Assessment of riparian forest vegetation of rivers supporting the Prespa trout in the Transboundary Prespa Park

Yannis Kazoglou1, 4, George Fotiadis2, Michael Vrahnakis3, Irene Koutseri4, Alain Crivelli5

1 Municipality of Prespa, Lemos, Greece (present address), e-mail: ykazoglou@gmail.com2 School of Forestry and Management of Natural Environment, Technological

Educational Institute (TEI) of Kavala / Branch of Drama, Greece3 School of Forestry and Management of Natural Environment, Technological

Educational Institute (TEI) of Larisa / Branch of Karditsa, Greece4 Society for the Protection of Prespa (SPP), Agios Germanos, Greece

5 Tour du Valat, Le Sambuc, Arles, France

AbstractThe QBR (Riparian Forest Quality) index and the RMP (Riparian Macrophyte Protocol) were used to assess habitat quality and inventory riparian forests in four rivers sustain-ing the endemic Prespa trout (Salmo peristericus). Total QBR index and total riparian cover (fi rst component of the QBR index) values were found signifi cantly higher in the upper parts of Brajcinska and Kranska rivers, while lower values were recorded in the upper parts of Agios Germanos river and Leva stream. Cover structure, cover quality and channel alteration (the other three components of the QBR index) did not differ signifi cantly between the four watersheds. The greater presence of Fagus syl-vatica in the former rivers principally contributes to their increased total riparian area and riverbed cover compared to those of the two latter rivers. In the altitudes below 900 m.a.s.l., where gradients are gentle and human activities intense, vegetation types in all four systems change considerably with the participation of non-native species, while riparian area and riverbed cover are reduced.

Key words: habitat quality, rapid assessment methods, macrophyte functional groups, Salmo peristericus conservation

DOI: 10.2478/v10104-011-0042-3

Vol. 11 No. 1-2, 63-782011 Water observation and information systems for decision support

1. IntroductionRiparian zones can be defi ned as semi-terrestrial

transition zones found on the ecotone of aquatic and terrestrial ecosystems often affected by freshwater; they include the shores of any kind of aquatic for-mation (rivers, lakes, marshes, swamps, springs,

etc.), fl oodplains, and riparian forests (forests with hydrophilous trees) (Zogaris et al. 2007). The latter, when developing along rivers and streams, are often named “riverine forests” to avoid confusion with similar forests growing on lakeshores. However, the terms “riparian forests/woodlands” are often used exclusively for river/stream ecosystems, thus

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64 Y. Kazoglou et al.

in this paper the term “riparian” addresses both river and stream environments found in the Prespa basin, namely those supporting populations of the Prespa trout (Salmo peristericus, Karaman 1938).

Detailed species-focused ecological studies for Salmo peristericus are not available, but sev-eral inferences can be made regarding preferred habitat types of the species, based on the general requirements of salmonids and other trout species of the Balkans. Besides standard requirements (e.g. food availability), habitat quality in trout is highly dependent on water temperature (optimum for trout survival ranges between 8-19°C; any value above 26°C may prove lethal) and oxygen content. Egg survival is ensured only within 0-15°C, while oxy-gen content requirements for brown trout and most members of the Salmonidae are higher than those for most other fi sh. High oxygen content values are also closely related to the quality of spawning ground and the subsequent egg survival. All salmonids prefer to spawn in cold, well-oxygenated, gravel-bottomed streams to ensure that there is constant fl ow through the gravel, delivering oxygen to the eggs and removing waste products (Elliott 1994; Hunter 1991). Both these factors are infl uenced by the riparian forest quality, which will limit erosion and fi ne sediments and ensure the quality of the streambed, while shading will contribute towards maintaining water temperature at the required low levels and contribute in reducing evaporation during the summer months (Crivelli et al. 2008). Along with temperature regulation and erosion – sedimentation prevention, additional positive effects of riparian vegetation include the provision of resting and hiding places (Wesche et al. 1987), and the contribution to food availability for trout in summer through allochtonous input (Zogaris et al. 2007; Crivelli et al. 2008). The relationship between trout population survival and the quality of riparian forests has led to the need for a riparian forest quality assessment in all four sub-basins of Prespa (Agios Germanos, Brajcinska, Kranska rivers and Leva stream) sustain-ing trout populations, within the recently published Species Action Plan (Crivelli et al. 2008).

Riparian woodlands are multifunctional systems and constitute a major feature of Mediterranean ripar-ian landscapes (Skinner, Zalewski 1995; Décamps, Décamps 2001). Despite the ecosystem services that riparian forests sustain, they continually face various threats especially when located in lowland areas where agricultural intensifi cation is persistent. Distortion of hydrology, pollution, land use changes and climate change are listed as major threats to riparian forests (Zogaris et al. 2007). According to Crivelli et al. (2008), some of the threats to the Prespa trout populations include altered or destroyed riparian forest, other alterations either due to heavy

grazing, road building (logging) or various human-induced modifi cations, habitat fragmentation and combined effects of all mentioned factors (seven in total) with a varying degree of signifi cance for each factor in the four different streams of Macro Prespa basin. Under increasing threats and in order to conserve and manage the remaining riparian forests, especially in protected areas where the legal framework supports such measures, it is use-ful to recognize and describe these habitats in a systematic and, if possible, low time-consuming way. Riverine systems are very diverse and their functions depend on the size of the water course, geology and topography, the fl owing regime, the volume of water present and its quality as well as the lateral and vertical dimensions of the associated riparian habitats (Dobson, Frid 1998); the latter can either be extremely complex and heterogeneous, as in fl oodplain rivers, or relatively simple as in headwater streams (Munné et al. 2003). Although riparian vegetation constitutes a major functional component of such habitats, it has been scarcely used in systematic studies on river ecological attributes. Emphasis is usually placed on species diversity rather than vegetation types, functional groups or vegeta-tion structure. Diffi culties rise from the azonal and climate-independent characteristics of its fl oristic elements that interfere with zonal, allochtonous, or even elements of agricultural origin. This compli-cated nature of riparian vegetation is responsible for the absence of a commonly accepted method for the classifi cation of riparian vegetation (Naiman et al. 2005). Nevertheless, the need to study the level of associations between riparian vegetation and other biotic elements (e.g. fi sh fauna) persistently exists (Zogaris 2009).

