127 Annales Universitatis Paedagogicae Cracoviensis Studia Naturae, 6: 127–145, 2021, ISSN 2543-8832 DOI: 10.24917/25438832.6.8 Anna Sołtys-Lelek1*, Zbigniew Caputa2 1Ojców National Park, Ojców 9, 32-045 Sułoszowa, Poland; *ana_soltys@wp.pl 2A. Ficka St. 4/1, 40-421 Katowice, Poland The influence of solar radiation on selected physiological processes of mosses in karst conditions of the spring niches of the Ojców National Park (Southern Poland) Solar radiation has various and multidirectional e�ects on the growth and development of plants. It a�ects, incl. on the anatomical and morphological structure of individual organism structures, photosynthetic apparatus, quantity and quality of plant pigments (Öpik, Rolfe, 2005; Pilarski et al., 2012; Możdżeń, 2019). Depending on the season and day, 15 to 30% of solar radiation reaches the forest layer. However, a signi�cant part of this solar radiation is scattered or re�ected at di�erent angles by plants from di�erent layers of the forest (Swanson, Flanagan, 2001). Mosses, as poikilohydric organisms, may remain metabolically inactive when the solar radiation intensity is high or the water level is too low. Due to their small size and tolerance to low light, mosses o�en colonise habitats that are characterised by low solar radiation intensity (Niinemets, Niinemets, 2009). �e photosynthesis process is highly sensitive to abiotic stress factors, including light (Rzepka, 2008; Możdżeń, 2019). �e intensity of photosynthetically active solar radiation is a factor that directly or indirectly in�uences the photochemistry of photosynthesis (Marschall, Proctor, 2004). �e �rst symptom of high intensity of solar radiation is the degradation of chlorophylls and the reduction of photosynthesis (Tallis, 1959; Rastorfer, 1970). Sensitivity to light is the result of phylo- and ontogenetic adaptation. For plants growing in extreme shaded conditions, light with an intensity of several thousand lux can inhibit photosynthesis, while in other plants this e�ect occurs only at intensities exceeding 100,000 lux. Plants adapt to light through structural adaptations and plant pigments. Bryophytes, unlike Tracheophytes, do not have a protective epidermis layer, under which there is a layer of palisade crumb, which additionally absorbs light before it reaches the pho- A nn a S oł ty s- Le le k, Z bi gn ie w C ap ut a 128 tosynthetic tissue of the spongy crumb. Duckett and Renzaglia (1988) and Nasrulh- aq-Boyce and Duckett (1991) described a large variation in the number of chloroplasts per cell between mosses exposed to direct and di�use radiation. Bryophytes need to “invest” more in protection at the cellular level to mitigate the harmful e�ects of high levels of light (Robinson, Waterman, 2014). Mosses are found in many habitats around the world, but knowledge of their respons- es to various environmental factors is still largely unexplored. �e aim of this study was to investigate the in�uence of solar radiation reaching the karst spring niches, on selected physiological parameters of the spring mosses: Cratoneuron �licinum (Hedw.) Spruce (obligatory krenophyte) and Brachythecium rivulare Schimp. (facultative krenophyte). �e impact of habitat conditions on their photosynthetic activity was investigated by: (1) imaging the parameters of chlorophyll a  �uorescence, (2) determining biomass and water content in gametophores and (3) analysing the degree of destabilisation of cell membranes. Material and methods Study area In the Ojców National Park (ONP) (southern Poland – 50°12′24″N 19°49′45″E ) the geological substrate consists of limestones and Upper Jurassic marls, with a thickness of over 250 m. �e network of vertical and horizontal fractures in them enables easy migration of water (Aleksandrowicz, Wilk, 1962). �e Prądnik and Sąspowska Valleys have the character of a deep ravine with asymmetrical slopes. �e eastern slopes are steeper and the rock formations on them are more numerous. Only two permanent watercourses �ow along the Valley bottoms – Prądnik and Sąspówka. All side valleys, connecting with the Prądnik and Sąspówka Valleys, are dry, without any permanent watercourses. �ere are numerous springs in this area – karst spring (Gradziński et al., 2008). Most of the springs are located in the Sąspówka and Prądnik alluvia, and the water �ows directly from the rock-mantle Jurassic limestones (Różkowski, Pawlik, 2001). �e morphological diversity of the Park’s terrain in�uences di�erent solar and microclimatic conditions (Caputa, 2009; Caputa, Wojkowski, 2015; Wojkowski, Capu- ta, 2015). �e region is characterised by a warm plateau region, a region of thermally diverse slopes and a region of cold valley bottoms (Brzeźniak, 1974; Kliein, 1972). �e study area located at the valley �oors is characterised by frequent thermal inversions, fogs and cold air (Brzeźnik, Partyka, 2008). �e �ve karst spring niches (4 in the Prądnik Valley, 1 in the Sąspowska Valley) were selected for the plant material collection, in which two of the moss species tested occurred simultaneously (Fig. 1–2). The influence of solar radiation on selected physiological processes of m osses in karst conditions of the spring niches of the O jców N ational P ark (S outhern P oland) 129 Spring of “Orczyk” in Sułoszowa A �ssure spring, located on the right side of the Prądnik stream, 390 m a.s.l. Exposition NE. It is made up of two rivers �owing from under a limestone slope. One of them has a concrete housing that distorts its natural character. It is a high capacity spring of 14.5 L/s (main �ow), 5.6 L/s (secondary �ow). Its waters are bicarbonate-calcium, sweet, slightly alkaline, hard (Pawlik, 1998). �e spring is surrounded by a forest, a meadow and a roadside. Fig. 1. Distribution of study stands: A  – rivers, B – Prądnik river, C – study stands, D – second-order catchment, E – park ONP border, F – boundary of the park’s bu�er zone; 1–4 spring niches in Prądnik Valley: 1 – spring of “Orczyk” in Sułoszowa, 2 – spring of a car park in Pieskowa Skała, 3 – spring near the chapel “Na Wodzie” in Ojców, 4 – spring opposite the Wapiennik Rock in Ojców, 5 – spring in the Sąspowska Valley A nn a S oł ty s- Le le k, Z bi gn ie w C ap ut a 130 Spring of a car park in Pieskowa Skała A �ssure-karst spring, near the riverbed, located on the le� side of the Prądnik stream, 390 m a.s.l., with an SSW exposure. It is made up of three out�ows. �e largest of them, being a spring niche, has a concrete