Spatiotemporal changes in Gothenburg municipality's green space, 1986 to 2019

Sammanfattning: As the world’s population is becoming increasingly more urban the infrastructure expands to accommodate the inhabitants’ needs. In a dense urban environment green space has an important function since it provides vital ecosystem services, contributes to recreational and cultural values and is essential for biodiversity. Gothenburg municipality, which harbours the second largest city in Sweden, has seen an increase from about 430 000 to 580 000 inhabitants between the years 1986 and 2019 and a future prognosis shows a population increase to 700 000 by the year 2035. The municipality is currently working on a new comprehensive plan which will dictate how the city will expand in the future. This study uses Normalized Difference Vegetation Index (NDVI) from Landsat 5 TM and Landsat 8 OLI satellite data across eight dates between 1986 and 2019 to analyze historical greenness change. Together with a qualitative content analysis of the consultation material, which is the basis for the work with the new comprehensive plan, a future outlook is constructed. NDVI is highly correlated to green biomass and increase or decrease of NDVI is translated to gain or loss of amount of greenness. Gothenburg municipality has lost a considerable amount of greenness(2.8%) between the years 1986 and 2019, while there has been a 0.83% gain in green area. The areas with the largest percentage of greenness loss are large industry, harbor and logistics followed by urban middle area, urban central area and urban outer area. The areas have lost 504.7, 430.7, 36.3 and 194.9 ha respectively during the time period which translates to 10.8%, 3.7%, 2.6% and 1.8% of the areas total land area. There has been a declining cumulative net change of greenness for all areas except for nature and recreational areas which has gained in greenness with 0.1%. A visual analysis shows that areas with lost greenness in the urban middle and outer area were mostly due to commerce, industry, and housing while in the urban inner area the loss was focused to private and public institutions. The expansion of communications, roads and public transport was a common cause for greenness loss in all areas. The urban middle and outer area are those where most future development will be focused and green areas will most likely decrease due to expansion, which should be prominent around already densely built-up parts in these areas. The consultation material also shows that future development will focus on public transportation, cycling lanes, sidewalks and roads to increase accessibility. Since the development of these kind of infrastructures have been shown to affect surrounding green space a similar trend can be expected in the future.