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Fig. 1. Location of study area and study sites.

Table 1. Average characteristics of the investigated stands.
Site No. Soil type Forest site type Composition of trees No. of trees per hectare Age, yr Site quality index Canopy cover Height, m Breast height diameter, cm Density of understory
1 Haplic Podzol Rhodococcum 100 Ps 149 180 IV 0.45 24 37 Low
2 Haplic Podzol Cladonia 100 Ps 191 190 IV 0.54 24 36 Low
3 Haplic Podzol Cladonia 100 Ps 98 200 IV 0.62 21 44 Low
4 Haplic Podzol Cladonia 100 Ps 143 210 IV 0.60 23 38 Low
Ps = Pinus sylvestris

Fig. 2. Venn diagram showing the overlapping and individuality of vascular plant species at different sites.

Table 2. The results of multiple response permutation procedure (MRPP) tests for the comparison of species composition on different dunes.
Test pair Site 1 vs. Site 2 Site 1 vs. Site 3 Site 1 vs. Site 4 Site 2 vs. Site 3 Site 2 vs. Site 4 Site 3 vs. Site 4
p-value <0.001 <0.001 <0.001 0.002 <0.001 0.011
Bold values are significant after the Bonferroni correction

Fig. 3. Venn diagram showing the overlapping and individuality of vascular plant species at different locations on dunes.

Table 3. Vascular plant indicator species with indicator values (IV) for different zones (bottom, slope and top) on dunes according to the indicator species analysis (ISA).
Bottom Slope Top
IV p-value IV p-value IV p-value
Site 1 Rubu ida 28 0.011 Empe nig 36 0.016 Call vul 32 0.05
Oxal ace 25 0.041
Mela pra 50 0.042
Site 2 Empe nig 53 0.0002 Hier umb 26 0.001
Fest pol 50 0.0004 Call vul 50 0.001
Conv maj 13 0.035 Mela pra 52 0.002
Soli vir 26 0.002
Fest rub 35 0.006
Trie eur 21 0.021
Site 3 Vacc myr 73 0.0002 Trie eur 61 0.001 Fest rub 41 0.05
Vacc vit 69 0.0002
Ledu pal 43 0.012
Site 4 Vacc uli 38 0.012 Fest pol 48 0.025 Empe nig 52 0.002
Call vul 59 0.008
Rubu ida = Rubus idaeus; Oxal ace = Oxalis acetosella; Mela pra = Melampyrum pratense; Empe nig = Empetrum nigrum; Fest pol = Festuca polesica; Conv maj = Convallaria majalis; Vacc myr = Vaccinium myrtillus; Vacc vit = Vaccinium vitis-idaea; Ledu pal = Ledum palustre; Vacc uli = Vaccinium uliginosum; Trie eur = Trientalis europaea; Call vul = Calluna vulgaris; Hier umb = Hieracium umbellatum; Soli vir = Solidago virgaurea; Fest rub = Festuca rubra
Table 4. Average values of soil and light characteristics from different sites and locations on the dunes. View in new window/tab.
Table 5. Significance (p-values, type 3 effects) of factors contributing to species richness and the coverage of vascular plants according to a linear mixed model.
Species richness of vascular plants DF F-value p-value
Location on dune (zone) 215.97 15.43 <0.001
Aspect of the quadrat 7.87 16.67 <0.001
Absolute height 183.53 0.17 0.685a
Cover of bryophyte and lichen layers 215.42 0.003 0.960a
PAR 215.18 15.46 <0.001a
VWC 216.36 26.54 <0.001
pH 216.54 10.70 0.001
Ntotal 215.46 29.22 <0.001a
P 216.92 0.002 0.969
K 216.85 4.98 0.027
O horizon 215.50 1.97 0.162
Total cover of vascular plant species DF F-value p-value
Location on dune 102.68 13.46 <0.001
Aspect of the quadrat 3.29 1.53 0.356
Absolute height 2.31 22.06 0.032
Cover of bryophyte and lichen layers 199.17 1.86 0.174a
PAR 216.78 0.04 0.844
VWC 205.64 22.96 <0.001
pH 124.85 4.78 0.031a
Ntotal 217.00 27.28 <0.001a
P 32.27 0.12 0.727
K 139.17 24.43 <0.001
O horizon 174.46 6.61 0.011
a – indicates a negative effect
PAR = below-canopy photosynthetically active radiation (μmol m–2 s–1); VWC = average soil volumetric water content (%);
pH = average pHH2O;
O = soil litter horizon thickness (cm);
Ntotal = nitrogen content (%);
P = phosphorus content (mg kg–1);
K = potassium content (mg kg–1)

Fig. 4. Non-metric multidimensional scaling (NMDS) ordination graph with fitted environmental variables. Arrows represent environmental variables that were most significantly (p ≤ 0.005) related to ordination. View larger in new window/tab.

Table 6. Relationships between species composition (non-metric multidimensional scaling (NMDS) ordination, Fig. 4) and environmental variables on dunes. Bold values are variables presented as arrows in Fig. 4.
Variable r2 p-value Level of significance
Habs 0.2541 0.001 ***
CC 0.2486 0.001 ***
Covbryolich 0.2054 0.001 ***
Site 0.2949 0.001 ***
Ntotal 0.2259 0.002 **
Asp 0.1552 0.003 **
K 0.2067 0.004 **
P 0.1634 0.005 **
Mg 0.1826 0.007 **
VWCaver 0.1553 0.008 **
pH 0.1248 0.022 *
Ca 0.1180 0.030 *
Hrel 0.0942 0.062 .
EC 0.0809 0.073 .
Degr 0.0622 0.158
Loc 0.0497 0.225
O 0.0150 0.655
A 0.0103 0.744
PAR 0.0026 0.914
Significance codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
Habs = absolute height of the quadrat location (m);
CC = average canopy cover;
Covbryolich = total coverage of bryophytes and lichens (%);
Ntotal = average total nitrogen content (%);
Asp = aspect of the quadrat;
K = average potassium content (mg kg–1);
P = average phosphorus content (mg kg–1);
Mg = average magnesium content (mg kg–1);
VWCaver = average soil water content (%);
pH = average soil pHH2O;
Ca = average soil calcium content (mg kg–1);
Hrel = relative height (m);
EC = electrical conductivity (µS);
Degr = degree of inclination or ascent;
Loc = location on dune (bottom, slope, top);
O = average litter horizon thickness (cm);
A = average humus horizon thickness (cm);
PAR = average photosynthetically active radiation (μmol m–2 s–1)