Key Biological Indicators to Assess Amorpha Fruticosa Invasive Terrestrial Plant Species in Romanian Protected Areas

Recent Advances in Environmental Science

Key biological indicators to assess Amorpha fruticosa Invasive Terrestrial Plant Species in Romanian protected areas.

MONICA DUMITRASCU1, MIHAI DOROFTEI2, INES GRIGORESCU1, GHEORGHE KUCSICSA1, SOFIA DRAGOTĂ1 Institute of Geography, Romanian Academy, 12 Dimitrie Racoviţă Street, sector 2, 023993, Bucharest ROMANIA 2 Danube Delta National Institute, 165 Babadag Street, 820112, Tulcea ROMANIA [email protected] http://www.geoinst.ro

Abstract: - Under the current human-induced impacts, native ecosystems become highly exposed to a wide range of environmental threats such as biological invasions. The paper is aiming to assess the occurrence, development and spread of one of the main Invasive Terrestrial Plant Specie (ITPS) in the Romanian protected areas, Amorpha fruticosa, considered one of the most dangerous ITPS in Europe as it causes damages to natural ecosystems. The study is centred on assessing species’ habitat requirements and relevant biological indicators (abundance, frequency, ecological significance and ecological significance) in relation to its key environmental driving forces (both natural and human-induced) in selected case-studies (Danube Delta Biosphere Reserve, Comana Natural Park and Mureş Floodplain Natural Park) relying on scientific cross-references, in-depth field surveys and accurate mapping.

Key-Words: - biological indicators, Invasive Terrestrial Plant Species (ITPS), Amorpha fruticosa, protected areas, Danube Delta Biosphere Reserve, Comana Natural Park, Mureş Floodplain Natural Park, Romania

1 Introduction goals, to diminish direct pressures on biodiversity Invasive Terrestrial Plant Species (ITPS) pose through identifying, controlling or eradicating significant treat to biodiversity and ecosystem invasive alien species and pathways as well as services particularly since the Convention on adopting measures to manage pathways and prevent Biological Diversity’s 2010 Biodiversity Target has their introduction and establishment [9]. stimulated global initiatives to quantify the extent of Although Romania has ratified the Convention of biological invasions, their impact on biodiversity Biodiversity (Rio de Janeiro, 1992) by means of law and the related policy responses [1]. As a 58/1994, until now there were no important steps consequence, are often categorized as economic, made, especially in terms of implementation of environmental, or social threats [2], [1], thus article 8, with respect to alien invasive species [10]. becoming key components of global change through Therefore, the qualitative and quantitative (using their high adaptive capacity enabling them to relevant biological indicators) assessment of ITPS penetrate natural geographic barriers or political species is essential in estimating potential spread boundaries [3], [4], [5]. and evolution pathways, undertaking proper and Consequently, ITPS have become successfully sustainable management decisions and mitigating established over large areas in Europe causing impacts. significant environmental socio-economic damages [6], [7] and, under the increasing trade and travel 2 Methods and data means the threat they produce is likely to increase The current study is trying to asses Amorpha [1]. In protected areas, in particular, biological fruticosa ITPS in the Romanian protected areas invasions are disturbing drivers for ecosystem focusing on: Danube Delta Biosphere Reserve, functioning and structure, as well as for species, Comana Natural Park and Mureş Floodplain Natural species communities or habitats [8]. Park (Fig. 1). The authors used scientific cross- Under the global context of increasing biological referencing, field surveys (using G.P.S device, invasions, the New Strategic Plan of the Convention sample taking, monitoring of the key areas) and GIS on Biological Diversity - Aichi Biodiversity Targets mapping in order to able to compute species for 2011-2020 is proposing, among its strategic spreading area.

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Fig. 1. Natural major protected areas in Romania

The surface areas chosen for the comparative of surveys in which the species is present; N = total research regarding the phenology data were of 10 m² number of surveys). According to the frequency for pastures and reed-covered areas and of 100 m² value of Ailanthus altissima, four categories can be for the forest and brushwood communities. The distinguished: F1 – accidental species (1 – 25% of quantitative biological indices taken into relevees); F2 – accessories species (25.1 – 50% of consideration for the current approach (coverage, relevees); F3 – characteristic species (50.1 – 75% of abundance, frequency and ecological significance) relevees); F4 – frequent characteristic species (75.1 were computed in several test-areas in the analysed – 100% of relevees). case-studies. Additionally, in order to identify species’ position Species’ coverage was undertaken based on the within the phytocenosis, the ecologic signification real and absolute coverage whose values vary index was computed as a relationship between depending on the phyto-individual habitus of frequency and abundance (Tab. 2). species. According to Braun-Blanquet the estimation system of coverage includes 5 levels: 1 Table 2. The ecological significance index values – weak, under 1/20 of sample surface; 2 – between 1/20 and 1/4 of sample surface; 3 - between 1/4 and Ecological significance index (W) (%) Class 1/2 of sample surface; 4 - between 1/2 and 3/4 of W1 (0,1-1) accidental sample surface; 5 - between 3/4 and 4/4 of the test W2 (1-5) accessory area (Tab. 1). W3 (5-10) associate W4 (10-20) complementary Table 1. Abundance – coverage scale according to W5 >20 characteristic Braun – Blanquet system [11] Class Coverage interval (%) Class value (%) Thus, based on this in-depth analysis the authors 5 75-100 87.5 and relate biological indicators with relevant key 4 50-75 62.5 natural and human-induced driving forces (Tab. 3). 3 25-50 37.5