Various assessment techniques have been devel-oped to quantify relevant parameters and character-ize riparian habitats. Rapid assessment protocols were developed to achieve easy-to-use information and gain in terms of time needed for fi eldwork and analyses (Sayer et al. 2000). The majority of such protocols aim to answer questions relevant to conservation, management, protection or monitor-ing themes and focus in gathering information not available from remote sensing, desk studies or spatial analysis techniques. In addition, they help in inferring over tangible generalities, easy to deal with by managers, conservationists, decision makers and local people (Bjorkland et al. 2001). According to Zogaris et al. (2007), the most widely used rapid assessment protocols are the river habitat survey (RHS) developed by Raven et al. (1998), the “qualitat del bosc de ribera” (riparian forest quality) protocol (QBR) (Munné et al. 2003), and the stream visual assessment protocol (SVAP) originally developed by Bjorkland et al. (2001) and modifi ed by Bjorkland

Assessment of riparian vegetation supporting Prespa trout 65

et al. (2006) to best fi t the conditions of riverine systems in Greece. Functional attributes of forest riparian vegetation can be assessed with the riparian macrophyte protocol (RMP), originally created by Ferreira et al. (2004) after the enactment of the Water Framework Directive 2000/60 and easily combined with the above mentioned methods.

Therefore, in an effort to contribute to the long-term conservation of the Prespa trout, the present study was conducted using the QBR protocol and the RMP (with adjustments) in order to (i) assess qualitative and compare structural components of forest riparian vegetation along the banks of the four rivers/streams, (ii) assess riparian forest quality and inventory riparian macrophytes growing alongside these banks, (iii) analyse the ecological settings of the riparian and riverbed environments of the four rivers in terms of vegetation, and (iv) formulate preliminary management and monitoring suggestions for the conservation of the Prespa trout habitats.

2. Materials and methods2.1. The study area

The Prespa basin (total area of 251,910 ha) is dominated by the Micro and Macro Prespa lakes and a number of water courses of several major rivers that discharge mostly into the latter. This network of water courses, together with the exceptional abi-otic, biotic, and anthropogenic elements constitutes the unique Prespa landscape, an area declared as Transboundary Prespa Park in 2000.

The Prespa trout (Salmo peristericus) is one of the nine endemic species of the area on a total of 23 fi sh species (Perennou et al. 2009). Karaman (1938) reports that there were evidences in the past that Lake Macro Prespa supported Prespa trout populations, but today it is extremely rare to fi nd this species in the lake (Crivelli et al. 2008). Nowadays, the Prespa trout is found in the upper parts of Agios Germanos river in Greece, and Brajcinska river, Kranska river, and Leva stream (a tributary of the Golema river) in the Former Yugoslav Republic of Macedonia, all outfl owing to Macro Prespa lake.

The Agios Germanos river (AGR) has a length of 14.5 km and forms a catchment area of 57 km2, while its mean annual discharge rate is 0.559 m3 s-1 (Crivelli et al. 2008). Two major tributaries are dis-tinguished: the left branch “Gaidouritsa” (11.2 km) and the right branch “Siroka”, both located upstream of Agios Germanos village. According to Crivelli et al. (2008), monitoring activities (1997-2008) have shown that trout populations in both streams seem to be stable (presenting large fl uctuations of the population sizes among years, which are however normal in trout populations) through the years, with Gaidouritsa sustaining steadily more individuals than

Siroka, the population of which approaches levels of doubtful viability or distinction (< 200 ind. ha-1). The natural vegetation alongside the AGR is spatially differentiated and dictated mainly by elevation and the allochtonous vegetation.

The Brajcinska river (BRR) is 15.8 km long, forms the largest catchment area (78 km2) and has a mean annual discharge rate of 0.927 m3 s-1. Main tributaries are the Baltanska, Rzsanska, Drmisar and Kriva Kobila that sustain large fluctuating populations of Prespa trout. The population size of Baltanska is far less than the critical value of 200 ind. ha-1 mostly due to low summer fl ows and the absence of large pools (Crivelli et al. 2008). Similar to the AGR, its natural vegetation is spatially differentiated and adjusted mainly by elevation and adjacent land uses, although in high altitudes (over 1100 m.a.s.l.) forest vegetation is relatively unaf-fected by human activities.

The Kranska river (KRR) has a length of 11.1 km and forms a catchment area of 30.4 km2 with a mean annual discharge rate of 0.459 m3 s-1. Main tributar-ies are the Upper Kranska that sustains a critical population size of Prespa trout (< 200 ind. ha-1), and Srbino (Crivelli et al. 2008). In altitudes less than 900 m.a.s.l., vegetation is mostly of anthropogenic origin with sporadically distributed representatives of forest or riparian vegetation like Salix alba, Clematis vitalba, etc.

Finally, the Leva stream (LVS), located above the main body of the Golema river, forms a catch-ment area of approximately the same size as KRR (30.8 km2), has the shortest length (9.4 km) and a mean annual discharge rate of 0.363 m3 s-1, which is the lowest of the four examined rivers indicating drier conditions among the four catchments (Crivelli et al. 2008). The fi sh monitoring stations in Sredna branch sustain a critical population size of Prespa trout. The azonal fl oristic elements of the natural vegetation in LVS is characterized by the domination of Alnus glutinosa, while depending on the levels of human intervention characteristic species like Juglans regia appear.

The lower parts of these four river systems do not sustain trout populations on a permanent basis due to water abstraction in summer for irrigation (which causes low fl ow and absence of large pools, while it may render the riverbed totally dry for some weeks or even months), habitat fragmentation, poaching and/or angling, and pollution by sewage waste (Crivelli et al. 2008).

2.2. The QBR and RMP protocols – fi eld data collection

Among the methods previously described, the QBR protocol is relatively simple and has the ad-vantage of being less time consuming (Munné et

66 Y. Kazoglou et al.

al. 2003). Additionally, it has been used for the as-sessment of various Mediterranean as well as Greek riverine forests without modifi cations (Zogaris 2009), a fact considered important for its use in the rivers of Prespa. The QBR protocol assesses the quality of the natural fl uvial ecosystem on the basis of some easy to recognise and measure characteristics of the riparian vegetation and the morphometry of the riparian zone. It results in the calculation of a QBR index value in the fi eld. This value is calculated by adding up the summing scores of four components: (i) total riparian cover, determined by the cover of trees, bushes, shrubs or helophytes and connectivity between the riparian forest and the woodland, (ii) cover structure, which depends on total tree cover (%) and the cover of shrubs and other vegetation in the under-storey, (iii) cover quality, which largely depends on the geomorphology of the riparian area and the number of native tree species, and (iv) channel alteration, whose score is shaped by the presence/absence of human-induced modifi ca-tions to the channel (Munné et al. 2003). Each part can score up to 25, thus the maximum value of the QBR index can be 100. The score of each part is formulated by parameters producing positive (e.g. > 80% of riparian cover excluding annual plants, > 75% of tree cover, presence of native trees, and absence of modifi cation to river channel respec-tively for the four components) or negative (low connectivity with terrestrial environments, regular distribution of trees, presence of non-native tree communities/garbage, and riverbed with rigid or transverse structures respectively) values, but it cannot be negative or exceeding 25 (Munné et al. 2003). Before applying the protocol, it is essential to divide the river into two sections, i.e. the main channel and the riparian area. The former is subdi-vided in the area permanently covered with water (“channel”, which is not considered in the scoring process and data analysis) and the bankfull zone (where helophytes are often met).

