DOI: 10.5061/dryad.gtht76j1k
title: Ecological factors shaping postfire resilience in mature black spruce forests of eastern North America

description: This dataset encompasses 536 entries, each representing a 400 m² stand of
 post-fire regeneration of black spruce (Picea mariana) in the eastern
 North American boreal zone, affected by 21 fires that occurred between
 1995 and 2016. It focuses on the post-fire recovery and resilience of
 mature stand of black spruce (Picea mariana), a species adapted to
 stand-replacing fires. The dataset includes unique identifiers,
 geographical locations, fire characteristics, and metrics for both
 pre-fire and post-fire vegetation, particularly post-fire seedling density
 (seedlings/ha). The dataset allows for exploring key ecological
 determinants of post-fire regeneration, including seed bank conditions,
 fire severity, and seedbed condition. This comprehensive network
 facilitates an unprecedented spatial and temporal analysis of black spruce
 regeneration. Legal and ethical considerations involve ensuring proper
 data handling. Research utilizing this dataset can inform forest
 management strategies and ecological assessments, underscoring the
 potential shifts, principally toward loss of black-spruce density, in
 boreal forest dynamics under climate-induced fire regime changes.
description: The studied fires were selected because: (i) they were located
 within the boreal closed crown forest in the province of Quebec; (ii) they
 were composed of mature (60 years) BS-dominated pre-fire stands
 (&gt;50% of the basal area occupied by BS); (iii) they had burned a
 minimum of three years before field surveys to allow time for post-fire
 seedling establishment; (iv) they had burned after 1984 (v) they had not
 been salvage logged; and (vi) they were accessible by road. Across all
 selected fires, 536 circular plots of 400 m² (r = 11.28 m) were sampled
 during the summers of 2017, 2018, 2019, and 2020 following a systematic
 sampling design, with at least three plots distributed along the lower,
 middle, and upper portions of each slope and spaced at least 100 meters
 apart. Depending on the fire size and accessibility, between 4 and 152
 plots were established by fire. The percentage cover of each understory
 plant species in each plot was assessed using the point-intercept method.
 This involved two perpendicular transect lines, each measuring 22.56 m,
 resulting in a total length of 45.12 m across the plot. At every 0.5 m
 increment along these lines,1.5-metre-long metal rods were placed
 perpendicularly. The number of rods that were touched by eachspecies
 across a plot was counted and divided by the total number of rods,
 yielding a percent cover value. The percentage ground cover of understory
 plants was obtained, including living Sphagnum spp. moss and ericaceous
 shrubs. All living post-fire tree seedlings (height &gt; 0.01 m) of
 each of the main tree species, which included BS, JP, paper birch or
 trembling aspen (forming 99.9% of all tree stems), were counted in 10
 evenly distributed 4m<sup>2</sup> subplots. Within-plot,
 stocking was also calculated as the percentage of subplots occupied by at
 least one seedling. The thickness (cm) of the post-fire residual organic
 layer was measured at the center of each of the 10 subplots.
description: # Ecological factors shaping postfire resilience in mature black spruce
 forest in eastern North America Fortin Stelsa^1^ and Boucher Yan^2^
 ^^1^^Corresponding author. Université du Québec en Abitibi-Témiscamingue
 and Université du Québec à Chicoutimi , email :
 [fors40@uqat.ca](mailto:fors40@uqat.ca) ^^2^^Data manager. Université du
 Québec à Chicoutimi, email : [yboucher@uqac.ca](mailto:yboucher@uqac.ca)
 **DATA SPATIAL COPE** The study area is located in the boreal forest of
 eastern North America between latitudes 49°70’N-51°90’N and longitudes
 73°58’W–67°68’W. The 21 fires studied had burned between 1995 and 2016 and
 are located in the bioclimatic domain of black spruce-feather moss of
 Quebec, eastern Canada. This bioclimatic domain is characterized by
 dominance of BS with JP, balsam fir (Abies balsamea [L.] Mill.), paper
 birch, and trembling aspen as companion species, depending on site
 conditions and successional stage. The study area is mostly covered by
 glacial deposits, particularly undifferentiated till. Its climate is
 characterized by average annual temperatures ranging between 0.05 and
 -2.19°C, with average annual precipitation varying between 946 and 1121
 mm. The growing season is short, generally extending between May and
 September. The mean fire return interval varies along a longitudinal
 gradient, ranging from about 220 years near Lake Mistassini in the west to
 approximately 640 years near the Manicouagan Reservoir in the east.
