Riparian Forest Communities Along

Glasnik Šumarskog fakulteta Univerziteta u Banjoj Luci 226, 2017, 95–111 Original scientific paper / Originalni naučni rad DOI: 10.7251/GSF1726095M UDK: 581.526.42:502.5(497.6Sutjeska) RIPARIAN FOREST COMMUNITIES ALONG WATERCOURSES IN THE SUTJESKA NATIONAL PARK (SE BOSNIA AND HERZEGOVINA) OBALNE ŠUMSKE ZAJEDNICE UZ VODOTOKE U NACIONALNOM PARKU SUTJESKA (JI BOSNA I HERCEGOVINA) Đorđije Milanović1*, Vladimir Stupar1 1 University of Banja Luka, Faculty of Forestry, Stepe Stepanovića 75A, 78 000 Banja Luka, Bosnia and Herzegovina *e-mail: [email protected] Abstract The paper deals with the floristic and ecological diversity of the riparian forest and scrub communities of the Sutjeska National Park in SE Bosnia and Herzegovina. Watercourses of the NP are represented by montane to submontane small rivers and creeks with fast-flowing water and frequent strong but short floods. This caused specific types of riverine forest vegetation to develop along their banks. Classifica- tion and ordination methods of numerical analysis were applied on 42 relevés sampled in the field. The classification has revealed five ecologically interpretable relevé groups: (1) willow scrub of Salix eleagnos and S. caprea on fertile fine grained deposits; (2) forests of Alnus glutinosa and Salix alba also on finer deposits; (3) narrow strips of Alnus glutinosa along the low banks of smaller streams; (4) narrow strips of Alnus glutinosaalong the steep banks of wider streams; (5) thermo-mesophilous scrub of Salix eleagnos and Ostrya carpinifolia on gravel beds. All five groups are floristically and ecologically well distinguished. While groups 1 and 3 are similar to already described communities from Central Europe (Salicetum eleagno-purpureae and Stellario nemorum-Alnetum glutinosae, respectivelly), groups 4 and 5 most probably present, up to date, undescribed associations. Group 2 is rather floristically and ecologically heterogeneous, and as such possess transitional character (betweenSalicion albae and Alnion incanae alliances). Ordination revealed ecological gradient from nutrient rich (groups 1 and 2) to less nutrient rich communities (groups 4 and 5). Key words: Alnion incanae, Alnus glutinosa, ecological gradient, phytosociology, Salicion eleagno- daphnoidis, Salix eleagnos, vegetation 1. INTRODUCTION / UVOD Although riparian forest and vegetation along al., 1979), and Čemernica Mt. (Redžić et al., the montane and submontane streams is rela- 1986) but without any relevés, while there was tively well studied across temperate Europe one published relevé from Neretva river valley (Sburlino et al., 2012; Chytrý, 2013; Dakskobler (Redžić et al., 1992). The only systematic study et al., 2013; Kalníková & Kudrnovsky, 2017), the of this vegetation in B&H, up to date, was under- same cannot be said about Bosnia and Herze- taken within the research of deciduous forests govina (B&H). This type of vegetation in B&H on Vranica Mt. (Barudanović, 2003; Barudanović was mentioned from Treskavica and Bjelašnica & Redžić, 2006). This resulted in low level of Mts. (Fukarek, 1957), Vranica Mt. (Lakušić et knowledge of these communities in B&H in 95 Milanović & Stupar: Riparian forest communities along watercourses in the Sutjeska National Park terms of their species composition, ecology, (Salicion eleagno-daphnoidis (Moor 1958) Grass syntaxonomy, but also their conservation status. 1993, Salicetea purpureae Moor 1958) (Mucina et al., 2016). Albeit they are physiognomically The same can be stated for the Sutjeska Nation- and floristically different these communities are al Park, the oldest and second largest national similar in a way that they thrive in the areas of park in B&H (Stupar, 2011). Although its flora constant periodic fluctuations of water level, and vegetation have been studied for a long with periods of flooding and periods of drought, time, not all habitats were equally investigated. and consequently disturbed and undeveloped Besides alpine and canyon non-forest habitats soil (Ellenberg, 2009). (Lakušić, 1968, 1970; Lakušić et al., 1969, 1987a, 1987b), as well as forest habitats of virgin forest These communities have been under extensive Perućica (Fukarek & Stefanović, 1958; Fukarek, human impact for a long time. They are espe- 1969, 1970; Fabijanić & Manuševa, 1984), other cially sensitive to management measures which plant communities remained fairly underinves- aim to change flood regime (hydroelectric pow- tigated. This is particularly true for the vegeta- er plants, stream regulations, gravel excavation tion of diverse tree and scrub formations along etc.). That is why they are among the Europe’s the fast flowing, gravel-bed watercourses. These most endangered habitats (Kalníková & Ku- habitats were reported for the first time by Fu- drnovsky, 