The RMP focuses on riparian habitats, fl oristic composition and anthropogenic pressures. In its initial appearance it was structured by eight dis-tinct parts: (i) technical information (researcher, time, date, locality, watershed), (ii) georeference information (altitude, margin geological substrata, inclination, GPS coordinates), (iii) geometric infor-mation (maximum/mean/minimum width of riparian zone), (iv) physicochemical information (water pH/temperature, air temperature), (v) information on potential anthropogenic impacts on vegetation (roads, reinforced banks, mineral extraction, etc.), (vi) information on current interventions (gabion, canalization, construction debris, etc.), (vii) mac-rophyte fl oristic information (percentage of species composition), and (viii) vertical vegetation structure.

The RMP is applied in land stripes of specifi c di-mensions (50 m, 100 m) in both banks; when these stripes coincide with stripes from other protocols that exclude the riverbed (e.g. the QBR), then the information provided by the RMP complements data of other protocols and its interpretation power is further amplifi ed.

The RMP has received a series of modifi ca-tions – the last one was made by Ferreira and her co-workers (INAG 2008). A series of further modi-fi cations adapted to the conditions of Greece were made by Zogaris and Dimopoulos (Zogaris 2009). These modifi cations were made to save time; the physicochemical part and the vertical arrangement of the vegetation (protocol parts iv, viii) were omit-ted, and the species composition part (part vii) has changed to species cover estimations. In the present research, we decided to proceed with some additions to the RMP sheet, at least in respect to the last one proposed by Zogaris (2009); in the second page of the RMP we condensed the two columns of spe-cies list recorded in the two banks to one and we added one column of species list for riverbed (see Appendix). In this way, the vertical arrangement of vegetation taxa (trees, shrubs and helophytes) is obtained in the fi rst (left) column for left and right banks. In addition, information for trees’ crown cover intercepted over water channel is recorded to the second (right) column, thus enabling us in a later phase (e.g. in the stage of analysis) to potentially associate crown cover (considered as indication of shade) with Prespa trout populations. Another alteration was the division of the “uncovered” area (right lower part of page 2 of the RMP) into three area classes, i.e. those expressing the area covered by rocks, soil (bare ground), and fallen leaves (ir-respectively of the existence of trees in the upper layer). This alteration was decided since in the case of the Agios Germanos river (at least) there were few areas uncovered (by trees); by distinguishing the area covered by soil particles we obtain an indica-tion of the suspended soil that will potentially be transferred to the water course and possibly affect trout habitat quality and populations (Crivelli et al. 2008). Rockiness is an indication of bank stability and avoidance of suspended soil excess (at least for short-term considerations), while the area covered by (dead, yellow) leaves serves as a natural pathway for a signifi cant erosion agent like the rain water that runs over the surface of the leaves ending up in the stream. In this case, the protective role of the yellow leaf carpet is similar to the one played by natural understorey vegetation that decelerates the massive transfer of soil particles. This was consid-ered especially important for banks structured with beeches (Fagus sylvatica) in the upper layer.

The QBR index and the improved RMP were calculated/applied in river and stream lengths of

Assessment of riparian vegetation supporting Prespa trout 67

100 m and both river banks were considered together (e.g. for vegetation cover). Details on the QBR method and fi eld protocol can be found in Munné et al. (2003). Field measurements took place in mid-July 2009 at Agios Germanos river and in mid-September 2009 at Brajcinska river, Kranska river, and Leva stream on a total of 58 sampling stations (20, 21, 11 and 6 respectively, including stations of the Prespa trout monitoring programme (Crivelli et al. 2008) as well as an adequate additional number of stations to obtain a more uniform distribution of the stations along the river lines) located along the rivers at altitudes varying from the lake level (approx. 845 m.a.s.l. to 1550 m.a.s.l.).

2.3. Statistical analyses

From the total of 58 sampling stations in the present paper we analysed data (i) from all 58 sta-tions to describe riparian vegetation types, fl oristic composition and species canopy cover in the riparian area and the riverbed as well as cover of dominant tree species in each river, based on the RMP and (ii) from 17, 17, 9 and 5 stations in Agios Germanos river, Brajcinska river, Kranska river and Leva stream respectively (48 stations in total) to assess riparian habitat quality (by means of the QBR index) of the upper parts of the four rivers that do sustain the Prespa trout, i.e. stations found in lower altitudes and below or inside settlement boundaries were excluded. In that way, the four river catchments are fully described in terms of vegetation, and data from 10 sampling stations that do not sustain Prespa trout populations on a permanent basis are not taken into account in habitat structural quality assessment (assessed by the QBR index and its components) to focus on the parts of the four rivers that do sustain the species. As one of the objectives of the present work is to reach preliminary proposals for conserva-tion measures for the Prespa trout habitats, in our analysis we decided not to include QBR data from sites/stations that would contribute to overall lower QBR values for each of the four rivers (Vrahnakis, Fotiadis 2009).

For the analysis of QBR data, independent variables included the values of the QBR index and its components, i.e. total riparian cover (TRC), cover structure (CST), and cover quality (CQU). The fourth component of the QBR, i.e. channel alterations (CHA) was excluded from the analysis since only 2 of the 48 stations had values other than 25 (one in Brajcinska river and one in Leva stream). The purpose of the analysis was to defi ne the signifi cance of the effect of location (i.e. the watershed of each river) on QBR values and its components (except CHA). For multiple comparisons the independent one-way ANOVA was performed in cases where

normality assumptions were met. The assumption of normality (i.e. if data are consistent to the nor-mal distribution) was explored by the means of the Kolmogorow–Smirnow (with Lilliefors’ signifi cance correction), FKS and Shapiro–Wilk, FSW tests, while the assumption of homogeneity of variance was explored by the Levene’s statistic (based on means). The report of the independent one-way ANOVA’s results included trend analysis through polynomial contrasts (for cubic terms, since four rivers are in-cluded in the analysis) and post-hoc comparisons (for equal variances assumed). The latter used the Gabriel’s procedure which is considered of having greater statistical power especially when samples sizes are unequal (like in this case) (Field 2009). ANOVA report included a measure of the effect size based on the calculation of the omega squared (ω2) which uses the variance explained by the regression model and the error variance (Olejnik, Algina 2003).

In cases where the assumptions of normality were violated the distribution-free Kruskal–Wallis test was performed. This test is considered equiva-lent to ANOVA. In addition, to search for trends that result from ordered patterns of the values the standardized Jonkheere-Terpstra (J-T) statistic (since it follows the normal distribution) and its effect size (rJ-T) were calculated. Also, the pairwise Mann–Whitney post hoc test was made in order to reveal signifi cant differences of the means of the ranks by adjusting the critical value to the number of comparisons (n) (i.e. 0.05/n). The effect size for the Mann–Whitney (U) tests is calculated as

1 2

Zr

n n

, where Z is the standardized U statistic and n1, n2 the sample sizes.

