The natural ‘exclosure effect’ and tree regeneration following post-windstorm salvage logging
Data files
Nov 30, 2023 version files 89.68 KB
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Dryad_Data.xlsx
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README.md
Abstract
Understanding the influence of post-disturbance forest management on tree regeneration is critical for assessing ecosystem recovery and guiding future responses. In particular, the influx of elevated coarse woody material (CWM) following wind disturbance, if left in situ, may impede herbivore access, thereby protecting saplings from browsing damage through a natural ‘exclosure effect.’
In 2013, a tornado in northcentral Maine, USA and subsequent salvage logging operations created three clear ‘treatments’ for evaluation of the exclosure effect: blowdown, blowdown plus salvage logging, and an undamaged control. Nine years post-tornado, we inventoried tree regeneration within these treatments to evaluate differences in sapling abundance, species composition, size structure, and browsing intensity. We also inventoried CWM, including the height above forest floor.
Results revealed significant differences in sapling composition and browsing intensity among treatments. The salvage treatment had the highest proportion of browsed saplings (56 ± 28%; mean ± standard error), followed by the control (9 ± 10%) and blowdown (5 ± 8%). Blowdown had by far the greatest mean (50 ± 9 cm) and average maximum (169 ± 43 cm) heights for CWM. Binomial generalized linear models revealed that browsing probability was a function of mean CWM height and an interaction between sapling density and proportion of sapling hardwoods. Thus, browsing damage was less likely in plots with greater CWM heights and more likely in plots with greater sapling density and more hardwood saplings.
Synthesis and applications: This study furthers our understanding of ecosystem recovery following blowdown and salvage logging. Results suggest that salvage logging created important differences in CWM abundance and height distribution, when compared to un-salvaged areas, and that these differences in turn altered sapling size structure and browsing intensity. These findings highlight the potential long-term effects of successive disturbances, as the differences evident in these early stages may persist for decades or longer. Importantly, we provide evidence of the exclosure effect, suggesting that CWM retained in the un-salvaged area protected saplings from moose browsing. Thus, in post-disturbance areas where browsing threatens regeneration, we recommend that managers consider retaining CWM to serve as a natural exclosure.
README: The Natural ‘Exclosure Effect’ and Tree Regeneration Following Post-Windstorm Salvage Logging
https://doi.org/10.5061/dryad.bnzs7h4hh
This dataset contains the coarse woody material (CWM) and sapling data analyzed for this manuscript. Details on methods and codes are located in the metadata sheets of the dataset. Additional details about the methodology can be found in the manuscript.
Description of the data and file structure
Data are sorted among two sheets, one containing coarse woody material data (CWM) and the other containg sapling data. The CWM data sheet lists the treatment, plot ID, transect direction, species (if known), diameter (taken using calipers), height (to midpoint), and decay class (five-class scale). The sapling data sheet lists treatment, plot ID, transect direction, species, browse (presence/absence), sapling diameter size class and total (sum of size class rows). Species codes are provided on a separate sheet and metadata tabs provide additional details.
Sharing/Access information
Contact the corresponding author for additional details about use of this dataset.
Code/Software
These data were analyzed in R, code avaliable upon request from the corresponding author.