2 10-25 17.5 1 1-10 5.5 Table 3. Key environmental driving forces responsible for the introduction and spread of the Species’ abundance was carried out based on ITPS in the Romanian protected areas Major driving forces Consequent driving forces Braun-Blanquet methodology which considers a soil soil type, texture visual scale: 1-very rare; 2-rare; 3-less abundant; 4- altitude, slopes exposure, abundant; 5-very abundant individuals. relief characteristics declivity, geomorphic features etc. Species’ frequency was computed based on dominant vegetation types, vegetation Raunkiaer (1934) method indicating the number of fragmentation phytocenosis in which the analysed species was NATURAL wetlands lakes, rivers, ponds, marches air/soil temperature, climate identified [11]: F = n/N x 100, in which: n = number precipitation, air humidity,

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wind, climate change signals flooding, wind and snow 4 Results and discussions extreme events felling, heavy rains Amorpha fruticosa can be easily adapted to different planting invasive for ornamental/ recreation, types of natural and disturbed habitats but its species forestry purposes crop type, land abandonment, preference for wetlands can be an explanation for its agricultural practices excessive fertilizers wide spread in the Danube Delta Biosphere deforestation/forest Reserve [4], [5], [15], [20]. The detailed forest exploitation fragmentation, forest infrastructure investigation undertaken in five pilot areas (Pardina grazing pastures and land degradation Agricultural Polder, Caraorman sand dunes, Şontea waste deposits, transport

HUMAN INDUCED INDUCED HUMAN – Fortuna Depression, Matiţa – Merhei lake urban development network (roads, railways etc.), building sites complex and Dunăvăt – Dranov fishing pond) for Source: [12] which relevant key biological indicators were computed revealed species preference for the fluvial sand banks along the main Danube branches and fluvial-marine sand banks as well as the flooded 3 Invasive Terrestrial Plant Species in areas (Fig. 2). the Romanian Protected Areas The first studies undertaken in Romania on ITPS date back to the beginning of 18th century mainly in works having a systematic and floristic character. Soon after, an increased number of invasive species were recorded and described in other relevant papers or floristic inventories which were synthesized in “Flora României”, vol. 1-13, 1957-1972 and more recently in “Flora IIustrată a României”, 2000 [4]. Presently, the invasive flora of Romania includes over 400 species (13.87% of the Romanian flora) [4], [13] which is continuously updated trough recent studies [13] In the Romanian protected areas, among the most dangerous ITPS, the following rank first: [14]: Elaeagnus anguistifolia, Amorpha fruticosa, Ailanthus altissima, Acer negundo, Robinia Fig. 2. The distribution of Amorpha fruticosa in the pseudoacacia, Fallopia japonica etc. Danube Delta Biosphere Reserve Recent studies consider Amorpha fruticosa as one of the worst invaders, especially in wetland Thus, highest coverage, frequency and habitats, endangering Salix spp. associations abundance values were registered in the Dunăvăt – (EUNIS code F9.12) [15]. Dranov fishing pond and Şontea – Fortuna Amorpha fruticosa belongs to the south-eastern Depression where wetland habitats prevail (Fig.3). part of North America flora and was introduced in In terms of habitat types, Amorpha populates in Romania in the first half of the last century for this protected area: 92A0 Salix alba and Populus decorative and practical (protection of degraded alba galleries; 92D0 Southern riparian galleries and land along the Danube River together with Salix) thickets (Nerio-Tamaricetea and Securinegion purposes.The species proved a high capacity of tinctoriae); 91E0*Alluvial forests with Alnus widening its spreading area, thus being adapted to glutinosa and Fraxinus excelsior (AlnoPadion, all types of habitats such as: along river banks Alnion incanae, Salicion albae); 91F0 Riparian (poplar or willow galleries, almond willow-osier mixed forests of Quercus robur, Ulmus laevis, U. scrubs), unvegetated or sparsely vegetated shores, minor, Fraxinus excelsior or F. angustifolia along water-fringing reedbeds, riverine and lakeshore the great rivers (Ulmenion minoris). scrubs etc. [16], metal-contaminated soils, tailing ponds, fertilized terrains [17], [18], [19] etc.