As a general rule the level of signifi cance was taken as α = 0.05. Details about the statistical back-ground are found in Field (2009). Statistical calcula-tions were facilitated by the use of the SPSS v. 14 statistical package (2005).

3. Results 3.1. Assessment of riparian forest quality and comparison of structural components of forest riparian vegetation in the four rivers

The normality test (Table I) and the Levene’s test for homogeneity of variances (Table II) revealed that the QBR summing scores were drawn from a population following the normal distribution, since in all cases FKS, FSW and FLevene statistics were not signifi cantly different than 0.05 (p > 0.05).

Consequently, the independent one-way ANOVA for searching signifi cant effects was appropriate to

68 Y. Kazoglou et al.

use. For the other variables (TRC, CST, CQU) the F statistics revealed that data came from populations that are more consistent with distributions other than normal. In these cases the distribution-free Kruskal–Wallis test was followed.

ANOVA revealed that experimental effect is sig-nifi cant F (3, 44) = 4.038*, p < 0.05, ω = 0.399 which represents a large effect (Kirk 1996) (Table III). Additionally, there was a signifi cant quadratic trend, F (1,44) = 10.307**, p < 0.01, indicating that as we move from Leva stream to Brajcinska river, QBR index values increased in a quadratic mode. The omega value (ω = 0.404) for the quadratic trend represents a large effect.

The Gabriels’ post hoc statistic (samples of unequal size) for detecting differences of the QBR means revealed that two homogenous subsets are formed: a) the one of Leva stream (QBR mean value ± standard error: 73 ± 4.36) and Agios Ger-manos river (76.18 ± 4.15) (mean absolute differ-ence equals 3.176, P = 0.997 NS), and b) Kranska (87.78 ± 3.64) and Brajcinska rivers (88.82 ± 2.33) (difference equals 1.046, P = 0.99 NS). All other

relations searched revealed signifi cant differences of the QBR means.

Based on the assumption-free test of Kruskal-Wallis, differences in the TRC, CST, and CQU components of the four riparian systems were found only for the TRC component which is signifi cantly affected by the watershed (p = 0.0005***), while the other two components (CST, CQU) did not signifi cantly differ (Table IV).

The boxplot (Fig. 1) of the TRC component revealed the same groups of rivers as in the QBR analysis, i.e. both Agios Germanos river and Leva stream had lower values than Kranska and Bra-jcinska rivers. The Jonkheere-Terpstra (J-T) test revealed that there is an ordered pattern of the medians only for the TRC (standardized J-T = 2.4, asymptotic P = 0.017*) (Table V). It means that a trend of ascending median of TRC is observed as we move from Agios Germanos and Leva stream (both having interquartile (50%) range (10-15) and medians equal to 15) to Kranska and Brajcinska rivers (both with interquartile range of 20-25 and medians equal to 25).

Table I. Outcomes of the Kolmogorov–Smirnov and Shapiro–Wilk tests for exploring the assumption of data consistency to normal distribution (NS: non-signifi cant, *, **, ***: signifi cant at 0.05, 0.01, and 0.001 levels respectively).

Variable Rivers of PrespaKolmogorov–Smirnov, FKS Shapiro–Wilk, FSW

Statistic Degrees of freedom (df)

Signifi cance (Sig.) Statistic df Sig.

Riparian forestquality (QBR)

Agios Germanos 0.182 17 0.136 NS 0.897 17 0.06 NSBrajcinska river 0.152 17 0.2 NS 0.915 17 0.124 NSKranska river 0.19 9 0.2 NS 0.923 9 0.414 NSLeva stream 0.421 5 0.004** 0.727 5 0.058 NS

Total ripariancover (TRC)

Agios Germanos 0.311 17 0*** 0.863 17 0.017*Brajcinska river 0.303 17 0*** 0.742 17 0***Kranska river 0.378 9 0** 0.659 9 0***Leva stream 0.246 5 0.2 NS 0.956 5 0.007 **

Cover structure (CST)

Agios Germanos 0.18 17 0.145 NS 0.92 17 0.045 *Brajcinska river 0.342 17 0*** 0.675 17 0***Kranska river 0.414 9 0*** 0.617 9 0***Leva stream 0.473 5 0.001** 0.552 5 0***

Cover quality (CQU)

Agios Germanos 0.413 17 0*** 0.626 17 0***Brajcinska river 0.391 17 0*** 0.679 17 0***Kranska river 0.259 9 0.083 NS 0.844 9 0.045 *Leva stream 0.241 5 0.2 NS 0.821 5 0.019 *

Table II. Outcomes of the Levene statistic (FLevene) for exploring the assumption for homogeneity of variance based on means (NS: non-signifi cant).

Variable Levene, FLevene df1 df2 Sig.Riparian forest quality (QBR) 1.008 3 44 0.398 NSTotal riparian cover (TRC) 0.658 3 44 0.582 NSCover structure (CST) 0.562 3 44 0.643 NSCover quality (CQU) 2.025 3 44 0.124 NS

Assessment of riparian vegetation supporting Prespa trout 69

Table III. Independent one-way Analysis of Variance (ANOVA), and trend analysis for QBR values (NS: non-signifi cant, *, **: signifi cant at 0.05, and 0.01 levels respectively).

Sources of variance Sum of Squares df Mean

Square F Sig.

Between groups (Combined) 2061.5 3 687.2 4.038 0.013*Linear Term Unweighted 44.7 1 44.7 0.263 0.611 NS

Weighted 78.4 1 78.4 0.461 0.501 NSDeviation 1983.1 2 991.6 5.826 0.006**

Quadratic Term Unweighted 1754.2 1 1754.2 10.307 0.002**Weighted 1983.1 1 1983.1 11.652 0.001**Deviation 0 1 0 0 0.998 NS

Cubic Term Unweighted 0 1 0 0 0.998 NSWeighted 0 1 0 0 0.998 NS

Within groups 7488.5 44 170.2Total 9550 47

Table IV. Output from the Kruskal–Wallis test (NS: non-signifi cant, ***: signifi cant at 0.001 level) for the total riparian cover (TRC), cover structure (CST), and cover quality (CQU) components of the riparian forest quality (QBR) index.

TRC CST CQUHK-W 17.66 6.23 2.25Df 3 3 3Asymp. Sig. 0.0005*** 0.101 NS 0.522 NS

Fig. 1. Boxplot for the total riparian cover (TRC) component of the riparian forest quality index (QBR) measured in the four rivers of Prespa (circles represent the cases with outlier TRC values; numbers refer to sampling stations’ code names).

Table V. Testing for trends of the medians according to the Jonkheere-Terpstra (J-T) test (NS: non-signifi cant, *: signifi cant at 0.05 level) for the total riparian cover (TRC), cover structure (CST), and cover quality (CQU) components of the riparian forest quality (QBR) index.

