1524 Distribution Mapping of Selected Invasive

DISTRIBUTION MAPPING OF SELECTED INVASIVE WEED SPECIES IN NORTH WESTERN AREA OF REPUBLIC OF SRPSKA (BOSNIA AND HERZEGOVINA) Gordana BABIĆ*, Vojislav TRKULJA Public institution „Agricultural institute of Republic of Srpska, Banja Luka“, Bosnia and Herzegovina *Corresponding author: [email protected] Abstract Invasive weed species are characterized by rapid spread and successful establishment, occupying different habitats and thus potentially pose a threat to the biodiversity around the world. In recent years, a wide distribution of invasive weed species in north western area of Republic of Srpska (RS) caused irreparable and obviously damage across different habitat type. Considering problems such as their wide spreading and negative ecological, economic and social impact, studies in north western area of RS is addressed to selected invasive weed species. Among many, the most invasive is Ambrosia artemisiifolia L., threatening agricultural production and human health. However, a significance importance is placed on other invasive weed species, such as: Asclepias syriaca L., Helianthus tuberosus L. and Fallopia japonica (Hout.) Ronse Decre. Distribution and abundance parameters for selected invasive weed species were done for 62 stands based on Blanque Braun (1964) method and GIS software. Assessment of their occurrence and distribution was taken along the roads in the urban areas, between the settlements in ruderal and less arable land, on the edges of farmland, on arable land, along the rivers and fish pond, in ditches and on the edges of forests. Mapping of above mentioned weed species revealed a wide-spread distribution and renewal potential of selected weed species, thus presenting a real threat to native flora and different habitat type. Keywords: distribution, mapping, invasive weed species, Republic of Srpska. Introduction Numerous invasive alien species have become successfully established over large areas in Europe, thus having an increasing invasive potential (Pysek and Hulme 2005; Hulme, 2007 loc. cit. Lambdon et al., 2008; Dumitraşcu et al., 2010). The invasive weed species are characterized by rapid spread and successful establishment, occupying different habitats and thus potentially pose a threat to the biodiversity around the world. Thus, biological invasions have been recognized as being one of the main components of global change (Shea and Chesson, 2002) that affects populations, communities and even whole ecosystems (Richardson et al., 2000). In recent years, a wide distribution of invasive weed species in north western area of Republic of Srpska caused irreparable and obviously damage across different habitat type. Considering problems such as their wide spreading and negative ecological, economic and social impact, studies in north western area of Republic of Srpska is addressed to selected invasive weed species. Among many, ragweeds (Ambrosia artemisiifolia L.) present one of the most invasive weed species in our area (Trkulja et al., 2012). However, a significance importance is placed on other invasive weed species, such as: common milkweed (Asclepias syriaca L.), Jerusalem artichoke (Helianthus tuberosus L.) and japanese knotweed (Fallopia japonica (Hout.) Ronse Decre.). Common milkweed is in past few years also in expansion and it is considerd that in 1524 the future could present a significant problem in ruderal as well in aglriciltural land (Trkulja et al., 2011). According to Babic and Trkulja (2014), Japanese knotweed stand occurs in wet grassy lowland areas but is also found on hillsides, sunny sites in coastal areas, wetlands and riparian areas, but predominantly it is found near human settlement, along river banks and in waste areas in the north western part of RS. Also regarding to H. tuberosus, the most sever areas are in the river banks of Vrbanja and Sava, as well as areas along the fish pond between Prnjavor and Derventa (Babic and Trkulja, 2015). Material and method The current research mainly focuses on the north western part of RS in relation to species habitat requirements and main environmental features. Field survey was conducted during the vegetation period in 2016. Assessment of the occurrence and distribution of invasive weed species were taken along the roads in the urban areas, between the settlements in ruderal and less arable land, and on the edges of farmland, on arable land, along the river Sava and Vrbanja, as well as along the fish pond, in ditches and on the edges of forests. Quantitative distribution, study species density measure was assessed based on Blanque Braun (1964) method. During fieldwork invasive weed species stands were mapped and recorded with GPS, while polygons were digitized using FITO GIS software. Species habitat requirements Helianthus tuberosus prefers certain habitat types (Fehér and Končeková, 2001). It is best adapted to rich, moist soil that can be found along roadways, in wasteland areas and gardens (Wyse et al., 1986). According to Hartmann et al. (1995) H. tuberosus is