The Main Environmental Driving Forces of the Invasive Species in the Romanian Protected Areas

Monica Dumitrascu 1, Ines Grigorescu 1, Mihaela Nastase 2, Carmen Dragota 1, Gheorghe Kucsicsa 1 Institute of Geography, Romanian Academy, Bucharest, Romania 2 Romanian Forest Administration, Romania

Abstract The invasive currently includes more than 400 species (13.87% of the Romanian flora) and according to the third National Report of Biological Diversity Convention, six of them are tree species. Within the protected areas, some of the most representative invasive plant species (IPS) are: Amorpha fruticosa in Balta Mica a Brailei National Park, Ailanthus altissima in Muntii Macinului National Park, Acer negundo, Amorpha fruticosa and Ailanthus altissima in Lunca Muresului Natural Park etc. The paper is aiming to identify and analyze the main environmental driving forces responsible for the introduction and spread of the IPS in Romanian protected areas (natural driving forces: relief, lithology and soil, climate, hydrology, vegetation etc. and human-induced driving forces: agricultural practices, grazing, forest exploitation, mining activities), that could develop introduction pathways whose dimension and dynamics are directly related to the restrictive measures imposed by each IUCN category. The authors have as main purpose to create a GIS-based inventory in order to realize the distribution maps of the main IPS existing in the protected areas of Romania. Based on this assessment and on other relevant case-studies, the authors are aiming to identify the impact of IPS upon the natural habitat of some rare species, especially when talking about protected areas and their conservative importance.

Keywords: Invasive plant species (IPS), environmental driving forces, protected areas, Romania

Introduction The invasive species are largely recognized as major cross-cutting issues in terms of threatening native biodiversity, ecosystem structure and functions, especially within protected areas, causing severe negative socio-economic consequences requiring effective management. They are large-scale phenomena of widespread importance and represent one of the major threats to European biodiversity. Numerous invasive alien species, many introduced into little more than 200 years ago, have become successfully established over large areas of the European community, and the geographical range of a large number of species is increasing (Pysek&Hulme 2005; Hulme, 2007 cited by Lambdon et al., 2008). By invasive alien species one can consider (according to the Biological Diversity Convention definition) all species and subspecies introduced outside their natural habitat, both past and present, from all taxonomic groups. This includes any part of the organism: gametes, seeds, eggs or propagules that might survive and later reproduce. According to IUCN, the invasive species are “immense, insidious and usually irreversible”, therefore suggesting the dimension of their environmental impact. Compared to other threats to biodiversity, invasive introduced species rank second only to habitat destruction, such as forest clearing. They could determine economic losses of about 12.7 billions EUR/an (European Commission, 2008). The invasive species issue is particularly important for European countries especially in terms of sharing common spaces and regions (coastlines, transboundary mountain ranges and protected areas and watercourses) as driving forces and pathways for their introduction and spreading. Thus, political boundaries do not represent efficient barriers as regarding biological and ecological barriers that are critical in determining restrictions of invasions (Richardson et al., 2000). Therefore, in order to exchange information and knowledge on invasive species and assure the connection to practice and policy the Invasive Species Specialist Group (ISSG) was established since 1994. ISSG is a global network in the framework of Species Survival Commission (SSC) of the World Conservation Union (IUCN) assuming an important role in fighting against invasive species by reducing the threats they stress upon to natural ecosystems and the native species they contain.

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Figure 1. Invasive plant species in the European Union countries (processed and adapted after FP6 - Delivering Alien Invasive Species Inventories for Europe - DAISIE and Lambdon et al., 2008)

In Europe, important contributions to the topic have been made by western and central states (Great Britain, Switzerland, Poland, Czech Republic, Finland etc.) trough providing ample but disparate studies. Since the development of the project Delivering Alien Invasive Species In Europe (DAISIE), funded by the sixth framework programme of the European Commission, valuable and comprehensive information on biological invasions in Europe were provided. The project gathered 19 partners from 15 nations plus a great number of contributors and was carried out by means of an international team of experts in the field of biological invasions, latest technologies in database design and display, and an extensive network of European collaborators and stakeholders. Therefore, DAISIE database contains records of 5,798 alien plant species in Europe, out of which 2,843 are alien to Europe (of extra-European origin) and the rest of 2,671 are of European origin (Lambdon et al., 2008).