TRC CST CQUNumber of levels in rivers of Prespa 4 4 4N 48 48 48Observed J-T 528 467.5 348.5Mean J-T 405 405 405Std. Deviation of J-T 51.33 49.5 46.78Std. J-T 2.4 1.26 -1.21Asymp. Sig. (2-tailed) 0.017* 0.207 NS 0.227 NSrJ-T 0.346 0.182 -0.175

70 Y. Kazoglou et al.

The Mann–Whitney post hoc test was used to compare in a pairwise manner statistical dif-ferences for the means of the ranks. Given the observed pattern of the TRC values obtained by the boxplot (Fig. 1) three pairwise compari-sons were made, i.e. Agios Germanos vs. Braj-cinska river, Kranska river vs. Brajcinska, and Leva stream vs. Brajcinska. The critical value for the test was adjusted to three comparisons as α = 0.05 / 3 = 0.0167. The test revealed that only the TRC values obtained from Agios Germanos were signifi cantly lower than Brajcinska since the observed signifi cant value of 0.0001 was less than 0.0167 (Table VI).

The effect size for the Mann–Whitney tests revealed that rAGR-BRR = -0.656, rKRR-BRR = -0.059, and rLVS-BRR = -0.471, thus indicating a strong negative effect size for Agios Germanos vs. Braj-cinska, a medium negative effect size for Leva stream vs. Brajcinska and a negligible size effect for Kranska river vs. Brajcinska river.

3.2. Analysis of riparian and riverbed environments and inventory of riparian macrophytes in the four rivers

Agios Germanos river (AGR)

In total, in AGR 16 species were recorded in the tree layer, 25 species in the shrub layer and 11 were helophytes (Table VII). The dominant species are Salix alba, Fagus sylvatica and Alnus glutinosa in the tree layer, the climbing Clematis vitalba in the shrub layer, and Juncus effusus in the helophytes group. Riverbed cover is mainly affected by the tree layer (more specifi cally, by the three dominant species), while shrubs and helophytes have little cover (Table VIII).

There is a strong differentiation in AGR veg-etation performed by both tree cover and fl oristic composition. This differentiation should mainly be attributed to human activities and altitude. More specifi cally, in the study area the following vegeta-tion types are present along the river (Table IX):

a) In high altitudes (1420 and 1536 m.a.s.l.), vegeta-tion types without cover offered by a tree layer (subalpine grasslands) are present containing few woody species, such as Rosa pendulina, R. corym-bifera and Crataegus laciniata. It seems that the lack of a tree layer is caused by intensive grazing and wood cutting for long periods.

b) A vegetation type with F. sylvatica being the domi-nant species in the tree layer at high altitudes (1447-1500 m.a.s.l.), which according to Mucina (1997) and Tsiripidis et al. (2007) is diagnostic of the zonal forests of Querco-Fagetea. In only one of the four stations of that particular vegetation type, the cover of F. sylvatica scores more than 90%, while in the other three tree layer cover is below 40%.

c) In medium and high altitudes (1117-1460 m.a.s.l.), vegetation types dominated mainly by S. alba and S. fragilis, which according to Dafi s et al. (2001) and Fotiadis (2004) are diagnostic of riparian forests of Populetea albae, and by Betula pendula (a pioneer species according to Dafi s (1986)), both with frequent presence of F. sylvatica. In these types, cover ranges from 1 to 80% and this varia-tion is mainly due to the dynamics of vegetation, which, in turn, is directly relevant to land uses in the area. In addition, most of these species are light demanding (Dafi s 1986) and create open canopy stands. Finally, it was found that the tree layer cover is higher at sites with higher F. sylvatica participation.

d) A vegetation type in lower altitudes (854-1018 m.a.s.l.) dominated by the hydrophilous A. gluti-nosa, S. alba, S. fragilis with a proportionally high presence of human activities-related species like J. regia and other invasive or cultivated species such as Populus x canadensis.

The presence of helophytes is fairly small at me-dium and high altitudes, where Equisetum telmateia and J. effusus are mainly met from this plant group; in lower altitudes, where the channel is moderately inclined, many helophytes are present, such as Lyco-pus europaeus, Lythrum salicaria, Alisma plantago-aquatica, Phragmites australis and J. effusus.

Table VI. Post hoc Mann–Whitney test for searching differences of the ranked means of the total riparian cover (TRC) values for three comparisons having the values of Brajcinska as control (critical value for comparisons is 0.05 / 3 = 0.0167).

AGR vs. BRR KRR vs. BRR LVS vs. BRRn1 + n2 34 26 22Mann–Whitney U 37 71.5 16Wilcoxon W 190 224.5 31Z -3.827 -0.303 -2.208Asymp. Sig. (2-tailed) 0.0001 0.762 0.0272 x (1-tailed exact signifi cance) 0.00009 0.792 0.039

Assessment of riparian vegetation supporting Prespa trout 71

Table VII. Species canopy cover (%) of the Agios Germanos river riparian area.

Tree layer Cover Shrub layer Cover Helophytes CoverAlnus glutinosa 6 Abies borisii-regis 0.38 Alisma plantago-aquatica 0.03Betula pendula 1.75 Calystegia sepium 0.08 Athyrium fi lix-femina 0.05Carpinus betulus 0.2 Chamaecytisus polytrichus 0.3 Carex sp. 0.68Clematis vitalba 0.03 Clematis vitalba 4.58 Equisetum telmateia 0.15Corylus avellana 3.35 Cornus sanguinea 0.13 Juncus effusus 1.2Fagus sylvatica 9.28 Corylus avellana 0.63 Juncus sp. 0.98Fraxinus ornus 0.03 Crataegus laciniata 0.15 Lycopus europaeus 0.03Humulus lupulus 0.08 Euonymus europaeus 0.08 Lythrum salicaria 0.08Juglans regia 2.98 Fagus sylvatica 0.45 Phalaris aquatica 0.55Populus xcanadensis 0.63 Humulus lupulus 0.9 Phragmites australis 0.11Prunus avium 0.33 Juglans regia 0.13 Typha latifolia 0.03Prunus cocomilia 1.85 Juniperus communis 0.15Salix alba 20.68 Prunus cocomilia 2.3Salix caprea 1.7 Rosa canina 1.53Salix cinerea 0.38 Rosa corymbifera 2.43Salix fragilis 2.15 Rosa pendulina 0.65

Rubus canescens 1.25Rubus hirtus 0.03Salix alba 1.38Salix amplexicaulis 0.05Salix caprea 0.1Salix cinerea 0.38Sambucus nigra 0.18Thymus longicaulis 1.03Thymus sibthorpii 0.51

Total 51.42 Total 19.78 Total 3.89

Table VIII. Species canopy cover (%) of the Agios Germanos river riverbed.

