Available online at www.notulaebotanicae.ro Not. Bot. Hort. Agrobot. Cluj 37 (2) 2009, 22-27 Print ISSN 0255-965X; Electronic ISSN 1842-4309 Notulae Botanicae Horti Agrobotanici Cluj-Napoca Virgin Status Assessment of Plje?evica Forest in Bosnia - Herzegovina ?emal VISNJIC1), Sead VOJNIKOVIC1), Florin IORAS2), Mirza DAUTBASIC1), Ioan Vasile ABRUDAN3), Dan GUREAN3), Ahmet LOJO1), Tarik TRESTIC1), Dalibor BALLIAN1), Muhamed BAJRIC1) 1) University of Sarajevo, 20 Zagrebacka St., 71000 Sarajevo, Bosnia-Herzegoina; mirzad@bih.net.ba 2) Buckinghamshire New University, Queen Alexandra Road, Bucks HP11 2JZ-High Wycombe, United Kingdom; Florin.Ioras@bucks.ac.uk 3) Transilania University, 1 Sirul Beethoen St., 500123 Braso, Romania; abrudan@unitbv.ro Abstract Virgin forests are relatively rare in the European temperate zone. is is due to the continuous use of forest historically and to increasing high population densities. Virgin forests are forest where the structure and dynamics have developed entirely under natural conditions, without any human interference or inuence. is article assesses the Plje?evica forest in Bosnia Herzegovina to establish whether it can be classied as virgin forest. e structure and components of the forest were assessed in a 1 ha sample plot and four 400m2 quadrats. e values of the biodiversity indexes (as dened by Shannon and Weaver, Krebs and Meyer), species richness and evenness, the distribution of the dierent stand development stages and the proportion of dead wood lead to the conclusion that Plje?evica forest presents a set of structural and dynamic characteristics close to the ones typical for virgin forests in Europe, so in order to maintain its status as such, in the meantime it should undergo a protection management programme. Keywords: diversity, evenness, dead wood, unmanaged forest Introduction e term ?virgin forest? has many denitions in the for- estry specic literature. ?ermak (1910) denes virgin for- est as ?a forest which looks like it was never touched by a human?, Leibundgut (1993) describes such forest as ?a for- est untouched by humans, with enormous trees, great vol- ume of trunk, and hardly passable oor space with much dead wood?, Rubner (1960) considers virgin forest to be ?forest vegetation which belongs to the climatic climax stage of vegetation in terms of development and growth?. According to Korpel (1995) the virgin forest is a ?forest whose composition, development, growth and other life processes are driven by the ecological parameters, primarily by the climate characteristics?. What these denitions have in common is the belief that life processes in virgin forests are determined by eco- logical factors and that the human inuence is negligible. In Europe, as well as in Bosnia Herzegovina (BiH), people have used forest resources in an unsystematic manner for centuries, taking what they needed when they needed it; such as material for construction, timber for rewood, wood for coal, etc. is kind of forest use inevitably inu- ences the composition, the presence and the variety of spe- cies and the structural development of stands which we call natural forests. e main dierences between managed forest and vir- gin forest are considered to be related to the proportion of standing and dead trees (occurrence of dead trees in virgin forest is higher), the horizontal and vertical structure of the stand (in virgin forest, trees are found in all develop- ment stages), and the presence of natural regeneration (in virgin forest, the natural regeneration occurs throughout the area). Virgin forests are important remnants of valuable and rare forest ecosystems. ey provide a basis for close-to- nature silvicultural research and applications, for designing national networks of protected forest and for providing a reference for naturalness assessment of other forests more or less managed Bosnia Herzegovina?s forests (1.266.000 ha) are part of the Piceo-Abieti-Fagetum associations, beech, r and Nor- way spruce representing more than 80 percent of Bosnia Herzegovina?s forest area (Pintari?, 1978). e vast major- ity of forests in BiH are managed primarily for wood pro- duction; however, Bosnia-Herzegovina (BiH) has 0.3% of its forests classied as virgin forests, namely Perucica, Janj, Lom and Trstionica forests. Plje?evica forest (Fig. 1) is con- sidered to be the h virgin forest located in BiH, but no detailed studies have recently been carried out to conrm this status. Visnjic, ?. et