Geographical gradient of fungal decay type in Norway spruce logs in Europe and its impact on seedling establishment

Norway spruce (Picea abies) is a dominant tree species across Eurasia. Understanding its regeneration dynamics is crucial for predicting forest sustainability under climate change. In certain types of Norway spruce forests, regenerates is more successful on decaying logs and stumps than on the forest floor. The type of wood decay, indicative of fungal decay capabilities, markedly influences spruce regeneration, demography, and growth. As fungal distribution and wood decay types are affected by macroclimate, the success of spruce seedling regeneration is expected to vary continentally and may be further influenced by climate change. The present study examined decay type frequencies and seedling densities on decaying Norway spruce logs, assessing effects on regeneration success across 15 sites in 6 European countries along a latitudinal gradient. White rot was dominating in central Europe compared with southern and northern Europe. Spruce seedling densities were positively correlated with..., We selected 15 old-growth forest sites spanning six countries across Europe to represent a latitudinal and climatic (temperature and precipitation) gradient (Fig. 1; Table 1). Each site included a study area of approximately 1 ha. The stand ages are unknown. The latitude ranged from 41.47ºN (Elatia, Greece) to 65.25ºN (Litltuva, Norway), with elevations ranging from 172 m (Tjøstøl, Norway) to 1,587 m (Parangalitsa, Bulgaria). Mean annual temperatures varied from 1.1°C (Hilmo and Råndalen, Norway) to 9.2°C (Elatia, Greece), and annual rainfall ranged from 620 mm (Elatia, Greece) to 1,630 mm (Litltuva, Norway). The distance between the two farthest sites (Elatia in Greece and Litltuva in Norway) was approximately 2,755 km. All sites featured a natural predominance of Norway spruce.
In total, 644 fallen Norway spruce logs (diameter range: 11–105 cm; average diameter: 32 cm) were investigated in this study (Table 1). We targeted fallen logs >3 m in length and of intermediate decay, which..., , # Geographical gradient of fungal decay type in Norway spruce logs in Europe and its impact on seedling establishment

[https://doi.org/10.5061/dryad.zs7h44jk9](https://doi.org/10.5061/dryad.zs7h44jk9)

## Description of the data and file structure

### Files and variables

#### File: Europe\_for\_analyses\_final.csv

**Description:** 

##### Variables

* Country: country name (categorical)
* Site: code name of the site (categorical)
* Plot: plot name in the site (categorical)
* Log: log ID in the site (categorical)
* DC: decay class (order)
* Diam_cm: diameter of the log (cm, continuous)
* Area: projected area of the log (cm2, continuous)
* Bark: bark coverage of the log (%, continuous)
* Moss: moss coverage of the log (%, continuous)
* Vegetation: vegetation coverage of the log (%, continuous)
* Soil: soil contact of the log (%, continuous)
* Openness: canopy openness above the log (%, continuous)
* Sap_W: presence of white rot in the sapwood of the log (binary)
* Sap_B: presence of b...,