lining; the other two �ow naturally, almost in the very channel of the stream. �is spring has a  low capacity of 0.5 L/s. Its waters are bicarbonate-calcium, sweet, slightly alkaline, medium hard (Dynowska, 1983; Pawlik, 1998). �e spring is surrounded by a forest and a parking lot. Spring near the chapel “Na Wodzie” in Ojców A �ssure-karst spring, terraced, by the riverbed, located on the right side of the Prąd- nik stream, 325 m a.s.l., with ENE exposure. It is enclosed in an unworked limestone casing. �e spring niche is an arti�cially directed out�ow of water, which �ows into Prądnik along a  natural slope of limestone rubble. �is spring has a  low capacity of 1.2–0.5 L/s. Its waters are bicarbonate-calcium, sweet, slightly alkaline, medium hard (Aleksandrowicz, Wilk, 1962; Sadowski, Różkowski, 1989; Pawlik, 1998). �e spring is surrounded by meadows and a small tourist infrastructure. Fig. 2. Selected study stands: A – spring the Sąspowska Valley, B – spring of “Orczyk”, C – spring opposite the Wapiennik Rock, D – spring near the chapel “Na Wodzie” (Photo. A. Sołtys-Lelek) The influence of solar radiation on selected physiological processes of m osses in karst conditions of the spring niches of the O jców N ational P ark (S outhern P oland) 131 Spring opposite the Wapiennik Rock in Ojców Fissure-karst spring, near-channel, located on the right side of the Prądnik stream, 310 m a.s.l., with ENE exposure. It is enclosed in a concrete housing, and part of its water supplies the farm. Part of the spring also �ows down to Prądnik in a small stream. �is spring has a low capacity of 1.4 L/s. Its waters are bicarbonate-calcium, sweet, slightly alkaline, medium hard (Aleksandrowicz, Wilk, 1962; Pawlik, 1998). �e spring is sur- rounded by meadows. Spring in the Sąspowska Valley A �ssure-karst spring, near-channel, located on the right side of the Sąspówka stream, 350 m a.s.l., with NE exposure. �ey are two out�ows of a natural character that merge and �ow into the Sąspówka stream. �is spring has a low capacity of 3.9 L/s. Its waters are bicarbonate-calcium, sweet, slightly alkaline, medium hard (Pawlik, 1998). �e spring is surrounded by a forest. �is spring is the only one of the surveyed, characterised by a completely natural spring niche, devoid of anthropogenic factors. Measurements of solar radiation and temperature Global solar radiation (Kc) and re�ected solar radiation were measured with the SP Lite pyranometer (Weiz, Austria). NR Lite Kipp & Zonen radiometer was used to measure net all-wave radiation (NR) for individual springs. Based on the quotient of re�ected to total radiation (Kodb/Kcal), the re�ectance coe�cient – Albedo was determined, which indirectly determines the ability of the surface to re�ect radiation. Air temperature (2 m above the surface) – Tp, water – Tw, on the spring surface – Tpo and inside moss turf – Tw was measured by thermometer LB401 with a Pt100 sensor with an accuracy of 0.1°C (Lab-El, Krakow, Poland). Solar radiation and temperature measurements were made on a sunny day from 11:00 to 16:00. Plant material – short botanical characteristic Brachythecium rivulare Schimp. in Bruch, Schimp. & W. Gümbel – (Canal moss) is green or yellow-green plagiotropic moss. It occurs all over Poland, in the mountains up to 1,800 m a.s.l. �e upward stems are usually pinnate, 3 to 6 cm long. �e leaves are ovoid-triangular, suddent at the top, sharpened brie�y, narrowed at the base, concave, irregularly longitudinally folded, and �nely, sharply serrated on the edge. �e leaf rib is single, tapering towards the top. �e leaf cells are elongated, prozenchymatic, with a small amount of chloroplasts, with thickened cell walls, orange in colour (Jusik, 2012). Cratoneuron �licinum (Hedw.) Spruce – (Triangle moss) it is a plagiotropic moss that forms a pale green turf. �is species is common throughout Poland. It occurs mainly in the Carpathians, Sudetes, Lakeland belt, Jura Krakowsko-Częstochowska and Roztocze. Its gametophores are creeping at the bottom, singly branched at the top, reaching 2 to 5 A nn a S oł ty s- Le le k, Z bi gn ie w C ap ut a 132 cm in length. �e leaves are wide, heart-triangular and ovate-lanceolate. �e rib is single, massive, biconvex, made of undi�erentiated cells. �e leaf cells are short-rectangular or 6-sided, and a few elongated, thick-walled, more elongated at the tip (Jusik, 2012). Chlorophyll a �uorescence Chlorophyll a �uorescence measurements were performed on 5 di�erent gametophores of mosses. During the study, the gametophores of mosses were put on �lter paper wet of distilled water and adopted for darkness for 20 min in a closed chamber FluorCam FC 800C (Photon Systems Instruments, Czech Republic) according to the method used by Możdżeń (2019). Among the results obtained, the following parameters were analysed: the zero �uorescence (F0), the maximum �uorescence (Fm), the maximum e�ciency of the photochemical PSII (Fv/Fm), the non-photochemical quenching (NPQ) and the vitality of PSII (Rfd). Fresh and dry mass, water content Fresh and dry masses (FM and DM, respectively) were determined on a  laboratory balance (Ohaus Adventurer Pro, USA) with an accuracy of 0.0001 g. Single moss gametophytes were dried for 48 h at 105°C temperature (dryer – Wamed SUP-100, Poland). On the basis of the masses obtained, the ratio of dry mass to fresh mass and the percentage of water content were determined according to the following formula (1): WC [%] = 100 – [(DM × 100) / FM] (1) where: WC – water content, DM – dry mass, FM – fresh mass Electrolyte leakage Separately gametophytes of two mosses were placed in vials containing 10 mL of deion- ised water with a  speci�c conductivity of 0.05 µS. Plant material was incubated on a shaker (Labnet, Rocker, USA) for 3 h at 25°C to determine the electrolytes leakage (E1). �en vials with mosses were frozen for 24 h at −80°C (Platilab 500Next, Ange- lantoni Industrie, Italy). Next day, samples were thawed and subjected to the shaking procedure described above. A�er this time, the �ow of electrolytes (E2) were measured. �e percentage of electrolyte leakage (EL) was calculated according to the formula: EL = (E1 / E2) 100%. �e electrolyte leakage measurements were made using a CX- 701 conductometer (Elmetron, Poland) with an electrode with a  constant K = 1.02 (Elmetron, Poland). Data analysis �e mean results from 5 replicates were analysed in Microso� Excel and StatSo�, Inc. The influence of solar radiation on