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 (SPI_IX) 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.

Monitoring plant phenology is one of the means of detecting the response of vegetation to changing environmental conditions. One approach for the study of vegetation phenology from local to global scales is to apply satellite-based indices. We investigated the potential of phenological metrics from moderate resolution remotely sensed data to monitor the altitudinal variations in phenological phases of European beech (Fagus sylvatica L.). Phenological metrics were derived from the NDVI annual trajectories fitted with double sigmoid logistic function. Validation of the satellite-derived phenological metrics was necessary, thus the multiple-year ground observations of phenological phases from twelve beech stands along the altitudinal gradient were employed. In five stands, the validation process was supported with annual (in 2011) phenological observations of the undergrowth and understory vegetation, measurements of the leaf area index (LAI), and with laboratory spectral analyses of forest components reflecting the red and near-infrared radiation. Non-significant differences between the satellite-derived phenological metrics and the in situ observed phenological phases of the beginning of leaf onset (LO_10); end of leaf onset (LO_100); and 80% leaf coloring (LC_80) were detected. Next, the altitude dependent variations of the phenological metrics were investigated in all beech-dominated pixels over the area between latitudes 47°44′ N and 49°37′ N, and longitudes 16°50′ E and 22°34′ E (Slovakia, Central Europe). In all cases, this large-scale regression revealed non-linear relationships. Since spring phenological metrics showed strong dependence on altitude, only a weak relationship was detected between autumn phenological metric and altitude. The effect of altitude was evaluated through differences in local climatic conditions, especially temperature and precipitation. We used normal values from the last 30 years to evaluate the altitude-conditioned differences in the growing season length in 12 study stands. The approach presented in this paper contributes to a more explicit understanding of satellite data-based beech phenology along the altitudinal gradient, and will be useful for determining the optimal distribution range of European beech under changing climate conditions.

Astrotourism is considered to be a modern form of ecotourism. The main resource for astrotourism is a high-quality night sky, but this is very sensitive to natural as well as anthropogenic factors; for example, land utilization and expansion of urban areas often cause the negative effect of light pollution. The aim of the study is to perform a lighting survey by night sky brightness (NSB) measurements using the sky quality meter (SQM-L) at 20 study sites of the Slovenské stredohorie Upland region (Slovakia) and to assess the region’s potential for astrotourism development (PAD) using a multicriteria analysis. The NSB values ranged from 19.90 (city Žiar nad Hronom at Žiarska kotlina Basin) to 21.54 mag/arcsec² (recreation area Poľana at Poľana Mountains). At 14 out of 20 study sites, the NSB values even reached 21.2 mag/arcsec², as recommended by the International Dark-Sky Association for dark-sky parks. Four study sites were categorized as sites with medium PAD, and sixteen with low PAD. No study site reached a high or very high PAD. The best conditions for astrotourism development are fulfilled mainly by the Poľana Mountains geographical unit. The findings can be used for sustainable astrotourism development, land management, and planning to ensure socioeconomic development, together with nature and dark-sky conservation.

Phenological observations record the dynamics of vegetation in relation to meteorological conditions as well as the long-term trends in relation to climate change. We processed 20-year data of the flowering (BBCH scale 60), leaves unfolding (BBCH 11) and ripening of fruits (BBCH 86) of four woody species in south-west and central Slovakia. The phenological year begins with the flowering of the hazel. This phenophase has the largest amplitude of onset (52–65 days) as well as interannual variability (s_x = 20.2–33.4%) as it enters an unstable condition in early spring. At all stations, the order of phenophases is the same from the end of April. We found the highest vertical phenology gradient of the BBCH 60 Tilia cordata Mill. (6 days/100 m) and the smallest of BBCH 11 T. cordata (2.4 days/100). The statistically significant trends (p < 0.05) in shifting to the earlier period were in BBCH 60 Crataegus oxyacantha L. (0.4–0.5 days per year), BBCH 86 Corylus avellana L. (0.6 days per year), BBCH 60 Prunus spinosa L. (0.5–0,6 days per year) and BBCH 11 Prunus spinosa L. (0.6–0.7 days per year). These shifts indicate the change in the onset of the phenophases in south-west and central Slovakia.

In this study, the snow conditions of South-Central Slovakia (Inner Western Carpathians; temperate zone) were analyzed to assess the suitability for ski slope operations without snow production under 1000 m a.s.l. For the study site of the Košútka Ski Centre, meteorological conditions for snowmaking, snowpack characteristics, and snow water equivalent (SWE) compared with seasonal precipitation were identified. To identify the months suitable for snowmaking, the number of potential snowmaking days (PSD) and the required number of snowmaking days (RNSD) were calculated for six winter seasons from 2010–2011 to 2015–2016. The results showed that the conditions of natural snow cover were not appropriate for ski slope operation because of a low natural snow depth. For the Košútka Ski Centre, it was concluded that the essential base layer snowmaking for ski slope operation is possible only for a few days in the winter season because of the increasing mean value of the mean average daily temperature and the consequently higher occurrence of liquid precipitation in the winter season. Essential high snow production results in the heterogeneous distribution of snow on the ski slope, and in high snow depth, density, and SWE of the ski slope snowpack, and in prolonged melting.