Invasive plant species in Romania

Convention of Biodiversity (Rio de Janeiro, 1992) set up a series of measures for in situ conservation. As a consequence of ratifying it by a growing number of states, the identification of invasive alien species as well as the measures of the prevention and control of these species has advanced significantly. Although Romania has ratified the Convention of Biodiversity by the law 58/1994, until now, there were no important steps made in this respect, especially in terms of implementation of the article 8 of the Convention, with respect to alien invasive species. The first invasive plants species (IPS) which have been signaled in Romania were at the beginning of 18th century, displayed in several works having a systematic and floristic character. Therefore, one can mention a large number of specimens of Amaranthus hybridus, between the villages Moftinul Mare, Terebeşti and Ardud (Satu Mare County), Amaranthus viridis in Sasca Montană (Caraş Severin County) and Echinochloa oryzoides in Banat. Afterwards, more and more invasive species were identified and cited in different scientific works or floristic lists which were synthesized in “Flora României”, vol. 1-13, 1957-1972 and more recently in “Flora Ilustrată a României”, 2000 (Anastasiu, Negrean, 2005). Presently, the invasive flora of Romania currently includes 435 species (13.87% of the Romanian flora) belonging to 82 families. According to the third National Report of Biological Diversity Convention, six of them are tree species (Acer negundo, Ailanthus altisima, Amopha fruticosa, Cytisus scoparius, Fraxinus americana, and Fraxinus pennsylvanica.). The most taxa belong to families known to invade habitually zones of temperate climate: Asteraceceae (61 taxa), Brassicaceae (38 taxa), Poaceae (30 taxa). Numerous families, like Orchidaceae do not have

BALWOIS 2010 - Ohrid, Republic of Macedonia - 25, 29 May 2010 2 alien representative in our flora, while others, like Amaranthaceae have almost exclusively alien representatives. Alien flora of Romania contains 51 (11.73%) archeophites (which arrived into Europe before) and 384 (88.27%) neophytes (which arrived into Europe after 1492) (Anastasiu, Negrean, 2005). Recent studies reveal that riparian zones appear to be more susceptible to invasion than other ecosystems, because periodic hydrological disturbances destroy or damage riparian vegetation creating openings that provide favorable conditions for the establishment of the invasive propagules. Moreover, rivers act like natural drivers and dispersal agents facilitating the spread of the species (Fenesi, Ruprecht, Vincze, 2009). For instance, some ornamental plants, such as Echinocystis lobata, Helianthus tuberosus, Solidago canadensis, Solidago gigantea subsp. serotina and Rudbeckia laciniata escaped from cultivation and they are abundant especially areas from Transylvania, Banat and Crişana where they invaded the local vegetal communities while other invasive species (Acer negundo, Ailanthus altissima, Aster lanceolatus, Ambrosia artemisiifolia, Parthenocissus inserta) are only scattered (Anastasiu et al., 2008).

The main environmental driving forces responsible for the introduction and spread of the IPS in the Romanian protected areas

There are many ways in which the introduction of non-native or exotic species can be made into new environments. When dealing with the level of invasion, the scientific literature considers some large-scale geographical factors able to explain why some countries in Europe harbor more alien species then others. Therefore some variables were taken into consideration: climatic factors (mean annual precipitation, mean annual temperature, temperature amplitude between July and January), geographical factors (latitude, longitude and area) and economic factors (population density, Gross Domestic Product and roads density). All these variables were taken into consideration as explanatory variables (Lambdon et al., 2008). At a smaller scale, the main environmental drivers responsible for the introduction and spread of the invasive alien species in Romania are of natural and human-induced character. The natural driving forces are referring to variables as lithology, soil, relief, vegetation, hydrology, climate and extreme events and the human-induced driving forces are referring to planting invasive species, agricultural practices, forest exploitation, grazing, mining activities and urban development (tab. 1).