selected physiological processes of m osses in karst conditions of the spring niches of the O jców N ational P ark (S outhern P oland) 133 2018. STATISTICA (data analysis so�ware system), version 13.1. �e signi�cance of di�erences between means (± SD) were analysed by Duncan’s test at p ≤ 0.05. Results �e in�ow of solar radiation and temperature Total shortwave (Kc) and re�ected (Ko) radiation were the highest on stand 3, and the lowest on stands 1 and 5 (Tab. 1). Albedo achieved the highest values on stand 2, and the lowest on stands 3, 4, 5. Air temperature (Tp) was the highest on stand 4, and the lowest on stand 1. Tab. 1. Characteristics of environmental factors on the researched springs in Ojców National Park (Wojkowski, Caputa, 2009) No. of spring Radiation coe�cients Spring temperature [°C] Annual sum of total radiation �e annual amount of potential insolation Measurement data [mV] Radiation [W × m–2] Kc Ko NR Kc Ko NR Albedo Tp Tpo Tm Tw [MJ × m–2] [h] 1 65 9 56 77 155 36 0.15 14.35 11.65 8.15 8.65 3484 3235 2 103 12 91 102 122 51 0.19 15.85 16.85 16.1 8.35 2871 2570 3 603 80 523 68 150 354 0.13 17.2 22.93 13.7 8.75 3566 3156 4 392 50 342 86 117 292 0.13 18.1 15.7 10.4 9.30 3302 2746 5 71 9 62 82 126 46 0.13 17.5 16.0 11.4 8.50 3200 < 2700 1 – spring of “Orczyk” in Sułoszowa, 2 – spring of a car park in Pieskowa Skała, 3 – spring near the chapel “Na Wodzie” in Ojców, 4 – spring opposite the Wapiennik Rock in Ojców, 5 – spring in the Sąspowska Valley; Kc – total short-wave radiation, Ko – re�ected short-wave radiation, NR – balance of short- and long-wave radiation, Albedo – determines the ability of a surface to re�ect short-wave radiation: albedo = Kodb/Kcal, Tp – air temperature, Tpo – surface temperature above the spring, Tm – temperature in the moss, Tw – water temperature �e surface temperature above the spring was the highest at stand 3, and the lowest at stand 1. �e temperature in the moss turf (Tm) was the highest on stand 2, and the lowest on stand 1. �e water temperature (Tw) was the highest at stand 4, and the lowest at stand 2. �e annual sum of total radiation reached the highest values at stand 3, and the lowest at stand 2. �e annual sum of potential insolation showed the highest values at stand 1, and the lowest at stand 2. Chlorophyll a �uorescence �e zero �uorescence (F0) Brachythecium rivulare was the highest in plants growing on stand 3 (the most yellow and red colour), compared to the gametophores from stands 1 and 5 (Fig. 3). Intermediate values of F0 were reached by mosses from stands 2 and A nn a S oł ty s- Le le k, Z bi gn ie w C ap ut a 134 4. �e maximum �uorescence (Fm) was similar between specimens of B. rivulare from stands 2 and 3 (the most yellow and red). Slightly lower values of this parameter were found for mosses collected from stands 1 and 4. �e lowest values of Fm were found for plants from stand 5 (green colour is dominant). �e maximum e�ciency of the photochemical PSII (Fv/Fm) was clearly the highest for the gametophores collected from stands 2 and 4 (intense red colour dominated). Intermediate values of this parameter were observed in plants from the remaining 3 stands (1, 3 and 5 – half yellow and red, respectively). �e non-photochemical quenching (NPQ) reached the highest values in B. rivulare taken from stand 5 (yellow and red predominance). �e lowest NPQ values were observed for gametophores from stand 3 (green and yellow colours dominate). Intermediate values of this parameter were found for plants from stands 1, 2 and 4 (mostly yellow and green, a small proportion of red). �e vitality of PSII (Rfd) reached the lowest values in B. rivulare from stand 1 (green was the dominant colour). �e Rfd values were similar in plants from the remaining 4 stands (Fig. 3). �e zero �uorescence (F0) Cratoneuron �licinum was similar in the 5 tested stands (red and green colours). Maximum �uorescence values were similar in plants collected from stands 1, 3 and 5. Clearly lower values were observed for plants from stands 2 and 4 (a small proportion Fig. 3. Imaging of �uorescence parameters of Brachythecium rivulare Schimp. from the �ve karst spring niches (1–4 in the Prądnik Valley, 5 in the Sąspowska Valley); F0 – the zero �uorescence, Fm – the maximum �uorescence, Fv/Fm – the maximum e�ciency of the photochemical PSII, NPQ – the non-photochemical quenching, Rfd – the vitality of PSII The influence of solar radiation on selected physiological processes of m osses in karst conditions of the spring niches of the O jców N ational P ark (S outhern P oland) 135 Fig. 4. Imaging of �uorescence parameters of Cratoneuron �licinum (Hedw.) Spruce from the �ve karst spring niches (1–4 in the Prądnik Valley, 5 in the Sąspowska Valley); F0 – the zero �uorescence, Fm – the maximum �uorescence, Fv/Fm – the maximum e�ciency of the photochemical PSII, NPQ – the non-pho- tochemical quenching, Rfd – the vitality of PSII of red, the dominant colour is green). �e maximum e�ciency of the photochemical PSII for gametophores from stands 2, 3 and 4 were similar (red and yellow colours were dominant). �e lowest Fv/Fm values were recorded for mosses from the stand 5 (a large share of red colour; however, a green colour also appeared). �e non-photochemical quenching values were similar in plants from standns 1, 2 and 5. C. �licinum gametophores from stands 3 and 4 achieved similar NPQ values (small proportion of red colour; green was the dominant colour). �e vitality of PSII (Rfd) was similar in plants harvested from all 5 stands (Fig. 4). Fresh and dry mass, water content �e fresh mass of Brachythecium rivulare gametophytes was signi�cantly the highest in plants growing on stand 5, compared to the other 4 stands. Intermediate values were observed for plants from stand 4, in relation to the other results. �e smallest increase in fresh mass was recorded in mosses collected from stands 1, 2 and 3. In the case of Cratoneuron �licinum gametophytes, fresh mass was the largest for plants harvested from stands 3 and 5. On stand 4, the fresh mass was smaller than the mass of gameto- phytes from stands 3 and 5, but larger than that of plants growing on stands 1 and 2. A nn a S oł ty s- Le le k, Z bi gn ie w C ap ut a 136 Mosses from stands 1 and 2 showed the lowest values of this parameter in relation to the remaining stands (Fig. 5A). �e dry mass of B. rivulare gametophytes was similar and was the largest in plants from stands 1, 2 and 5. On the other two stands (3 and 