completely naturalized on moist, nutrient-rich, sandy or loamy soils, especially along rivers. The most substantial site of occurrence includes riparian nitrophilic vegetation along watercourses, but also a variety of anthropogenic sites. In the landscape, it spreads very aggressively and settles more and more areas. It is contributed not only by spreading through generative diaspores, but also by vegetative propagation of broken-off parts of corms washed away by water to new sites along the watercourse (Cvachová et al., 2002). Fallopia japonica can usually tolerate a wide variety of environmental conditions ranging from high shade, high temperatures (even drought) to high salinity. In its native range, Japanese knotweed is a pioneer species on volcanic slopes and as invasive it invades disturbed habitats, tolerating a variety of soil structures and textures and pH levels, ranging from 3 to 8 (Pysek, 2006). It frequently occurs in riparian habitats (e.g. along river banks), but because of its invasive nature it also tolerates disturbed habitats, such as railroad tracks and roadsides (Forman and Kesseli, 2003). Other studies undertaken on F. japonica also revealed its preference for: boundary walls in farmlands, urban non-industrial land, ruderal habitats, meadows, natural/semi-natural forests, roadways etc. (Tiébré et al., 2008). The species usually installs in open places, its growth and abundance being seriously affected by shading. The rhizomes are very resistant to low temperatures, thus permitting its survival in harsh climatic conditions (up to absolute minimum temperature of -30.2° C) (Barney et al., 2006). Asclepias syriaca invades soils due to insufficient cultivation and herbicide use, fertilizers and irrigation measures (Cramer and Burnside, 1981). Ambrosia artemisiifolia grows best in warm and moist conditions (Deen et al., 1998). However according to Trkulja et al. (2010) ragweed is present also in dry lands, but can develop in different soil type independently regarding to a quality of soil, and thus often could be seen in very poor or in soil with very bad or damage structure (pH level – 3). Same author stated that ragweed distribution goes to north up to 50 parallels, which why are south parts of 1525 continent and Mediterranean are the most favourable areas for spreading this invasive weed species in Europe. Results and discussion Distribution and mapping of selected invasive weed species was observed in the number of municipality of Republic of Srpska, in Banja Luka, Gradiška, Srbac, Vrbanja, Čelinac, Kotor Varoš, Prnjavor and Derventa between the above mentioned municipalities along the roads in populated areas, between settlements in ruderal and less arable land, on the edges of farmland and arable land, near the water sources, along the river Sava and Vrbanja, as well as along the fish pond, in ditches or even in the urban aerias (photo 1-4). Photo 1. A. syriaca in wheat crop Photo 2. A. artemisiifolia and F. japonica in urban area along the roads Photo 3. H. tuberosus on river bank of Photo 4. H. tuberosus along fish pond Vrbanja in Čelinac During the research it is noticed that H. tuberosus behaves as an invasive weed species in the studied region. Frequent expansion of the species into the surrounding sites inner town, near agricultural lands and the cultivated field is also noticed, beside the expansion on the river bank of Vrbanja and Sava. The abundance of Jerusalem artichoke points to a high density of individuals e.g. up to 60-70/m2 along the fish pond between Prnjavor and Derventa, as well on river bank of Vrbanja and Sava (up to 30-40/m2). The abundance, estimated based on the number of steams, points to a high density of individuals of F. japonica on sq.m, e.g. up to 40-50 steams m-2 in the Sava river flood plain as well between Srbac and Derventa along the roads in populated areas, in ruderal and less arable land, on the edges of farmland, and on the edges of forests. In Banja Luka, Gradiška, Srbac, Vrbanja, Čelinac, Kotor Varoš, Prnjavor and Derventa a high density of A. artemisiifolia is determineted. It is present in different habitants and in different 1526 communities. In some areas density of individuals was over 70 m-2 . The highest density is recorded along roads, as well in all type of crops, farmland and less arable lands, stubble fields especially etc. It is noticed that species is highly adjustable to different type of soil, and thus the only place that is not present are forest communities. The lowest abundance was determinate in case of A. syriaca. A highest recorded density of individuals was up to 28 m-2 and mostly in wheat crops, less arable lands and along the roads between the urban areas, near the river Sava. Even the species is present and have the invasive potential, outside the wheat crops, and less arable lands, the highest density was no more than 12 individuals m-2 . With current research 62 invasive weed species stand was recorded in the north western part of RS in 8 municipalities.

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