Moving out of town? The status of alien plants in high‐Arctic Svalbard, and a method for monitoring of alien flora in high‐risk, polar environments

Rising human activity in the Arctic, combined with a warming climate, increases probability of introduction and establishment alien plant species. While settlements are known hotspots for persistent populations, little is about colonization particularly susceptible natural habitats. Systematic monitoring lacking available survey methods vary greatly. Here, we present most comprehensive vascular species high-Arctic archipelago Svalbard to date, aimed at (i) providing status within settlements; (ii) surveying high-risk habitats such as those high visitor numbers nutrient enrichment from sea bird colonies; (iii) presenting systematic method that can be implemented future work on Arctic environments; (iv) discuss possibilities mapping using unmanned aerial vehicles. The grid survey, covering 1.7 km2 over three six cliffs, detected 36 Alien were exclusively found areas activity, associated current or historic animal husbandry. identified successful eradication Anthriscus sylvestris Barentsburg, well rapid expansion Taraxacum sect. Ruderalia last few decades. As there currently no consistent tailored polar environments, propose methodology could structured regime part an adaptive strategy towards Arctic. 1. Økende menneskelig aktivitet i Arktis kombinert med et varmere klima øker sannsynligheten introduksjon og etablering av fremmede plantearter. Selv om bosetninger er kjente etablerte bestander plantearter, vet vi lite deres kolonisering ut særlig egnede naturlige habitat. Systematisk overvåking mangler, kartleggingsmetoder har variert mye. 2. Her presenterer den mest omfattende kartleggingen karplanter på per dag, mål å: i) få en oppdatert bosetninger, ii) undersøke høyrisiko naturtyper slik som områder under fuglefjell økt næringstilførsel tillegg mange ilandstigninger, iii) utarbeide systematisk overvåkingsmetodikk å overvåke plantearter Arktis, iv) diskutere mulighetene kartlegge de planteartenes habitat droner. 3. Den systematiske ruteundersøkelsen, dekket tre seks fuglefjell, kartla De planteartene vokste bare aktivitet, hovedsakelig tilknyttet nåværende historisk dyrehold. I Barentsburg fant bekjempelsen hundekjeks (Anthricus sylvestris) vært vellykket, men også ugrasløvetann (Taraxacum Ruderalia) ekspandert kraftig siste tiårene. 4. Ettersom det ikke etablert reproduserbar metode tilpasset arktiske forhold foreslår metodikk kan inkluderes overvåkingsopplegg del tilpasningsdyktig overvåkingsstrategi arter Arktis. Humans have acted agents ecological change millennia, through new regions habitats, lately also anthropogenic climate loss (Sala, 2000). Introduced considered when they ‘introduced outside its past distribution by humans’ (IUCN, 2020). Combined, rapidly planet two pertinent issues impacting terrestrial ecosystems today, likely escalate species’ establishments throughout (CAFF-PAME, 2017; Meltofte al., 2013). among significant contributors global biodiversity disruption, pest causing substantial economic loss, invasive (IAS), defined IUCN, outcompeting natives, leading declines richness Simberloff IAS risk compromising used sustenance cultural importance local indigenous people Ebbert & Byrd, 2002). Recently, rising instances occurrence reiterated call urgent effective action necessary protect (Wasowicz generally lower (in absolute terms) than rest world, cold climates limit survival reproduction, whilst historically low limits propagule pressure (Frenot 2005; Wasowicz Therefore, usually occur distinct offer some relief harsh environment: For instance, Svalbard, soils enriched nutrients husbandry ‘hotspots’ (see Coulson 2013; Liška Soldán, 2004). one fastest planet, ameliorated will expand potential both native alike (Meredith 2019). We therefore reasonably assume degradation barrier instigate rise region (Lassuy Lewis, Remote archipelagos like geographic barriers dispersal, yet, recent years, introductions via pathways globally (Seebens 2018), into general (e.g. Huiskes 2014; Ware 2012). Once introduced, zoochory wind dispersal act further pathways: Sea ice even driftwood factors long-distance plants to, within, (Alsos 2016), large population birds, seed epi- endozoochory may pathway around Svalbard. Bird cliffs suitable establishment, where not only do vectors tourists congregate (Eeg-Henriksen Sjømæling, 2016; Ravolainen al. 2020), but rich result guano build up (Zwolicki impacts potentially become detrimental (Benediktsson, 2015), typically, more succeed changing environments Johnson 1993) affect whole (Simberloff Vilá 2011). There surveys presence any sites rather incidental observations unsystematic