Table 1. The main environmental driving forces responsible for the introduction and spread of the IPS in the Romanian protected areas rocks type lithology chemistry of rocks soil type soil pH altitude relief declivity characteristics slopes exposure

present-day geomorphological processes

dominant vegetation types NATURAL vegetation DRIVING fragmentation rivers FORCES type lakes hydrology chemism temperature air/soil temperature precipitation air humidity climate wind climatic influence global climatic change flooding Salix alba, Salix caprea etc. extreme events wind and snow felling

BALWOIS 2010 - Ohrid, Republic of Macedonia - 25, 29 May 2010 3 for ornamental/ recreation purposes Acer negundo, Ailanthus alissima, planting invasive for forestry purposes Impatiens glandulifera, Fraxinus species for ecological reconstruction pennsylvanica, Amorpha fruticosa etc. purposes crop type Cirsium arvense, Galinsoga parviflora, agricultural farmland fragmentation Conium maculatum, Xanthium practices agricultural pollution italicum, Prunus spinosa etc. land abandonment HUMAN- INDUCED deforestation/forest fragmentation DRIVING forest exploitation Rubus caesius, Rubus idaeus etc. FORCES forest infrastructure

pastures degradation Rumex alpinus, Urtica dioica, grazing land degradation Pteridium aquilinum etc. excessive fertilizers Phragmites australis; Tussilago farfara waste material storing etc. mining activities quarry exploitation uncovering pollution determined by mining changes in water/soil chemism waters Sambucus ebulus; Lycium barbarum waste deposits urban development etc. (urban sprawl) infrastructure (roads, railways etc.) Acer negundo; Ailanthus alissima etc. building working places

The above mentioned environmental stressors are mainly responsible for developing introduction pathways which are considered as “any means that allows the entry or spread of a pest” (FAO- International Plant Protection Council), whose dimension and dynamics are directly related to the restrictive measures imposed by each IUCN category in discussion. Referring to the European territory, ornamental and horticultural plants are considered by far the largest and the most diverse group of plants introduced in Europe as well as the most representative way of introduction. Among unintentional introductions, contaminants of seed, mineral materials and other commodities are responsible for the larger number of alien species introduction (tab. 2) (Lambdon et al., 2008).

Table 2. Pathways of introduction for naturalized alien flora in Europe Pathway Alien in Europe European Origin Alien to Europe Forestry 80 39 38 Amenity 248 119 119 Ornamental 1661 668 946 Agricultural 488 318 156 Horticultural 1018 589 415 Total intentional 2407 1160 1232 Seed contaminant 675 454 215 Mineral contaminant 129 83 43 Other commodity contaminant 287 151 145 Stowaway 363 118 235 Total unintentional 1425 846 565 TOTAL 3832 2006 1797 Source: Processed after Lambdon et al., 2008

When dealing with biodiversity conservation and diminishing the spread and impact of invasive species, the Global Invasive Species Program (GISP), an international partnership dedicated to addressing the global threat of invasive species, recommends the examination of pathways as one of the a more comprehensive approaches of this issue. Through the Invasive Alien Species: A Toolkit of Best Prevention and Management Practices, 2001 and the Global Strategy on Invasive Alien Species 2008-2010 the program is having a vast contribution to the knowledge and awareness of invasive species.

BALWOIS 2010 - Ohrid, Republic of Macedonia - 25, 29 May 2010 4 Invasive plant species in the Romanian protected areas Protected natural areas in Romania cover 1,798,782 hectares, that is, 7.55% of the national territory. Law No. 5/2000 and the Government Decision 2,151/2004 provide for 958 protected areas: 13 national parks (316,047.3 h), 14 natural parks (827,799.6 ha) out of which 2 geoparks (206.978,3 ha), 3 biosphere reserves, 54 scientific reserves (100,224 ha), 240 monuments of nature (2,213.3 ha), 626 nature reserves (161,838.3 ha) (fig. 2). Additionally, after the EU accession (2007), Romania had to reach a 17% protected surface of the national territory (from 7% as it had previously been) by means of other important conservative tools, such as “Natura 2000” European Network (273 Sites of Community Interest - 3,291,854.6 ha and 108 Special Protected Ares - 2,988,713.6 ha) (Bălteanu et al., 2009).

