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We simulated Gross Primary Production (GPP) of Finnish forests using a landsurface model (LSM), JSBACH, and a semi-empirical stand-flux model PRELES, and compared their predictions with the MODIS GPP product. JSBACH used information about plant functional type fractions in 0.167° pixels. PRELES applied inventory-scaled information about forest structure at high resolution. There was little difference between the models in the results aggregated to national level. Temporal trends in annual GPPs were also parallel. Spatial differences could be partially related to differences in model input data on soils and leaf area. Differences were detected in the seasonal pattern of GPP but they contributed moderately to the annual totals. Both models predicted lower GPPs than MODIS, but MODIS still showed similar south--north distribution of GPP. Convergent results for the national total GPP between JSBACH and PRELES, and those derived for comparison from the forest ghg-inventory, implied that modelled GPP estimates can be realistically up-scaled to larger region in spite of the fact that model calibrations may not originate from the study region, or that a limited number of sites was used in the calibration of a model. [ABSTRACT FROM AUTHOR]

In boreal forests, some growing sites are more vulnerable to decreased soil moisture than others, which might result in stress symptoms in trees and thus affect their growth. We combined Finnish forest health data (ICP Level 1) with GIS data describing growing conditions, soil properties and soil water conditions to find out ways to identify the most vulnerable risk areas. The summer of 2006 was extremely dry, and the relative soil water index (SWI) in August relative to the 30-year average was only about 25%. This led to a higher percentage (24%) of sites (603 in total) where trees showed drought-damage symptoms. Our study shows that the risk of drought damages differs spatially depending on climatic conditions and soil properties. The most important variables to identify risk areas are the proportion of bare-rock areas, topographic wetness index (TWI), soil water indices (absolute and relative) and the spatial location on the north--south axis. [ABSTRACT FROM AUTHOR]

We analyzed forest landscape changes in a western Finnish breeding area of Siberian jays utilizing Landsat MSS and TM satellite images taken during a 29-year period (1976-2005). We found that Siberian jays appeared to favour closed spruce-dominated forest patches, possibly because they provide better visual protection against predators. Such spruce-dominated forest patches became smaller and increasingly fragmented during the study period. According to a 25-m pixel analysis, the total area of spruce-dominated habitats decreased from 14.7% to 11.0% and the mean patch size from 2.0 ha to 1.4 ha during 1987-2005. This was mainly due to intense loggings of spruce forests and a special form of land ownership, which has induced narrow forest estates measuring few dozens of metres in width. The parallel decline in potential breeding habitats as well as Siberian jay population size suggests that loss and fragmentation of key habitats, and possibly related changes in predator community, are the most probable causes for the decline of Siberian jay population in the study area. [ABSTRACT FROM AUTHOR]

The forest soil carbon sink is of potentially great monetary value under subsequent climate conventions, but the costs of reliable monitoring have never been analysed. Our study aimed at evaluating (1) costs and precision of varied sampling intensities at the plot level, (2) sample size, and (3) costs needed to detect a change in soil carbon at the national scale. Organic layer carbon measurements cost 520 euros per plot if 10 samples are analysed. At plot scale, the precision obtained with such sampling allows detection of a large change > 860 g C m-2. At the national scale, two measurement rounds on a minimum of 3000 plots are needed to detect an expected change of 11 g C m-2 yr-1 in the organic layer of upland forest soils with a 10-year sampling interval. Measuring such a network once costs approximately 4 million euros, which is about 8% of the value of the annual CO2 sequestration of 2.57 × 106 t CO2 of upland forest soils in Finland. [ABSTRACT FROM AUTHOR]

In the early phases of succession, the proportion of biomass comprising understorey vegetation may be considerable and, therefore, it plays a significant role in the annual nutrient and carbon cycling of forest ecosystems. The aim of our study was to identify the most significant forest-site attributes affecting the above-ground biomass of understorey vegetation and to develop models that can be used to predict this biomass in the boreal zone using readily available variables. The study was based on vegetation data consisted of percentage coverage observations collected from a network of permanent sample plots established by the National Forest Inventory in Finland. The coverage data were transformed to biomass with previously published models. According to our results, above-ground biomass can be predicted by such forest stand and site attributes as stand age and site nutrient level. In Scots pine, Norway spruce and broad-leaved forests growing on upland soil, the relative RMSE of predicted above-ground biomass of all understorey vegetation was 16.6%, 22.3% and 3 1.6%, respectively. In hardwood-spruce mires and paludified forests, the relative RMSE predicted above-ground biomass of all understorey vegetation was 12.2%. In pine mires it was 9.9%. The modelled relationship between biomass and forest site attributes can be used in ecosystem and carbon cycle modelling as a rapid non-destructive method to predict the above-ground biomass of understorey vegetation. [ABSTRACT FROM AUTHOR]