Assessing anthropogenic pressures on montane riparian forests of Greek rivers

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1 8ο Πανελλήνιο Συμποσιο Ωκεανογραφίας & Αλιείας 887 Assessing anthropogenic pressures on montane riparian forests of Greek rivers S. Zogaris³, Y. Chatzinikolaou ², A.N. Economou, S. Giakoumi, A. Gossiou³, and P. Dimopoulos³ Hellenic Center for Marine Research, Institute of Inland Waters, 46,7 km Athens-Sounio, Anavissos, Attiki, Greece, ²Aristotle University of Thessaloniki, School of Biology, Department of Zoology, Laboratory of Zoology, GR , Thessaloniki, Greece ³Laboratory of Ecology & Biodiversity Conservation, Dept. of Environmental and Natural Resources Management, University of Ioannina, 2 Seferi St., GR- 31, Agrinio, Greece Abstract Since riparian zones are known to be of critical value for maintaining natural river functioning it is important to assess their condition in holistic river quality assessments. Very little published information exists on riparian forests or their ecological status in Greece. In order to survey riparian forest structure, ecological quality status, and to compile information on the main pressures affecting these habitats we developed and applied an assessment procedure which promotes the collection of relevant data at sites where in-stream conditions are also sampled. This work was developed within the RIPIDURABLE Interreg Project and included the sampling of 19 sites in the mountain reaches of the Alfios, Acheloos, Arachthos and Aoos rivers in 25. The results contribute to the identification of riparian forest zones and provide data on specific pressures at the surveyed sites. Overall, the sites showed a variety of anthropogenic pressures but a large proportion of them had riparian stands in relatively good or medium condition. This assessment provides evidence of the importance of riparian forest zones as indicators of river basin quality. ΕκτΙμηση ανθρωπογενων πιεσεων σε ορεινα παραποταμια δαση ΕλληνικΩν ποταμων Σ. Ζόγκαρης³, Γ. Χατζηνικολάου², Α.N.Οικονόμου, Σ. Γιακουμή, Α. Γκόσιου³ και Π. Δημόπουλος³ ΠερΙληψη Οι παραποτάμιες δασικές συστάδες επηρεάζουν και επηρεάζονται από τα παρακείμενα ρέοντα ύδατα αποτελώντας δυναμικές μεταβατικές ζώνες μεταξύ των χερσαίων και των ποτάμιων ενδιαιτημάτων. Στην Ελλάδα υπάρχει ελάχιστη αναφορά σε παραποτάμιες ζώνες και πολύ λίγα γνωρίζουμε για την κατάσταση διατήρησής τους. Κατά τη διάρκεια του ερευνητικού προγράμματος RIPIDURABLE αναπτύχθηκε και εφαρμόστηκε μια μέθοδος προσδιορισμού και αξιολόγησης της κατάστασης των παραποτάμιων δασών των ορεινών ποταμών Αλφειού, Αχελώου, Άραχθου και Αώου, οι οποίοι μελετήθηκαν το 25. Η ανάλυση στηρίχθηκε σε 19 δειγματοληψίες σε θέσεις όπου έχουν συλλεχθεί και άλλα αβιοτικά και βιοτικά δείγματα προκειμένου να καθοριστεί η οικολογική κατάσταση των ορεινών ποταμών. Η μέθοδος περιλαμβάνει την αποτύπωση της κυρίαρχης βλάστησης των παραποτάμιων ζωνών και την εκτίμηση της κατάστασής τους με τη χρήση στατιστικών δεικτών. Οι επιμέρους ανθρωπογενείς πιέσεις σε επίπεδο θέσης δειγματοληψίας, αλλά και στο ευρύτερο ποτάμιο τμήμα προσδιορίσθηκαν με οπτική εκτίμηση κατά τις επιτόπιες αυτοψίες. Τα αποτελέσματα της έρευνας δείχνουν ότι πολλά ορεινά ποτάμια συγκροτούν σχετικά καλής ή μέτριας ποιότητας συστάδες παραποτάμιων δασών και συχνά η οικολογική τους κατάσταση αντανακλά τη γενική κατάσταση αλλοίωσης των ευρύτερων ποτάμιων τμημάτων. Τα αποτελέσματα της παρούσας έρευνας ενισχύουν την άποψη ότι τα παραποτάμια δάση αποτελούν καλούς ενδείκτες οικολογικής ποιότητας και σχετίζονται άμεσα με την οικολογική ακεραιότητα των ποταμών.

