Search

Through a change in climatic conditions and variability, for example, certain extreme weather events (heat waves, droughts, etc.) are likely to occur more frequently in different spatial and time scales in future. Since agriculture is one the man’ activities more dependant on weather behaviour, the impact on risks of agricultural production is indeed one of the most important issues in climate change assessments. Therefore an early recognition of risks and implementation of adaptation strategies is crucial as anticipatory; precautionary adaptation is more effective and less costly than forced, last minute, emergency adaptation or retrofitting. Results of climate change impact and adaptation studies often show considerable different results, depending on the spatial scale of regionalisation. However, for a decision maker, only a high spatial resolution of related study results is useful as it can represent local conditions and its spatial variability much better. This paper is based on the findings of the ADAGIO project (adagio-eu.org), which was focused on regional studies in order to uncover regional specific problems. In this context a bottom-up approach was used beside the top-down one of using scientific studies, involving regional experts and farmers in the evaluation of potential regional vulnerabilities and adaptation options. Results show, for example, that production risks, such as increasing drought and heat, are reported for most European regions. However, the vulnerabilities in the different regions are very much influenced by characteristics of the dominating agroecosystems and prevailing socio-economic conditions.

Many wetland ecosystems such as peatlands and wet tundra hold large amounts of organic carbon (C) in their soils, and are thus important in the terrestrial C cycle. We have synthesized data on the carbon dioxide (CO2) exchange obtained from eddy covariance measurements from 12 wetland sites, covering 1-7 years at each site, across Europe and North America, ranging from ombrotrophic and minerotrophic peatlands to wet tundra ecosystems, spanning temperate to arctic climate zones. The average summertime net ecosystem exchange of CO2 (NEE) was highly variable between sites. However, all sites with complete annual datasets, seven in total, acted as annual net sinks for atmospheric CO2. To evaluate the influence of gross primary production (GPP) and ecosystem respiration (R-eco) on NEE, we first removed the artificial correlation emanating from the method of partitioning NEE into GPP and R-eco. After this correction neither R-eco (P = 0.162) nor GPP (P = 0.110) correlated significantly with NEE on an annual basis. Spatial variation in annual and summertime R-eco was associated with growing season period, air temperature, growing degree days, normalized difference vegetation index and vapour pressure deficit. GPP showed weaker correlations with environmental variables as compared with R-eco, the exception being leaf area index (LAI), which correlated with both GPP and NEE, but not with R-eco. Length of growing season period was found to be the most important variable describing the spatial variation in summertime GPP and R-eco; global warming will thus cause these components to increase. Annual GPP and NEE correlated significantly with LAI and pH, thus, in order to predict wetland C exchange, differences in ecosystem structure such as leaf area and biomass as well as nutritional status must be taken into account.

This paper presents a method, which has been recently developed in the Department of Agrometeorology of the Poznan Agricultural University, for estimating heat balance components based on standard meteorological data, plant development stage, and land-use conditions. Estimates of latent heat flux components made it possible to obtain values of areal evapotranspiration and surface runoff. The method was applied in four catchment areas in Central Poland under present climatic conditions as well as under new, expected climatic conditions caused by an increase of ‘greenhouse gases’ in the atmosphere. Some changes in land use were also considered. The results show significant changes in the water balance when comparing present and future conditions of precipitation and evapotranspiration.

Ecosystem respiration (R eco ) is controlled by thermal and hydrologic regimes, but their relative importance in defining the CO2 emissions in peatlands seems to be site specific. The aim of the paper is to investigate the sensitivity of R eco to variations in temperature and water table depth (WTD) in a wet, geogenous temperate peatland with a wide variety of vegetation community groups. The CO2 fluxes were measured using chambers. Measurements were made at four microsites with different vegetation communities and peat moisture and temperature conditions every 3 to 4 weeks during the period 2008–2009, 2 years with contrasting WTD patterns. Models were used to examine the relative response of each microsite to variations in peat temperature and WTD and used to estimate annual total R eco . Temporal variations in R eco were strongly related to peat temperature at the 5 cm depth. However, two of the microsites did not show any significant change in this relationship while two others showed contrasting responses including an increase and decrease in temperature sensitivity with deeper WTD. Average R eco varied among the microsites and tended to be greatest for those with greatest leaf area which also positively correlated with deeper WTD, ash content and degree of peat decomposition at 20 cm. A combined temperature and WTD model explained up to 94 % of the temporal variation in daily average R eco and was used to show that on an annual basis, R eco was between 5 and 18 % greater in the warmer year with deeper WTD. Microsite-specific responses were related to differences in vegetation and peat characteristics among microsites. R eco may have remained insensitive to WTD variations at one microsite due to the dominance of autotrophic respiration from abundant sedge biomass. At a Sphagnum-dominated microsite, a lack of response may have been due to relatively small variations in WTD that did not greatly influence microbial respiration or due to offsets between decreasing and increasing respiration rates in near-surface and deeper peat. The microsite with the most recalcitrant peat had reduced R eco sensitivity to temperature under more aerobic conditions while another microsite showed the opposite response, perhaps due to less nutrient availability during the wet year. Ultimately, micro-site specific models with both soil temperature and WTD as explanatory variables described temporal variations in R eco and highlighted the significant spatial variations in respiration rates that may occur within a single wetland.