al. / Not. Bot. Hort. Agrobot. Cluj 37 (2) 2009, 22-27 23 Methodology In order to investigate the virgin status of Plje?evica forest, species composition, distribution of the diameter classes and development stages, proportion of dead wood and dieback trees were assessed in a 1 ha (100x100m) sam- ple plot situated in the centre of the studied forest. Four polygons were randomly selected for phytoceno- sis assessment according to Braun ? Blanquet method (1964) as well as for species richness by adopting a quadrat method (20 x 20 m size) - see Fig. 2. Each species was recorded by frequency and coverage range and all plant species identied within the quadrat were recorded in a Turboveg 2.38 database (Hennekens and Schaminee, 2001), and exported to Juice 6.4 pro- gramme (Tichy and Holt, 2006) for analysis. For each quadrat, the biodiversity and evenness in- dexes were calculated using the Shannon-Wiener Index (Krebs, 1999). Also, the identied plant species were cross checked against the Red Book of Bosnia and Herzegovina as enlisted by ?ili? (1996). Each such species was scored according to IUCN standards as follows: E ? highly en- dangered species, V ? endangered or vulnerable species, R ? rare or potentially endangered species. Results and discussions Forest phytocenosis A total of 71 species were identied and recorded (based on the quadrats established in the study area), of which 4 were rare and/or endangered species. On the ba- sis of oristic system analysis (Tab. 2) it resulted that the plant community is part of the Dinara forests of Abieti- Fagetum dinaricum association (Tregubov, 1957). is community of beech and r belongs to Aremonio - Fagion alliance (T?r?k et al. 1989). is alliance is stipulated in Annex I of the Habitat Directive (Directive 92/43/EEC) as habitat 91K0 - Illyrian Fagus sylvatica forests, which is of community interest. e survey identied the presence of four species which are classied according to IUCN standards as endangered (Tab. 3). e biodiversity indexes were also calculated for the study plots, and their values are presented in Tab. 4. According to Krebs (1999), the maximum values of Shannon ? Wiener index do not exceed 5,00 for biologi- e only virgin forest in BiH which has been subject of several scientic investigations in the past is Perucica forest (1,434 ha). Most of the work was of a phytosocio- logical and entomological nature, and was conducted by Drini? (1956), Fukarek (1962, 1964, 1964a), Leibundgut (1982), Pintari? (1978), Stefanovi? (1970, 1988). Re- cently a study was carried out on the virgin forests of Janj and Lom (Maunaga, 2001), and on a further small forest enclave in Trstionica near Kakanj, that was described by Ballian and Miki? (2002). In the present study the authors conducted a vegeta- tion survey in Plje?evica forest in order to investigate the extent to which this forest has the characteristics of a vir- gin forest. Study area e study area is a forest stand of 38,8 ha, located at 44?45?north latitude, 15?45?east longitude, at an average altitude of 1120 m on a north-eastern slope of Plje?evica Mountain, which is located east of the Una River, near the border between Croatia and Bosnia Herzegovina. Plje?evica belongs to the Dinara Mountain system, which is mostly made up of Jurassic limestone. e dominant soil type is eutricambosol and small patches of renzina are also found. e climate characteristics of the area are summarised in Tab. 1 based on the data provided by the meteorologi- cal stations of Bosanski Petrovac and Drini?, which are the closest ones to the investigated forest. Tab. 1. Climate data Meteorological station Altitude (m) Mean air temperature (?C) Mean rainfall (mm) Length of the growing season (days) Potential evaporation in April-September (mm) Annual April-September Annual April- September Bosanski Petrovac 650 8.7 14.6 1198 630 170 528 Drini? 730 7.6 12.4 1350 625 156 503 Fig. 1. Location of virgin forests in Bosnia Herzegovina Visnjic, ?. et al. / Not. Bot. Hort. Agrobot. Cluj 37 (2) 2009, 22-27 24 cal communities, therefore the diversity of higher plants in the examined area could be described as average. e index of ?Evenness? (Krebs, 1999) established for the study plots shows no over domination of one or more species. Distribution of tree diameter One indicator for the lack of past production man- agement could be the diameter distribution of trees. Fig. 3 presents the stand composition by diameter classes and shows an uneven age structure with a slightly irregular dis- tribution of trees in the higher diameter classes (from 65 to 105 cm). Fig. 2. Location of sample plots in Plje?evica virgin forest Tab. 2. Synoptic tab. with percentage constancy and coverage range 1,2) Group No. 1 No. of relev? 