Direct and indirect climate forcing of ecological processes: integrated scenarios across freshwater and terrestrial ecosystems

Temperature and food affect growth and age at maturity in poikilothermic animals. We demonstrated how increased temperature and fat content in food reduced age at maturity in Atlantic salmon with effects on fish size. Food is like fuel for an engine and temperature is the accelerator. 2. Temperature during embryonic development affects how fast salmon will grow later in life. Increased temperature during early development allows faster growth, make the fish store more reserve energy (fat), and develop larger eggs and gonads. Thus, in a moderate climate change, salmon adapts quickly through interactions between genes and environment (adaptive plasticity). 3. Trout and char have different competitive advantages. Trout outcompete charr in warm, productive lakes, charr outperforms trout in lakes with low productivity and long, dark winters. We have experimentally demonstrated how this, and not thermal preference, is essential for the distribution of trout and charr in Norway. 4. There have been major changes in the population dynamics of small rodents in recent years. It is longer between the population peaks, and the peaks have been lower than in previous years. One possible explanation is that warmer winters with rain in mid-winter, freeze their food solid. Especially lemmings are sensitive to mild winter weather. Our hypothesis is that areas with frequent mild periods in winter have fewer lemmings, and that lemings do not reach as high densities and frequent population peaks as in areas with cold, stable winter conditions. 5. Four areas with different climatic conditions were used to study effects of temperature and rainfall on the growth of pine. There was correlation between increased growth in tree diameter and high July temperature. For growth in height, there was an association between August temperature in the previous year, with negative influence to the north and positive in the south in the study areas. 6. We removed snow cover from areas in and around streams that flowed through different vegetation in the transition zone between forest and tundra. At air temperature of -20°C, the temperature 10cm into the soil was about -15°C in streams where the snow was removed. With snow cover, the temperature was ca 0°C. Effect of reduced snow cover was reduced species diversity in the benthic fauna and occurrence of more opportunistic species. Diversity and presence of zoobenthos increased with increasing number of trees along the streams. The effect of reduced snow cover was stronger in tundra streams than in forest streams. Streams flowing through shrub vegetation was less affected by reduced snow cover, than streams flowing in open areas. 7. We studied relationships between organic carbon and biological productivity in Norwegian lakes. At low concentrations of organic carbon, a positive effect on fish production was observed. At high concentrations, the effect was negative. Shallow lakes better than deep lakes tolerated higher carbon supply before production became limited. The relationship between organic carbon supply and fish production also depends on the composition of the fish community. The negative effect of increased carbon supply on trout production is stronger the more fish species there is present. 8. Changed production in freshwater affects the migratory tendency of anadromous salmonids, especially trout and charr, which both are partly migratory. At high freshwater production, benefits of the sea migration decrease, and the benefits of being resident in fresh water increase. Higher temperatures and increased vegetation in a lake increase the probability of sea migration, whereas increased migratory distance and steeper river gradient decrease the probability of that anadromous fish will be present. Because of this, the number of sea charr populations in Northern Norway may be reduced in the future. 9. Global warming and climate change are among the environmental issues that have the greatest political attention. Among climatologists, there is agreement, but it is less agreement within the Norwegian population. Most Norwegians believe that the climate is changing, but many believe that this is not a human-induced phenomenon. Men more than women are skeptical, older are more skeptical than younger ones. People with higher education believe in anthropogenic climate change to a greater extent than those with lower education. Low confidence in the organizations working with environmental and climate issues are associated with an increased likelihood of being climate skeptic. Climate skepticism apears to be an anti-elite phenomenon. People with high cultural capital has both the highest and lowest probability of being climate skeptic. They were separated by whether or not they have confidence in the policy and management of environmental issues. Trust means less in groups with low cultural capital.

The climatic variables, temperature and precipitation, are in interaction with herbivory and land use, major drivers of terrestrial vegetation dynamic. Vegetation patterns are again, major drivers of run-off patterns and nutrient and carbon fluxes, which have pervasive effects on aquatic production and biodiversity. Both energy and matter are transported across ecosystem boundaries. Thus, ecosystems do not respond independently of each other to climate change. This project will analyze population and ecos ystem effects of climate change. We will construct local and national climate effect scenarios by integrating forecast of climate and land-use driven vegetation structure with run-off, aquatic production and biodiversity. In order to model large scale cli mate effects on terrestrial vegetation and to link this to freshwater ecosystems, field observations at various temporal and spatial scales needs to be combined with remote sensing data, existing digital maps, and run-off models. The project involves seve ral tightly integrated work packages involving various types of time-series and spatial analyses and GIS tools. This will be merged with hydrological models, and carbon/nutrient run-off models developed through NIVAs climate SIS program. Results from the project will be presented as scenarios, and we will also study how climate change scenarios are perceived and given meaning at the level of everyday experience, helpful when presenting climate change scenarios to managers, policy makers and the public.