Figure 2. Natural protected areas in Romania

As an expression of both geographical diversity and local evolution of human-environment relations over time, the Romanian protected areas mirrors unique and rich natural landscapes whose main traits are put into risk by the invasion of alien species with severe consequences on the native habitats. Therefore, the present paper focuses on three case studies, two natural parks (The “Balta Mică a Brăilei” Natural Park and The Mureş Floodplain Natural Park) and one national park (The „Munţii Măcinului” National Park) displaying both different environmental conditions (wetlands, floodplains, scrubs grasslands etc.) as well as different management measures according to each IUCN category they fall into. Among the wide range of invasive plant species encountered in the protected areas of Romania, the paper wants to call attention to some of the most representative: Amorpha fruticosa in ”Balta Mica a Brăilei” National Park, Ailanthus altissima in ”Munţii Măcinului” National Park, Acer negundo, Amorpha fruticosa and Ailanthus altissima in Mureşului Floodplain Natural Park etc. The “Balta Mică a Brăilei” Natural Park is located in the eastern part of the Romanian Plain between the Braila Plain and “Insula Mare a Brăilei”, on the lower course of the Danube, within the Călăraşi-Brăila sector, bounded by the River Danube and the Vâlciu Arm and covering a surface of about 17,529 ha. The Park is a wetland of international interest (RAMSAR site), the last natural landmark on Danube lower sector, which, after being affected by hydrotechnical changes, the aquatic complex and terrestrial ecosystems are preserved in a state close to the original one.

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Figures 3 and 4. Landuse (Corine Land Cover, 2000) and Amorpha fruticosa in the “Balta Mică a Brăilei” Natural Park (processed after the “Balta Mică a Brăilei” Natural Park Administration), respectively

It includes an undyked sector of the Danube Floodplain with a luxurious vegetation of riverside coppice, reed, and club rush, lakes, ponds, numerous colonies of water birds, some of them monuments of nature. The region contains a complex of lakes, swamps or backwaters, deserted arms and fluvial levees, the last ones forming alongside the main arms, the majority overflow during high floods (Bălteanu et al., 2005). From climatic point of view, the area under study lies under the plain climatic region with excessive- continental influences characteristic for the east and south-east of Romania. The main climatic parameters frames the Balta Mica a Brăilei Natural Park in a sector with average annual temperatures between 10-11 0C (with over 22 0C in July and around 0 ... -1 0C in January) influenced by a sunshine time among the highest in the country, over 2200 hours/year, out of which more then 1600 in the warm semester of the year. The main climatic feature is revealed by the annual mean interval without frost (200- 225 days), the annual relative humidity of more than 76 % and by the moderated quantities of precipitation (400-500 mm/year). This plain sector is bearing the influence of winds with north-south dominant direction and the local wind Băltăreţul (having east-west direction), an important natural dissemination vector for the existing species (anemocoria). The vegetation of the area under study is mainly of intra-zonal nature depending on the local hydro- climatic conditions, being characterized by floodplain forests with different species of Salix, Populus, Fraxinus, Fraxinus etc. Within the “Balta Mică a Brăilei” Natural Park 221 species of plants were identified, among which, the most known are the: willow (Salix alba, Salix cinerea, Salix fragilis), poplar (Populus alba, Populus nigra), elm (Ulmus foliacea), Myricaria germanica, blackberry bush (Rubus caesius). In the wetland, the plants most seen are the: reed (Phragmites australis), rush (Typha latifolia, Typha angustifolia) etc. The diversity of the fauna reflects the diversity of the habitats, especially because more than half of the ecosystems are natural. Presently, 623 different species have been identified, out of which 99 are protected through national legislation (OUG 57/2007) and European Directives. From the total of birds identified here, over 40 are on the Birds Directive and 34 species are on the Berna Convention List (e.g., Pelecanus crispus, P. onocrotalus, Phalacrocorax pygmeus, Ciconia nigra, Egretta alba etc.) The area under study is mainly developed on Protisoils (Underdeveloped, truncated or trenched soils) characterized by an early stage of evolution with an incomplete profile and only less on Chesnisols (Mollisols) located in the western extremity.

