Effect of tree species and soil properties on nutrient immobilization in the forest floor

To investigate the effect of tree species and soil properties on organic matter accumulation and associated nutrients, an area-based sampling of the forest floor was carried out in a 28 years old species trial including Norway spruce, Douglas fir, beech, and common oak at two sites, a poor and sandy soil, and a fertile loamy soil.The accumulation of C, N and P in the forest floor was significantly higher at the sandy site than at the loamy site under all species. At the loamy site, oak was characterized by lesser accumulation of C, N and P than the other species. Remarkably, the C/N-ratios showed no substantial differences, whereas the C/P-ratios were significantly higher at the sandy site for all species. pH was significantly lower at the sandy site for all species, and among the species, pH was lower in the conifer forest floors than in the broadleave forest floors. The concentration of ammonium, nitrate and phosphate in the soil solution was much higher at the loamy site under all species showing a stronger microbial activity. It is therefore hypothesized that the differences in accumulation rates were, at least partly, caused by differences in the mineralization regimes. Strong root infiltration in the forest floors at the sandy site compared to almost none at the loamy site, is probably responsible for the differences in mineralization rate due to competition between the organic matter decomposers and the tree-roots/mycorrhiza for nutrients.     

Demonstrating the importance of intangible ecosystem services from peri-urban landscapes

Among ecosystem services, the various categories of intangible services linked to human perception, such as aesthetics, recreational values and cultural heritage, must be rated alongside tangible services linked to physical processes, such as wildlife habitats, clean water and air, and filter- and buffer effects. This is a pre-requisite for a sustainable development with a balance between ecological, social and economic values. We analyse ecosystem services in areas of the urban fringe of Copenhagen, where the services provided are mainly related to human perception. We employ relatively simple methods in selected landscapes to qualify or quantify the aesthetics and recreational value, and the scale of the welfare economic value of these ecosystem services. In the first case area, the Danish state acquired 50 villas covering more than 50 ha in order to recreate open vistas and gain access for the public to the seaside. In the second case area, peri-urban open landscapes were protected by conservation orders, to maintain and enhance the benefits of green space for the growing urban population. We assess the value – in a broad sense – of these ecosystem services using three practical methods: a landscape evaluation in terms of services and qualities, an assessment of actual recreational use, and finally an assessment of the costs – in terms of residential development values lost – of securing the provision of aesthetic qualities and recreational opportunities.Searching the original planning documents we uncovered the original motivation for the land evaluation and decision. The arguments behind the designation and protection of the areas were primarily aesthetic and potentials for recreational use. The two areas receive annually 2–2.5 million and 400.000 visits respectively, proving their strong recreational value. The value of the demolished houses in the first case area exceeds 115 million €, and the value of the lost development opportunities in the second case area exceeds 280 million €.By combination the three methods, we substantiated that the intangible services may dominate the tangible in cases like these, stressing the need for planners to assess the role and value hereof.