Fungi and wind strongly influence the temporal availability of logs in an old-growth spruce forest.

Coarse woody debris (CWD) is a key habitat for many species in forest ecosystems. To ensure the long-term survival of such species, forest management regimes must include measures that promote dead wood dynamics similar to those of natural forests. Thus, information on CWD dynamics under natural conditions is required, including data pertaining to the underlying agents of disturbance. This study examines modes of mortality, decay rates, and temporal patterns in the availability of Picea abies logs in a Swedish old-growth forest affected by internal, small-scale disturbance. All 684 logs in a 6.6-ha plot were mapped and classified into one of six decay classes. Logs in the early stages of decay were examined for the presence of heart-rot fungi. Six years later all logs were re-inventoried, including newly formed logs. Matrix models based on the transition rates between decay classes showed that it took about 60 years for 90% of the logs to decay beyond class 6 (a deformed trunk with soft wood). Large logs (> 26 cm) decayed 40% more slowly than small logs (< 25 cm). The initial volume of logs was 37.6 m3/ha but increased to 44.8 m3/ha after six years. In addition, there was a large shift in the decay-class distribution. The volume of logs in early and late decay classes increased by 71% and 45%, respectively, while the volume of logs in the intermediate decay classes decreased by 32%. The fluctuations appear to result from pulses in mortality, driven by a combination of strong winds and the heart-rot fungus, Phellinus chrysoloma, which was present in more than 30% of all logs at an early stage of decay. These results show that large temporal fluctuations in dead wood also occur in the absence of large-scale disturbance, and that heart-rot fungi are important factors driving the overall dynamics of dead wood. Since many wood-inhabiting species are naturally rare and have very specific substrate demands, such temporal variability in dead wood availability may have effects on biodiversity and should be taken into account when designing small, protected forest areas.     

Bioconcentration of the insecticide pyridaphenthion by the green algae Chlorella saccharophila

A study was undertaken to examine the uptake of the organophosphate insecticide pyridaphenthion in the chlorophyta Chlorella saccharophila. Algae cultures were exposed to the initial nominal concentration 10.0 mg l(-1) pyridaphention during seven days. The insecticide bioconcentrates in the biomass to the highest level of 441.5 +/- 25.9 mg kg(-1) on the fifth day of exposure and was followed by a decrease to 76.6 +/- 5.1 mg kg(-1) on the seventh day. A model was constructed to describe the dynamic process, which estimated a bioconcentration factor (BCF) equal to 28. The study demonstrates the potential of accumulation of pyridaphenthion in aquatic organisms and helps to expand the pyridaphenthion toxicity database. The replacement of fenitrothion by pyridaphenthion concerning their use in rice flooded cultures is discussed.     

Drivers of inter-year variability of plant production and decomposers across contrasting island ecosystems

Despite the likely importance of inter-year dynamics of plant production and consumer biota for driving community- and ecosystem-level processes, very few studies have explored how and why these dynamics vary across contrasting ecosystems. We utilized a well-characterized system of 30 lake islands in the boreal forest zone of northern Sweden across which soil fertility and productivity vary considerably, with larger islands being more fertile and productive than smaller ones. In this system we assessed the inter-year dynamics of several measures of plant production and the soil microbial community (primary consumers in the decomposer food web) for each of nine years, and soil microfaunal groups (secondary and tertiary consumers) for each of six of those years. We found that, for measures of plant production and each of the three consumer trophic levels, inter-year dynamics were strongly affected by island size. Further, many variables were strongly affected by island size (and thus bottom-up regulation by soil fertility and resources) in some years, but not in other years, most likely due to inter-year variation in climatic conditions. For each of the plant and microbial variables for which we had nine years of data, we also determined the inter-year coefficient of variation (CV), an inverse measure of stability. We found that CVs of some measures of plant productivity were greater on large islands, whereas those of other measures were greater on smaller islands; CVs of microbial variables were unresponsive to island size. We also found that the effects of island size on the temporal dynamics of some variables were related to inter-year variability of macroclimatic variables. As such, our results show that the inter-year dynamics of both plant productivity and decomposer biota across each of three trophic levels, as well as the inter-year stability of plant productivity, differ greatly across contrasting ecosystems, with potentially important but largely overlooked implications for community and ecosystem processes.     

Effects of grazer richness and composition on algal biomass in a closed and open marine system

Most natural local systems exchange organisms with a regional pool of species through migration and dispersal. Such metacommunity processes of interconnected multispecies assemblages are likely to affect local dynamics of both species and processes. We present results from an artificial marine outdoor rock pool system in which we investigated the factors of (1) local grazer richness and composition, and (2) connectivity of local patches to a regional species pool, and their effects on algal biomass. Local species richness of six grazers was manipulated in both open and closed pools, which were embedded in a regional species pool containing all six grazers. Grazer richness showed significant net biodiversity effects on grazing in the closed, but not in the open, system. Grazer composition, on the other hand, showed significant effects on grazing in both open and closed systems, depending on which species were initially present. The two most efficient grazers were able to compensate for less efficient grazers in species mixtures, hence ensuring the function of grazing. The efficiency of top-down control of algal biomass in open systems thus depends on which particular species are lost. Further, differences in grazing between the open and closed system changed over time due to temporal dynamics in grazer composition. The results emphasize the importance of including system connectivity in experimental designs to allow an extrapolation of biodiversity ecosystem-functioning relationships to natural systems.     

