Landscape‐level variability in historical disturbance in primary Picea abies mountain forests of the Eastern Carpathians, Romania

Abstract

Questions: How have the historical frequency and severity of natural disturbances in primary Picea abies forests varied at the forest stand and landscape level during recent centuries? Is there a relationship between physiographic attributes and historical patterns of disturbance severity in this system? Location: Primary P. abies forests of the Eastern Carpathian Mountains, Romania; a region thought to hold the largest concentration of primary P. abies forests in Europe's temperate zone.Methods: We used dendrochronological methods applied to many plots over a large area (132 plots representing six stands in two landscapes), thereby providing information at both stand and landscape levels. Evidence of past canopy disturbance was derived from two patterns of radial growth: (1) abrupt, sustained increases in growth (releases) and (2) rapid early growth rates (gap recruitment). These methods were augmented with non-metric multidimensional scaling to facilitate the interpretation of factors influencing past disturbance.Results: Of the two growth pattern criteria used to assess past disturbance, gap recruitment was the most common, representing 80% of disturbance evidence overall. Disturbance severities varied over the landscape, including stand-replacing events, as well as low-and intermediate-severity disturbances. More than half of the study plots experienced extreme-severity disturbances at the plot level, although they were not always synchronized across stands and landscapes. Plots indicating high-severity disturbances were often spatially clustered (indicating disturbances up to 20 ha), while this tendency was less clear for lowand moderate-severity disturbances. Physiographic attributes such as altitude and land form were only weakly correlated with disturbance severity. Historical documents suggest windstorms as the primary disturbance agent, while the role of bark beetles (Ips typographus) remains unclear. Conclusions:The historical disturbance regime revealed in this multi-scale study is characterized by considerable spatial and temporal heterogeneity, which could be seen among plots within stands, among stands within landscapes and between the two landscapes. When the disturbance regime was evaluated at these larger scales, the entire range of disturbance severity was revealed within this landscape.

Integrating tree-ring and inventory-based measurements of aboveground biomass growth: research opportunities and carbon cycle consequences from a large snow breakage event in the Swiss Alps

“…Tree-ring data have been previously used for a variety of research fields ranging from climate reconstructions (Esper et al 2014;Frank et al 2010), forest ecology studies (Esper et al 2007;Svoboda et al 2014), archeological dating (Martin-Benito et al 2014) to reconstructions of geomorphic activity (Gärtner et al 2004;Stoffel and Corona 2014). Tree-rings are a direct measure of radial stem growth, which is closely linked to annual wood formation and carbon accumulation (Bouriaud et al 2005;Kerhoulas and Kane 2012).…”

Age, competition, disturbance and elevation effects on tree and stand growth response of primary Picea abies forest to climate

“…Primary forests of Norway spruce are very rare in Europe because of a long history of anthropogenic influence. Natural disturbances (e.g., windstorms, bark beetle outbreaks) are the major drivers of primary Norway spruce forest dynamics (Lännenpää et al, 2008;Shorohova et al, 2008;Svoboda et al, 2014;Trotsiuk et al, 2014), and could also influence the climate-growth response of trees (Rozas, 2001).…”

Effects of topography and forest stand dynamics on soil morphology in three natural Picea abies mountain forests

“…3a). A previous dendrochronological study by Svoboda et al (2014) revealed a significant effect of topography on the disturbance history of C1. Thus the relatively highly shared effect may also be understood as a topography-induced pattern in the forest stand with a secondary effect on soils (e.g., dbMEM3, Table S.2).…”

“…A detailed site survey was carried out on sample plots of 500 or 1 000 m 2 (depending on stand density and heterogeneity; Svoboda et al 2014), established using regular randomized selection within an approximately square grid. Orthogonal distances between neighboring plots ranged from 50 to 140 m at C1 and G1, and from 78 to 127 m at S1.…”

“…Tree proximity -reaches values from 0, for the nearest tree being≥1.5 m apart, to 1 for a tree in the closest proximity to the soil profile a calculated from the dendrochronological datasets bySvoboda et al (2014) andTrotsiuk et al (2014) b calculated followingSvoboda et al (2014) Table 4 Means and standard deviations (SD) of unscaled environmental data in the overall dataset (all sites) and at the level of each site (C1, G1 and S1), assessed within 40, 42 and 41 plots, or at 200, 210 and 205 soil profiles (variables with cross), respectively. Variables with no unit have values on a relative scale.…”