Normalized difference vegetation index as a tool for the evaluation of agricultural drought

The paper deals with the evaluation of agricultural drought in Slovakia by remote sensing data. For this purpose, monthly normalized difference vegetation index (NDVI) values were derived from MODIS spectroradiometer at district level during the time period of 2000 to 2014. Verification was based on correlations with the Palmer drought severity index (PDSI) for twelve sites selected according to limited climatic parameters. Correlations showed a strong relationship (α ≤ 0.1) between NDVI and PDSI values, mainly in the middle of the growing season (June to September). The aim of the paper is testing NDVI as a suitable tool for drought assessment in an agricultural land in Slovakia

Identifying the relationships of climate and physiological responses of a beech forest using the Standardised recipitation Index: a case study for Slovakia

The paper presents relationship between the Standardised Precipitation Index (SPI) and physiological responses of individual trees in a beech stand using an example of an experimental plot in Bienska valley (Zvolen, Slovakia). SPI is a widely used tool for monitoring both short-term and long-term droughts, and for the assessments of drought impacts on agriculture. Due to the complex ecosystem bonds, monitoring of drought in forests often requires a sophisticated technological approach. The aim of the paper was to correlate the SPI on the physiological responses of trees that were recorded during the performed physiological research (sap flow, and stem circumference increment) at the site in the growing seasons (May to September) of the years 2012–2014. The results revealed a relationship between the index and the physiological responses, although the problem with the impact of other environmental factors has also come up. The secondary correlation, in which soil water potential that significantly affects physiological responses of forest tree species was used as a dependent variable, showed a tighter relationship with the SPI. We found the highest correlation between the soil water potential and the values of SPI aggregated for five weeks. This indicates that the beech forest has a five week resistance to drought stress. The results also enable simple monitoring of the initiation of the drought stress by applying SPI for five weeks

Current Wildland Fire Patterns and Challenges in Europe : A Synthesis of National Perspectives

Changes in climate, land use, and land management impact the occurrence and severity of wildland fires in many parts of the world. This is particularly evident in Europe, where ongoing changes in land use have strongly modified fire patterns over the last decades. Although satellite data by the European Forest Fire Information System provide large-scale wildland fire statistics across European countries, there is still a crucial need to collect and summarize in-depth local analysis and understanding of the wildland fire condition and associated challenges across Europe. This article aims to provide a general overview of the current wildland fire patterns and challenges as perceived by national representatives, supplemented by national fire statistics (2009-2018) across Europe. For each of the 31 countries included, we present a perspective authored by scientists or practitioners from each respective country, representing a wide range of disciplines and cultural backgrounds. The authors were selected from members of the COST Action "Fire and the Earth System: Science & Society" funded by the European Commission with the aim to share knowledge and improve communication about wildland fire. Where relevant, a brief overview of key studies, particular wildland fire challenges a country is facing, and an overview of notable recent fire events are also presented. Key perceived challenges included (1) the lack of consistent and detailed records for wildland fire events, within and across countries, (2) an increase in wildland fires that pose a risk to properties and human life due to high population densities and sprawl into forested regions, and (3) the view that, irrespective of changes in management, climate change is likely to increase the frequency and impact of wildland fires in the coming decades. Addressing challenge (1) will not only be valuable in advancing national and pan-European wildland fire management strategies, but also in evaluating perceptions (2) and (3) against more robust quantitative evidence.Peer reviewe

Drought in the Upper Hron Region (Slovakia) between the Years 1984–2014

Climate change causes an increase in the frequency and severity of weather extremes. One of the most relevant severe and damaging phenomena in Europe is drought. However, a difference in the spatial frequency of the occurrence and drought trends is evident between southern and northern Europe. Central Europe and particularly the West Carpathian region form a transitional zone, and drought patterns are complicated because of the geomorphologically complicated landscape. Since almost half of the Slovak state territory is represented by such natural landscape, it is necessary to investigate regional drought specifics. Therefore, we decided to analyze drought occurrence and trends using the SPI (Standardised Precipitation Index) and the SPEI (Standardised Precipitation Evapotranspiration Index) at available climatological stations of the Slovak Hydrometeorological Institute (SHMI) in the upper Hron region within the 1984–2014 period. We found that (1) drought incidence decreased with increasing altitude, (2) increasing air temperature increased the difference in drought trends between lowlands and mountains during the studied period, and (3) abrupt changes in time series of drought indices, that could indicate some signals of changing atmospheric circulation patterns, were not revealed. Finally, we constructed a simplified map of drought risk as an explanation resource for local decision-makers