BALWOIS 2010 - Ohrid, Republic of Macedonia - 25, 29 May 2010 6 The only invasive plant specie identified in the “Balta Mică a Brăilei” Natural Park is Amorpha fruticosa (fig. 4 and 5), considered invasive exotic specie for Romania, with the origins in south-east side of the Nord America. It was firstly introduced in the country in the first half of the last century for decorative purposes and also, together with other species (Salix), for the protection of inclined and degraded land. Later on it spreads in the natural Populus and Salix forests and also in the artificial forests along the Danube River. Starting with 1975 it becomes invasive specie and after 1985 it invades broader areas proving a high capacity of widening its habitat.

Figures 5 and 6. Amorfa fructicosa (photo: Cristina Muică) and Acer negundo (The Mureş Floodplain Natural Park Administration), respectively

Presently, in the the “Balta Mică a Brăilei” Natural Park Amorpha covers 13,877 hectares of forests, 54 hectares of pastures and 17 hectares of agriculture land. It occurs on poor, degraded, dry and sandy soils and can survive to extreme climatic conditions. Besides that, the specie is very productive, which leads to a high expansion with a negative impact upon the environment. The false indigo is fast rising specie, struggling the native species with whom it shares the area (Salix triandra, Salix purpurea), sometimes succeeding in replacing them. Over the last years, in the study area, one could noticed that the false indigo is becoming adapted to very humid soils, thus invading the “Balta Mică a Brăilei” Natural Park area, mainly the second floor of forest vegetation, making imposable the natural regeneration of the woods. Slowly Amorpha has eliminating some important priority European habitats such as: habitats with Tamarix ramosissima, with Lemna minor, L. trisulca, Spyrodela polyrhiza and Wolffia arrhiza, with Potamogeton perfoliatus, P. gramineus, P. Lucens, Elodea canadensis and Najas marina, with Sparganium erectum, Berula erecta and Sium latifolium, as well as with Poa pratensis, Festuca pratensis and Alopecurus pratensis. Since 2000, in and around the “Balta Mică a Brăilei” Natural Park, the forest county branch has eliminated this specie on 1214 hectares in the framework of Prototyp Carbon project. Amorpha was mechanic eliminated initially and after that 2 to 3 times/year for 5 years and species of Populus and Salix were planted instead, leading to a significant decrease of the specie. Nowadays the area under study is in progress of eliminating the invasive specie on 212 hectares in the framework of the ongoing Life Natura Project (LIFE 06 NAT/RO/000172). So far, 133 hectares were cleaned and more than 100 hectares was planted with natural species of poplars. Removing the Amorpha bushes is extremely difficult and involves high costs, mainly because of the specie’s high productivity. The methods used are of mechanic nature, with less negative impact upon the environment and on other species. The „Munţii Măcinului” National Park is situated in the northern Dobrogea (Tulcea County) covering about 11,321 ha. It shelters the only old Hercynian Mountains in Romania and some of the oldest in Europe. Its relief, underlain by granites and crystalline schists, consists of jagged crests, tower-like erosion outliers, scarps and tallus trains, so that some summits, no higher than 467 m, actually look like mountains (Bălteanu et al., 2005). Măcin Mountains National Park is characterized by a climate with influences of aridity in the east and pontic in the west. Due to the altitudes varying between 7 and 467m it falls in the low hills and tablelands climatic region with an increased dryness with hot and arid summers, long autumns and snow less winters.

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Figure 7. Land use in the „Munţii Măcinului” National Park (Corine Land Cover, 2000)

The sunshine time has among the highest annual mean values in Romania with more than 2200 hours/year enabling temperature annual means of 8-9 0C (-3…-4 0C in January and 19-20 0C in July). The annual period without snow cover outruns 175-200 days/year. The degree of aridization is also emphasized by the relative humidity (under 78%) and the low amount of precipitation (300-500 mm/an) out of which more than 60% fall in the warm semester of the year. The dominant wind have a north and north-east direction with mean wind speeds of about 4-6 m/s and locally, one can notice an increased frequency of the local wind called “Suhovei”. The hydrographic network is mainly supplied with water coming from precipitations (only to a small extent they result from snow or come from underground source), and from small rivers belonging to Danube (Jijila, Luncaviţa, Cerna, Sorniac rivers) and Black Sea (Taiţa River) drainage basins. Their flows are characterized by big variations, most of them having a seasonal character, mainly as a consequence of the continental aspect of the climate. The vegetation is attributed to the deciduous forests, mainly Quercus pubescens and Q. pedunculiflora and at higher altitudes Q. petraea in alternation with rock vegetation, as well as steppe vegetation characteristic for the limitrophe areas. The fitotaxons’ importance in the study area, as compared to the other rare plants in Romania, results from their composition, in which prevail the Pontic-Balkan (26,4%) and Pontic species (16,7%), to which also add species of Euro-Asian (12,5%), Balkan (11,1%), Mediterranean (8,3%), Mediterranean-Pontic (6,9%) origin, as well as other Caucasian, Asian, African and cosmopolitan species (18,1%). The international importance of these rare taxons is conferred by the presence of some vulnerable, rare and subendemic species (Campanula romanica Dianthus nardiformis, Centaurea tenuiflora, Centaurea gracilenta, Silene cserei etc.), of which 4 are nominated on the “Red European List” as vulnerable or rare species. Macin Mountains are considered an important centre of speciation, due to the intraspecific diversity and to the 11 local taxons identified so far in Romania. Măcin Mountains stand for the genetic centre of Euphorbia măcinensis, Corydalis dobrogensis and Herniaria glabra var. dobrogensis and represents the northern limit of the sub-Mediterranean zone in the Balkan Peninsula making a distinct unit of the floriferous Macedo-Tracian province. Thier bio-geographical importance also results from the interference of species situated at the crossroads of different biogeographical regions. The Măcin Mountains fauna is less studied and is characterized by a great diversity due to the presence of some rare species protected through international regulations. Of the total number of species identified in the Park, 37 species are strictly protected at international level and they are listed in the Birds Directive and the Bern Convention; for this reason, „Munţii Măcinului” National Park have been included in the “List of the European zones important for birds”. Additionally, 41 mammalian species and 11 reptile species have been identified and protected under the Berna Convention. Among the rare species protected at international level we mention: lepidoptera - Polia cherrug (endemism described only in this zone), Chersotis laeta măcini and Chersotis fibriola niculescui, reptiles –

BALWOIS 2010 - Ohrid, Republic of Macedonia - 25, 29 May 2010 8 Spur-thighed tortoise (Testudo graeca ibera), Four lined snake (Elaphe quatorlineata), Nose-horned viper (Vipera ammodytes montadoni), birds – Salker falcon (Falco cherrug), Isabelline wheather (Oenanthe isabelina), existing at the western limit of the worldwide habitat etc. Among the mammal species we can mention: Red deer (Cervus elaphus), present in Dobrudja only in Macin Mountains, Roe deer (Capreolus capreolus), Wild boar (Sus scrofa), Fox (Vulpes vulpes), Wild cat (Felis silvestris) etc. The Golden jackal (Canis aureus) has appeared and bred excessively over the last years, being the main predator for the mammals in the park. Due to the particular physico-geographical conditions, „Munţii Măcinului” National Park stands out by their great variety of soil types. The soils in the park belong to the classes of Chernisoils (Mollisoils) – grey- luvic phaeozems (grey soils) and chernozems and Cambisols. The most aggressive invasive specie in the The „Munţii Măcinului” National Park, Ailanthus altissima, concurrently is considered the most aggressive and dangerous invasive tree specie in Europe because it penetrates into natural vegetation and irreversibly changes its composition. It tolerates dry, very cold and polluted environments. Ailanthus is native to and was introduced into Europe (firstly to England and France) in the late 18th century. In Romania was introduced as ornamental tree, due to its resemblance with palm trees, and for protection on degraded and inclined terrains. It is a very productive specie generating a huge number of fruits to be disseminated. In the „Munţii Măcinului” National Park, the heaven mainly affects the steppe and sylvo-steppe dry grasslands, forest skirts, riparian habitats etc. by competing and removing the native local species (fig. 8). The control of this specie is quite difficult because the mechanical eradication methods (cutting, hand pulling etc.) are not always efficient, therefore they must be completed with other mechanical and even chemical methods.

