Dinamika ogljika v gozdnih tleh in rizosferi (Slovene)

Forests cover 4 billion hectares or 30% of the Earth's land surface and trees constitute about 80% of the world's biomass. Global climate change and other stresses and disturbances may weaken C uptake by forest ecosystems and reverse C fluxes from sinks to sources. The total below ground flux of carbon represents between 25 and 63% of gross primary production. A number of processes are neglected in the models, in particular the C input through hyphae of mycorrhizal symbionts and fine root turnover. These uncertainties are likely to severely limit our ability to make reliable predictions of how climate change will impact on ecosystem functioning. The structure of fine roots and associated mycorrhizas varies greatly in different species and sites and the relationships of structural variation to functioning is a new challenging research area. The ERM plays key ecological roles in ecosystem processes, including C flux through ERM, formation of soil organic matter (SOM) and effects on decomposition of SOM. National reporting manuals include the pool of C held in tree stumps and coarse roots but, to date, few countries have been able to report this or separate it from the dead-wood pool. Countries that are signatories to the UNFCCC and its supplementary Kyoto Protocol are obliged to report changes in carbon pools. Several models have been applied in different climate zones and forest types, yet all lack any specificity as well as the fine root and mycorrhizal mycelia turnover based C fluxes. There is an international need to improve knowledge and to develop high-quality tools for estimating biomass, carbon-equivalents and carbon fluxes belowground. Objectives: 1) To understand how mycelial systems develop under natural conditions, the extent to which season drives this, as well as their function in situ and at an elevated temperature and [CO2]. 2) To define the relationships of structural variation to functioning of fine roots and associated mycorrhizas, which vary greatly in different species and sites 3) To develop decomposition functions for quantifying the remaining dry weight of the biomass of litter, individual stumps and their associated coarse roots. 4) To provide an assessment of dead wood as a potential input for a general C dynamics model, and to develop an experimentally based soil module which could be applied for prediction of C dynamics in beech forest ecosystems. Our goal is to improve knowledge and to develop high-quality tools for estimating C-fluxes through different compartments in the soil and (myco)rhizosphere and contribute to more reliable C accounting at national and international level. Increased scientific knowledge to assess the belowground C pools and fluxes by measuring turnover rates for fine roots, mycorrhizal mycelia, and soil C stocks under elevated T and CO2 will be applied in development of relevant experimental models, as well as in supporting more specific general C stocks and C changes reporting systems at a global scale. The project coincides with technologies for sustainable economies, specially with energy and environmental protection technologies, use of new and renewable resources, maintenance and control of soils, forests, water and air, conservation of heritage, including the Renewable Energy Directive (2009/28/EC) and the proposal for the Slovenian Act on climate change. The project activities will be organized in five working groups with defined scientific background, goals, methods and expected results: Mycelial turnover; Fine root turnover; Decomposition of wood and litter; Compilation of a databases for forest C dynamics models; Dissemination and management. The interdisciplinary and internationally based research team will consist of scientists from two research institutes, two groups from University and an SME, with collaboration of groups from Germany, Belgium and USA. The project will be complemented by existing PhD student projec

Carbon dynamics in forests soils are largely based on mycorrhizosphere functioning and complexity. Mycorrhizal fungi constitute a considerable sink for carbon in most ecosystems. This carbon is used for building extensive mycelial networks in the soil as well as for metabolic activity related to nutrient uptake. There is great uncertainty about the rate of turnover of EMM. There is increasing evidence that residues of EM fungi play a major role in the formation of stable N and C in SOM. We have reviewed methods to quantify production, standing biomass and turnover of extramatrical mycorrhizal mycelia (EMM) in the field, and highlighted the need to extend the application of current methods to focus on a greater range of habitats and mycorrhizal types enabling incorporation of mycorrhizal fungal biomass and turnover into biogeochemical cycling models. However, although ectomycorrhizal fungi play an important role in forest ecosystem functioning, they are usually not included in forest growth or ecosystem models. Simulation is hampered by two main issues: a lack of understanding of the ecological functioning of the ectomycorrhizal fungi and a lack of adequate basic data for parameterization and validation. Concerning these issues, much progress has been made during the past few years, but this information has not found its way into the forest and soil models. We have contributed to a better understanding of the EMM growth and functioning under elevated temperatures, as well as to the influence of environmental factors on fine root turnover.

Inventory of emissions, identification and quantification of primary anthropogenic sources and sinks of greenhouse gases of individual countries is essential for tackling climate change. This inventory takes into consideration a) a comprehensive and detailed set of methodologies for assessing sources and sinks of anthropogenic greenhouse gases, and b) a common and consistent mechanism that allows Parties of the United Nations Framework Convention on Climate Change (UNFCCC) to compare relative contributions of various sources of emissions and greenhouse gases to climate change. For quantification, it is essential to know the turnover of functional components of forest ecosystems, such as decomposition of large woody debris, hives, fine roots and mycorrhizal fungi mycelium. These components were included into the development of a semi-mechanistic experimental model for the assessment of carbon dynamics in forest soils and mycorrhizosphere. Additionally, we have examined general models of carbon dynamics for specific conditions in Slovenia and finally proposed development of an evaluation system for carbon dynamics under the influence of changing weather conditions and patterns. These and additional project results on the importance of fine roots and mycelium turnover for assessment of carbon dynamics in forest soils, litter decomposition and large woody debris, assessment, testing and development of models to assess the importance of individual components of forest ecosystems, the impact of silviculture measures and climate change on the dynamics of carbon fluxes as well as contribution to the development of methods for reporting at different levels, represent a significant contribution to the implementation of system requirements and compliance of state obligations within forestry sector and other sectors associated with climate change.