Vol. 113, No. 1-2 * Pages 1–156 * January - June 2009

During the past decades, many new software tools were developed to be used for agricultural research as well as for decision making. For example, crop and whole farm system modeling, pest and disease warning models/algorithms, models for irrigation scheduling or agroclimatic indices can help farmers significantly in decision making for crop management options and related farm technologies. The aim of Working Group 1 of COST 734 was a review and assessment of agroclimatic indices and simulation models relevant for various European agricultural activities. The key results, based on a survey by questionnaires among the COST 734 participating countries (see: www.cost734.eu) and a literature survey, are presented in this study. It includes an overview of most used agrometeorological or agroclimatic indices and process oriented crop models for operational as well as scientific applications, an analysis of the limitations for applications, and an overview of spatial applications in combination with GIS and remote sensing in Europe. The COST734 survey showed, for example, that research activities regarding the development of agroclimatic indices in Europe are focused on indices on drought, phenology, frost, and heat stress. Process oriented crop models are mainly applied for wheat and maize, which is related to their importance in European crop production. In many cases there are still limitations of crop model applications in Europe, which are often related to the availability of input data. Spatial crop model applications including a combination with remote sensing data are still rare. There are a number of different models and indices in use, varying by regions and countries. From the survey it can be concluded that there is a need of standardization and harmonization of applications of agroclimatic indices as well as crop models in Europe in order to allow inter-comparison of the results and to improve the interpretation of results.

Characterization of climatic hazards for agriculture can be done using global circulation models (GCMs) and/or regional circulation models (RegGCMs). The GCMs provide credible information of climate, at least for subcontinental scales, while the RegCMs are used to determine specific characteristics of the weather in mesoscale. Regardless of whether these models provide meteorological data through either long-term or short-term runs, the land surface models are strong links between the underlying surface and the atmosphere. Recently they have been remarkably improved in the segment of the parameterization of turbulent fluxes inside and above the tall grass canopies, making them more relevant, in assessing how regional climate may affect agriculture. Except these schemes many other environmental/agricultural models (UV radiation, plant diseases, crop, irrigation models, etc.), linked with the new generation of non-hydrostatic mesoscale models, can provide highly sophisticated information for farmers and agricultural planners. In this paper we shortly describe environmental models, mostly designed in the Centre for Meteorology and Environmental Predictions, University of Novi Sad (Serbia). All of them are linked with the NMM non-hydrostatic mesoscale model for the purpose of an intensive use in agricultural planning. The description and comments are supported by the corresponding numerical simulations.

The paper summarizes the indices used for identification of drought phenomenon in the agricultural meteorology practice. Many drought definitions and indices are known. Drought indices seem to be the simplest tools in drought analysis. The indices are classified into six groups, namely atmospheric, precipitation, water balance, soil moisture, recursive, and remote sensing indices. For each group typical expressions are given and analyzed for their performance and comparability. Taking into consideration that the drought is a compound concept, a few drought definitions are examined together with the drought indices. As any classification, the presented categories have got their limitation. The discussion on drought definition together with the survey of the indices tries to highlight the wide possible categorization of this very important phenomenon mainly from the meteorological point of view.

The growing degree-days (GDD) for different temperature thresholds above 5 °C at Croatian stations with long-term time series of meteorological data have been analyzed. The range of the mean annual GDD for the 5 °C threshold is from approximately 2000 °C in the highlands to 4200 °C in the mid-Adriatic. The results of the linear trend and the Mann-Kendall test indicate significant positive trends in annual GDD values at the 0.05 significance level for all thresholds in the northern and mid-Adriatic. A progressive test in the mid-Adriatic shows that the GDD for the 25°C threshold has become significant since the early eighties and in the northern Adriatic since the early nineties. Such increase has a negative effect on plant growth and development on the Adriatic coast and islands.

