DOI: 10.5683/sp3/ujvz9i
title: Data for: Modeled seed accumulation patterns explain spatial heterogeneity of shrub recruitment within the taiga-tundra ecotone

description: These data were collected to investigate the fine-scale drivers of tundra shrub recruitment patterns with a specific focus on seed dispersal and ground cover suitability. To do this we established 15 m resolution grids of seed traps and paired seedling abundance measures at three &lt;i&gt;Alnus alnobetula&lt;/i&gt; (green alder) patches near the Trail Valley Creek Research Station situated within the taiga-tundra ecotone of the Northwest Territories. For each observation (i.e., target point) we estimated the relative seed input expected based off a set of seed dispersal mechanisms hypothesized to be important at the site. These included overland hydrochory (OVERLAND), blowing snow transport (SNOW), dominant wind direction (WIND), and distance from source (DISTANCE). We also estimated topographic wetness index (TWI) for each target point. The model-averaged relationship between these mechanisms and seedling abundance was then used to predict seedling recruitment across the Siksik creek sub-catchment by estimating the seed input from each hypothesized mechanism across 2000 random points. To validate these predictions and the resulting map, we selected 51 points across the basin and estimated seedling abundance by measuring the distance to the third nearest seedling from each point.&lt;p&gt;&lt;p&gt;
In addition to the grid and validation data, this dataset also includes information on the abundance of alder seedlings across topographic gradients at ten sites. Each site included transects running through alder patches, with sampling quadrats established above the patch, at the exterior and interior of both patch edges and at the patch centre. The patch transects were paired with transects in the adjacent alder-free tundra which included top, middle, and bottom sampling quadrats. At each of these quadrats we established two 1 m2 vegetation plots in which we estimated ground cover abundance and counted the number of alder seedlings, allowing for the investigation of plot-level associations. Five of these sites were then selected for intensive ground cover surveys to investigate the proportions of seedlings growing directly out of specific ground cover types.&lt;p&gt;&lt;p&gt;
For detailed methodological information see Wallace et al. 2024. Modeled seed accumulation patterns explain spatial heterogeneity of shrub recruitment within the taiga-tundra ecotone. In review at JGR:Biogeosciences.
description: ArcGIS, 10.5
description: R, 3.6.2
description: This study was conducted within the Inuvialuit Settlement Region under Aurora Research Institute research licenses 16017, 15898, and 15609. The authors would like to thank K. Black, T. Giguère, J. Rabley, E. Way-Nee, A. Sniderhan, and C. Proctor for their assistance with field work and K. McDonald for sorting and counting seed traps. We would also like to thank C. Larsen, M. Sturm, C. Parr, and C. Derksen for access to the 2013 LiDAR snow depth data. We also gratefully acknowledge the Wilfrid Laurier University-Government of the NWT Partnership Agreement and the logistical support of B. Walker and the entire Trail Valley Creek Research Station team.
Some of the ground cover data published here was included in the dataset "Abiotic and vegetation community data from Alnus alnobetula shrub and open tundra sites at Trail Valley Creek, NT" (Wallace and Baltzer, 2019).