4), the dry mass values were signi�cantly lower. For C. �licinum, the signi�cantly largest dry mass increase was ob- tained for plants collected from stands 3, 4 and 5, compared to other stands (Fig. 5B). �e percentage of water content in B. rivulare cells was signi�cantly the highest in plants from stand 4, compared to the other stands. �e lowest values of this parameter were found for mosses from stand 2. For C. �licinum, the highest water content was found in plants from stand 5. Intermediate values are shown in stand 3. �e lowest water concentration in the tissues of this moss was observed in plants growing on stand 2 (Fig. 5C). �e ratio of dry mass to fresh mass in B. rivulare was the highest for plants collected from stands 1 and 2, compared to the other 3 stands. Intermediate values of this coef- �cient were shown for mosses from stands 3 and 5. �e smallest ratio was calculated for the gametophytes from stand 4. For C. �licinum, the value of this parameter was clearly the highest in the plants from stand 4, compared to the other stands (Fig. 5D). �e percentage of electrolyte leakage from B. rivulare gametophores was the highest in plants from stand 2. Intermediate values were observed for the gametophores from Fig. 5. Fresh and dry mass, and water content in gametophytes of Brachythecium rivulare Schimp. – A and Cratoneuron �licinum (Hedw.) Spruce – B. �e �ve karst spring niches (1–4 in the Prądnik Valley, 5 in the Sąspowska Valley); mean values (n = 5, ± SD) marked with di�erent letters di�er signi�cantly according to Duncan’s test at p ≤ 0.05 The influence of solar radiation on selected physiological processes of m osses in karst conditions of the spring niches of the O jców N ational P ark (S outhern P oland) 137 stands 4 and 5. Signi�cantly, the lowest destabilisation of cell membranes was demon- strated for plants from stands 1 and 3. For C. �licinum, the signi�cantly highest elec- trolyte leakage was found for plants from stand 1, in relation to the remaining 4 stands. �e lowest degree of destabilisation of cell membranes was observed for gametophores from stands 4 and 5 (Fig. 6). Discussion �e analysed stands in the Ojców National Park are located in the bottoms of deep karst valleys (Fig. 1–2). �e concave terrain forms such as the bottoms of valleys and canyons are characterised by much lower incoming solar radiation values compared to plateaus (Caputa, Wojkowski, 2009, 2013, 2015). According to Bárány-Kevei (2011), microclimatic di�erences are responsible for the diversity of vegetation in the karst ecosystem. In such ecological conditions, pioneering plants, such as bryophytes, �nd their refuge. �ese are the conditions of the variable ratio of short-wave and long-wave radiation and direct radiation that appear systematically in the same place during the day such as “sun �akes” (Sołtys-Lelek, 2009; Pilarski et al., 2012). In the conducted research, the solar radiation �ux at individual measurement stands was strongly di�erentiated due to the topography and vegetation growing there (Fig. 1–2; Tab. 1). High values of solar radiation above the sunlit surface proved that mosses strongly absorbed light. Lower values obtained in the immediate vicinity of shaded trees indicated limitations in absorption of di�use radiation (Caputa, Wojkowski, 2015). �ese types of changing conditions a�ect the formation of speci�c morphological and physiological features of mosses and allow them to occur in a variety of ecosystems. Fig. 6. Electrolyte leakage of Brachythecium rivulare Schimp. and Cratoneuron �licinum (Hedw.) Spruce. �e �ve karst spring niches (1–4 in the Prądnik Valley, 5 in the Sąspowska Valley); mean values (n = 5, ± SD) marked with di�erent letters di�er signi�cantly according to Duncan’s test at p ≤ 0.05 A nn a S oł ty s- Le le k, Z bi gn ie w C ap ut a 138 Bryophytes have developed �lters that help protect them from high levels of solar radia- tion. For example, some species of the genus Polytrichum have lamellae, surrounded by a curled leaf blade, so that their structure does not di�er much from that of a tree leaf. Others have leaves with �laments – Crossidium, hyaline tips (Hedwigia ciliata, Bryum argenteum), and awns (Tortula sp., Syntrichia sp.), that overlap the next leaf and help to de�ect light before it reaches the cell interior. Other mosses have warts that become more transparent when wet, doubling their ability to absorb solar radiation (Glime, 2017). �e anatomical and morphological di�erences of mosses are treated as an ex- pression of the adaptation arising in the phylogenetic development, allowing them to operate the photosynthetic apparatus in the most favourable conditions in the given habitat (Krupa, 1974). In many studies, the response of bryophytes – e.g. Bryum argenteum (Rastorfer, 1970), Racomitrium lanuginosum (Kallio, Heinonen, 1975), Grimmia pulvinata and Tortula ruralis (Alpert, Oechel, 1987) – to solar radiation showed saturation of photo- synthesis even at low, 20% light intensity. Murray et al. (1993) showed that mosses from shady areas, exposed to hight intensity of light, lost their ability to photosynthesize. On the other hand, mosses that had been transferred from full sun to shade grew at a rate of 2–3 times higher. �e photosynthesis in bryophytes is limited at very low light levels, yet these plants can survive in low light conditions, as previously mentioned. According to Smith et al. (2009) and Niinemets and Niinemets, (2014) the total leaf area can absorb much more light and increase photosynthetic activity. �e leaf structure of bryophytes, with lower plant density, seems to provide the plant with an increased e�ciency of light uptake (Niinmets, Niinmets, 2009; Rice et al., 2008). �e phenomena accompanying the disintegration of the photosynthetic appara- tus are re�ected in changes in the values of chlorophyll a  �uorescence parameters (Lichtenthaler et al., 1986; Bolhàr-Nordenkampf, Öquist, 1993; �ach et al., 2007; Demmig-Adams et al., 2014; Ruban, 2016). In this study, the variability of chlorophyll �uorescence may suggest that it was the result of photoinhibition (Murray et al., 1993). �e photoinhibition was indicated by lower Fv/Fm values and activated photoprotection mechanisms, as evidenced by higher NPQ values, depending on the habitat conditions in the analysed stands (Marschall, Proctor, 2004). According to Proctor et al. (2007) the increase in NPQ can be explained by the degree of cell hydration, which