Tree layer Cover Shrub layer Cover Helophytes CoverAlnus glutinosa 5.4 Clematis vitalba 1.1 Alisma plantago-aquatica 0.1Betula pendula 2.5 Cornus sanguinea 0.25 Athyrium fi lix-femina 0.15Corylus avellana 2.5 Prunus cocomilia 0.05 Equisetum telmateia 0.05Fagus sylvatica 9.65 Rosa canina 0.05 Helophytes (unidentifi ed) 1.3Juglans regia 3 Rosa corymbifera 0.33 Juncus effusus 0.5Salix alba 13.15 Rubus hirtus 0.05 Juncus sp. 0.2Salix caprea 0.7 Salix alba 0.05 Lycopus europaeus 0.05Salix cinerea 0.5 Salix cinerea 0.5 Phalaris aquatica 0.1Salix fragilis 1 Phragmites australis 0.1

Typha latifolia 0.1Total 38.4 Total 2.38 Total 2.65

Table IX. Cover of dominant tree species in Agios Germanos river.

Tree cover (%) No. of stations Altitude (m a.s.l.) Dominant tree species

> 801 1500 F. sylvatica1 865 A. glutinosa, S. alba, Juglans regia

40-802 854, 1018 A. glutinosa, S. alba, Juglans regia2 1210, 1360 S. alba, S. fragilis, B. pendula

1-403 1447-1475 F. sylvatica9 1140-1460 S. alba, S. fragilis, B. pendula

0 2 1420, 1536 -

72 Y. Kazoglou et al.

Table X. Species canopy cover (%) of the Brajcinska river riparian area.

Tree layer Cover Shrub layer Cover Helophytes CoverAbies alba 3.24 Abies alba 1.19 Arundo donax (cf.) 0.1Acer campestre 0.12 Acer pseudoplatanus 0.48 Equisetum telmateia 0.17Acer pseudoplatanus 2.12 Alnus glutinosa 0.48 Lycopus europaeus 0.02Alnus glutinosa 6.74 Betula pendula 0.33 Petasites hybridus 0.17Betula pendula 1.86 Carpinus betulus 0.31 Phragmites australis 0.05Carpinus betulus 0.05 Clematis vitalba 1.57Clematis vitalba 0.57 Colutea arborescens 0.02Cornus sanguinea 0.31 Cornus mas 0.29Corylus avellana 1.5 Corylus avellana 1.38Fagus sylvatica 49.31 Euonymus europaeus 0.52Humulus lupulus 0.6 Fagus sylvatica 4.43Juglans regia 1.14 Hedera helix 0.12Malus domestica 0.12 Humulus lupulus 2.02Populus canadensis 0.24 Juglans regia 0.48Prunus avium 0.19 Ligustrum vulgare 0.02Prunus cocomilia 1 Malus domestica 0.19Quercus cerris 1.07 Prunus cocomilia 1.07Robinia pseudoacacia 1.74 Quercus cerris 0.29Salix alba 7.57 Robinia pseudoacacia 2.74Salix caprea 0.1 Rosa canina 0.88Salix fragilis 1.9 Rosa corymbifera 0.14Salix triandra 0.02 Rosa sp. 0.05

Rubus canescens 0.24Rubus hirtus 1.02Rubus idaeus 1.33Rubus sp. 0.02Salix caprea 0.07Salix fragilis 0.24Sambucus ebulus 0.4Sambucus nigra 0.83Ulmus montana 0.17

Total 81.51 Total 23.32 Total 0.51

Brajcinska river (BRR)

At BRR, 22 species were recorded in the tree layer, 31 species in the shrub layer, i.e. a lot more than the number recorded in AGR, as well as 5 helophytes (Table X). F. sylvatica, S. alba, A. glutinosa and Abies alba are the dominant tree species. F. sylvatica dominates in the shrub layer as well, with an important presence of the invasive Robinia pseudoacacia, while helophytes are sparsely present. The greatest proportion of riverbed cover is due to the tree layer with the four dominant species playing the most important role, while shrubs and helophytes offer very little cover (Table XI). Riverbed cover is much greater than that of the AGR.

In BRR, vegetation is particularly differentiated in respect to AGR since there are no stations without cover in the tree layer. As previously mentioned, this differentiation is relevant to human activities and altitude. More specifi cally, along the BRR the following vegetation types are present (Table XII):

a) In medium and high altitudes (1140 and 1560 m.a.s.l.) the zonal type with the dominance of F. sylvatica and in one station of A. alba. Cover in 8 stations exceeds 80%, and in 6 stations var-ies at 40-80%.

b) In lower altitudes (858-1100 m.a.s.l.), a type dominated by the hydrophilous species A. glutinosa and S. alba, while human activities-related species such as Juglans regia appear in large proportion.

c) In medium altitudes (1150-1230 m.a.s.l.), vegeta-tion types dominated by the hydrophilous species S. alba and the pioneer B. pendula and others, while species like Ulmus montana and Acer pseu-doplatanus also participate; the latter, according to Bergmeier (1990), characterize the unaffected by human plant communities of Tilio-Acerion. In these vegetation types cover varies from 40 to 80%.

d) At the lowest altitudes (865-970 m.a.s.l.), S. alba and the invasive R. pseudoacacia are dominant in vegetation types, which seem to have been catalytically affected by human presence, since the moderate relief favoured cultivation activities.

Assessment of riparian vegetation supporting Prespa trout 73

Table XI. Species canopy cover (%) of the Brajcinska River riverbed.

Tree layer Cover Shrub layer Cover Helophytes CoverAbies alba 5.14 Abies alba 0.43 Athyrium fi lix-femina 0.05Acer pseudoplatanus 1.43 Acer pseudoplatanus 0.14 Equisetum telmateia 0.1Alnus glutinosa 5.48 Betula pendula 0.24 Lemma minor 0.48Betula pendula 1.48 Clematis vitalba 0.57 Persicaria lapathifolia 0.1Clematis vitalba 0.24 Cornus mas 0.71 Petasites hybridus 0.48Cornus sanguinea 0.24 Corylus avellana 0.24 Phragmites australis 0.1Corylus avellana 3.33 Euonymus europaeus 0.48Fagus sylvatica 56.24 Fagus sylvatica 1.81Populus nigra 0.24 Prunus cocomilia 1.19Prunus cocomilia 0.24 Rubus hirtus 0.14Quercus cerris 0.24 Salix caprea 0.24Robinia pseudoacacia 1.33 Sambucus ebulus 0.24Salix alba 10.95 Sambucus nigra 0.48Salix caprea 0.24 Ulmus montana 0.1Salix fragilis 0.48Total 87.29 Total 7 Total 1.29

Table XII. Cover of dominant tree species in Brajcinska river.

