Alpine and Arctic tundra shrub populations show similar ontogenetic growth trends but differing absolute growth rates and lifespan

The majority of terrestrial primary production is performed by plants, the ontogenetic growth trends of which greatly influence biomass and carbon dynamics. Here, we study ontogenetic trends of primary (apical) and secondary (stem thickening) growth in Arctic (Svalbard, Norway) and alpine (Krkonoše, Czechia) populations of black crowberry (Empetrum nigrum), the dominant plant species of certain tundra communities. The environmental conditions in alpine areas are more favourable for plant growth than those in the High Arctic, where temperatures are lower, there is less precipitation and soils are shallower, among other differences. These differences were reflected in significant differences in absolute growth rates and shrub age between the populations under study. However, we found almost no differences in ontogenetic growth trends between the populations. In both populations, primary growth and secondary (stem base) growth decrease throughout ontogeny whereas secondary (stem top) growt..., Study sites and sampling
Arctic and alpine populations of the black crowberry (Empetrum nigrum L.), be it the nominal subspecies or E. nigrum subsp. hermaphroditum (Hagerup) Böcher, is exposed to different climatic, soil, and vegetation conditions. We sampled forty individuals from an Arctic population at the end of August 2018 in the Colesdalen valley (78°6′ N; 15°5′ E), Svalbard, Norway. The average annual precipitation in the valley is 190 mm, mostly in the form of snow. From 1969 to 1990, the average annual temperature was −6.7°C, the coldest month was February, with an average temperature of −16.2°C, and the warmest month was July, with an average temperature of 5.9°C (Longyearbyen Airport station, 18 km north of the site; Norwegian Meteorological Institute, 2010). The onset of the growing season spans between days number 165 and 174 (12–23 June) in the Svalbard Islands. Samples were taken at elevations between 40 to 80 m a.s.l. on a south-facing slope with an inclination of 10–20%..., , # Alpine and Arctic tundra shrub populations show similar ontogenetic growth trends but differing absolute growth rates and lifespan

[https://doi.org/10.5061/dryad.w9ghx3frk](https://doi.org/10.5061/dryad.w9ghx3frk)

## Description of the data and file structure

### Files and variables

#### Files: empetrum\_data.txt and empetrum\_data.csv

##### Variables

* Age = mean age of the shrub section compared to the stem base
* Primgr = Primary (shoot) growth rate for each section (mm)
* Secgr_base = the rate of secondary (diameter) growth at the shrub base (using the measurements at the basal cross-section) for the corresponding set of tree rings (mm)
* Secgr_top = the rate of secondary (diameter) growth at the shrub top (using the measurements at the basal cross-section) for the corresponding set of tree rings (mm)
* Secgr_bai = secondary (diameter) growth expressed as the basal area increment at the shrub base (using the measurements at the basal cross-section) for the corresponding set ...