This article analyzes trends in the occurrence of dry and wet periods in altitudinal vegetation stages in the West Carpathian region of Slovakia for the period 1951–2007. The relative evapotranspiration, drought index, and radiation drought index were applied on meteorological data from eight meteorological stations representing the predominant vegetation stages in the investigated region. These indices were used to characterize humidity conditions. The radiation drought index ranges from 1.31 for the area heavily prone to drought (southern part), to 0.41 for the mountainous areas (northern part), where the sum of precipitation exceeds potential evapotranspiration. The relative evapotranspiration shows values as high as 97% in northern mountainous regions to the low value of 58% in the Danubian Lowland. A significant increase in the severity of drought was identified by means of the radiation drought index for the period 1951–2007 only in the Danubian Lowland (stage 1, oak vegetation). A significant trend in the case of humidity was determined in the mountains and in the northern part of East Slovakia.

Agriculture is a primary productivity sector which is highly dependent on environmental conditions. The agroclimatic potential of agricultural areas has to be assessed in order to achieve sustainable and efficient use of natural resources in combination with production maximization. Temperature and rainfall, in terms of quantity and spatiotemporal variability, are variables which determine the type of crops suitable to a given location. Rainfall variable can also be interpreted as availability of sufficient water required for production of given crops. These variables, in combination with soil type and geomorphology, also determine areas where high levels of production are appropriate, avoiding the threat of degrading the natural resources. In the current work, zones indicating water availability are combined with topographic features and soil types in order to identify areas for sustainable production. Firstly, aridity index (AI) and vegetation health index (VHI) are used in order to define zones adequate for sustainable farming according to water limitations. As crop growth is affected by water supply, these zones are named water limited growth environment (WLGE) zones. AI and VHI are computed on monthly time step for twenty hydrological years, from October 1981 to September 2001. VHI is derived from NOAA/AVHRR data, while in AI computations both satellite and conventional field data are used. Then, WLGE zones are combined with soil maps and a digital elevation model (DEM) of the area under investigation in order to define zones appropriate for sustainable production. The study area is the aquatic district of Thessaly, located in Central Greece. The current application has resulted in the definition of sustainable production zones by means of parallelepiped supervised classification using the two indices, soil maps and DEM. These zones can be further used for agroclimatic classification.

Global warming is causing wide changes in atmospheric events with critical impacts on vegetations. Indeed, an increase of temperature variability has been observed, primarily due to increase in warm extremes. Temperature rising will lead to several consequences. For example, growing season lengthening is observed, but at the same time, plants grow faster, thus giving productions low in quality and quantity. Finally, concerning the Mediterranean region, it is evaluated that a greater water request is needed for irrigation. Besides, high maximum temperatures during summer months may cause drop in quality. On the opposite, concerning winter risks, earlier bud break will increase late frost risks. The aim of this study is to cover some aspects of warming temperature and phenological responses on grapevine in central Italy. The research is focused on climatic and agroclimatic indices calculated in 1955–2007 period. Regression trend, linear or non-parametric, depending on the distribution of data, was fitted to provide pictures of changes that have occurred.

In regional studies the effect of elevated CO₂ level on crop biomass and yield had not been considered in most cases, although several approaches were described in literature. Different algorithms describing CO₂ response on crop growth and crop water use efficiency have been integrated in the soil-crop model HERMES. The approaches are different in complexity and parameter requirement. Their suitability to explain crop growth responses and soil water dynamics observed in a six-year agricultural crop rotation (winter barley, sugar beet, winter wheat) under elevated atmospheric CO₂ level in a FACE experiment was tested. All algorithms were able to describe an observed increase in above-ground dry matter for all crops in the rotation. Increasing water use efficiency with rising CO₂ was also reflected. A combination of a semi-empirical Michaelis-Menten approach describing a direct impact of CO₂ on photosynthesis and a Penman–Monteith approach with a simple stomata conduction model for evapotranspiration yielded the best simulation result expressed by model performance indicators. Scenario simulations with and without CO₂ effect were performed for different sites in Germany for the present situation and the SRES-A1B scenario using statistically downscaled climate change scenarios from the WETTREG model. Results show that without consideration of the CO₂ effect mostly negative impacts on crop yields were simulated. Considering the CO₂ effect compensated the negative trend in most cases and turned yield effects to a positive impact.