Figure 8. Ailanthus altissima in the „Munţii Măcinului” National Park (processed after the „Munţii Măcinului” National Park Administration)

The Mureş Floodplain Natural Park was established in 2004 and occupies the embanked enclosure of the Mureş River between the city of Arad and the state border with Hungary. Specific wetland habitats covers a surface of about 17,166 ha and hosts plant and animal species of great scientific value, protected before the Park was created, within four nature reserves: Prundu Mare–Pecica, Igriş Isles, Insula Mare Cenad and Cenad Forest. The park also shelters many archaeological sites and historical monuments (Bălteanu et al., 2005). The Mureş Floodplain Natural Park is a typical wetland ecosystem with running and still waters, alluvial forests as well as an important place for nesting and passage for about 200 bird species, many of them of international importance.

BALWOIS 2010 - Ohrid, Republic of Macedonia - 25, 29 May 2010 9 From climatic point of view, the Mureş Floodplain Natural Park is overlapping the plain climatic region with oceanic and submediterranean influences. The annual mean value of sunshine time is 2100 hours/year with above 1500 hours during the warm semester, drafting an area with mean annual temperatures outrunning 10 0C with over -1…-2 0C in January and 21-22 0C in July. The morpho- hydrological conditions grant rich air humidity (with relative humidity over 74%) and precipitations of about 500-600 mm/an out of which 60% during the warm semester of the year. The wind has a south-east and north dominant direction with speeds of 1-2 m/s in the Mureş river floodplain and 2-3 m/s in the rest of the territory. The local wind is “Austrul” with south-west – north-east direction.

Figure 9. Land use in the Mureş Floodplain Natural Park (Corine Land Cover, 2000)

The Mureş Floodplain Natural Park is characterized by sylvo-steppe vegetation (on the Mureş River terraces) and intra-zonal vegetation in the floodplain area. The species frequently found are Quercus robur and ash Fraxinus anguistifolia together with Populus nigra, Populus alba and Salix alba. These species are mostly found in the small forest in the Cenad area and in the 6,000 ha forest along the Mureş River between Arad and the village of Semlac (which includes the Ceala Forest). From place to place halophile elements can be found. A large number of plants in the park are on “the red list of superior plants in Romania”, namely yarrow (Achillea thracica), water soldier (Stratiotes alloides), Cirsium brachycephalum, prostrate false pimpernel (Lindernia procumbens), brittle waternymph (Najas minor) hog’s fennel (Peucedanum officinale), lesser Butterfly-orchid (Platanthera bifolia) etc. Besides this, there are also three species which are strictly protected according to the Bern Convention: European waterclover (Marsilea quadrifolia), floating watermoss (Salvinia natans) and (Trapa natans). The fauna in the park encompasses a multitude of species, from large mammals to species living on the river bottom. There are large populations of mammal species living within the park, such as the European hamster (Cricetus cricetus), European polecat (Mustela putorius), otter (Lutra lutra), European wildcat (Felix sylvestris), red fox (Vulpes vulpes), red deer (Cervus elaphus) etc. Approximately 200 species of birds live or pass through the park every year. Nearly all the birds living in The Mures Floodplain Natural Park are included in the annexes of the Bern Convention and the EU’s Habitats Directive as since 1988 was designated as an “Important Bird Area”. Among them the most significant is the lesser spotted eagle (Aquila pomarina). Nearly half of the entire population of sand martins (Riparia riparia) on the Mureş River can be found within the Mureş Floodplain Natural Park and all six of the reptile species and nine amphibians species identified within the park are mentioned in the annexes of the Bern Convention and the EU’s Habitats Directive due to the regress of these species, which are considered barometers for the state of an ecosystem’s health (eg. Emys orbicularis, Natrix tessellata, Triturus cristatus etc.). The main soil types characteristic for the area under study are Hydrisoils (Hydromorphic soils), mainly gleysoils which are formed in the condition of excess moisture, Luvisoils (Argilluvic soils) and Salsodisoils (Halomorphic soils).

