Data from: Quantifying natural disturbances using a large-scale dendrochronological reconstruction to guide forest management

Estimates of historical disturbance patterns are essential to guide forest
management aimed at ensuring the sustainability of ecosystem functions and
biodiversity. However, quantitative estimates of various disturbance
characteristics required in management applications are rare in
longer-term historical studies. Thus, our objectives were to: (1) quantify
past disturbance severity, patch size, and stand proportion disturbed, and
(2) test for temporal and sub-regional differences in these
characteristics. We developed a comprehensive dendrochronological method
to evaluate an approximately two-century-long disturbance record in the
remaining Central and Eastern European primary mountain spruce forests,
where wind and bark beetles are the predominant disturbance agents. We
used an unprecedented large-scale nested design dataset of 541 plots
located within 44 stands and 6 sub-regions. To quantify individual
disturbance events, we used tree-ring proxies, which were aggregated at
plot and stand levels by smoothing and detecting peaks in their
distributions. The spatial aggregation of disturbance events was used to
estimate patch sizes. Data exhibited continuous gradients from low- to
high-severity and small- to large-size disturbance events. In addition to
the importance of small disturbance events, moderate-scale (25-75% of the
stand disturbed, >10 ha patch size) and moderate-severity (25-75%
of canopy disturbed) events were also common. Moderate disturbances
represented more than 50% of the total disturbed area and their rotation
periods ranged from one to several hundred years, which is within the
lifespan of local tree species. Disturbance severities differed among
sub-regions, whereas the stand proportion disturbed varied significantly
over time. This indicates partially independent variations among
disturbance characteristics. Our quantitative estimates of disturbance
severity, patch size, stand proportion disturbed, and associated rotation
periods provide rigorous baseline data for future ecological research,
decisions within biodiversity conservation, and silviculture intended to
maintain native biodiversity and ecosystem functions. These results
highlight a need for sufficiently large and adequately connected networks
of strict reserves, more complex silvicultural treatments that emulate the
natural disturbance spectrum in harvest rotation times, sizes, and
intensities, and higher levels of tree and structural legacy retention.