Sustainability conveys the idea of a balance between human needs and environmental concerns. A common theme amongst definitions of sustainability is that sustainable agricultural systems remain productive over time. They should provide for the needs of current, as well as future generations, while conserving natural resources. The enhancement of environmental quality and careful use of resource base on which agriculture depends is viewed as a requisite for sustained agricultural productivity. The notion that sustainable agricultural systems maintain output in spite of major disturbances, e.g., such as those caused by projected climate change, is relevant to vulnerable areas, especially in the semi-arid and sub-humid regions of developing countries.
According to the Fourth Assessment Report of the WMO/UNEP Intergovernmental Panel on Climate Change (IPCC) released in 2007, semi-arid regions of Asia, Africa, and Latin America are likely to warm during this century, and freshwater availability is projected to decrease. Agricultural productivity in tropical Asia is sensitive not only to temperature increases, but also to changes in the nature and characteristics of monsoon. In the semi-arid tropics of Africa, which are already having difficulty coping with environmental stress, climate change resulting in increased frequencies of drought poses the greatest risk to agriculture. In Latin America, agriculture and water resources are most affected through the impact of extreme temperatures and changes in rainfall.
Climate change mitigation strategies which include interventions to reduce the sources or enhance the sinks of greenhouse gases have a marked management component aiming at conservation of natural resources such as improved fertilizer use, improved ruminant digestion, use of water harvesting, and conservation techniques. These strategies are equally consistent with the concept of sustainability. Adaptation strategies include initiatives and measures to reduce the vulnerability of agroecosystems to projected climate change, such as changing varieties, altering the timing or location of cropping activities, improving the effectiveness of pest, disease and weed management practices, making better use of seasonal climate forecasts, etc. It is essential to develop and integrate agriculture mitigation and adaptation frameworks for climate change into sustainable development planning at the national and regional levels to cope with the projected impacts of climate change. 

It is generally agreed that agricultural activities contribute to greenhouse gas (GHG) build up in the atmosphere which influences climate change and climate variability. Worldwide agriculture is responsible for about 13 percent of the total anthropogenic emissions. The scientific community has placed considerable efforts on developing ways to mitigate this effect through improvements in agricultural management practices. Improved management practices such as precision farming, implementation of less intensive tillage, changes in crop rotation, improved feed quality for better digestibility, improved manure handling, better water management of rice paddies, and biofuel/bioheat production are commonly employed as a means to mitigate GHG emissions. Even with all these mitigation measures, climate change is likely to have a wide range of effects on agricultural systems and we must adapt to these changes to ensure that agricultural production is not only maintained but is increased to support a growing world population. In some areas shifts in crop zones are expected, whereby cool season crops may be replaced by warm season crops and new cropping zones may open up for production. Most adaptation scenarios are likely to influence GHG emissions. Production of bioenergy crops, particularly lignocellulosic crops can, in some cases, provide a means to both mitigate net CO₂ emissions and adapt to a changing climate and world energy needs. There are numerous potential mitigation strategies to reduce GHG emissions from agriculture, but their effectiveness depends on climate, soil, and economic conditions which vary across regions. Process-based models can potentially act as a useful tool for examining the influence that climate change may have on mitigation and adaptation efforts. However, there are gaps in knowledge regarding processes that govern GHG emissions and much uncertainty regarding future trends in climate. In this paper the DeNitrification-DeComposition (DNDC) model was used to investigate the influence that a changing climate might have on GHG emissions in agricultural systems. Results indicate that N₂O emissions will be highly variable across different landscapes, and that net CO₂ emissions will generally increase, particularly in cooler regions. In regions with an average annual temperature of less than 10°C, enhanced soil carbon decomposition due to increased temperatures is expected to cause a loss of approximately 70 kg CO₂ ha^–1 y^–1 by 2100.

