Spread of the Introduced Sitka Spruce (Picea sitchensis) in Coastal Norway

Abstract

Positive and negative effects on ecosystem services from plantation forestry in Europe have led to conflicts regarding non-native tree species. Sitka spruce (Picea sitchensis (Bong.) Carr.) is the most common plantation species in northwest Europe, covering 1.3 Mha. In costal Norway, Sitka spruce was intentionally introduced and is currently occupying about 50,000 ha. Sitka spruce was blacklisted in Norway in 2012, mainly based on the risk for invasive spreading, but little quantitative documentation exists on spread. Here we quantify spread from plantations into abandoned heathland and pastures in thirteen sites where natural regeneration occurs. Spread distances and zero-square distributions related to the nearest edge of the parent stand were fitted by use of Weibull. The median expansion rate was 0.8 m·year −1 in north Norway and 4.4 m·year −1 in west Norway. The maximum establishment distance measured was 996 m. A peak in sapling density occurred within 50 m from the edge, and there was a general decrease in saplings with increasing distance. Conversely, increase in zero-squares percentages occurred with increasing distance. We argue that inclusion of abundance in assessing spread is necessary to define invasiveness. Based on spread models and prevailing forestry practices we recommend that the establishment of new Sitka spruce plantations within 200 m of protected areas should be avoided.

Explaining landscape preference heterogeneity using machine learning-based survey analysis

“…This conversion was not made in eastern Norway. Existing evidence suggests that past negative experiences with Sitka spruce that spread seeds beyond the plantation area may affect overall preferences for planted spruce (Nygård & Øyen, 2017;Saure et al, 2013).…”

Site‐specific risk assessment enables trade‐off analysis of non‐native tree species in European forests

“…A possible motivation for such a study could be to obtain knowledge on the composition of a regenerating community at smaller spatial scales. In this case, information about the current stage of NNT establishment, dispersal distances, and site‐specific factors that influence NNT recruitment can be collected in plots or transects (Dyderski & Jagodziński, 2018 ; Nygaard & Øyen, 2017 ; Woziwoda et al, 2018 ). To assess local effects on biodiversity, additional ecological data such as cover and diversity of the herb layer may be collected as well (Woziwoda et al, 2014 ).…”

Evaluating the terrestrial carbon dioxide removal potential of improved forest management and accelerated forest conversion in Norway

“…Forestation can also affect energy budgets of the surface and lower atmosphere via changes to biogenic aerosol regimes, which can affect atmospheric chemical and physical processes influencing both short-and long-wave radiation transfer (Spracklen, Bonn, & Carslaw, 2008;Unger, 2014 in Norway but has double the productivity (i.e., mean annual atmospheric CO 2 sequestration over the rotation period) to that of Norway spruce in the coastal regions of western Norway (Godal & Grønlund, 2014) where the largest total IFM + AFC candidate area potential is found. The reason behind the blacklisting of Sitka spruce is due to the potential threat on biodiversity outside plantations and further spreading, although some research has shown that such "invasion" threats can be greatly reduced if Sitka spruce plantations are given a 200 m buffer from protected areas (Nygaard & Øyen, 2017).…”