BALWOIS 2010 - Ohrid, Republic of Macedonia - 25, 29 May 2010 10 Invasive species are some of the most key issues in the Mureş Floodplain Natural Park which is affected by the three plant species: Acer negundo, Ailanthus altissima and Amorpha fruticosa. The most aggressive invasive specie in the study area is Acer negundo (fig. 6), a species of maple native to . The first records of this specie in Romania date back to the late 19th century in the Mureş floodplain area. Presently the species is not widely distributed in the country as it occurs mainly in towns (as an ornamental tree) and spontaneous in abandoned agricultural fields, near railways and roads and in riparian habitats (Fenesi, Ruprecht, Vincze, 2009). In the Mureş Floodplain Natural Park, Acer negundo put at risk the preservation status of the most important natural forest habitats: mixed floodplain forests with Quercus robur, Ulmus minor, Ulmus laevis, Fraxinus excelsior or Fraxinus angustifolia, situated along the river banks as well as the and gallery- forests with Salix alba and Populus alba (fig. 10). It is extremely fast growing specie with a higher invasive character whose regeneration capacity is superior to the one of the native species, thus being an important competitor for Salix, Populus even Fraxinus. Even though it covers only few areas in the Park, Ailanthus altissima could develop into a stronger invasive specie if one takes into consideration its behaviour in some cities (e.g. Arad) where it develops and regenerates in some of the most isolated places (fig. 10).

Figure 10. Invasive plant species in the Mureş Floodplain Natural Park (processed after the Mureş Floodplain Natural Park Administration)

Amorpha fruticosa is another invasive plant specie which is affecting the Mureş Floodplain Natural Park, being introduced at first as decorative specie and as nourishment for pheasants and later becoming an important competitor for the native species. Presently it covers the lowlands situated in close proximity to the dykes and alongside the Mureş River (fig. 10). Besides the above mentioned invasive plant species, one can notice another specie (Juglans nigra) planted for its quality wood. The species is in competition with the native ones but without having an entirely invasive character.

Conclusions The invasion of alien species is considered as one of the most important ecological consequences of the global changes as well as one of the leading threats to biodiversity. Over the last century, the unrestrained development of human activities determined an enhanced spread of invasive species, allowing them to get through natural geographic barriers. This has caused high costs on agriculture, forestry etc. as well as on human health. Even if Romania is hosting a large number of alien species, they are not causing important damages to biodiversity on a large scale, but when dealing with protected areas and their ecological significance, a relatively small number of alien species are causing small-scale ecosystem changes with long-term consequences. Therefore, it is worth mentioning that in Western European countries, the problem of invasive species is stressed not only by the researchers but also by the governments, thus adapting the European Community legislation to controlling the phenomenon. Presently, related programmes are in progress. The importance of assessing IPS in protected areas is increasingly important in terms of establishing the best management measures for invasive species mitigation and promotion of efficient cooperation at national and regional level to prevent or minimize their adverse impacts. At international level, the Rio Convention of Biological Diversity (1992) recognized the threat of the spread of invasive species and

BALWOIS 2010 - Ohrid, Republic of Macedonia - 25, 29 May 2010 11 called for action to limit it. Besides that, a Global Invasive Species Program, formed by the United Nations and other international organizations, is beginning to answer this call with a series of programs designed to deal with particular sorts of introduced species.

Acknowledgements The authors are grateful to Administrations of the Balta Mica a Brăilei” National Park, ”Munţii Măcinului” National Park and Mureşului Floodplain Natural Park for all the support in assessing the case studies. The entire study is developed in the framework of the FP7 – Building Capacity for Black Sea Catchment Obsrvation and Assessment System supporting Sustainable Development (EnviroGRIDS); Project. Coordinator: Université de Genève (UNIGE), Switzerland; http://www.envirogrids.net/.

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