2 888 8ο Πανελλήνιο Συμποσιο Ωκεανογραφίας & Αλιείας Introduction Montane riparian forests are known to influence stream environments in many ways, such as by providing natural habitats and physico-chemical conditions, resource provisioning, erosion control and stability of in-stream aquatic conditions (Verry, 24). Since riparian vegetation directly affects the structure and functioning of river corridors it is important not to overlook riparian vegetation integrity when assessing the ecological status of rivers and streams (Ferreira et al. 22). Simple statistical indices can be used to summarize the condition of riparian zones within the scope of site-based river health monitoring projects. In Greece, there is remarkably little published data on riparian forests or the threats they may face. We developed and applied a procedure to collect pertinent riparian forest data and relevant environmental and anthropogenic pressures data from site-based river surveys. This presentation exhibits preliminary results concerning riparian forest zone identification, and ecological status assessments with a focus on anthropogenic pressures. Method and Materials Approaches towards a definition of riparian forests vary according to the specific research scope. We conducted two different assessment approaches in this survey procedure: a) collecting vegetation data from riparian forests zones and, b) assessing the ecological state of the wider riparian ecotone. For the riparian forest vegetation survey we focused our attention on a particularly vulnerable stream-side vegetation area, within the ecotone termed here the riparian forest zone. This relatively narrow zone of woody vegetation immediately adjacent to the active channel of the river represents the functional, strictly stream-side riparian zone and includes those features of woody vegetation that contribute most directly to the aquatic food base, shading and habitat structure of the stream environment. Considering this premise, our specific riparian forest zone definition does not encompass adjacent terrestrial vegetation areas that are often considered part of the riparian ecotone (sensu Verry et al. 24) nor the river s wetted channel or the treeless portion of the active channel (Fig. 1). When using indices to diagnose general riparian degradation, a laterally wider area, the area usually referred as the riparian ecotone is considered, as communicated by Munne et al. (23) and Verry et al. (24). Site selection and survey assessment metrics Fig. 1. Sketch of the riparian ecotone and the stream-side riparian forest zone which is a component of this ecotone and is defined by the dominance of hydrophilous woody vegetation and its topographic proximity to the river s active channel.

3 8ο Πανελλήνιο Συμποσιο Ωκεανογραφίας & Αλιείας 889 Table.1. Data elements collected with different protocols with respect to site (1 m reach) or segment (1 or 5 km lengths depending on river catchment size). Data from Riparian and In-stream s Indices Index type Riparian Macrophyte Field Form In-stream Fish Field Form Pressures (within Instream Fish Field Form) Riparian Forest Quality Index (QBR) Stream Visual Assessment (SVAP) Reference M. T. Ferreira (pers. com.) EU Fame project Modified from EU Fame project Munne et al. (23) Modified from Bjorkland et al. (21) Only montane rivers were surveyed ranging from 231 m to 1331 m elevation on perennial tributaries and the main stems of the rivers Alfios, Acheloos, Arachthos, and Aoos (Fig.3). Site selection was effected by choosing relatively accessible sites for conducting a full range of instream bioassessments that followed a roughly representative stream macrohabitat and stream degradation selection procedure. Hence, representative river reaches characterized by a fairly typical range of anthropogenic degradation impacts were chosen (FAME, 25). The survey was undertaken on an expedition from 21 July to 21 September 25 and a total of 19 surveyed sites are analyzed here. Five sets of data concerning riparian structure and condition were collected at each site; these included also indices Collected information categories Vegetation structure (% strata cover), Dominant woody plant list and percent cover per segment for left and right bank streaches. Margin Substrate; 5 Site Modifications (% cover), 8 Anthropogenic alterations for left and right bank reaches (% cover of alteration) Instream features and physicochemical data, habitat, shadedness 8 pressures affecting riparian ecotone: Land use per segment; Urbanization per segment; Connectivity per segment; Floodplain Lateral movement per segment; Riparian zone segment; Hydrological regime per site; Morphological condition per site; Overgrazing per site. Four metrics: Total Riparian Cover; Cover Structure; Cover Quality; Channel Alteration; Channel Typology 15 metrics referring to in-stream and riparian corridor; including riparian vegetation integrity such as the Spanish QBR (Table 1). Assessing anthropogenic pressures and ecological status was based on pressure identification at the 1 m site reach and the segment scale. River segments stretches were defined as the following: 1 km length in small streams with catchments <1 km²; 5 km river segment when catchments are 1-1 km²; 1 km river segment when catchments are >1 km² (FAME, 25). Pressures were visually assessed following a fiveclass scale (i.e. 1= excellent conditions status; 5 =bad conditions status) based on conceptual type-specific reference conditions as promoted in the WFD 2/6/EC) (FAME 25) (Table 1).