Tree cover (%) No. of stations Altitude (m a.s.l.) Dominant tree species> 80 8 1140-1430 Fagus sylvatica

40-80

5 1155-1500 F. sylvatica1 1560 A. alba2 858, 1100 A. glutinosa, S. alba, J. regia2 1150, 1230 S. alba, B. pendula2 905, 970 S. alba, R. pseudoacacia

1-40 1 865 R. pseudoacacia, S. alba

Kranska river (KRR)

In KRR a total of 13 species was recorded in the tree layer, 20 species in the shrub layer, and 2 were helophytes (Table XIII). Dominant tree species are F. sylvatica, A. glutinosa and S. alba. The former dominates the shrub layer as well, the climbing C. vitalba and Rubus canescens are nota-bly present and helophytes are sparse. The greatest proportion of riverbed cover originates from the tree layer – mainly the dominant species (F. sylvatica, A. glutinosa, S. alba) (Table XIV). Riverbed cover in KRR is much greater than in the AGR; less than in the BRR concerning the tree layer, but higher concerning the shrub layer.

Similarly to the BRR, in KRR vegetation is particularly differentiated in respect to AGR as there are no stations without cover in the tree layer, and the presence of stations dominated by S. alba is greatly reduced. Again, this differentiation is affected by human activities and altitude. More specifi cally, along the KRR the following vegetation types are present (Table XV):

a) In medium and high altitudes (1220-1390 m.a.s.l.), the zonal F. sylvatica-dominated type with cover exceeding 80%.

b) In various altitudes (915-1410 m.a.s.l.), vegetation types dominated by A. glutinosa, S. alba, with a large proportion of species relevant to human activities like Juglans regia.

c) In lower altitudes (868, 1175 m.a.s.l.), a vegeta-tion type dominated by the hydrophilous species S. alba and less by other species like S. caprea. Non-native species, like Robinia pseudoacacia, are also present here.

Leva stream (LVS)

In LVS, 8 species were recorded in the tree layer, 11 species in the shrub layer and 5 were helophytes (Table XVI). A. glutinosa is the domi-nant tree species, and, in contrast to the other three rivers, the presence of F. sylvatica here is notably reduced along the stream. A. glutinosa is dominant also in the shrub layer, where the climbing C. vi-talba and Rubus canescens, as well as Rosa canina

74 Y. Kazoglou et al.

Table XIII. Species canopy cover (%) of the Kranska river riparian area.

Tree layer Cover Shrub layer Cover Helophytes CoverAcer pseudoplatanus 0.23 Acer pseudoplatanus 0.09 Persicaria lapathifolia 0.09Alnus glutinosa 14.09 Alnus glutinosa 0.91 Phragmites australis (cf.) 0.09Clematis vitalba 0.45 Clematis vitalba 2.5Corylus avellana 1.14 Corylus avellana 1.82Fagus sylvatica 51.5 Fagus sylvatica 6.95Juglans regia 1.59 Humulus lupulus 0.68Populus canadensis 0.23 Juglans regia 0.27Prunus cocomilia 2.64 Juniperus communis 0.23Quercus cerris 0.09 Ononis spinosa 0.09Salix alba 3.09 Prunus cocomilia 0.09Salix caprea 0.82 Quercus cerris 0.05Salix fragilis 0.45 Rosa arvensis 0.64Sambucus nigra 0.82 Rosa canina 1.59

Rubus canescens 3Rubus hirtus 0.91Salix alba 0.09Salix fragilis 0.45Sambucus ebulus 2.05Sambucus nigra 1.27Tilia platyphyllos 0.14

Total 77.14 Total 23.82 Total 0.18

Table XIV. Species canopy cover (%) of the Kranska River riverbed.

Tree layer Cover Shrub layer Cover Helophytes CoverAcer pseudoplatanus 0.27 Acer pseudoplatanus 0.09 Persicaria lapathifolia 0.27Alnus glutinosa 14.09 Alnus glutinosa 0.91 Phragmites australis (cf.) 0.27Clematis vitalba 0.45 Clematis vitalba 1Corylus avellana 1.36 Corylus avellana 1.36Fagus sylvatica 51.27 Fagus sylvatica 5.27Juglans regia 0.27 Juglans regia 0.27Prunus cocomilia 1.64 Juniperus communis 0.27Salix alba 4.27 Rosa arvensis 0.64Salix caprea 0.91 Rosa canina 0.18Salix fragilis 0.45 Rubus canescens 0.91Sambucus nigra 1.64 Rubus hirtus 0.64

Salix alba 0.27Salix fragilis 0.45Sambucus nigra 1Tilia platyphyllos 0.27

Total 76.64 Total 13.55 Total 0.55

Table XV. Cover of dominant tree species in Kranska river.

Tree cover (%) No. of stations Altitude (m.a.s.l.) Dominant tree species> 80 6 1220-1390 F. sylvatica40-80 2 1100, 1410 A. glutinosa, S. alba, Juglans regia

1-401 915 A. glutinosa, S. alba, Juglans regia1 1175 S. alba, S. caprea1 868 S. alba

Assessment of riparian vegetation supporting Prespa trout 75

are extensively present; helophytes have a minor presence. The largest proportion of riverbed cover comes from the tree layer, namely the dominant species (A. glutinosa); however it is much smaller than riverbed cover in Brajcinska river and Kranska river (Table XVII). Shrubs contribute considerably to riverbed cover.

Vegetation in LVS is azonal and dominated by A. glutinosa (Table XVIII). Apart from the domi-nant species, other azonal species are present to a smaller degree, such as hydrophilous species like S. alba, zonal species like F. sylvatica and Quercus cerris, and human activities-relates species such as Juglans regia and Malus domestica.

4. DiscussionAccording to Munné et al. (2003), the QBR

values (max. score 100) classify the upper parts of Brajcinska (88.82), Kranska (87.78) and Agios Germanos (76.18) rivers to the “some disturbance, good quality” class which is the second best in their

list of fi ve classes. The upper Leva stream (73) is classifi ed between the previous class and the “dis-turbance important, fair quality” class (third in the list) as the authors do not present fi rm boundaries between classes and purposefully leave margins of 5 grades between them as they propose that these boundaries should be checked for other geographi-cal areas.

The statistically signifi cant differences in total riparian cover values are the main source of the re-spective signifi cantly important differences found in total QBR values, which, in turn form the two groups of rivers, i.e. Leva stream and Agios Germanos river upper parts on the one hand (with lower TRC, QBR values), and Kranska river and Brajcinska river upper parts on the other (with higher values). These differ-ences can be attributed to the fact that in the former rivers human activities (e.g. agriculture adjacent to the water courses in Leva stream, which probably also suffers from regular droughts, intensive cattle grazing in Agios Germanos river, and uncontrolled logging activities in the past in both) are present

Table XVI. Species canopy cover (%) of the Leva stream riparian area.