Public participation in water resources management: stakeholder voices on degree, scale, potential, and methods in future water management

The European Water Framework Directive puts strong emphasis on stakeholder and public participation in water management. Several practical questions regarding who should be involved, why, when, and how still remain unanswered. This paper investigates stakeholders' own experiences and views of increased public participation in water management. The article also explores the potential for increasing levels of participation by forming catchment committees with representation from stakeholder groups and through the use of various practical methods for participation. For both these aspects of participation, the views, expectations, and apprehensions of different stakeholder groups involved in nutrient loss management are investigated. Stakeholder opinions were collected by inviting representatives from five stakeholder groups within the R?nne? catchment in southern Sweden to a catchment dialog process.     

Results from the first year of the Swedish dioxin survey

PCDD/F levels are presented for food baskets, raw and fried herring, wolf muscle and moose tallow collected from the same area, three burbot liver samples, a sediment core from the Baltic Sea and leach water from three garbage dumps. Levels in food baskets were at or below detection limits making the estimation of intake via the diet difficult. Frying herring produces no net change in PCDD/F levels. Moose have lower PCDD/F levels than wolf from the same area. Levels in burbot liver samples are much higher near industrial discharges than in a more undisturbed area. The top 4 cm of the sediment core contain the highest levels of PCDD/F. Thereafter the levels drop and reach a low level. This low level is probably caused by contamination during sampling and is not evidence of PCDD/F presence far back in time. Leach water from city dumps contains low levels of PCDD/F but that from a dump that takes industrial wastes had higher levels and a different congener pattern.     

Modelling Dissolved Organic Carbon Turnover in Humic Lake Örträsket, Sweden

The organic carbon balance of a lake with high input of allochthonous organic carbon is modelled integrating physical, chemical and biological processes. The physical model captures the behaviour of real thermal stratification in the lake for different flow situations during the period 1993–1997. The dissolved organic carbon model is based on simulated trajectories of water parcels. By tracking parcels, account is kept of environmental factors such as temperature and radiation as well as DOC quality for each parcel. The DOC concentration shows seasonal variations primarily dependent on inflow. The organic matter degradation (bacterial- and photodegradation) in the lake amounts to 1.5–2.5 mg C l^–1 yr^–1, where photooxidation is responsible for approximately 10%. The estimated DIC production in the lake is large compared to sediment mineralisation and primary production. The main conclusion is that the model with the selected parameterisations of the degradation processes reasonably well describes the DOC dynamics in a forest lake.     

Vulnerability and adaptation to heat in cities: perspectives and perceptions of local adaptation decision-makers in Sweden

Climate change vulnerability is disproportionately distributed between different population segments in society. This study qualitatively explores how key stakeholders in municipalities (i.e. planning and operational staff in municipalities and the vulnerable themselves) construct social vulnerability in relation to climate change with a specific focus on thermal stress (i.e. heat waves) and which adaptive responses they identify at different levels. The empirical material consists of five focus groups with actors in a large Swedish municipality where the “Vulnerability Factor Card Game” was used as stimulus material to create 10 fictional individuals. The results show that there is a substantial amount of local knowledge about vulnerability drivers and inter-relations between social factors and vulnerability. Local decision-makers also defined a wide range of possible adaptation measures at different municipal levels. Our study clearly indicates that contextualised knowledge, which could complement the quantitative approaches in research, is abundant among municipal planners, staff employed at municipal operations such as health care, and among the vulnerable themselves. This knowledge remains untapped by research to a great extent and only seems to have an insignificant influence on policy-making. In particular, how impacts vary between different social and demographic groups and how adaptation strategies that target the most vulnerable could be defined are of great interest. The present study clearly indicates that social hierarchy may produce increased inequality in the specific context of climate change, vulnerability and adaptive responses at different levels.     

Science-practice interactions linked to climate adaptation in two contexts: municipal planning and forestry in Sweden

This paper examines the science-practice interface in the process of adapting to climate change in society. This paper analyses science-based stakeholder dialogues with climate scientists, municipal officers and private individual forest owners in Sweden, and examines how local experts both share scientific knowledge and experience and integrate it into their work strategies and practices. The results demonstrate how local experts jointly conceptualise climate adaptation, how scientific knowledge is domesticated among local experts in dialogue with scientific experts, the emergence of anchoring devices, and the boundary-spanning functions that are at work in the respective sectors.