2017). They are listed in the Annex I of karek (1969) but with very little detail provided. Habitats Directive as priority habitat 91E0* - Al- The only more detailed study of riparian forest luvial forests with Alnus glutinosa and Fraxinus communities in Sutjeska National Park, up to excelsior (Alno-Padion, Alnion incanae, Salicion the present, was made by Fukarek (1970) bring- albae) and habitat 3240 - Alpine rivers and their ing five relevés from Alnus glutinosa formations ligneous vegetation with Salix eleagnos along along the Perućica stream in the virgin forest their banks (Council of the European Communi- Perućica. ties, 1992). Syntaxonomically, this vegetation belongs to two The objective of this paper was to classify ripar- alliances of two different classes: a) alder-ash ian tree and scrub communities of the Sutjeska and oak riparian floodplain forests on nutrient- National Park, to characterize them by their rich alluvial soils in the nemoral zone of Europe species composition and ecology and to reveal (Alnion incanae Pawłowski et al. 1928, Alno glu- ecological drivers of their floristic composition tinosae-Populetea albae P. Fukarek et Fabijanić variation. This work also aims to start the pro- 1968) and b) willow scrub on the gravelly stream cess of settling these important plant commu- banks in the submontane to subalpine belts of nities into syntaxonomical scheme of national, the Alps, the Pyrenees and the Carpathians regional and European level. 2. MATERIALS AND METHODS / MATERIJAL I METODE The field research was conducted inside Sutjes- We studied riparian tree and scrub vegetation along ka National Park (Fig. 1) in southeastern Bos- the watercourses of Sutjeska National Park, which nia and Herzegovina over a four-year period included narrow streamside forests, gravel bar for- (2014–2017). Established in 1962 by the border mations or woodland of wider floodplains, domi- between Bosnia and Herzegovina and Monte- nated by Alnus glutinosaand/or Salix eleagnos. negro, Sutjeska National Park, encompassing Study included streams Sutjeska, Hrčavka, Jabučica the area of 16 052 ha, is the oldest, and until and Izgorka. All of these watercourses belong to recently the largest national park in Bosnia and the Sutjeska river watershed which drains to the Herzegovina (Stupar, 2011). In terms biodiver- Drina river (Zubčević, 1969). They are gravel-bed, sity, this area is one of the most important parts fast flowing and impetuous streams whose narrow of Bosnia and Herzegovina (Redžić et al., 2009; steep valleys often transform into canyons, while Redžić, 2012; Lubarda et al., 2014). 96 Glasnik Šumarskog fakulteta Univerziteta u Banjoj Luci 226, 2017, 95–111 Figure 1. Location of the relevés with location of the Sutjeska National Park in B&H (upper right) / Slika 1. Položaj lokaliteta snimaka sa položajem Nacionalnog parka Sutjeska u BiH (gore desno) gentle slope or flat flood plains are rare and small 20 cm, maximum high water is 370 cm, while the (Bušatlija, 1969). They cut their beds through a mean annual water is 80 cm (Zubčević, 1969). variety of bedrocks including flysch, limestone Vegetation sampling was performed using the and dolomites, schists and shales (Trubelja & Central European phytosociological method Miladinović, 1969). The elevation ranges between (Braun-Blanquet, 1964). Relevés were made only 530 and 1000 m. These streams are prone to fre- in typical stands with closed canopy, while all quent and often dramatic changes of water level; structurally degraded stands, mosaics and transi- e.g., for the Sutjeska river minimum low water is tional communities were not taken into account. 97 Milanović & Stupar: Riparian forest communities along watercourses in the Sutjeska National Park A total of 42 relevés was compiled in the Tur- measure of cluster heterogeneity. We subjective- boveg database (Hennekens & Schaminée, ly accepted the classification level of five clusters 2001) and exported to JUICE 7 software (Tichý, as being most ecologically interpretable. Floristic 2002) for further analysis. Although during the differences among clusters were revealed by cal- sampling vertical structure was recorded in sev- culating their diagnostic species on the basis of en vegetation layers, for the means of numerical species frequency. Only species with frequency analysis it was reduced to four layers: tree layer above 50% in particular cluster were considered (A), higher shrub layer (B1), lower shrub layer diagnostic if they fulfill additional criterion that (B2) and herb layer (C). Mosses were discarded the difference in species frequency between the due to inconsistent sampling. Taxonomy and no- particular cluster and other clusters is more than menclature followed The Plant List (The

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