Understanding the Complexity of Drought within the Soil Profile in Beech Ecosystems on Their Lower Altitudinal Limit in Slovakia

Due to the ongoing climate change, decreasing amounts of available water and increasing evapotranspiration during the growing season may impact the stability of some beech ecosystems at lower altitudes. This paper aims to evaluate the risk of drought from a meteorological point of view and the subsequent response in soil hydrology throughout hydrological years 2015 and 2016 in beech forests situated in Central Slovakia. Precipitation sufficiency was assessed by means of a climate irrigation index (CII). Hydrological modelling was carried out using GLOBAL, the simulation model of water movement in a soil profile with an emphasis on the root zone. The greatest drought risk occurs during the summer, when the ecosystem suffers from long periods of water deficiency according to the CII (>20 days). The water content in specific soil horizons responds differently to changing meteorological situations. Simulations indicated a later decrease (approx. 5 days) of the water content in the B horizon (main root zone) compared with the A horizon. Drought lasts longer in deeper layers and retreats only in the case of long-lasting rainfall. Sudden heavy rainfall has proven ineffective at moistening the entire soil profile and impacts only the upper few centimetres while the main root zone suffers from water shortage

Identifying the relationships of climate and physiological responses of a beech forest using the Standardised recipitation Index: a case study for Slovakia

The paper presents relationship between the Standardised Precipitation Index (SPI) and physiological responses of individual trees in a beech stand using an example of an experimental plot in Bienska valley (Zvolen, Slovakia). SPI is a widely used tool for monitoring both short-term and long-term droughts, and for the assessments of drought impacts on agriculture. Due to the complex ecosystem bonds, monitoring of drought in forests often requires a sophisticated technological approach. The aim of the paper was to correlate the SPI on the physiological responses of trees that were recorded during the performed physiological research (sap flow, and stem circumference increment) at the site in the growing seasons (May to September) of the years 2012–2014. The results revealed a relationship between the index and the physiological responses, although the problem with the impact of other environmental factors has also come up. The secondary correlation, in which soil water potential that significantly affects physiological responses of forest tree species was used as a dependent variable, showed a tighter relationship with the SPI. We found the highest correlation between the soil water potential and the values of SPI aggregated for five weeks. This indicates that the beech forest has a five week resistance to drought stress. The results also enable simple monitoring of the initiation of the drought stress by applying SPI for five weeks

Drought impact on ground beetle assemblages (Coleoptera, Carabidae) in Norway spruce forests with different management after windstorm damage – a case study from Tatra Mts. (Slovakia)

After the windstorm of November 2004, the ground beetle assemblages (Coleoptera, Carabidae) differentiated after the windstorm into four groups reflecting degree of damaging and forestry management (intact stand, fallen timber in situ, extracted timber, fire). The stand with fallen timber reduced abundances of original species. Removal of timber eliminated sensitive forest species and favored tolerant species, whereas the fire allowed invasions of field species. Later, the assemblages on burned sites converged to those in the unburned sites. Their restoration has a sigmoid-like course. Independently on the above differentiation and course assemblage succession, episodes of severe drought resulted with a 1-2-years delay in sudden decline of number of individuals and species. Their numbers were restoring after longer humid periods. Because these extremes occur with a considerable regularity, the observed extremes of fluctuations of number of species and individuals represent the variability limits of the Carabid assemblages in such conditions. The Standardized Precipitation Evapotranspiration Index was shown, using the cross-correlation of SPEI and number of individuals and species of Carabids, as a suitable means to explain and predict such changes for the period of 1-2 years

