Recent research published in the Arboricultural Journal presents the first comprehensive assessment of Reykjavik's urban forest ecosystem. The study by Aaron Shearer and Duncan Slater (2025) employed plot-based sampling methodology across 278 stratified random plots (400 m²) throughout urban neighborhoods, parks, cemeteries, and woodlands to establish foundational data on forest structure and ecosystem service provision. Analysis revealed an overall canopy cover of 8.7% (±0.9% SE), significantly lower than comparative Northern Hemisphere urban centers, which typically exhibit 15-20% coverage. This positions Reykjavik's urban forest as quantitatively understocked compared to most European cities, despite its critical importance for ecosystem service provision in this highly urbanized northern capital.

Resilience comes with increased diversity

The urban tree population, estimated at 350,000 (±40,000 SE) specimens with a density of 71 trees/ha, demonstrated remarkably limited taxonomic diversity. Only 19 species were identified within sample plots, with four dominant taxa (Betula pubescens (35%), Populus trichocarpa (19%), Picea sitchensis (13%), and Sorbus aucuparia (11%)) comprising 78% of the total population. This limited species diversity (Shannon-Wiener index value: 2.0) presents substantial vulnerability to emerging biotic and abiotic stressors, including climate change impacts, pest outbreaks, and diseases.

While plots captured only 19 species, the field survey noted an additional 50 tree species outside sample plots, predominantly in residential gardens and arboreta. These serve as de facto common garden experiments and assisted migration trials. These existing trials provide urban forest managers with valuable tools to reduce vulnerability to climate change, improve biosecurity, and guide species selection beyond biogeographic origin toward functional traits conferring resilience in warming conditions.

Significant community value

Spatial heterogeneity was evident across land uses, with highest tree densities in urban woodlands (380 trees/ha) and cemeteries (163 trees/ha), contrasting with residential areas (49 trees/ha). The age structure analysis revealed a predominantly young forest demographic, with 74% of trees having DBH measurements below 30 cm (median: 19 cm), reflecting relatively recent establishment of most urban forest components. Ecosystem service quantification using i-Tree Eco determined that Reykjavik's urban forest currently stores 39,800 metric tonnes (±4,600 SE) of carbon, sequesters 2,100 metric tonnes annually (±200 SE), and removes 19.7 metric tonnes of air pollutants yearly. Capital Asset Value for Amenity Trees (CAVAT) methodology established the urban forest's total worth at 576 billion ISK, with a replacement value of 32 billion ISK, underscoring its significant municipal asset value.

Useful for planning and conservation

This research establishes critical reference data for developing comprehensive urban forest management strategies addressing species diversification, canopy expansion, and enhanced integration of tree preservation within municipal planning frameworks. The study's findings suggest implementing a 30% canopy cover target by 2050 through systematic annual planting programs (approximately 35,000 trees per year) and developing robust tree preservation policies to mitigate pressures from urban densification initiatives. This assessment provides essential baseline metrics for future monitoring of Reykjavik's urban forest dynamics and ecosystem service provision in this distinctive high-latitude urban environment.

The Arboricultural Journal Paper: Characteristics and benefits of Reykjavik’s urban forest, Iceland