Tree layer Cover Shrub layer Cover Helophytes CoverAcer monspessulanum 0.17 Alnus glutinosa 12.92 Carex remota 0.17Alnus glutinosa 59.58 Clematis vitalba 6.17 Carex sp. 0.17Carpinus betulus 0.42 Corylus avellana 0.83 Equisetum telmateia 0.25Fagus sylvatica 1.25 Crataegus monogyna 0.83 Juncus effusus 0.17Juglans regia 0.83 Juniperus communis 0.83 Persicaria lapathifolia 0.17Malus domestica 1.5 Malus domestica 2.08Quercus cerris 1.08 Prunus cocomilia 1.42Salix alba 2.08 Quercus cerris 0.67

Rosa canina 7Rubus canescens 6.75Rubus hirtus 0.83

Total 66.91 Total 40.33 Total 0.93

Table XVII. Species canopy cover (%) of the Leva stream riverbed.

Tree layer Cover Shrub layer Cover Helophytes CoverAlnus glutinosa 55 Alnus glutinosa 12.5 Carex remota 0.3Carpinus betulus 0.83 Clematis vitalba 1.67 Carex sp. 0.3Fagus sylvatica 0.5 Corylus avellana 0.83Salix alba 1.67 Prunus cocomilia 1.33

Rubus canescens 0.83Total 58 Total 17.2 Total 0.7

Table XVIII. Cover of dominant tree species in Leva stream.

Tree cover (%) Number of stations Altitude (m a.s.l.) Dominant tree species> 80 - - -40-80 5 1010-1090 A. glutinosa1-40 1 970 A. glutinosa

76 Y. Kazoglou et al.

all along the riparian zones, while in the latter it is clear that similar disturbances are far less intensive or have ceased since many years. This is defi nitely the case concerning goat and sheep grazing which is presently very low in terms of stocking densities or absent (goat grazing in forests and natural pastures was banned from 1948 to 1990). Moreover, based on the trees age and size in many of the stations of Kranska river and Brajcinska river it is evident that forest management activities (mainly logging) are maintained at reasonable distances from the riparian zones. Especially for Brajcinska river, this condition may be further supported by the fact that the Pelister National Park boundaries were recently (2009) extended to include some of the upper parts of the river, thus rendering forest management more conservation-oriented, which should be the case at all protected sites of the transboundary Prespa Park.

The main conclusions that can be drawn from the present work are the following:1. Total riparian cover (fi rst component of the QBR

index) values were found signifi cantly higher in the upper parts of Brajcinska river and Kranska river compared to upper parts of Agios Germanos river and Leva stream suggesting that the former provide better conditions for the populations of the Prespa trout (more shade to the channel and better regulation of water temperatures). Differ-ences are mainly attributed to human practices performed along the riparian zones of the four systems, with low intensity in the former two and higher in the latter two.

2. Cover structure, cover quality and channel al-teration (the other three components of the QBR index) did not differ signifi cantly between the four examined watersheds. Channel alteration scores were maximum at 46 out of 48 sampling stations suggesting unmodifi ed river channels in the upper parts of the four rivers, a quality worth maintaining in the future.

3. The comparison of total QBR index values fol-lowed the pattern of the total riparian cover com-ponent (and were largely affected by the latter) indicating that the upper parts of Brajcinska and Kranska rivers sustain better riparian habitat quality than the upper parts of Agios Germanos river and Leva stream.

4. Vegetation in the rivers/stream of AGR, BRR, KRR and LVS is particularly affected by human activities and signifi cantly infl uenced by altitude. More specifi cally, at high altitudes and only in Agios Germanos river, subalpine grasslands are present and their maintenance is largely due to intense grazing. Where conditions are more suitable, zonal forests with Fagus sylvatica are present, which seem to offer the largest propor-tion of both riparian area and riverbed cover. Especially for BRR and KRR, the important

presence of F. sylvatica principally contributes to the totally higher cover of riparian areas and riverbeds in relation to those of AGR and LVS. At lower altitudes and along the settlements in higher altitudes, azonal vegetation types are pres-ent, dominated by A. glutinosa and S. alba. At altitudes below 900 m.a.s.l., where gradients are gentle and human activities intense, vegetation types change considerably in all four systems with the participation of non-native species, while riparian area and riverbed cover are reduced.

5. The actual values of the QBR index for Brajcinska, Kranska and Agios Germanos rivers watersheds (excluding their lower parts) indicate that these three rivers maintain good riparian habitat qual-ity (with some disturbance present), while for Leva stream riparian habitat quality is fair and disturbance is important. Although these indica-tions should be further processed, they can be considered as a base for conservation management activities in the Prespa basin watersheds support-ing Salmo peristericus. Priority should be given to the lower-scoring watersheds of Leva stream and Agios Germanos river, while the target for Brajcinska river and Kranska river should be at least to maintain the existing situation.

6. Riparian forest habitat quality (as described by the QBR index and the RMP) in the upper parts of the four examined rivers, i.e. above the villages found along the river courses, is healthier than in the areas found between the villages and the lake.

7. In the long term, and in order to restore riparian habitats in the four river systems along their full length, conservation efforts should also target the lower part of these rivers where, at present, human activities limit the riparian forest and riverbed functions for wildlife.

8. The implementation of the QBR methodology and the RMP, as applied in the present work, should be repeated every 3-5 years (or earlier if necessary) to monitor riparian forest habitats quality and status in respect to the 2009 condi-tions presented in this paper.

AcknowledgementsThe present study was funded by the SPP

in the framework of the project “Inventory and Assessment of Riparian Forest and Pseudoalpine Rangeland and Forest Vegetation in the Prespa area of Greece and Former Yugoslav Republic of Macedonia” granted to the TEI of Larissa, Greece, Branch of Karditsa/School of Forestry and Manage-ment of Natural Environment. The authors thank Annita Logotheti and Lazaros Nikolaou from the SPP, Vasko Machkovski, Jonce Gagovski and Ioanna Giannou for their assistance in fi eld work conducted in the four rivers of the Prespa basin.

Assessment of riparian vegetation supporting Prespa trout 77

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Appendix

The second page of the modifi ed Riparian Macrophyte Protocol (RMP) as used in the present study (underlined fi elds’ names are inserted by the authors of this research).

FLORISTIC COMPOSITIONSPECIES SPECIES

Banks % PCS Left

% PCS Right Riverbed % PCS

Trees

Shrubs

Helophytes

Herbs

SUMMARY OF SURVEYED AREA AND RIPARIAN VEGETATION WIDTH AT SURVEYED SITE

Left Right SUMTOTAL SURVEYED AREA (x Ha-1)RIPARIAN VEGETATION WIDTH MAX (m)RIPARIAN VEGETAT. WIDTH MEAN (m)RIPARIAN VEGETATION WIDTH MIN (m)UNCOVERED (x Ha-1) rocksUNCOVERED (x Ha-1) soilUNCOVERED (x Ha-1) leaves