Nitrogen (N) availability plays multiple roles in the boreal landscape, as a limiting nutrient to forest growth, determinant of terrestrial biodiversity, and agent of eutrophication in aquatic ecosystems. We review existing research on forest N dynamics in northern landscapes and address the effects of management and environmental change on internal cycling and export. Current research foci include resolving the nutritional importance of different N forms to trees and establishing how tree–mycorrhizal relationships influence N limitation. In addition, understanding how forest responses to external N inputs are mediated by above- and belowground ecosystem compartments remains an important challenge. Finally, forestry generates a mosaic of successional patches in managed forest landscapes, with differing levels of N input, biological demand, and hydrological loss. The balance among these processes influences the temporal patterns of stream water chemistry and the long-term viability of forest growth. Ultimately, managing forests to keep pace with increasing demands for biomass production, while minimizing environmental degradation, will require multi-scale and interdisciplinary perspectives on landscape N dynamics.

The effects of clear-cutting on stream-water chemistry in northern Sweden remain largely unexplored. Here we report data collected during a reference period and the first two years after logging in two typical partially harvested northern catchments; the objective was to compare water chemistry along the stream with and without a forest buffer. Two typical uncut reference catchments are included for comparison. Runoff was measured at the outlet of each catchment, and water samples were generally taken every second week and analyzed for 20 constituents. Logging resulted in increased runoff and increased concentrations of sodium, potassium, chloride, total nitrogen, total phosphorus, and suspended material from both catchments. Nitrate (NO3−) leaching increased only from the catchment without a forest buffer. It has not yet been possible to evaluate fully the effects of the forest buffer on the NO3− leaching because the uphill clear-cut area leached minimal amounts of NO3−.

This study focuses on avoiding negative effects on surface waters using new techniques for identifying wet areas near surface waters. This would aid planning and designing of forest buffer zones and off-road forestry traffic. The temporal variability in the geographical distribution of the stream network renders this type of planning difficult. A field study was performed in the 68 km² Krycklan Catchment to illustrate the variability of a boreal stream network. The perennial stream length was 140 km while the stream length during high-flow conditions was 630 km. Comparing the field-measured stream network to the network presented on current maps showed that 58% of the perennial and 76% of the fully expanded network was missing on current maps. Similarly, cartographic depth-to-water maps showed that associated wet soils constituted 5% of the productive forest land during baseflow and 25% during high flow. Using a new technique, maps can be generated that indicate full stream networks, as well as seasonally active streams and associated wet soils, thus, forestry planning can be performed more efficiently and impacts on surface waters can be reduced.

Additions of nutrients, faster growing tree varieties, more intense harvest practices, and a changing climate all have the potential to increase forest production in Sweden, thereby mitigating climate change through carbon sequestration and fossil fuel substitution. However, the effects of management strategies for increased biomass production on soil resources and water quality at landscape scales are inadequately understood. Key knowledge gaps also remain regarding the sustainability of shorter rotation periods and more intensive biomass harvests. This includes effects of fertilization on the long-term weathering and supply of base cations and the consequences of changing mineral availability for future forest production. Furthermore, because soils and surface waters are closely connected, management efforts in the terrestrial landscape will potentially have consequences for water quality and the ecology of streams, rivers, and lakes. Here, we review and discuss some of the most pertinent questions related to how increased forest biomass production in Sweden could affect soils and surface waters, and how contemporary forestry goals can be met while minimizing the loss of other ecosystem services. We suggest that the development of management plans to promote the sustainable use of soil resources and water quality, while maximizing biomass production, will require a holistic ecosystem approach that is placed within a broader landscape perspective.