decreased in Brachythecium rivulare and Cratoneuron �licinum specimens from stands 1 and 2 (Fig. 3–5). �e ability of the protective mechanisms that make up NPQ is speci�c and characteristic of a given moss species. Most o�en it is related to the PSII antenna sys- tem, i.e. performance of two essential light-harvesting complex (LHC)-like proteins, photosystem II subunit S (PSBS) in plants and light-harvesting complex stress-related (LHCSR) (Rintamaki et al., 1994; Pinnola et al., 2015; Dikaios et al., 2019). Mosses, depending on the species, are able to quickly regenerate physiological activity disturbed The influence of solar radiation on selected physiological processes of m osses in karst conditions of the spring niches of the O jców N ational P ark (S outhern P oland) 139 by a stress factor (Proctor, Tuba, 2002; Ciu et al., 2008; Możdżeń, 2019). �ey share many photoprotective mechanisms with vascular plants. However, there are some key di�erences in the photoprotection available (Robinson, Waterman, 2014). �e state of hydration of the cells a�ects the moss ability to absorb or re�ect light (Lappalainen et al., 2008). �is suggests that the mosses have developed mechanisms that allow them to scatter light internally and/or externally. In dried mosses, increased re�ection (albedo) and reduced solar radiation absorption (low NR values) should provide them with some protection against the harmful e�ects of light. In fully hydrated mosses (low albedo and high NR), the surface and interior are more homogeneous and absorb solar radiation more e�ectively (Lovelock, Robinson, 2002). In the analyses carried out here, the di�erences in the fresh and dry mass in�uenced the water content in the gametophores of the studied species (Fig. 5). �e water content was signi�cantly the lowest in both mosses collected from stands 1 and 2, compared to the 3 remaining stands. �is was most likely due to the fact that mosses are highly �exible in relation to environmental conditions. At these two stands, the measurements show a high temper- ature and strong absorption of solar radiation by the surface of the mosses (Tab. 1). �is is probably why the tested mosses were characterised by the lowest masses and water content values (Fig. 5). �is result could also depend on other environmental factors (Tab. 1). It can be assumed that the substrate, species composition of other plants, temperature and humidity of the environment played an important role here. At stands 1 and 2, the spring niche is created by a semi-circular concrete lining, which makes the substrate highly exposed to drying out. In the remaining stands, mosses grew on soil or calcareous rock-mantle mixed with soil (Fig. 1–2). Mosses are characterised by di�erent hydration depending on, among others light, the availability of surface water, the action of capillary forces, supported by the setting of gametophore leaves (Proctor et al., 2007; Romańska, 2020). �is directly a�ects the rate of their elongation growth, masses gain and changes in the chemical composition of plant pigments and other metabolites. Such interactions are also perceived at the cellular and molecular level (Ueneka, 2005). �e e�ects of stress caused by di�erent spectral composition and light intensity destabilise the proper functioning of mosses, causing changes in the permeability of cell membranes (Możdżeń, 2019). Cell membranes react the fastest to the in�uence of a stress factor. �ey are highly selective permeation barriers but do not completely isolate because they contain speci�c channels, conveyors and pumps. Undamaged cell membrane allows water molecules to enter the cell interior and is a barrier for molecules of substances dissolved in the cell. �e higher the degree of damage to membranes by stress factors, the higher part of the cell contents �ows out (Kocheva et al., 2014). �e stress-induced electrolyte leakage is accompanied by changes in the structure of proteins and lipids, the concentration of ions in the vacuole and cytoplasm, and the generation and accumulation of reactive oxygen species, which in extreme cases leads to cell death A nn a S oł ty s- Le le k, Z bi gn ie w C ap ut a 140 (Demidchik et al., 2014; Scotti-Campos, Pham-�i, 2016). �e studies of electrolyte leakage carried out here in B. rivulare and C. �licinum showed the highest membrane destabilisation in plants from stands 1 and 2, respectively, compared to other stands (Tab. 1; Fig. 6). �e obtained results prove the most unfavourable environmental con- ditions for the existence of mosses in these stands. Within them, mosses do not occur on natural ground, because the spring niches have been quite strongly transformed by human – the surrounding of the out�ow with a concrete lining (Fig. 2). Comparing the photosynthetic activity of moss gametophores is not easy, because the response of plants is o�en the result of many di�erent environmental factors. From an ecological point of view, an important role is played by the leaf area to volume ratio and the percentage of assimilation tissues in the total leaf mass (Miyata et al., 2015). �e comparison of photosynthesis e�ciency to mass is relative and it seems that there is no adequate relationship in terms of the total photosynthetic production (Krupa, 1974). �e analysis of selected physiological parameters did not clearly indicate which of the studied stands is the most optimal for mosses. �erefore, further research in this area is necessary in order to distinguish both the most convenient stands of spring mosses in the ONP area and to verify which environmental factors play a key role in their physiology. Conclusion (1) �e photosynthetic activity of mosses was speci�c and depended on the stand and species. Such reactions most likely resulted from the structure of mosses and their di�erent adaptations to environmental conditions. (2) �e fresh mass of gametophytes was signi�cantly the largest in plants growing on stand 5, where there is the only completely natural spring niche among the studied. Mosses from stands 1 and 2 showed the lowest values of this parameter. �e dry mass of mosses varied and also depended on the species and stand. �e percentage of water content of both tested mosses was the lowest for plants growing in stand 2 with the most transformed spring niche; bryophytes appeared here only on the arti�cial substrate of concrete lining. (3) �e degree of destabilisation of the cell membranes of Brachythecium rivulare and Cratoneuron �licinum gametophores was speci�c and, as in the previous parameters, depended on the species and location. In general, the highest percentage of electrolytes leakage was found in plants harvested from stands 1 and 2, which proves the highest environmental stress in these two examined positions. The influence of solar radiation on selected physiological processes of m osses in karst conditions of the spring niches of the O jców N ational P ark (S outhern P oland) 141 Acknowledgements �e authors wish to express their gratitude to PhD Katarzyna Możdżeń for her help in plant physiological analyses. We are very grateful to the Reviewers for their valuable comments to improve the manuscript. Con�ict of interest �e authors declare no con�ict of interest related to this article. References Aleksandrowisz, S.W., Wilk, Z. (1962). Budowa geologiczna i źródła doliny Prądnika w Ojcowskim Parku Narodowym (Geological structure and springs of the Prądnik valley in the Ojców National Park). Ochrona Przyrody, 28, 187–210. [In Polish] Alpert, P., Oechel, W.C. (1987). Comparative patterns of net photosynthesis in an assemblage of mosses with contrasting microdistributions. American Journal of Botany, 74, 1787–1796. Bárány-Keve, I. (2011). Changes in the vegetation of dolines in Aggtelek and Bükk mountains. Acta Cli- matologica et Chorologica Universitatis Szegediensis, 44–45, 25–30. Bolhàr-Nordenkampf, H.R., Öquist, G. (1993). Chlorophyll �uorescence as a  tool in photosynthesis research. In: D.O., Hall, J.M.O., Scurlock, H.R., Bolhàr-Nordenkampf, R.C., Leegood, S.P., Long (eds.), Photosynthesis and production in a  changing environment. Dordrecht: Springer. https://doi. org/10.1007/978-94-011-1566-7_12 Brzeźniak, E. (1974). Ogólna charakterystyka warunków mikroklimatycznych w okolicy Ojcowskiego Parku Narodowego (General characteristics of microclimatic conditions in the vicinity of Ojców National Park). In: K. Zabierowski (ed.), Rozmieszczenie przestrzenne i struktura leśnych pasów ochronnych wokół Ojcowskiego Parku Narodowego. Kraków: Zakład Ochrony Przyrody PAN, ss. 35. [In Polish] Caputa, Z. (2009). Kontrasty mezo- i  mikroklimatyczne w  Ojcowskim Parku Narodowym (Meso- and microclimatic contrasts in the Ojców National Park). Prądnik Prace i  Materiały Muzeum im. Prof. Władysława Szafera, 19, 195–218. [In Polish] Caputa, Z., Wojkowski, J. (2013). In�uence of solar radiation on air and soil temperature in the Cracow Upland. Prądnik Prace i Materiały Muzeum im. Prof. Władysława Szafera, 23, 65–74. [In Polish] Caputa, Z., Wojkowski, J. (2015). Structure of radiation balance in diverse types of relief. Annals of Warsaw University of Life Sciences, 47(4), 343–354. Ciu, X., Gu, S., Wu, J., Tang, Y. (2008). Photosynthetic response to dynamic changes of light and air hu- midity in two moss species from the Tibetan Plateau. Ecological Research, 24(3), 645–653. https://doi. org/10.1007/s11284-008-0535-8 Demidchik, V., Straltsova, D., Medvedev, S.S., Pozhvanov, G.A., Sokolik, A., Yurin, V. (2014). Stress-induced electrolyte leakage: the role of K+-permeable channels and involvement in programmed cell death and metabolic adjustment. Journal of Experimental Botany, 65(5), 1259–1270. https://doi.org/10.1093/ jxb/eru004 Demmig-Adams, B., Garab, G., Adams III, W., Govindgee (2014). Non-photochemical quenching and energy dissipation in plants, algae and cyanobacteria, Advances in Photosynthesis and Respiration 40. Netherlands: Springer Science+Business Media Dordrecht. Dikaios, I., Schiphorst, C.H., Dall’Osto, L., Alboresi, A., Bassi, R., Pinnola, A. (2019). Functional analysis of LHCSR1, a protein catalyzing NPQ in mosses, by heterologous expression in Arabidopsis thaliana. Photosynthesis Research, 142, 249–264. https://doi.org/10.1007/s11120-019-00656-3 Duckett, J.G., Renzaglia, K.S. (1988). Ultrastructure and development of plastids in bryophytes. Advances in Bryology, 3, 33–93. A nn a S oł ty s- Le le k, Z bi gn ie w C ap ut a 142 Dynowska, I. (1983). Źródła Wyżyny Krakowsko-Wieluńskiej i Miechowskiej (Springs of the Kraków-Wie- luń Upland and Miechowska). Studia Ośrodka Dokumentacji Fizjogra�cznej, 11, 62–71. [In Polish] Glime, J.M. (2017). Light: e�ects of high intensity. In: J.M., Glime (ed.), Bryophyte ecology. Physiological Ecology, 1, 931–9327. Gradziński, M., Grzdziński, R., Jach, R. (2008). Geologia, rzeźba i zjawiska krasowe okolic Ojcowa (Ge- ology, sculpture and karst phenomena in the Ojców area). In: A. Klasa, J. Partyka (eds.), Monogra�a Ojcowskiego Parku Narodowego. Przyroda. (Monograph of the Ojców National Park. Nature). Ojców: Wyd. OPN. s. 31–95. [In Polish] Jusik, S. (2012). Klucz do oznaczania mchów i wątrobowców wodnych dla potrzeb oceny stanu ekologicznego wód powierzchniowych w Polsce (�e key to the determination of mosses and aquatic liverworts for the purposes of assessing the ecological status of surface waters in Poland). Warszawa: Inspekcja Ochrony Środowiska. Kallio, P., Heinonen, S. (1975). CO2 exchange and growth of Rhacomitrium lanuginosum and Dicranum elongatum In: F.E., Wiegolaski (ed.), Fennoscandian Tundra Ecosystems. Ecological Studies (Analysis and Synthesis), vol 16. Berlin: Heidelberg: Springer. https://doi.org/10.1007/978-3-642-80937-8_16 Klein, J. (1974). Mezo- i  mikorlimat Ojcowskiego Parku Narodowego (Meso- and microclimate of the Ojców National Park). Studia Naturae, ser. A, 8, 1–155. [In Polish] Kocheva, K.V., Georgiev, G.I., Kochev, V.K. (2014). An improvement of the di�usion model for assess-ment of drought stress in plants tissues. Physiologia Plantarum, 150, 88–94. https://doi.org/10.1111/ppl.12074 Krupa, J. (1974). Anatomical structure of bryophytes leaves and their physiological activity (Struktura anatomiczna liści mszaków, a  ich aktywność �zjologiczna). Kraków: Wydawnictwo Naukowe WSP Kraków. [In Polish] Lappalainen, L.M., Huttunen, S., Suokanerva, H. (2008). Acclimation of a pleurocarpous moss Pleurozium schreberi (Britt.) Mitt. to enhanced ultraviolet radiation in situ. Global Change Biology, 14, 321–333. https://doi.org/10.1111/j.1365-2486.2007.01489.x Lichtenthaler, H., Buschmann, C., Rinderle, U., Schmuck, G. (1986). Application of chlorophyll �uores- cence in ecophysiology. Radiation and Environmental Biophysic, 25, 297–308. https://doi.org/10.1007/ BF01214643 Lovelock, C.E., Robinsn, S.A. (2002). Surface re�ectance properties of Antarctic moss and their relation- ship to plant species, pigment composition and photosynthetic