rapid establishment of field layer vegetation had a significant role in energy balance recovery at the clear-cut site. At partial harvest, chlorophyll fluorescence measurements and model-data comparison suggested the shade-adapted spruce undergrowth was suffering from light stress during the first post-harvest growing season. We conclude that in addition to stand basal area, species composition and stand structure need to be considered when controlling WTL in peatland forests with partial harvesting. Our results have important implications on the operational use of continuous cover forestry on drained peatlands. A continuously maintained tree cover with significant evapotranspiration capacity could enable optimizing WTL from both tree growth and environmental perspectives.

Environmental and economic performance of forestry on drained peatlands was reviewed to consider whether continuous cover forestry (CCF) could be a feasible alternative to even-aged management (EM). CCF was regarded feasible particularly because continuously maintaining a tree stand with significant transpiration and interception capacity would decrease the need for ditch network maintenance. Managing CCF forests in such a way that the ground water levels are lower than in clear-cut EM forests but higher than in mature EM forests could decrease greenhouse gas emissions and negative water quality impacts caused both by anoxic redox reactions and oxidation and mineralization of deep peat layers. Regeneration studies indicated potential for satisfactory natural regeneration under CCF on drained peatlands. An economic advantage in CCF over EM is that fewer investments are needed to establish the forest stand and sustain its growth. Thus, even if the growth of trees in CCF forests were lower than in EM forests, CCF could at least in some peatland sites turn out to be a more profitable forest management regime. An advantage of CCF from the viewpoint of socially optimal forest management is that it plausibly reduces the negative externalities of management compared to EM. We propose that future research in drained peatland forests should focus on assessing the economic and environmental feasibility of CCF.

Forest clearfelling is potentially a major environmental problem with respect to the degradation of water quality in receiving water courses due to phosphorus (P) release from soil and clearfelling residue stocks. Recent studies have highlighted the need to investigate the performance and benefits of potential mitigation methods such as whole tree harvesting (WTH) and grass seeding. In this study, fifteen plots (0.014 ha each) were constructed in a standing coniferous forest and P concentrations in plot runoff were monitored for one year prior to clearfelling. Following clearfelling three replicates of five forest harvesting management practices/treatments were applied to the plots: brash with grass seeding (Treatment 1), brash (Treatment 2), brash mat/ tree extraction route (Treatment 3), WTH (Treatment 4) and WTH with grass seeding (Treatment 5). These treatments were designed to comparatively assess the benefits of WTH and grass seeding practices on mitigating P released from forested peatlands following clearfelling and to determine the sources and sinks of P following clearfelling operations. Annual average total reactive phosphorus (TRP) concentrations in the plot runoff were −1 in all treatments before clearfelling, and increased to 79 μg L −1 , 160 μg L −1 , 335 μg L −1 , 50 μg L −1 and 38 μg L −1 in Treatments 1, 2, 3, 4 and 5, respectively, after clearfelling. These results highlight that WTH and grass seeding can be used efficiently as methods to improve water quality, aiding in the protection of the biota residing in the aquatic systems draining peatland catchments.

Economic development creates challenges for land-use planners in balancing between increasing the use of natural resources and safeguarding biodiversity and ecosystem services. We developed and utilized multi-objective numeric optimization models to analyze the trade-offs between biodiversity and ecosystem services (BES). The approach was used in the land-use planning process in northern Finland when selecting potential peat production sites as a part of the development of the regional master plan. We first quantified Net Present Value (NPV) of peat production, biodiversity, greenhouse gas (GHG) emissions, and water emissions of peatlands. Then we applied multi-objective optimization to examine the trade-offs between the variables as well as to determine a cost-efficient selection of potential peat production sites, that is, a selection which would simultaneously generate the greatest possible economic returns and environmental benefits. Our results showed that with a relatively small decrease in NPV, a substantial decrease in biodiversity loss and a reduction in water emissions compared to the benchmark level could be attained. However, a significant decrease in GHG emissions resulted in a substantial decrease in NPV. We conclude that it is possible to significantly improve land-use management by applying multi-objective optimization in land-use planning.

Ce mémoire a comme objectif de présenter une revue de la littérature et une analyse comparative des différents modèles existants pour le calcul de la capacité de support d’un plan d’eau aux apports en phosphore. Ce document a aussi pour but d’évaluer les différentes options pour l’utilisation de ce genre d’outil au Québec, ainsi que d’amorcer une réflexion sur les applications possibles de ce concept au niveau local, en lien avec l’aménagement du territoire des bassins versants. L’analyse comparative des modèles théoriques, combinée à la réflexion d’acteurs clés impliqués actuellement dans un processus qui consiste à tester leur utilisation dans les Laurentides au Québec, a permis de mettre en relief l’importance de calibrer les modèles régionalement. De plus, certains avantages semblent résider dans l’utilisation d’un modèle de nature empirique afin d’effectuer les prédictions sur les apports naturels et totaux en phosphore pour les lacs de cette région. Par contre, l’utilisation d’une approche de type « bilan de masse », s’avère tout de même indispensable afin de relativiser l’importance des différents apports anthropiques en phosphore du bassin versant. Dans l’avenir, l’utilisation de tels modèles permettra possiblement de justifier certaines mesures restrictives au développement des bassins versants, qui pourront s’insérer parmi les outils d’urbanisme actuels. Ce sont principalement les municipalités qui détiennent les pouvoirs nécessaires afin d’intégrer les prescriptions découlant de ce genre d’analyse à l’aménagement du territoire des bassins versants. Plusieurs outils d’urbanisme, tels que les plans d’aménagement d’ensemble (PAE) ou bien les règlements de zonage et de lotissement, semblent donner assez de latitude afin de permettre aux municipalités d’intervenir en ce sens. Toutefois, les modèles de capacité de support ne pourront pas être utilisés afin de calculer un nombre précis d’habitations qu’il est possible de construire dans le bassin versant d’un lac., This study presents a literature review of current carrying capacity models developed in Ontario and Quebec (Canada) for the estimation of phosphorus (P) loading in lakes. Another objective is to evaluate their applications to land and watershed management practices in Quebec. A comparison of theoretical and empirical models, combined with the observations of keys stakeholders, confirms the importance of calibrating models regionally. The analysis further reveals that empirical models estimate more accurately P concentrations in lakes. However, the use of traditional mass balance approaches is still a necessity for the estimation of different P sources in the watershed. These models can support decision makers and land managers in Quebec in the application of more restrictive measures in lakes where the carrying capacity is currently exceeded. In Quebec, the use of the models and their implementation in the legislation will be a municipal responsibility. Many urbanism tools already allow this kind of intervention (zoning, « outils à caractère discrétionnaire »). But, model use alone will not be sufficient to justify a total interdiction of land development in a watershed or to impose a strict limit to house and cottage development.