DOI: 10.5061/dryad.kd51c5bdc
title: Data for: Climatic and management-related drivers of endemic European spruce bark beetle populations in boreal forests

description: Climate change is already reducing carbon sequestration in Central
 European forests dramatically through extensive droughts and bark beetle
 outbreaks. Further warming may threaten the enormous carbon reservoirs in
 the boreal forests in northern Europe, unless disturbance risks can be
 reduced by adaptive forest management. The European spruce bark beetle
 (Ips typographus) is a major natural disturbance agent in spruce-dominated
 forests and can overwhelm the defences of healthy trees through
 pheromone-coordinated mass-attacks. We used an extensive dataset of bark
 beetle trap counts to quantify how climatic and management-related factors
 influence bark beetle population sizes in boreal forests. Trap data was
 collected during a period without outbreaks and can thus identify
 mechanisms that drive populations towards outbreak thresholds. The most
 significant predictors of bark beetle population size were volume of
 mature spruce, extent of newly exposed clearcut edges, temperature, and
 soil moisture. For clearcut edge, temperature, and soil moisture, a
 three-year time lag produced the best model fit. We demonstrate how a
 model incorporating the most significant predictors, with a time lag, can
 be a useful management tool by allowing spatial prediction of future
 beetle population sizes. Synthesis and Applications: Some of the
 population drivers identified here, i.e., spruce volume and clearcut
 edges, can be targeted by adaptive management measures to reduce the risk
 of future bark beetle outbreaks. Implementing such measures may help
 preserve future carbon sequestration of European boreal forests.
description: # Dataset: Climatic and management-related drivers of endemic European
 spruce bark beetle populations in boreal forests
 Authors note: We advice
 those wanting to utilize this data, first contact
 **Summary of experimental efforts
 underlying this dataset** The data include counts from Ipslure® pheromone
 (methylbutenol, cis-verbenol, and ipsdienol) baited funnel traps, that
 attract the European spruce bark beetle (Ips typographus). The trapping
 effort was carried out in spruce dominated areas of southern Norway in the
 time period 2004-2021 (N = 1 731). **Description of file structure and
 contents** The csv file contains trap counts and several covariates. Some
 covariates (indicated below) are from three years before the corresponding
 trapping data, which is due to a time lag in the effect of some variables
 on local beetle populations. year - year of trapping north - trapping
 location latitude (decimal degrees) east - trapping location longitude
 (decimal degrees) masl - trapping location altitude (meters above sea
 level) trapcounts - number of bark beetles captured (full season of
 trapping) spruce_vol - volume of mature spruce (m3/ha) in a 5 km radius
 around the trapping site (obtained from the Norwegian forest resources map
 [SR16; Astrup et al. 2019]) veg_zone - indicates which of three vegetation
 zones (‘boreonemoral’, ‘boreal &lt; 61.7 N°’, and ‘boreal &gt; 62.8 N°’)
 trapping was carried out in felling_border - the total circumference (m)
 of new clearcuts in a 5 km radius around the trapping site (obtained from
 Global Forest Watch data set [Hansen et al. 2013] and collated three years
 prior to the year of trapping) temperature - temperature (Celsius) data
 from senorge.no, three years prior to the year of trapping precipitation -
 precipitation (mm) data from senorge.no, three years prior to the year of
 trapping soil_moisture - soil moisture (percentage of the maximum value
 registered for each grid cell in the period 1981-2010) data from
 senorge.no, three years prior to the year of trapping **Links to other
 publicly accessible locations of the data**