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Abstract In post‐fire Siberian larch forests, where tree density can vary within a burn perimeter, shrubs constitute a substantial portion of the vegetation canopy. Leaf area index (LAI), defined as the one‐sided total green leaf area per unit ground surface area, is useful for characterizing variation in plant canopies. We estimated LAI with allometry for trees and tall shrubs (>0.5 and <1.5 m) across 26 sites with varying tree stem density (0.05–3.3 stems/m2) and canopy cover (4.6%–76.9%) in a uniformly‐aged mature Siberian larch forest that regenerated following a fire ∼75 years ago. We investigated relationships between tree density, tree LAI, and tall shrub LAI, and between LAI and satellite observations of Normalized Difference and Enhanced Vegetation Indices (NDVI and EVI). Across the density gradient, tree LAI increases with increasing tree density, while tall shrub LAI decreases, exhibiting no patterns in combined tree‐shrub LAI. We also found significant positive relationships between tall shrub LAI and NDVI/EVI from PlanetScope and Landsat imagery. These findings suggest that tall shrubs compensate for lower tree LAI in tree canopy gaps, forming a canopy with contiguous combined tree‐shrub LAI across the density gradient. Our findings suggest that NDVI and EVI are more sensitive to variation in tall shrub canopies than variation in tree canopies or combined tree‐shrub canopies in these ecosystems. The results improve our understanding of the relationships between forest density and tree and shrub leaf area and have implications for interpreting spatial variability in LAI, NDVI, and EVI in Siberian boreal forests.
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Tall shrub (Alnus, Betula, Juniperus, Salix, and Shepherdia) densities at Brooks Range treelines, Alaska (2019-2022)
Stem counts of tall shrubs (height from 0.3 to greater than 2 meters) during 2019, 2020, 2021 and 2022 as sampled within n = 594 5-meter radius plots (area = 78.5 square meters), each centered on a selected white spruce adult called "Focal Tree". The purpose of this dataset was to examine spatial variation in tall shrub densities of the most important genera across the Brooks Range and in relation to local microclimates. It also provides a baseline for future shrub stem counts to determine changes in abundance.
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- Award ID(s):
- 1748773
- PAR ID:
- 10475444
- Publisher / Repository:
- NSF Arctic Data Center
- Date Published:
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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