Use climatic space-for-time substitutions with care: not only climate, but also local environment affect performance of the key forest species bilberry along elevation gradient

An urgent aim of ecology is to understand how key species relate to climatic and environmental variation, to better predict their prospects under future climate change. The abundant dwarf shrub bilberry (Vaccinium myrtillus L.) has caught particular interest due to its uphill expansion into alpine areas. Species’ performance under changing climate has been widely studied using the climatic space-for-time approach along elevation gradients, but potentially confounding, local environmental variables that vary along elevation gradients have rarely been considered. In this study, performed in ten sites along an elevation gradient (200–875 m) in W Norway, we recorded species composition and bilberry performance, both vegetative (ramet size and cover) and reproductive (berry and seed production) properties, over one to four years. We disentangled effects of local environmental variables and between-year, climatic variation (precipitation and temperature), and identified shared and unique cont..., We studied bilberry performance in 2017–2020 along an elevation gradient in a boreal, bilberry-dominated Scots pine (Pinus sylvestris) forest in Sogndal, Vestland county, W Norway (61°13’N, 7°9’E). The study site extended along a 2.7 km SW-facing ridge, covering the altitudinal interval 200–875 m a.s.l., from dense lowland forest up to the alpine tree line.
In 2017, we subjectively placed ten blocks of 5 × 10 m along the elevation gradient, all facing S–SW with an average slope of 10–30 °. Each block spanned the variation from open to shaded sites. In each block, we randomly placed and permanently marked five plots of 0.5 × 0.5 m with a minimum between-plot distance of 1 m.
We collected six data sets in the 50 plots; (1) species composition in 2017, (2) bilberry vegetative performance (ramet size) in 2017-2018, (3) bilberry vegetative performance (bilberry cover) in 2017, (4) bilberry reproductive performance (berry production) in 2017-2020, (5) bilberry reproductive performance (seed p..., All data are stored in an Excel Workbook, in separate sheets., ## Description of the data and file structure

We studied bilberry performance in 20172020 along an elevation gradient in a boreal, bilberry-dominated Scots pine (Pinus sylvestris) forest. The study site extended along a 2.7 km SW-facing ridge, covering the altitudinal interval 200875 m a.s.l., from dense lowland forest up to the alpine tree line.

In 2017, we subjectively placed ten blocks of 5 10 m along the elevation gradient, all facing SSW with an average slope of 1030 . Each block spanned the variation from open to shaded sites. In each block, we randomly placed and permanently marked five plots of 0.5 0.5 m with a minimum between-plot distance of 1 m.

We collected six data setsin the 50 plots;
(1) species composition in 2017
(2) bilberry vegetative performance (ramet size) in 2017-2018
(3) bilberry vegetative performance (bilberry cover) in 2017
(4) bilberry reproductive performance; berry production in 2017-2020
(5) bilberry reproductive performance; seed production in 2017-2...