DOI: 10.5061/dryad.08kprr507
title: Data from: Quantifying natural disturbances using a large-scale dendrochronological reconstruction to guide forest management

description: 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, &gt;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.
description: We used a plot network
 established in the remaining primary mountain spruce forests of Central
 and Eastern Europe (www.remoteforests.org). Data span large geographical gradient covering the Carpathian Mountains of southern and northern Romania, Ukraine, southern and northern Slovakia, the Bohemian Forest in the Czech Republic, and the Harz Mountains in Germany. We used a hierarchical sample design of 541 plots nested within 44 stands (4-63 plots·stand-1; median: 11) nested within 6 sub-regions (4-13 stands·sub-region-1; median: 6). The “West” sub-region was comprised of the Harz and Bohemian Forest mountain ranges to avoid any sub-region with a single stand. We used a comprehensive dendrochronological method to reconstruct past disturbances based on analyses of increment cores extracted on each study plot. To quantify individual disturbance events, their severities, and stand proportions disturbed, we used tree-ring proxies (two types of radial growth patterns were assumed to indicate past disturbance: release from suppression and rapid early growth rate), 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. The data collection and analyses are described in detail in the related article published in Ecological Applications. The supplementary material of the article also contains the R code which were used to obtain and process the data [besides the patch size data, which were obtained by analysis in ArcGIS 10.5 (ESRI, Redlands, United States, http://www.esri.com)].
description: The dataset contains the
 disturbance event data resulting from dendrochronological analyses. There
 are three separated tables that are related to three disturbance
 characteristics: <b>disturbance severity</b>,<b> patch
 size</b>, and<b> stand proportion disturbed</b>.
 Individual plot-level disturbance events are included in the first table
 (<i>standlevel_dist_events_joined</i>). Each plot-level event
 is characterized by the plot (<i>plotid</i>) and
 <i>year</i> of occurrence together with its
 <i>severity</i> and stand-level disturbance year
 (<i>peakyear</i>) it is related. Stand-level disturbance
 events are characterized in the second table
 (<i>plotsprop_disturb</i>) by <i>stand</i> and
 year (<i>peakyear</i> - equals to <i>peakyear
 </i>in <i>standlevel_dist_events_joined</i>) together
 with the stand proportion disturbed
 (<i>plotsprop_disturb</i>). Disturbance patch sizes are
 characterized in the third table (<i>dist_patches</i>) that
 contains same characteristics as second table
 (<i>plotsprop_disturb</i>) to identify the stand-level events
 (<i>stand</i> and <i>peakyear</i>) and adds the
 characteristics of patch sizes related to individual stand-level events:
 area of patch size before correction for a maximum size of patches
 represented by a single plot (<i>patch_area_pre</i>), number
 of plots within the patch (<i>Join_Count</i>), final
 <i>patch area </i>after mentioned correction, and
 <i>stand size</i>. Each table also contains identification of
 sub-region (<i>landscape</i>) and <i>country</i>,
 where the plots and stands are located.