The restoration of unused urban-industrial areas has largely been neglected despite their great potential for nature conservation purposes. The research activities of the Group have been transferred to the East of Hungary in 2013 when the new LEGO factory requested the re-naturalization of its industrial territory at 26,5 hectares. The Nyírség area, where the factory is built, has sandy and slightly acidic soil, compacted by construction and dry climate that is challenging for restoration. Further problem is the lack of native seed market in Hungary, therefore multiple approaches have been introduced for re-vegetation.

Hierarchical restoration prioritization was applied to select best target for habitat reconstruction at a Hungarian industrial area. Multiple potential natural vegetation model, a novel approach, supported restoration prioritization satisfying both ecological (sustainability and nature conservation value) and other needs (feasibility, rapid green surface, amenity, and education value). The target that met all priorities was the open steppe forest that has a mosaic arrangement with open and closed sand steppes. The potential area of this xero-thermophile oak wood is expected to expand in Hungary with climate change, therefore the selected target has a likelihood of long-term sustainability, if established.

Hay transfer from donor grasslands, commercial seeds and collected seeds with and without nurse plants have been used for grassland reconstruction. Trees of the 2014 plantings died due to the severe drought in the summer of 2015 and replanted in 2015 winter. Over 10,000 undercut 1-2-year-old saplings of 16 tree and shrub species were planted in patches of various size in November 2015 at ca. 20 % of the restoration area. Specific plans were developed for each woody patch within the restored grassland. Tree and shrub survival was counted for all saplings in all patches in the summer of 2016.

First results demonstrate that nurse plants can contribute to fast greening and suppressing weeds that help target plants to survive. The species composition of seeded restoration plots became similar to that of reference grasslands. Both types of seeding resulted in a similar cover, whereas seeding a commercial seed mixture and hay transfer resulted in a species richness similar to that of reference grasslands. First year woody survival rates ranged between 4-66 %, depending greatly on the species. Woody survival was basically independent of the grassland reconstruction techniques, but dependent on the height of herbaceous vegetation.

Based on our results, the introduction of propagules in degraded industrial areas can provide communities similar, after three years, to those of secondary reference grasslands that are 30 years of age. Our results support that the reconstruction of complex native habitats with a park-like appearance is a viable alternative to landscaping in industrial areas that can counteract land degradation and increase green infrastructure connectivity. We conclude that investing in the restoration of native grasslands at unused urban-industrial sites can be a great opportunity to enhance biodiversity.

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