Agriculture is one of the most important economic sectors of global society. Agricultural production continues to expand into forest lands and marginal crop areas in an attempt to keep pace with the ever-increasing world population. Environmental damage is increasing, including erosion, salinity, desertification, deforestation, threats to biodiversity, and water scarcity. Moreover, climate change/variability is having a profound influence on agroecosystems, posing serious threats to food security, human health, and protection of the environment. Thus, comprehensive agrometeorological adaptation policy guidelines, focusing on preparedness, mitigation, and adaptation measures to support sustainable agricultural development, are needed to cope with the impacts of climate change/variability. Adaptation policy can not be an effective “stand alone” strategy, but should be incorporated into a broader policy objective. For example, adaptation to climate change should be a part of a broader socio-economic policy such as agricultural, forest, water resources, natural resources, or coastal-zone management policy. Poorer countries that will require resources to improve capacity in order to cope with impacts, undertake specific adaptation measures.

The COUP–ENGNOR ley crop modeling system was calibrated on relevant yield data from field trials in southern Norway. This parameterized version was used to compare the potential ley production at Fokstua (62^oN; 970 m a.s.l.) for the period 1961–1990 with that of a Hadley A2 climatic scenario for the period 2071–2100. The impact of a climatic change, which projects a temperature increase by 2–3 °C, and a lengthening of the growing season by approximately 1.5 months, is an appreciable increase in production potential, especially as to fodder quality and feed unit yield. This is due to a new harvesting regime, which favors an early first cut and thus allows two seasonal cuts. The impact of the increased production potential of the mountainous districts of southern Norway towards the end of this century are considered, including the value of ley plant breeding towards optimal combination of  late seasonal growth with maximum winter hardiness.

Drought analysis of the Slovak territorry was based on evaluation of climatic conditions during the growing season limited by daily mean air temperature T  >10 °C. Precipitation total (R in mm), and potential (E₀ in mm) and actual (E in mm) evapotranspiration were calculated for this period. Consequently, climatic index of drought (E₀ – R) and evapotranspiration deficits (E₀ – E) were evaluated on the background of agricultural productive regions. Climatic data from the database of the Slovak Hydrometeorological Institute in Bratislava in period of years 1960 –1990 were used for evaluating the reference climate condition. Climatic stations used for GIS analyses were selected from the point of view of altitude, limiting plant production areas (up to 900 m a.s.l. – this altitude represents acreage 45,000 km²) and spatial distribution. Climate change conditions were generated by general circulation model CCCM for emission scenario SRES B2.
According to the results, agricultural regions of the Slovak Republic will become more sensitive in conditions of climate change on drought occurrence as compared with climate conditions of the last normal period 1961–1990. While 5 categories of drought conditions were recognized on the territory of the Slovak Republic in the reference period 1961–1990, additional two very dry categories can be recognized in agricultural regions of Slovakia according to climatic indices of both drought and evapotranspiration deficit. This fact has serious effects on potential acreage of some crops. High totals of potential evapotranspiration can evoke occurrence of drought more frequently. This fact should be taken into account in the future on the levels of both crop selections and water saving rotations.

The influences of global climate change on sensible and latent heat fluxes of maize were studied by using the simulation model of Goudriaan (1977). Eight scenarios were made, an increase of CO₂ content until doubling the recent content was included in the scenarios. Some of the scenarios were developed by downscaling the IPCC (2007) report (A2 and B2) to Hungary, and the others by taking into account more serious weather changes. Surprisingly, the distribution of intercepted radiation among sensible and latent heat fluxes in the individual scenarios was not significantly modified. A given increase in ambient air temperature caused a lesser rise in crop temperature at cob level, demonstrating the compensation role of the canopy. The moderate rise in crop temperature indicated that the plants did not suffer significantly from lack of water in any of the scenarios. However, there was a variation during the diurnal cycle. The doubled CO₂ concentration alone increased the net carbon assimilation rate of maize by 40%. Photosynthesis decreased only in cases with warmings higher than 6 °C. Decreased precipi­tation counteracted the positive influence of elevated CO₂ on carbon assimilation.
In other scenarios the latent heat flux increased in comparison to control run. This justifies the existence of reserve soil water at Keszthely, even in on extra hot day during July.