walks settlements. A inventory documented 98 species, which 19 naturalized, received quantitative impact assessment (Elven Westergaard, 2018b; Sandvik accessible meaning it higher introductions. Established reported transient recorded 2015). Despite increasing biosecurity measures region, lack protocol general. In (Anthriscus settlement has had focus attempts measure prevent spread (Lutnæs first records 1883, 200 years after whaling stations established (Gyllencreutz, 1884). was conducted 1941 (Hadac, 1941) occurrences been irregularly noted studies flora 20th century Elvebakk, 1989; Hadac, 1944; Rønning, 1964, 1972). decades, intermittent evaluated settlements, varied Alsos 2015; Arnesen Elven 1996; Liska Norwegian government Ministry Climate Environment tasked Governor Polar Institute Agency monitor their (Norwegian Environment, 2007). Whilst, ‘Circumpolar Biodiversity Monitoring Programme’ (CBMP; working group endorsed Council United Nations Convention Biological Diversity) aims develop Plans, identifies ‘focal ecosystem component’ (Christensen Invasive Species plan (ARIAS) states now time order (CAFF-PAME 2017). line defence against well-implemented practices (Bartlett, Radcliffe, 2021; Hughes Early detection response (EDRR) management realistic (Waugh, 2009): Establishing regular methodologies enable early reporting introductions, thereby instigating actions timely manner vulnerable answering several national international committees. aim this map tourist landing improve (a) synthesizing evaluating previously recording (b) developing implementing spatial–temporal absence pilot dataset assessing vehicles (UAVs). synthesis light overall strategy. Surveys undertaken August 2017, team five people. Nine selected based existing information occurrence, likelihood activities secondary birds (Figure 1). Previous literature ‘Artskart’ database June 2017 (https://artskart.artsdatabanken.no, Supporting Information S1a). Sites prioritized nine registered reproductively viable Alchemilla millefolium subcrenata; sylvestris; Barbarea vulgaris; Ranunculus acris; Rumex acetosa; Tripleurospermum maritimum; Poa annua; Ruderalia; Stellaria media relatively easy access boat good sites, 1996–2015 collaboration (The unpublished database). Accordingly, Pyramiden Ny-Ålesund surveyed, along following locations: Skansbukta; Bjørndalen; Alkhornet; Ossian Sarsfjellet; Stuphallet; Fjortende Julibukta. Longyearbyen subject separate year prior commission results discussed addition our (Arnesen 2016). To obtain presence, approximate abundance identifying diversity ‘high-risk habitats’ (immediately cliffs), 20 m × cells (pixel) created each study area ArcMap 10.4.1 (ArcGIS® software Esri). Each pixel assigned unique identification code ensure reproducibility quality control data analyses. Due geographical scale task, pixels pre-classified, reviews previous observations, either ‘high-intensity’ (HI) ‘low-intensity’ (LO) (Figures 2, S1a S1b). One person engaged month assess selection ‘HI vs. LO’ sites. Cells included ‘town’ centres, roads trails, thus levels ground disturbance and/or Lembrechts given HI treatments. treatments applied dense vegetation 2b), nutrient-rich moss banks cliffs. Figure 2 shows examples hypothetical staked corners surveyed 2-m parallel lines, transects evenly traversed 2a). LO pixels, routes walked paths, overview pixel. cases, GPS tracking. Observer track stored overlaid all pixels. individual recorded, exception highly abundant carpet forming possible. these instances, classification system differing systems cover number made, depending characteristics Table Where situ possible, herbarium samples taken formal University Museum Norway. Individual indiscrete: Achillea conjugates turfs rhizomatous shoots. repens distributes prostate running stems creating mats. <50 = counted >50 estimated critically evaluate methodologies, relevant reviewed. Particular attention used, locations surveyed. Our review published peer-reviewed original papers papers, grey literature. total 15 manuscripts reviewed spanning 1941–2018 (Table 2). methodological inconsistencies between surveys, avoided direct analysis what data. decade study: ‘Alien list 2012’ Norway (Gederaas 2012) (2015). N (Research report, Nature Research (MSc thesis) Russian Academy Sciences) Research) (Biological consultancy ‘Ecofact’ government) UAV successfully located Dash During summer 2019, carried out high-density suitability technology regions. UAV-based imagery (RGB: red–green–blue photographs photogrammetry) meets demands ‘HI’ detect individuals multi-spectral images mappings landscape variation (surface reflectance specific wavelengths absorption relate leaf chlorophyll content; Curran 1990; Filella 1995). photogrammetry setup consisted commercial camera (Alpha 6000, Sony, Japan) wide angle lens (12 mm APS-C–19.2 relative full frame; Touit 2.8/12, Zeiss, Germany) linked navigation satellite high-accuracy image georeferencing (Zhang RGB measurements 3–5 flight altitude resolution (0.25 ha plot scale, 1-mm resolution) allow visual classification. (RedEdge MX, MicaSense, USA) 30–40 consists wavelength bands visible near infrared (NIR; range 475–840 nm). NDVI (normalized difference index; Rouse 1974) calculated red NIR band NDVI-based maps then compared Festuca rubra simultaneously surveys. 4260 1), 12% 27% maximum 3a S3). diverse site, 22 32% eight 3b S2). And occurring pixel, 0.8% 3c S4). Some mapped due topography (too steep), contamination (open sewage system, Ny-Ålesund) restrictions construction. Full details sampling effort, (including Longyearbyen, S1–S5. showed magnitude pratense, rubra, vulgaris next respectively (Supporting S6). Four sexually reproductive: millefolium, vulgaris, subcrenata maritimum, S6); however, routine consistently check reproductive status. location shown S6. Six (2158 pixels) ranged 134 Sarsfjellet 1106 Alkhornet reflecting size degree accessibility site. reports since repeated involved Furthermore, many standardized scientific methodology: Out databases evaluated, four element in-field peer-reviewed. Of 11 level surveying, found, reviews. Thus, 40% peer publication (Belkina 2013), focussed easily test flights proximal sensed interpreted background knowledge larger flowers (minimum diameter ca. 1 cm), colour shape 4a), case subcrenata, repens) (e.g., Bistorta vivipara, Carex rupestris, Cerastium arcticum, Oxyria digyna, Salix polaris Saxifraga cernua) detected. Using setup, would normally mounted, belt telescopic pole instead means acquisition during field 4b). fused precisely georeferenced orthophoto (georeferencing error <10 cm) enables accurate documenting indicated productivity patterns site reflected approximately 0.4 0.95. At abundant/lawn-forming distinctively communities 5a). These lawns did show strong connection spatial high-NDVI detailed 5b). represents baseline inform environmental assessments action. Answering Conservation Flora Fauna's (CAFF) CBMP 2013) ‘ARIAS’ 2017), form anchored national, regional strategies Westergaard 2018a, Lutnæs 2019) 6). suggested exclusive adapted tundra dynamics finding severe descriptions highlights urgency transparent repeatable methodology. find association historical husbandry, supporting findings non-native 2015) invertebrates (Coulson Although reveal ranges future, require continued (Lembrechts Myers-Smith 3 activities: Pixels greater impact, including 4, Typically, prime establish in, being main predictor invader success nutrients, input, temperature, etc. Disturbed reduces competition typically slower growing often suppressed seedling stage disturbance, allowing fast-growing ‘weed’ gain advantage Kaarlejärvi Olofsson, 2014). increased availability invasion greater, study, alpine south (i.e. efforts 2013 2016 remove successful. This re-found nor observed 2018, 2019 2020 (V. Ravolainen, K. I. Paulsen, personal observations). Compared reports, maritimum Pyramiden, targeted search (K. seems increased, former frequented paths settlement. Whilst annua repeatedly field-survey. Also, P. pratense annua, report mentions trivialis, neither question validity identifications, highlight need updated key works, recommend retention materials specimens reference. variance different earlier entirely comparative. Rather, indicative broad changes again reinforces statistically evaluated. Horizon scanning go way pre-identify ‘door-knocker invading Peyton 2019; Roy 2014, 2019), without reduced thought exercises. NOBANIS (NOBANIS, 2009), recently (2018b) who assessed, 14 already reproducing another door-knocker survey: repens. All other leaving just remaining yet (Capsella bursa-pastoris, Lepidotheca suaveolens, subborealis subsp. villosus). works ‘in-field’ assessments, techniques deployed tended surface appears body biased compilations handful studies, incomparable inaccurate identification. Efforts date largely relied informal unstructured record absence, broadly unrepeatable. clearly define spatiotemporal needs fully grasp ongoing threat Svalbard's ecosystems. limited systematically collected still best understood terms biodiversity, makes excellent invasions. testing feasibility UAVs sensors identify invasions, supplement through, approaches: documentation single plants: provisional trials (3–4 above altitude). Such visually automatically classified demonstrated Pflanz (2018). combines high-resolution orthophoto, ground-based season. With overlap precision 10 cm, conjunction presented provide surveyin