4 Euphorbia amygdaloides 100 + Fagus sylatica 100 1-4 Aremonia agrimonoides 100 + Stellaria nemorum 100 +-2 Galium odoratum 100 +-1 Galium rotundifolium 100 1 Sanicula europaea 100 +-1 Prenanthes purpurea 100 + Anemone nemorosa 100 2-4 Dryopteris lix-mas 100 +-1 Athyrium lix-femina 100 1-2 Oxalis acetosella 100 1-2 Abies alba 100 1-3 Viola reichenbachiana 100 + Mycelis muralis 100 + Cardamine enneaphyllos 75 +-1 Glechoma hirsuta 75 +-1 Fagus sylatica 75 +-1 Polystichum lonchitis 75 +-1 Acer pseudoplatanus 75 +-1 Asplenium scolopendrium 75 + Abies alba 75 +-1 Cardamine kitaibelii 75 1-2 Geranium robertianum 75 + Senecio germanicus 75 + Cardamine waldsteinii 75 +-2 Acer pseudoplatanus 50 +-1 Lonicera alpigena 50 + Rubus hirtus 50 + Abies alba 50 1 Arum maculatum 50 + Rhamnus alpinus s. fallax 50 +-1 Symphytum tuberosum 50 +-1 Picea abies 50 + Abies alba 50 1 Maianthemum bifolium 50 + Hordelymus europaeus 50 + Cardamine bulbifera 50 + Polygonatum verticillatum 50 + Ruscus hypoglossum 50 + Actaea spicata 50 + Paris quadrifolia 50 + Solanum dulcamara 25 + Lonicera nigra 25 1 Festuca altissima 25 1 Gentiana asclepiadea 25 + Sorbus aucuparia 25 + Carex sylatica 25 + Luzula sylatica 25 + Sambucus racemosa 25 + Cystopteris agilis 25 + Vaccinium myrtillus 25 1 Picea abies 25 2 Picea abies 25 + Epilobium angustifolium 25 + Lilium martagon 25 + Lonicera alpigena 25 + Polygonatum multiorum 25 1 Heracleum sphondylium 25 + Daphne mezereum 25 + Epilobium montanum 25 + Lunaria rediviva 25 + Fagus sylatica 25 1 Polypodium vulgare 25 + Daphne laureola 25 + Scrophularia nodosa 25 + Galeopsis speciosa 25 + Rubus hirtus 25 1 Salia glutinosa 25 + 1) Presence of the same species in the tab. is explained by the occurrence of species in several layers 2) Individual names of species are automatically converted by the soware into names according to the standard database for Croatia, for example: Asperula odorata into Galium odoratum or Senecio nemorensis into Senecio germanicus. Visnjic, ?. et al. / Not. Bot. Hort. Agrobot. Cluj 37 (2) 2009, 22-27 25 e presence of large-size trees is one of the major indi- cators for a virgin forest according to Leibundgut (1993). In addition to this, in a managed forest the tree diameter does not usually exceed 80 cm (Pintari?, 1999), so the tree distribution by diameter classes in the studied forest is close to the diameter distribution typical for an uneven aged/un-managed forest. Forest development stages Within the 1 ha studied plot, the presence of dier- ent development stages was assessed in rectangular plots (quadrats) of 20 m x 20 m placed inside the study area. e size of these plots (400 m2) is considered adequate for establishing the presence of dierent development stages in a virgin forest, as described by Meyer (1999). e distri- bution of the development stages within the studied plot is shown in Fig. 4, and their description and frequency is presented in Tab. 5. It can be noticed that all the development stages typi- cal for a virgin forest were identied within the 1 ha study area. Development stages are rotating on a relatively small area and have approximately the same frequency of occur- rence. In order to assess the diversity of developme stages, the Shannon-Wiener index (Shannon and Weaver, 1976) and Evenness index (Pielou, 1966) were calculated by us- ing the presence of individual development stages in re- lation to the area they covered, instead of the number of species. e values of the Shannon?s index (2.455) and Even- ness index (0.807) for the study plot in the Plje?evica for- est are signicantly above those calculated for some virgin forest reserves in Germany and Albania (presented in Tab. 6) (Tabaku, 1999), thus indicating a potential virgin for- est. Natural regeneration was found on 96% of the area, being well represented in all plots but one quadrat, where it covered less than 25% of the plot, indicating that the entire area surveyed in this study has gone through a natu- ral process of rejuvenation, following a pattern found in unmanaged forests. Dead wood and dieback trees Presence of dead wood is important to biological di- versity within a forest stand, and it is a critical factor for the development of some species like