function. Plant Cell and Environment, 25(10), 1239–1250. https://doi.org/10.1046/j.1365-3040.2002.00916.x Marschall, M., Proctor, M.C.F. (2004). Are bryophytes shade plants? Photosynthetic light responses and proportions of chlorophyll a, chlorophyll b and total carotenoids. Annals of Botany, 94, 593–603. https://dx.doi.org/10.1093%2Faob%2Fmch178 Miyata, K.H., Nakaji, M., Raj Kanel, D., Terashima, I. (2015). Rate constants of PSII photoinhibition and its repair, and PSII �uorescence parameters in the �eld plants in relation to their growth light environ- ments. Plant and Cell Physiology, 56(9), 1841–1854. https://doi.org/10.1093/pcp/pcv107 Możdżeń, K. (2019). Wpływ składu spektralnego światła na wybrane procesy �zjologiczne mchów w warunk- ach stresu ozonowego (Impact of the spectral composition of light on selected physiological processes of mosses under ozone stress). Kraków: Wydawnictwo Naukowe UP. [In Polish] Możdżeń, K., Saja, D., Ryś, M., Skoczowski, A. (2014). Impact of light spectral composition on the length and weight of the gametophyte of Polytrichastrum formosum (Hedw.) G.L. Smith, Plagiomnium cusp- idatum (Hedw.) T.J. Kop. and Pleurozium schreberi (Brid.) Mitt. Modern Phytomorphology, 5, 73–78. http://doi.org/10.5281/zenodo.161007 Murray, K.J., Tenhunen, J.D., Nowak, R.S. (1993). Photoinhibition as a  control on photosynthesis and production of Sphagnum mosses. Oecologia, 96, 200–207. https://doi.org/10.1007/BF00317733 The influence of solar radiation on selected physiological processes of m osses in karst conditions of the spring niches of the O jców N ational P ark (S outhern P oland) 143 Nasrulhaq-Boyce, A., Duckett, J.G. (1991). Dimorphic epidermal cell chloroplasts in the meso- phyll-less leaves of an extreme-shade tropical fern. New Phytologist, 119, 433–444. https://doi. org/10.1111/j.1469-8137.1991.tb00044.x Niinemets, U., Niinemets, M. (2009). Acclimation of photosynthetic characteristics of the moss Pleuro- zium scherberi to among-habitat and within-canopy light gradients. Plant Biology, 1–13. https://doi. org/10.1111/j.1438-8677.2009.00285.x Niinemets, U., Niinemets, M. (2014). Scaling light harvesting from moss “leaves” to canopies. Chapter 9 In: D.T., Hanson, S.K., Rice (eds.), Photosynthesis in Bryophytes and early land plants, 37, 151–171. Öpik, H., Rolfe, S. (2005). �e physiology of �owering plants. Cambridge, UK: Cambridge University Press, 4th edition, s. 246–269. Pawlik, O. (1998). Wybrane problemy hydrologiczne rejonu Ojcowskiego Parku Narodowego (Selected hydro- logical problems of the Ojców National Park area). Praca magisterska. Sosnowiec: Uniwersytet Śląski, Katedra Geomorfologii, 245 ss. [In Polish] Pilarski, J., Tokarz, K., Kocurek, M. (2012). Adaptacja roślin do składu spektralnego i  intensywności promieniowania (Plant adaptation to light spectra composition and intensity). Prace Instytutu Elek- trotechniki, 256, 223–236. [In Polish] Pinnola, A., Ghin, L., Gecchele, E., Merlin, M., Alboresi, A., Avesani, L., Pezzotti, M., Capaldi, S., Cazza- niga, S., Bassi, R. (2015). Heterologous expression of moss Light-harvesting Complex Stress-related 1 (LHCSR1), the chlorophyll a-xanthophyll pigment-protein complex catalyzing non-photochemical quenching, in Nicotiana sp. �e Journal of Biological Chemistry, 290, 24340–24354. https://dx.doi. org/10.1074%2Fjbc.M115.668798 Proctor, M.C.F., Ligrone, R., Duckett, J.G. (2007). Desiccation tolerance in the moss Polytrichum formosum: physiological and �ne-structural changes during desiccation and recovery. Annals of Botany, 99, 75–93. https://doi.org/10.1093/aob/mcl246 Proctor, M.C.F., Tuba, Z. (2002). Tansley review No. 141: Poikilohydry and homoihydry: antithesis or spec- trum of possibilities? New Phytologist, 156, 327–349. https://doi.org/10.1046/j.1469–8137.2002.00526.x Rastorfer, J.R. (1970). E�ects of light intensity and temperature on photosynthesis and respiration on two East Antarctic mosses, Bryum argenteum and Bryum antarcticum. Bryologist, 73, 544–556. Rice, S.K., Aclander, L., Hanson, D.T. (2008). Do bryophyte shoot systems function like vascular plant leaves or canopies? Functional trait relationships in Sphagnum mosses. American Journal of Botany, 95, 1366–1374. https://doi.org/10.3732/ajb.0800019 Rintamaki, E., Salo, R., Aro, E.M. (1994). Rapid turnover of the D1 reaction-center protein of Photosystem II as a protection mechanism against photoinhibitionin a moss, Ceratodon purpureus (Hedw.) Brid. Planta, 193, 520–529. https://doi.org/10.1007/BF02411557 Robinson, S.A., Waterman, M.J. (2014). Sunsafe bryophytes: Photoprotection from excess and damaging solar radiation. In: D.T., Hanson, S.K., Rice (eds.), Photosynthesis in bryophytes and early land plants. Advances in Photosynthesis and Respiration, 37, 113–130. Romańska, M. (2020). Impact of water stress on physiological processes of moss Polytrichum piliferum Hedw. Annales Universitatis Paedagogicae Cracoviensis Studia Naturae, 5, 129–141. https://doi. org/10.24917/25438832.5.9 Różkowski, J., Pawlik, O. (2001). Źródła szczelinowo-krasowe w rejonie Ojcowskiego Parku Narodowego (Fissure-karst springs in the area of Ojców National Park). In: J. Partyja (ed.), Badania naukowe w po- łudniowej części Wyżyny Krakowsko-Częstochowskiej, Ojców, p. 83–86. [In Polish] Ruban, A.V. (2016). Nonphotochemical chlorophyll �uorescence quenching: mechanism and e�ectiveness in protecting plants from photodamage. Plant Physiology, 170(4), 1903–1916. https://doi.org/10.1104/ pp.15.01935 A nn a S oł ty s- Le le k, Z bi gn ie w C ap ut a 144 Rzepka, A. (2008). Eko�zjologiczne aspekty reakcji różnych gatunków mchów na abiotyczne czynniki stresowe (Ecophysiological aspects of the response of various moss species to abiotic stress factors). Kraków: Wy- dawnictwo Naukowe WSP Kraków. [In Polish] Scotti-Campos, P., Pham-�i, A. (2016). Correlation between total lipids, linolenic acid and membrane injury under PEG-induced dehydration in leaves of Vigna genotypes di�ering in drought resistance. Emirates Journal of Food and Agriculture, 28(7), 485–492. https://doi.org/10.9755/ejfa.2016-04-342 Smith, W.K., Hughes, N.M. (2009). Progress in coupling plant form and photosynthetic function. Castanea, 74, 1–26. https://doi.org/10.2179/08-009R5.1 Sołtys-Lelek, A. (2009). Struktura i zmiany zbiorowisk roślinnych na powierzchniach badawczych „Gro- dzisko” i w dolinie Sąspowskiej (Ojcowski Park Narodowy) (Changes in plant communities and their structure in the study