Autumn Phenological Response of European Beech to Summer Drought and Heat

The changes in precipitation and temperature regimes brought on by the current climate change have influenced ecosystems globally. The consequences of climate change on plant phenology have been widely investigated during the last few years. However, the underlying causes of the timing of autumn phenology have not been fully clarified yet. Here, we focused on the onset (10%) of leaf colouring—LCO—(Biologische Bundesanstalt, Bundessortenamt und Chemische Industrie (BBCH) 92) of European beech (Fagus sylvatica, L.) as an important native tree species growing throughout Europe. Studied beech stands are located along the natural distribution range of the European beech in Western Carpathians (Slovakia) at different altitudes from lowlands (300 m a.s.l.) to uplands (1050 m a.s.l.) and climatic regions from warm to cold. To define limiting climate conditions for LCO, we established several bioclimatic indices as indicators of meteorological drought: climatic water balance (CWB), standardized precipitation index (SPI), standardized precipitation-evapotranspiration index (SPEI), dry period index (DPI), and heat waves (HW). In addition, meteorological variables such as monthly mean temperatures and precipitation totals were taken into account. Throughout the 23-year period (1996–2018) of ground-based phenological observations of temperate beech forests, the timing of LCO was significantly delayed (p ≤ 0.05) in the middle to high altitudes, while in the lowest altitude, it remained unchanged. Over the last decade, 2009–2018, LCO in middle altitudes started at comparable to low altitudes and, at several years, even later. This resulted mainly from the significant negative effect of drought prior to this phenological phase (p ≤ 0.01) expressed through a 1-month SPI in September (SPIIX) at the stand at the low-altitude and warm-climatic region. Our results indicate that the meteorological drought conditioned by lower total precipitation and higher evapotranspirative demands in the warmer climate advance leaf senescence. However, at present time, growth in rising temperature and precipitation is acceptable for most beech stands at middle to high altitudes. Beech utilizes these conditions and postpones the LCO by 0.3–0.5 and 0.6–1.2 day per year at high and middle altitudes, respectively. Although we show the commencing negative effect of drought at mid-altitudes with lower (below 700 mm) total annual precipitation, the trend of LCO in favourable warm climates is still significantly delayed. The ongoing warming trend of summer months suggests further intensification of drought as has started to occur in middle altitudes, spreading from the continual increase of evapotranspiration over the next decades

The effect of climate change on spring frosts and flowering of Crataegus laevigata – The indicator of the validity of the weather lore about “The Ice Saints”

The onset and duration of phenological events are key indicators of the ecological impact of climate change on vegetation. During the flowering time in spring, late frosts are one of the most dangerous meteorological phenomena leading to damage to crops. During 1987–2016, we analyzed the occurrence and intensity of frosts during the period around the weather lore “Frost on the Ice Saints burns all the flowers” in short, “The Ice Saints” and their effects on the flowering phenology of hawthorn (Crataegus laevigata (Poir.) DC.). The late frosts were identified at 0.05 m and 2.0 m above ground from temperature measurement data at five phenological stations located from 160 m to 700 m a.s.l. in Slovakia. Results indicate that recent climate change caused the beginning of flowering (BBCH60) for Crataegus laevigata to start significantly earlier by 4.2, 5.0, 6.2 and 3.6 days per decade at 160, 300, 400 and 500 m a.s.l., respectively. Thus, the risk of late frost damage to flowers during “The Ice Saints” is getting highly probable, particularly at 160, 300 and 500 m a.s.l., where the flowering and frosts occur simultaneously. Decreased risk of frost damage during “The Ice Saints” was found at 400 and 700 m a.s.l. It was because of the rare frost occurrence at 400 m a.s.l. in the last decade (2007–2016) of the studied period, and due to the flowering onset dated mostly after “The Ice Saints” at 700 m a.s.l. in the same period

Drought Analyses of the Horn´e Poˇzitavie Region (Slovakia) in the Period 1966–2013

+is study focuses on the characterization of historical drought occurrences in the Horn´e Poˇzitavie region of Slovakia over the period 1966–2013 using Standardized Precipitation-Evapotranspiration Index (SPEI). Trend analyses were evaluated by the Mann–Kendall (MK) test as well as cumulative sum of rank difference (CRD) test. +e results showed that drought occurs in the region regularly (recurrent climate feature), while the trend analysis indicated the trend toward more arid climatic conditions. However, CRD trend analyses showed that the subtrend changed direction toward less drier conditions in the late 1980s and early 1990s. Analyses of SPEI trends in individual months showed a decreasing trend of drought occurrences during the cold months of the year (i.e., October to March), while an increasing trend was indicated from April to August. +e evaluation of the impact of drought on agricultural production based on the oilseed rape yield indicated that drought represents a significant natural risk for the agrarian sector of the region. In addition, August value of the SPEI for six months was evaluated as a good indicator of drought impacts on agriculture. +e trend analyses revealed no significant increase of drought impacts on agricultural production within the studied period