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Fig. 3. Key biological indices for Amorpha fruticosa in Danube Delta Biosphere Reserve Fig. 5. Key biological indices for Amorpha fruticosa in Comana Natural Park Besides riparian habitats the species also inhabits dune and steppe-like habitats such as: 2160 Dunes The monitoring of the areas and the results of the with Hippophaë rhamnoides; 92D0 Southern computed biological indicators revealed higher riparian galleries and thickets (Nerio-Tamaricetea values for abundance and coverage in the Crucea de and Securinegion tinctoriae); 62C0* Ponto-Sarmatic Piatra Village and Budeni Lake and frequency in steppes as well as 3270 Rivers with muddy banks Călugăreni Forest and Budeni Lake, thus showing with Chenopodium rubri pp and Bidention species’ preference for riparian and edge habitats vegetation. such as: 92A0 Salix alba and Populus alba galleries; In the Comana Natural Park Amorpha 92D0 Southern riparian galleries and thickets fruticosa prove to have a higher dominance in the (Nerio-Tamaricetea and Securinegion tinctoriae); surroundings of wetlands (margins of Comana 91E0*Alluvial forests with Alnus glutinosa and Lake), river channels and alongside the transport Fraxinus excelsior (Alno Padion, Alnion incanae, network, especially on the spoiled soils located next Salicion albae). to the non-electrificated railroad as well in the In the Mureş Floodplain Natural Park, outskirts of forests (Fig. 4). Amorpha fruticosa have a preference for forest roads and forest glades (especially north to Mureş river), as well as pastures and edges of arable lands (Fig. 6). This endorsed the authors to select as main key areas for analysis the following: Zădăreni Village along the banks of the Mureş River; Popinilor Forest; Raţa-Vaida Forest (Pecica Village); Bezdin Forest (Sânpetru German village); riparian habitats, meadows and modified vegetation in Şeitin Village and Igriş Village.

Fig. 4. The distribution of Amorpha fruticosa in the Comana Natural Park

In accordance with the identified preferred habitats, the authors selected seven pilot areas for a detailed analysis: Crucea de Piatră Village, the Fig. 6. The distribution of Amorpha fruticosa in the northern side of Călugăreni village, southern part of Mureş Floodplain Natural Park Comana Village (along the rail road), Budeni Lake (south side shore), north of Vlad Ţepeş Village, The computed indices for the selected key areas Fântânele Forest along Neajlov River and south of show a higher development of the analysed species Mihai Bravu Village (Fig. 5). in Zădăreni Village and Popinilor and Raţa-Vaida Forests, mainly preferring riparian habitats (Tab. 7): 92A0 Salix alba and Populus alba galleries; 92D0 Southern riparian galleries and thickets (Nerio- Tamaricetea and Securinegion tinctoriae);

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91E0*Alluvial forests with Alnus glutinosa and Fraxinus excelsior (AlnoPadion, Alnion incanae, Salicion albae); 91F0 Riparian mixed forests of Quercus robur, Ulmus laevis, U. minor, Fraxinus excelsior or F. angustifolia along the great rivers (Ulmenion minoris); 3270 Rivers with muddy banks with Chenopodium rubri pp and Bidention vegetation.

Fig. 9. Average ecological significance for Amorpha fruticosa in the studied areas

The average values points Danube Delta Biosphere Reserve fist in terms of ecological significance of Amorpha fruticosa followed by Comana Natural Park and Lunca Muresului. In all studied areas, the species is considered (W3) associate species (Tab. 2, Fig. 9).

Fig. 7. Key biological indices for Amorpha fruticosa in Mureş Floodplain Natural Park 5 Conclusion The landscapes of protected areas were transformed, The investigation of ITPS Amorpha fruticosa in over the last years, by human activities through the selected case-studies has slight differences in tourism, deforestation, overgrazing, overexploitation terms of the analysed biological indicators. Thus, of natural resources etc. All of these have led to the Danube Delta Biosphere Reserve shows higher replacement of natural forest and pasture abundance and coverage values while the frequency ecosystems with secondary meadow and scrub seems lower as compared to the other two study- associations, thus affecting the floristic structure and areas. composition. Considering the strong relationship between biological invaders and their key driving forces of change, assessing species dynamics, impact and spreading potential becomes an important task in identifying natural habitats’ pressures and threats. The identification of both natural and human-induced disturbances and relating them to in-depth biological (through detailed observations, computing biological indicators etc.) and geographical assessment (GIS- based investigations, integrated spatial analysis etc.)

Fig. 8. Average class values of the key biological could support sustainable management strategies to indicators for Amorpha fruticosa in the studied areas prevent the invasion of species in natural protected areas. On the other hand, Comana Natural Park displays higher frequency rates while in the case of Acknowledgements Mures Floodplain Natural Park the values for the The entire study is developed in the framework of three indicators show rather even value (Fig. 8). the FP7 – Building Capacity for Black Sea Consequently, the ecological significance Catchments Observation and Assessment System considered as the relationship between frequency supporting Sustainable Development and abundance, shows values from between 2 and (EnviroGRIDS); http://www.envirogrids.net/.

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