Figure 1
Distribution of the surveyed lakes
Figure 2
Sampling scheme
Table 1
Examined species of macrophytes with frequency of over 1%; F – average value of species frequency in the whole pH range and P – average value of species coverage in the whole pH range
| Bryophytes | F | A | Stoneworts | F | A | Vascular plants excluding isoetids | F | A | Isoetids | F | A |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Sphagnum denticulatum | 14.1 | 25.8 | Chara delicatula | 8.4 | 15.5 | Myriophyllum alterniflorum | 19.0 | 15.2 | Isoëtes lacustris | 27.4 | 35.0 |
| Fontinalis antipyreti ca | 12.0 | 12.7 | Chara fargilis | 6.1 | 32.5 | Elodea canadensis | 12.4 | 12.8 | Lobelia dortmanna | 13.5 | 21.8 |
| Warnstorfia exannulata | 7.9 | 7.6 | Nitella flexilis | 3.6 | 3.2 | Potamogeton obtusifolius | 2.1 | 2.3 | Litorella uniflora | 8.6 | 33.3 |
| Drepanocladus sordidus | 7.0 | 9.7 | Nitellopsis obtusa | 1.7 | 6.1 | Myriophyllum spicatum | 1.8 | 7.1 | Luronium natans | 2.9 | 28.8 |
| Fontinalis delecarlica | 3.6 | 12.0 | Nitella gracilis | 1.1 | 12.3 | Ceratophyllum demersum | 1.6 | 7.6 | - | - | - |
| Drepanocladus aduncus | 1.4 | 8.8 | - | - | - | Potamogeton natans | 1.1 | 6.8 | - | - | - |
| Sphagnum fallax | 1.1 | 40.6 | - | - | - | - | - | - | - | - | - |
Figure 3
Abundance of plant species in the water pH gradient
Figure 4
Number of species groups in 12 702 samples (mosses, stoneworts, vascular plants, isoetids; upper graph), their percentage (middle graph) and abundance of plants (bottom graph) in the water pH gradient.
Figure 5
Relationship between water pH and occurrence of isoetid species (1 – 5) in lakes (bottom chart), where: 1 – Isoëtes echinospora, 2 – Luronium natans, 3 – Isoëtes lacustris, 4 – Lobelia dortmanna, 5 – Littorella unifiora and abundance (coverage) of isoetids in the water pH gradient (upper chart)
Figure 6
Species diversity along the gradient of water alkalization
Table 2
Differences in the Shannon–Wiener index (H’) in different pH ranges (see Fig. 6)
| Shannon–Wiener index (H’) | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Mean | 0.17 | 0.41 | 0.21 | 0.18 | 0.32 | 0.23 | 0.37 | 0.31 | 0.31 | 0.32 | 0.24 | 0.40 |
| SD | 0.31 | 0.37 | 0.29 | 0.28 | 0.35 | 0.30 | 0.36 | 0.37 | 0.39 | 0.33 | 0.35 | 0.37 |
| pH | 4.0 | 4.5 | 5.0 | 5.5 | 6.0 | 6.5 | 7.0 | 7.5 | 8.0 | 8.5 | 9.0 | 9.5 |
| 4.0 | *** | - | - | *** | * | *** | *** | *** | *** | - | * | |
| 4.5 | *** | *** | - | *** | - | ** | * | - | * | - | ||
| 5.0 | - | *** | - | *** | ** | - | ** | - | - | |||
| 5.5 | *** | - | *** | *** | *** | *** | - | - | ||||
| 6.0 | * | - | - | - | - | - | - | |||||
| 6.5 | *** | - | - | - | - | - | ||||||
| 7.0 | *** | ** | - | ** | - | |||||||
| 7.5 | - | - | - | - | ||||||||
| 8.0 | - | - | - | |||||||||
| 8.5 | - | - | ||||||||||
| 9.0 | - | |||||||||||
Figure 7
Model of the relationship between plant species and water parameters in soft-water lakes with isoetids, ordered by the RDA method
Abbreviations: TP – total phosphorus, TN – total nitrogen, PAR – photosynthetically active radiation; vascular plants: Cd – Ceratophyllum demersum, Ec – Elodea canadensis, Ma– Myriophyllum alterniflorum, Ms – Myriophyllum spicatum, Pn – Potamogeton natans, Po– Potamogeton obtusifolius; mosses: Da – Drepanocladus aduncus, Ds – Drepanocladus sordidus, Fa– Fontinalis antipyretica, Fd – Fontinalis delecarlica, Sd – Sphagnum denticulatum, Sf – Sphagnum fallax, We – Warnstorfia exannulata; stoneworts: Chd – Chara delicatula, Chg – Chara globularis, Nif – Nitella flexilis, Nig – Nitella gracilis, Nito – Nitellopsis obtusa
Table 3
Results of RDA analysis of the relationship between plant species and water characteristics in soft-water lakes with isoetids
| Axes | 1 | 2 | 3 | 4 | Total variance |
|---|---|---|---|---|---|
| Eigenvalues | 0.123 | 0.020 | 0.013 | 0.001 | 1.000 |
| Species-environment correlations | 0.474 | 0.397 | 0.377 | 0.175 | |
| Cumulative percentage variance | |||||
| of species data | 12.3 | 14.3 | 15.6 | 15.7 | |
| of species-environment relation | 77.5 | 90.3 | 98.4 | 99.2 | |
| Sum of all eigenvalues | 1.000 | ||||
| Sum of all canonical eigenvalues | 0.158 | ||||