Patterns and processes of initial terrestrial-ecosystem development.

Ecosystems are characterized as complex systems with abiotic and biotic processes interacting between the various components that have evolved over long-term periods. Most ecosystem studies so far have been carried out in mature systems. Only limited knowledge exists on the very initial phase of ecosystem development. Concepts on the development of ecosystems are often based on assumptions and extrapolations with respect to structure process interactions in the initial stage. To characterize the effect of this initial phase on structure and functioning of ecosystems in later stages, it is necessary to disentangle the close interaction of spatial and temporal patterns of ecosystem structural assemblages with processes of ecosystem development. The study of initial, less complex systems could help to better identify and characterize coupled patterns and processes. This paper gives an overview of concepts for the initial development of different ecosystem compartments and identifies open questions and research gaps. The artificial catchment site Chicken Creek is introduced as a new research approach to investigate these patterns and processes of initial ecosystem development under defined boundary conditions. This approach allows to integrate the relevant processes with related pattern and structure development over temporal and spatial scales and to derive thresholds and stages in state and functioning of ecosystems at the catchment leve

Ex ante impact assessment of land use changes in European regions - The SENSOR approach

Land use includes those human activities that exhibit a spatial dimension and that change the bio-geophysical conditions of land. Land use policy making at European level aims at fostering sustainability pathways of natural resource use and rural development through the decoupling of economic growth from environmental degradation while supporting social cohesion in rural areas. Targeted policy making requires tools for the ex ante assessment of impacts of policy driven land use changes on sustainable development opportunities in European regions. These tools have to cover all relevant land use sectors and impact issues including their interrelations. They have to be spatially explicit, allow scenario analysis of possible future developments, be based on reproducible analyses, and be transparent and easy to use. The European Commission funded Integrated Project SENSOR is dedicated to develop such ex-ante Sustainability Impact Assessment Tools (SIAT) for land use in European regions. SIAT is designed as a meta modelling toolkit, in which global economic trend and policy scenarios are translated into land use changes at 1km2 grid resolution for the area of Europe. Based on qualitative and quantitative indicator analyses, impacts of simulated land use changes on social, environmental and economic sustainability issues are assessed at regional (NUTS2/3) scale. Valuation of these impacts is based on the concept of multifunctionality of land use. It is conducted through expert and stakeholder valuations leading to the determination of sustainability choice spaces for European regions. This paper presents the analytical approach in SENSOR and describes the impact assessment framewor

Root distribution and nutrient status of mycorrhizal and non-mycorrhizal Pinus sylvestris L. seedlings growing in a sandy substrate with lignite fragments

The original publication can be found at www.springerlink.comReclaimed mine soils of the Lusatian mining district are characterised by small-scale heterogeneous distribution of lignite fragments of varying size embedded in a matrix of Tertiary and Quaternary sandy material. Despite amelioration with basic fly ashes, ongoing pyrite oxidation and the subsequent acidification generate a high physical and chemical heterogeneity within the substrate, which could negatively affect root proliferation. We hypothesised that this limitation for the root system may be compensated for by intensive exploration of the porous lignite fragments by roots and/or mycorrhizal hyphae to access water and nutrients stored in these fragments. To test this hypothesis, we compared growth, shoot nutrient content, and root distribution of mycorrhizal and non-mycorrhizal Pinus sylvestris L. seedlings in lignite-containing and lignite-free sandy substrate. Rhizotrons used for this experiment were filled with a sandy matrix with 6–9 evenly distributed spots of lignite fragments. Treatments included different levels of water and nutrient availability. After 8 months of growth, root tip vitality as well as growth and shoot nutrient concentration of the plants was higher for treatments with lignite spots in the sandy substrate than for sandy substrate without such amendments. Compared to the non-mycorrhizal plants, the seedlings inoculated with Paxillus involutus (Batsch) Fr. had a higher root dry mass, an increased number of root tips and a higher root length. These results confirm our hypothesis that the lignite fragments are an important nutrient and water reservoir for plants in these mine soils and they indicate that mycorrhizal colonisation may allow an intensive exploration of porous lignite fragments by mycorrhizal hyphae.K. Baumann, B.U. Schneider, P. Marschner and R.F. Hütt

Changes in the chemical composition of water percolating through the soil profile in a moderately polluted catchment

Throughfall (TF), stemflow (SF), soil solution below the organic layer (SSorg) and at 50 cm depth (SS50), and output with stream water (SW) were measured and analyzed for four years in a moderately polluted forest catchment in southern poland. The input of water with stemflow was ca. 6 A of input with TP. However, due to higher concentrations of most ions in SF, the input of most elements with SF was from 8% to 9%. Sulphate (SO42-), chloride (Cl-) and magnesium (Mg2+) were the only ions steadily increasing in concentrations in water percolating through the soil profile. Nitrogen reached the forest floor mainly as ammonium (NH4+). In the soil organic layer the NH4+ concentration decreased, while concentrations of nitrate (NO3-) and hydrogen (H+) increased, probably due to nitrification. For NO3-, sodium (Na+) and calcium (Ca2+), the highest concentrations were found in SSorg and SW. This indicates both efficient cycling in the biotic pool of the ecosystem and intensive weathering processes in the mineral soil below the plant rooting zone. The latter was especially pronounced for Mg and Ca. Concentrations of zinc (Zn), lead (Pb) and cadmium (Cd) were the highest in SSorg and SS50. As this was accompanied by a low pH and constant input of H+, NH4+ and heavy metal ions to the catchment area, it may pose a serious threat to forest health