Data for: Floristic changes following the chestnut blight may be delayed for decades
Data files
Jan 03, 2024 version files 20.28 KB
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Chestnut_Table_1.xlsx
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Chestnut_Table_2.xlsx
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README.md
Abstract
A survey conducted in the 1920s, prior to the chestnut blight, indicated that chestnuts and oaks were codominant canopy species in White Oak Canyon, Shenandoah National Park, Virginia. A second survey in 1977 suggested that chestnuts were being replaced by tree species present before the blight, particularly oaks. In 2021, we resurveyed the 10 sites included in our 1977 survey and also recorded canopy and understory trees that grew above remnant chestnut sprouts. The canopy changed more substantially during the second interval (since 1977). Birch and maples were now more abundant and species less tolerant of shade were generally better represented in the canopy. Hemlock declined, and oaks were less common in the canopy. Chestnut sprouts have become much less common since 1977, presumably as repeated cycles of diebacks have weakened rootstocks. Those sites where chestnut sprouts have persisted until 2021 differed from neighboring sites without them. Chestnut sprouts were rare in sites with birch and hemlock; chestnut has persisted in locations with red oaks in the canopy and with few other understory competitors. This survey has been conducted over a longer time interval than previous studies that asked similar questions and our results suggest that changes to the forest composition following the loss of the American chestnut may be greater than previously recognized although the relative contribution of losing this codominant species is unclear.
README: Data for Floristic Changes Following the Chestnut Blight May Be Delayed For Decades
https://doi.org/10.5061/dryad.4b8gthtkk
Description of the data and file structure
Table 1 shows the frequency of canopy tree species in White Oak Canyon (Shenandoah National Park) during Braun’s survey that preceded the chestnut blight (roughly 1930) and surveys that we conducted in 1977 and 2021. We also include the number of canopy trees for the 2021 survey. The letters next to each tree species indicate whether that species was classified as early (E), middle (M), or late (L) in the successional sequence.
Table 2 shows the number of canopy and understory individuals that were recorded above chestnut sprouts and above the four control points in the vicinity of each chestnut sprout in 2021.
Methods
We resurveyed 10 sites in White Oak Canyon in 1977 and again in 2021. Lucy Braun published a survey of the canopy trees in the canyon that she sampled prior to the arrival of the chestnut blight around 1930 (Braun 1950:225). She did not provide precise sampling locations. In August 1977 we surveyed 100 randomly selected canopy trees at each of ten southeast-facing sites in White Oak Canyon although these are not necessarily the same sites that Braun surveyed. We returned to these 10 sites in 2021 and resurveyed 100 canopy trees at each site.
In 1977 we surveyed 400 sampling points in White Oak Canyon, 176 of which had chestnut sprouts. We returned to those sites in 2021 and searched for chestnut sprouts or boles. When we located a chestnut sprout in 2021 we recoreded the species identity of trees that were growing over any part of the space immediately above the chestnut sprout and noted whether these other trees reached the canopy or were only in the understory. We moved 20m in each of the four cardinal directions from each chestnut sprout and recorded the canopy and understory trees above each of these points that were taller than 2m.