4 89 8ο Πανελλήνιο Συμποσιο Ωκεανογραφίας & Αλιείας Tree Cutting Roads Rubbish Livestock Trampling Mineral Extraction Reinforced Banks Builder's Waste Other Channel Alterations Fig.2. The eight most prevalent site-based anthropogenic pressure types recorded at 19 sites. The category other channel alterations compresses the following pressures: deflectors/ intrusions, canalization, gabion and small weirs. Results and Discussion Various indicators of anthropogenic disturbance were employed and visually assessed at the site and stream segment scale, of which three are presented here. The pressures score summarizes 5 segment and 3 site anthropogenic pressure types (Table 1). The results show that most of the sites had a relatively limited number of dif Correlations among the riparian structure and two indices vs. : r 2 =,511; p=, vs. : r 2 =,597; p=, vs. : r 2 =,4577; p=, , 1, , 9 5 2,425 2, 9 3, , 1,5 2, 2,5 3, 3, Fig. 3. Correlations among the metric, the Total Pressure Score and the QBR Index in the 19 studied sites in Western Greece. The horizontal s axis direction from left to right in the histograms refers from low to high degrees of the pressure or condition (i.e. 9-1 shows least impacted sites). Inset map depicts site locations with black dots.

5 8ο Πανελλήνιο Συμποσιο Ωκεανογραφίας & Αλιείας 891 ferent pressure types at this scale (Fig. 3). Riparian structure at the segment scale is a metric of the pressures score and this pressure was found to correlate well with the combined pressures score and the QBR index score. In this way the segment-scale assessment of riparian forest integrity alone seems to be a good indicator of both the cumulative pressures score and the riparian forest habitat condition at the site as diagnosed by the QBR. One assumption here is that if riparian conditions are disturbed over a wider segment river stretch, specific conditions at the site level will also be similarly degraded. QBR index results show that a large proportion of sites are in fairly good or medium condition, but only 13 sites had a score of above 9 (i.e. high status or near-natural conditions). Additional pressure types were also visually documented in the site-based field form at each 1 m long site reach (8 dominant anthropogenic pressures are shown in Fig 2). It is important to note that most montane rivers show relatively limited channel alterations, but key problems are: tree cutting, roads, rubbish and livestock grazing. These four pressures were present at a very large number of surveyed sites (Fig 2.). Despite initial sampling design constraints (i.e. limited by accessibility) the recorded conditions present a fairly representative snapshot of typical pressures over a fairly large portion of the montane rivers and streams of western Greece. Overall, this assessment provides evidence on the importance of riparian zones as indicators of river basin quality. Acknowledgements We acknowledge the assistance of Prof. M.T. Ferreira, Dr. R. Bjorkland, N. Koutsikos, D. Kommatas, and N. Manthos (Via Natura Rafting) for help with protocol development and/or field assistance. References BJORKLAND, R., PRINGLE, C.M. and NEW- TON, B. 21. A stream visual assessment protocol (SVAP) for riparian landowners. Env. Monitoring and Assessment, 68: FAME 25. Final Report; Manual for the application of the European Fish Index EFI. FERREIRA, M.T., ALBUQUERQUE, A., AQUIAR, F.C., and SIDORKEWICZ, N., 22. Assessing reference sites and ecological quality of river plant assemblages from an Iberian basin using a multivariate approach. Arch. Hydrobiol. 155(1): MUNNE, A., PRAT, N., SOLA, C., BONADA, N., and RIERADEVALL, M., 23. A simple field method for assessing the ecological quality of riparian habitat in rivers and streams: QBR index. Aquatic Conserv: Mar. Freshw. Ecosyst. 13: VERRY, E.S., DOLLOFF, C.A. and MAN- NING, M.E., 24. Riparian ecotone: a functional definition and delineation for resource assessment. Water, Air, and Soil Pollution: Focus. 4: