Zooming in on Arctic urban nature: green and blue space in Nadym, Siberia

The city of Nadym (65° 32' 0'' North, 72° 31' 0'' East) is located in the Yamal-Nenets Autonomous Okrug, Russia. Nadym has a continental subarctic climate. It is located on territories that have traditionally been occupied by the Nentsy nomadic indigenous people (figure 1). Contemporary Nadym was founded as a base for shift workers in 1960s. In 1972, it transformed into a city with a permanent population.

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Nadym is a typical Soviet city consisting of microrayons. Mirorayons are residential areas that are densely built following the 'closed contour principle' to protect people from strong winds and snow, especially in the winter. Schools, kindergartens, and other facilities are located within walking distance inside of the microrayon (Jull 2016, Romantsov 2016). Construction in the city was more dense than usual, however, because architects had originally planned to build a dome over the city to isolate it entirely from the Arctic environment; the project was later abandoned due to its high cost (Leontyeva and Karpova 2016). The first urban plan estimated that the city's population would only be 12 000 people (NII PG 2017). The population, however, exceeded 26 000 by 1979 (Stas' 2014). The population peaked in the 1980s and, after declining in the 1990s, has stabilized at about 46 000 people. Nadym is one of the major oil cities in Siberia. It is experiencing an economic boom brought about by the oil and gas industry. Construction work is still ongoing.

The development of the Nadym area has induced climatic and ecological transformations. Land Use - Land Cover (LULC) changes have resulted in significant ground warming (Yakubson et al 2012), followed by the greatest loss in ground bearing capacity (over 40%) among the Russian Arctic cities (Streletskiy et al 2012). Soils on aeolian sands in this area experience particularly significant warming, in part because of deep heating caused by penetrating precipitation and meltwater (Kurchatova and Proskonina 2018). Large changes in sandy plots are reported for other areas of the Arctic as well (Lara et al 2018). More than half of Nadym is built on aeolian sand dunes on the second terrace of the Nadym River. Other parts of the city include areas of large, hilly bogs, floodplains, and Siberian pine/larch woodlands. LULC changes following climate warming could be also significant here, as shown in plot studies (Moskalenko 2009).

The Nadym municipal area (3.7 thousand ha) includes the city of Nadym, an airport, the Nadym railroad station, and an industrial area known as 'the 107th km.' Only the city has residential and business areas and has been developed following a master plan, with designated open public spaces. Urban green spaces include natural vegetation at the margins of the city and artificially planted vegetation (mainly white birch trees, different kinds of willow trees, and flowers) along the main streets and squares (Pechkina 2019). In this study, we focus only on the city itself and its adjacent industrial zone. The total area under consideration comprises 835.878 ha.

Our selection of data and methods for this study is guided by the aim to find informative objective indicators to valuate subjective public attitudes to the urban natural environment. Urban green and blue spaces in Nadym are under high anthropogenic pressure. High urban density (see figure 1) and the harsh climate each reduces the regenerative capacity of nature, making human pressures more easily detectable. We take a non-traditional, interdisciplinary approach to examining the impact of those pressures by combining quantitative information from very high-resolution satellite remote sensing systems with qualitative analyses of urban planning documents and interviews. More specifically, this analysis included both existing scholarly works on the subject and municipal and other local open access documents and web-based social media sources.

We gathered 12 semi-structured interviews including three with former local stakeholders responsible for the city planning and management and nine with ordinary residents. The respondents' recruitment was conducted using a 'snowball' approach. To receive the written answers, we sent to the respondents the standardized guides of the interviews with questions on the green and blue spaces, their use and structure (see supplementary materials (available online at stacks.iop.org/ERL/16/075009/mmedia)). The structure of interviews was a combination of standardized guide and open questions that varied depending on the area of the competence of the interviewees. The interviews with the former stakeholders included additional questions on their expertise in the area of urban planning and development. Interviews with other residents contained more detailed questions about their individual experience of usage of green and blue spaces. The answers were then thematically coded.

We apply a content analysis methodology to analyze the coded interviews and municipal documents. We identify local practices and values attached to development, maintenance and enhancement of green and blue spaces in the city. These practices and values were compared with quantitative indicators derived from satellite imagery. In addition, the census data gathered in 1979 and 1989 and more detailed data from the local source My City (www.mojgorod.ru/janao/nadym/index.html) were involved in the study.

After qualitative characterization of the societal values of the specific urban places we look at their quantitative characteristics that would open for further routine statistical analysis and perhaps modeling and prediction. We identified buildings and infrastructure using OpenStreetMap (Barrington-Leigh and Millard-Ball 2017) and satellite imagery. We assessed the dynamics of green space in Nadym by comparing vegetation cover in 1968 (from CORONA imagery) and 2012 (from WorldView imagery). We then applied object-oriented processing (Blaschke 2010): we first segmented satellite imagery using eCognition software and manually identified vegetation class by attributing the corresponding segments. Then we estimated the Normalized Difference Vegetation Index (NDVI), which characterizes vegetation greenness in the city (Walker et al 2012). Our new data are of much higher resolution than NDVI estimations that are based on the moderate resolution spectroradiometer (MODIS) data products. The MODIS NDVI data for Nadym have already been analyzed in Esau et al (2016) and Esau and Miles (2016, 2018). For convenience, our methods, data, and data sources are listed in table 1.

One of the tasks we must solve for the urban green spaces is to quantify their difference from undisturbed green plots. Both urban and undisturbed green areas are experiencing climatic variations. Urban impact is an additional factor that must be estimated having only one contemporary review of both green areas. To solve this problem, we compared the vegetation traits of urban green space with those of natural, undisturbed green space in similar geomorphological conditions and with similar vegetation composition. We selected a lichen thin forest (Siberian pine, Scots pine) on fixed aeolian sands 35 km southeast of Nadym, near the mouth of the Heigiyakha river. We collected measurements with unmanned aerial vehicles. We calculated tree height in ArcGIS by subtracting digital terrain model (DTM) values (the height of the surface without vegetation) from digital surface model (DSM) values (the height of the surface with vegetation). We used the Gaussian normal distribution function in order to obtain the differences between individual and average tree canopy heights using MATLAB. We analyzed the influence of climate on NDVI variability from 1985 to 2019 through an analysis of precipitation and growing degree days (GDD) (Spinoni et al 2015, 2018, Box et al 2019).

Similarly, for the urban blue space, we must find quantitative indicators that characterize values of water bodies for the public. We assessed the dynamics of blue space in Nadym by manually comparing the digitized boundaries of bodies of water as seen in Corona (1968) and WorldView (2012) imagery. We conducted our own direct depth measurements in the largest and most socially significant lakes in Nadym. We performed depth interpolation by using the inverse distance weighted (IDW) method, with a grid cell of 4 m.

The current composition of the green, blue, and built spaces in Nadym is influenced by a variety of factors, that form a compromise between the need for housing and infrastructure, environmental maintenance, available resources, and the desires of residents. Although Nadym is a densely built city with limited parking and courtyards spaces, its planning indicates a strong hierarchy of environmental values among inhabitants, at least among stakeholders in the administration and cornerstone industry. Figure 2 reveals that they have preserved forests within the city and clear-water lakes at urban margins.

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Comparison of satellite images from 1968 to 2012 shows that the urban core was built on barren land (table 2). Simultaneously, a significant loss of green space within the urban area was partially remediated by the gain in vegetation cover from artificial plantings (almost one third of its current green space). In contrast, the share of blue space decreased almost three-fold. Construction work blocked many channels and water bodies in the center, while, in the margins they have been preserved. Other spaces, including built-up areas, barren lands, and disturbed areas such as waste landfills and areas covered with asphalt, almost doubled in 44 years.

Socio-environmental interactions are perhaps the most apparent in changes and tending of urban forest. Residents alter green spaces in Nadym directly through mechanical disturbance and indirectly through artificial planting of trees and bushes. They preserve native trees and introduce other, more resilient plants. This 'domestication' of nature has led to a specific urban composition of native and non-native tree species enhancing biodiversity and public attractiveness of green areas (figure 3).

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This study looks at dynamics of two larger parks—Cedar Grove (area: 23.2 ha) and Kozlov's Park, a forest named after E F Kozlov (area: 15.9 ha)—that are found within the city margins. Efforts to meet all-Russian standards for public green space in urban areas are especially noticeable in the parks. The most recent master plan of the city envisions the conservation and maintenance of the Cedar Grove Siberian pine woodland (Pechkina 2019) and of Kozlov's Park in the city center (Popov et al 2014, Pechkina et al 2016, NII PG 2017, Pechkin et al 2018). The latter is popular among citizens and serves as a focal point for the city: most of the city's public institutions, such as sports facilities, cultural centers, the registry office, school, and kindergarten, are concentrated around the park, making it attractive for public use (NII PG 2017). By contrast, Cedar Grove is seen as a natural conservation area; local authorities carefully manage and maintain its tree composition. In the 1970s, Cedar Grove was threatened by birch expansion, which was supposedly caused by changes in soil structure, moisture, and microclimatic conditions after the construction of multi-story buildings nearby (source: Interview with the former deputy head of the Nadym municipality). The unwanted trees were cut down. These public places did not exist in the original master plan and were a bottom-up initiative from city builders, constituting a rather unique movement for the oil cities of Western Siberia (Museum of History and Archaeology of Nadym; Stas' 2014).

An analysis of satellite imagery clearly reveals considerable efforts to preserve, sustain, and even expand the city's green spaces. Figure 3 shows new green areas in immediate proximity to apartment blocks and along streets. According to Pechkina (2019), most of the artificial plantings take place along the central streets of the city. The industrial zone, in contrast, is often covered by spontaneous vegetation (Kuklina et al 2021). That distribution of artificial and natural green areas is indicative of residents' attribution of higher societal value to green urban construction and afforestation near their homes (Riley et al 2018). Annual tree planting events are part of the local Gasprom office's corporate ecological policy (Gasprom Nadym Dobycha 2020).

Yet, the public use of the green spaces is limited in summertime. Respondents explain that both green and blue spaces have high concentrations of bloodsucking insects (midges). Midges plague walkers, who prefer to communicate 'on their feet' rather than stop or rest on park benches. During the summer, residents often prefer open, windy areas outside the city where midges are blown away, such as the banks of the Nadym and Longyugan rivers, hills, the roadsides of country highways, etc. On warm days during the off-season, however, urban green spaces are in demand. In the fall, e.g. the residents pick mushrooms, berries, and pinecones in Cedar Grove.

Urban park maintenance requires significant efforts from the residents and contributions from the municipal budget. Therefore, it can be seen as an objective indicator of the green space significance for the residents. In the Arctic climate, we propose the height of tree canopies as such an objective indicator. The fits are shown in figure 4. McBride and Douhovnikoff (2012) study emphasized high public significance of and attention to trees in the Arctic settlements. We found that trees in Kozlov's Park are significantly taller (the mean height is 982 cm with 95% statistical confidence interval ± 220 cm) than in corresponding undisturbed areas (827 ± 218 cm). This difference indicates that the tree heights in these two areas are statistically different with at p < 0.05 in a standard t-test (Krzywinski and Altman 2013). Moreover, the difference in 155 cm is outside the 95% confidence interval given by the two standard deviations for the interannual variability of the natural NDVI over the last 17 years (the MODIS data over 2001–2018; Esau et al 2016).

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Surprisingly, the residents value urban blue space far less than it could be expected on the basis of extrapolated results from temperate latitudes (Bockarjova et al 2020). Open blue spaces in Nadym study area include several lakes. Lake Yantarnoye is the biggest natural lake in the area, with a length of about 2 km, area of 0.8 km², and depth of 2 m. In 2018 and 2019, as part of a program for the improvement of the urban environment, city authorities built an embankment along the lake's shore.

Two artificial lakes (sand dugouts), unofficially called Second Yantarnoye and Prodolgovatoye, were created during the development of the city. The maximum depth of these dugouts is 22 m, more than ten times deeper than that of natural lakes (figure 5). In the cold local climate, natural lakes have rather distinct hydrological and temperature characteristics (Pointner et al 2019)—unlike them, the artificial lakes do not freeze through to the bottom and do not have an ice floor. That makes them more attractive for summertime recreational activities. These dugouts have become popular public spaces.

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Unlike green spaces, which benefit from anthropogenic interference, blue spaces demonstrate more varied effects of human involvement. While artificial lakes, which coincidentally obtained desired physical traits, benefit from their acceptance as public space, shallow natural lakes are poorly maintained. For example, Lake Yantarnoye is unsuitable for swimming or fishing due to chemical contamination, and its algae blooms cause a foul smell. In the summer, residents often walk at some distance from the shore to avoid gnats. Insect density reduces residents' use of the lake's constructed waterfront. Moreover, blue spaces located in the industrial zone of the city face littering. Littering often takes place along the shores of bodies of water that the local residents find unattractive, significantly reducing their recreational potential and highlighting the distinct boundaries between domesticated and 'wild' nature (figure 6).

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