Disturbance history of an old‐growth sub‐alpine Picea abies stand in the Bohemian Forest, Czech Republic

Abstract

Questions What historical natural disturbances have shaped the structure and development of an old‐growth, sub‐alpine Picea abies forest? Are large‐scale, high‐severity disturbances (similar to the recent windthrow and bark beetle outbreaks in the region) within the historical range of variability for this forest ecosystem? Can past disturbances explain the previously described gradient in stand structure that had been attributed to an elevation gradient? Location Šumava National Park (the Bohemian Forest) of the southwest Czech Republic. Methods We reconstructed the site's disturbance history using dendroecological methods in a 20‐ha study plot, established to span an elevation gradient. Growth patterns of 400 increment cores were screened for: (1) abrupt increases in radial growth indicating mortality of a former canopy tree and (2) rapid early growth rates indicating establishment in a former canopy gap. Results Spatial and temporal patterns of canopy accession varied markedly over the 20‐ha study area, resulting in disturbance pulses that corresponded to an elevation gradient. On the lower slope of the plot, the majority of the trees reached the canopy during two pulses (1770–1800 and 1820–1840), while most trees on the upper slope accessed the canopy in one pulse (1840–1860). Historically documented windstorms roughly coincide with peaks in our disturbance reconstruction. Conclusions Our study provides strong evidence that these forests were historically shaped by infrequent, moderate‐ to high‐severity natural disturbances. Our methods, however, could not definitively identify the agent(s) of these disturbances. Nevertheless, the recent mid‐1990s windstorm and the ensuing spruce bark beetle outbreak may provide an analogue for past disturbance, as the duration and severity of these events could easily explain past patterns of growth response and recruitment in our results. Thus, it seems reasonable to assume the interaction of windstorms and bark beetles seen in the contemporary landscape has occurred historically. Finally, our results suggest that the previously documented elevation gradient in forest structure may not be related to elevation per se (lower temperatures and shorter growing season) but rather to changes in disturbance severity mediated by elevation.

Landsat Imagery Spectral Trajectories—Important Variables for Spatially Predicting the Risks of Bark Beetle Disturbance

“…Moreover, the affected forest area is predicted to double in the next two decades because of climate change and cultivation of large areas of coniferous plantations outside their natural distribution [5]. Even though bark beetle disturbances are a part of the natural dynamics of coniferous forest [6][7][8] they also represent a significant threat for timber production and certain forest-provided ecosystem services [9]. Therefore, the need for both detection and prediction of bark beetle infestation is increasing.…”

A growth simulation model as a support tool for conservation management strategy in a mountain protected area

“…Its survival is currently threatened by drought resulting from ongoing climate changes (Neuner et al 2015). Both the natural Norway spruce forests and the artificially established pure Norway spruce forests in the mountains suffer from various types of natural or man-made disturbances (Hresko et al 2015;Svoboda et al 2012), such as windthrow, ice breakage, and bark-beetle outbreaks (Hanewinkel et al 2008). Although bark beetles have an important role in the dynamics of montane Norway spruce forests, there are no sufficiently large areas of montane Norway spruce-dominated forests in the HJM which could enable us to consider spontaneous forest ecosystem development, with bark beetles as a natural driver of this dynamic.…”

Assessment of Forest Management in Protected Areas Based on Multidisciplinary Research

“…These climate-induced tree-line shifts can be slowed by the competition between the Norway spruce and the Dwarf Pine (Pinus mugo Turra), which was artificially planted in European mountains to stabilize the tree line disturbed by past grazing [12]. This phenomenon is therefore highly dependent on past human activities, such as the medieval colonization of mountains associated with an intensive local exploitation of forests by grazing and litter raking [13]. Understanding the historical development of mountain forest ecosystems is therefore of great importance for explaining their current state [14].…”