mushrooms, lichens, mosses, arthropods, rodents, birds etc. Based on research Tab. 3. Rare and endangered species found in Plje?evica forest Study plot Species Status 1 Y ? coordinate X - coordinate 1 2 3 Cardamine kitaibelii V 5559179 5559261 5559199 4964186 4964207 4964329 1 Daphne laureola R 5559179 4964186 2 Lilium martagon V 5559261 4964207 4 Ruscus hypoglossum E 55591795559137 4964186 4964275 1) Species status according to the IUCN standards: E ? highly endangered species, V ? endangered or vulnerable species, R ? rare or potentially endangered species. Tab. 4. Indexes of diversity and evenness Biodiversity indexes P1 P2 P3 P4 Mean values Number of species 33 32 35 33 33 Shannon ? Wiener Index 2,59 3,12 3,10 2,76 2,89 Evenness 0,72 0,84 0,82 0,76 0,78 Fig. 3. Distribution of trees by species and diameter classes (10 cm) in the 1 ha study plot in Plje?evica forest Visnjic, ?. et al. / Not. Bot. Hort. Agrobot. Cluj 37 (2) 2009, 22-27 26 focused on optimising tree stand diversity, it has been sug- gested that the proportion of dead wood in relation to the total wood mass should be around 20-25 % (Siitonen, 2001; Alexander, 2003) in unmanaged forests. In man- aged forests that share is much lower, at around 1-10 % (Meyer, 1999). us, one can conclude that an increasing proportion of dead wood is followed by increased biologi- cal diversity. Current forest management does not encour- age increased presence of dead wood and the management guidelines prescribe its removal, as the presence is per- ceived as an increased risk of pest infestation. erefore, the higher proportion of dead wood found in an area the less probability of a production management plan being in place. is could be a further indication of a possible unmanaged/virgin forest presence. e dead wood proportion in the forest of Plje?evica is presented in Tab. 7. is tab. shows that the proportion of dead wood is 12 % of total wood mass for the 1 ha study plot, and it is higher for r (14 %) than for beech (9 %). e larger pro- portion of dead wood in the case of r might be explained by its smaller proportion in lower diameter classes (Fig. 3). e proportion of dead wood is higher than in managed forests and yet is within the limits specied by Droessler (2006) for European virgin forests. On the other hand, Fig. 4 shows that the dieback trees and dead trunks (quite common for the decaying and senescence phases) are un- evenly distributed all over the study area. Conclusions Despite the fact that the work presented in this paper has some limitations due to a relatively small number of plots, the results show clearly that Plje?evica forest pres- ents a set of structural and dynamic characteristics close to the ones typical for virgin forests in Europe. Further inves- tigations are needed in this respect and a protection status for Plje?evica forest is recommended considering the small area of virgin forests in Bosnia-Herzegovina. Fig. 4. Distribution of the development stages within the 1 ha study plot Tab. 5. Frequency of the development stages within the study area Development stages within the study area of 1 ha Frequency of occurrence Canopy opening ? At least 25% of the area is covered by mature trees, and progeny and young trees cover less than 50% of the area 1 Rejuvenating ? Occurrence of the natural progeny within clearings in more than 50% of the area 5 Intensive growth ? Intensive increase of wood mass through competition between species 4 Maturity ? Increase of wood mass becomes constant and does not change 5 Senescence ? Increase of wood mass stagnates over a longer period, certain trees are dying back and the process of wood degradation starts 4 Decaying ? Decomposition of large wood mass relative to the increase of new wood mass 6 Tab. 6. Development stage diversity indexes for virgin forests reserves1) in Albania and Germany (Tabaku, 1999) Albania Germany Virgin forest Puka Rajka Miridita Heilige Hallen Bleicherode Dassel Shannon- Wiener Index 1.67 1.49 1.47 1.81 1.63 1.28 Evenness 0.80 0.72 0.75 0.92 0.84 0.66 1) Beech forest with silver r and ash. Visnjic, ?. et al. / Not. Bot. Hort. Agrobot. 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Proportion of dead wood in total wood mass in Plje?evica forest Species Volume of living trees (m3/ha) Volume of dead wood (m3/ha) Total volume (m3/ha) % of dead wood Beech 277.4 28.6 306.0 9.3 Fir 352.8 60.4 413.2 14.6 Spruce 17.5 0 17.5 0 Sycamore 3.4 0 3.4 0 European ash 0.4 0 0.4 0 Elm 0.001 0 0.001 0 TOTAL 651.5 89.0 740.5 12.0