 **SHARING/ACCESS** This work is licensed under a CC0 1.0 Universal (CC0
 1.0) Public Domain Dedication license. **DESCRIPTION OF THE DATA** The
 following sections present the information necessary to understand each
 column of the dataset.csv. Here is a list of all columns in the
 dataset.csv 1\. id_unique 2\. stocking_bs_jp 3\. id_fire 4\.
 time_since_fire 5\. latitude 6\. longitude 7\. seasonality_real_date 8\.
 seasonality_adjusted 9\. CBI 10\. sphagnum_cover 11\. ericaceous_cover
 12\. rom_med 13\. age 14\. basal_area_prefire_bs 15\.
 prefire_bs_proportion 16\. seedlings_ha_bs 17\. seedlings_ha_jp 18\.
 seedlings_ha_bl **id_unique** A unique alphanumeric identifier for each
 plot. It consists of the measurement year, the year of the fire, and a
 plot identifier. Example: 2017199512 - Plot 12, in a fire that burned in
 1995 and measured in 2017. **stocking_bs_jp** Stocking value for black
 spruce (bs) and jack pine (jp). Calculated based on the number of future
 microplots. In each plot, we had 10 microplots. Therefore, a stocking of 0
 = 0%, 1 = 10%, 2 = 20%... 9 = 90% and 10 = 100% **id_fire** Unique
 identifier for each fire **time_since_fire** Time (years) between the fire
 and the forest inventory **latitude** Latitude (in degrees) **longitude**
 Longitude (in degrees) **seasonality_real_date** Actual date of the fire.
 Determine using the Modis hotspot and the Canadian National Fire Database
 (CNFDB), available at
 [https://cwfis.cfs.nrcan.gc.ca/ha/nfdb](https://cwfis.cfs.nrcan.gc.ca/ha/nfdb). **seasonality_adjusted** This metric is calculated from the date of the fire, adjusted to align with the start of the fire season for each year, where the start of the fire season is designated as Day 1 **CBI** Value of the Composite Burn Index (CBI), a numerical scale that quantifies the severity of the burn. The scale ranges from 0 to 3, with 0 being unburnt and 3 being completely charred. **sphagnum_cover** The percentage of live sphagnum moss cover in each plot was determined using the point-intercept method, where the number of stems that contacted sphagnum moss was compared to the total number of stems, yielding a cover percentage. **ericaceous_cover** The percentage of ericaceous cover in each plot was determined using the point-intercept method, where the number of stems that contacted ericaceous was compared to the total number of stems, yielding a cover percentage. **rom_med** The median thickness (mm) of residual organic matter (ROM) in each plot was calculated by measuring the thickness in each of the 10 microplots and taking the median of these values. **age** The age (years) of the plot at the time of the fire was determined by assessing a minimum of five trees present prior to the fire event. **basal_area_prefire_bs** The basal area (m²/ha) of all black spruce (bs) stems present before the fire was calculated, providing a measure of the pre-fire tree density in the area **prefire_bs_proportion** The percentage of black spruce (bs) in the landscape before the fire was calculated by comparing the number of black spruce trees to the total number of all tree species present. **seedlings_ha_bs** Number of black spruce (bs) seedlings by hectare in a plot **seedlings_ha_jp** Number of jack pine (jp) seedlings by hectare in a plot **seedlings_ha_bl** Number of broadleaves (bl) seedlings by hectare in a plot