plots Grodzisko and the Sąspowska Valley (Ojców National Park)). Prądnik. Prace i Materiały Muzeum im. Prof. Władysława Szafera, 19, 265–320. [In Polish] Tallis, J.H. (1959). Studies in the biology and ecology of Rhacomitrium lanuginosum Brid. II. Growth reproduction and physiology. Journal of Ecology, 47, 325–350. Uenaka, H., Wada, M., Kadota, A. (2005). Four distinct photoreceptors contribute to light-induced side branch formation in the moss Physcomitrella patens. Planta, 222, 623–631. https://doi.org/10.1007/ s00425-005-0009-y Wojkowski, J., Caputa, Z. (2009). Modelowanie dopływu promieniowania słonecznego na obszarze Oj- cowskiego Parku Narodowego (Modelling the in�ow of solar radiation in the Ojców National Park). Prądnik. Prace i Materiały Muzeum im. Prof. Władysława Szafera, 19, 141–152. [In Polish] Wojkowski, J., Caputa, Z. (2015). Structure of radiation balance in diverse types of relief. Annals of Warsaw University of Life Sciences, 47(4), 343–354. http://doi.org/10.1515/sggw-2015-0036 Wojkowski, J., Caputa, Z. (2016). �e impact of karst relief on the diversity of insolation conditions and mesoclimate variation: Case study of the Ojców National Park, Poland. International Journal of Geo- heritage, 4(1), 33–43. Abstract �e availability of light is one of the most important environmental factors in�uencing the �oristic diversity of spring niches, especially in the speci�c conditions of deep, karst valleys occurring in the Ojców National Park (southern Poland). �e aim of this study was to investigate the in�uence of solar radiation reaching the karst spring niches, on selected physiological parameters of the spring mosses: Cratoneuron �licinum (Hedw.) Spruce (obligatory krenophyte) and Brachythecium rivulare Schimp. (facultative krenophyte). �e �ve karst spring niches (4 in the Prądnik Valley, 1 in the Sąspowska Valley) were selected for the plant material collec- tion, in which two of the moss species tested occurred simultaneously. On sunny days, measurements of total and re�ected radiation, as well as the radiation balance in the full spectrum range over the vegetation were made. �e temperature was measured for air, water, and on the surface and inside the plants. �e collected biological material was subjected to laboratory analysis. Fresh mass of moss gametophytes was signi�cantly the highest from plants growing on stand 5 (intermediate values of light and temperature parameters), and the lowest from mosses on stands 1 and 2 (including lowest air temperatures). Dry mass varied depending on the species and stand. �e percentage of water in B. rivulare was highest in plants from stand 4 (highest air and water temperature), and in C. �licinum from stand 5. Signi�cantly the lowest values of this parameter were found for plants growing in stand 2 (lowest temperature of water). �e electrolytes leakage from moss cells was speci�c and depended on the species. �e greatest destabilisation of cell membranes was demonstrated in plants harvested from stands 1 and 2, where it was the coldest. �e �uorescence of chlorophyll a varied depending on the moss species and the habitat of spring niches. �is paper, presenting of preliminary results, is a kind of introduction to wider research in this topic. The influence of solar radiation on selected physiological processes of m osses in karst conditions of the spring niches of the O jców N ational P ark (S outhern P oland) 145 Key words: albedo, biomass, Brachythecium rivulare, Cratoneuron �licinum, chlorophyll a �uorescence, electrolyte leakage, net all-wave radiation Received: [2021.02.22] Accepted: [2021.05.15] Wpływ promieniowania słonecznego na wybrane procesy fizjologiczne mchów w warunkach krasowych nisz źródliskowych Ojcowskiego Parku Narodowego (Południowa Polska) Streszczenie Dostępność światła jest jednym z najważniejszych czynników środowiskowych wpływających na różnorod- ność �orystyczną nisz źródliskowych, zwłaszcza w specy�cznych warunkach głębokich, krasowych dolin, występujących w Ojcowskim Parku Narodowym (Południowa Polska). Celem niniejszej pracy było zbadanie wpływu promieniowania słonecznego, docierającego do nisz źródliskowych, na wybrane parametry �zjolo- giczne mchów źródliskowych: Cratoneuron �licinum (Hedw.) Spruce (kreno�t obligatoryjny) i Brachythecium rivulare Schimp. (kreno�t fakultatywny). Do zbioru materiału roślinnego wytypowano 5 krasowych nisz źródliskowych (4 w dolinie Prądnika, 1 w dolinie Sąspowskiej), w których występowały jednocześnie obydwa gatunki mchów. W słoneczne dni dokonano pomiarów promieniowania całkowitego, odbitego oraz salda promieniowania w pełnym zakresie widma nad roślinnością. Pomierzono temperaturę powietrza, wody oraz na powierzchni i wewnątrz roślin. Zebrany materiał biologiczny poddano analizom laboratoryjnym. Świeża masa gameto�tów była istotnie największa u roślin rosnących na stanowisku 5 (pośrednie wartości parametrów światła i temperatury), a najmniejsza u mchów ze stanowisk 1, 2 (m.in. najniższe temperatury powietrza). Sucha masa zmieniała się w zależności od gatunku i siedliska. Procentowa zawartość wody u B. rivulare była największa dla okazów ze stanowiska 4 (najwyższa temperatura powietrza i wody), a u C. �licinum ze stanowiska 5. Istotnie najmniejsze wartości tego parametru stwierdzono dla roślin rosnących na stanowisku 2 (najniższa temperatura wody). Wypływ elektrolitów z komórek mchów był specy�czny i zależał od gatunku. Największą destabilizację błon komórkowych wykazano u roślin zebranych ze stanowisk 1 i 2, gdzie było najchłodniej. Fluorescencja chloro�lu a zmieniała się w zależności od gatunku mchu i źródliska. Niniejsza praca prezentująca pilotażowe wyniki, stanowi niejako wstęp do szerzej zakrojonych badań w tym zakresie. Slowa kluczowe: albedo, biomasa, Brachythecium rivulare, Cratoneuron �licinum, �uorescencja chloro�lu a, wypływ elektrolitów, saldo promieniowania krótko i długofalowego Information on the authors Anna Sołtys-Lelek https://orcid.org/0000-0002-9595-3167 Author of numerous scienti�c and popular science studies in the �eld of botany and environmental protec- tion. Her research interests relate particularly to the critical type of rose (Rosa) and hawthorn (Crataegus). Member of the Polish and Slovak Botanical Society. Zbigniew Caputa He is a climatologist, polar explorer, former employee of the Silesia University. His research focused in particular on the long-term variability of the climate and modelling the in�ow of solar radiation.