DOI: 10.5061/dryad.7rd7s
title: Data from: Limited stand expansion by a long-lived conifer at a leading northern range edge, despite available habitat

description: 1. In an era of rapid climate change, understanding the natural capacity
 of species’ ranges to track shifting climatic niches is a critical
 research and conservation need. Because species do not move across the
 landscape through empty space, but instead have to migrate through
 existing biotic communities, basic dispersal ecology and biotic
 interactions are important considerations beyond simple climate niche
 tracking. 2. Yellow-cedar (Callitropsis nootkatensis), a long-lived
 conifer of the North Pacific coastal temperate rainforest region, is
 thought to be undergoing a continued natural range expansion in southeast
 Alaska. At the same time, yellow-cedar’s trailing edge is approaching its
 leading edge in the region, due to climate-induced root injury leading to
 widespread mortality over the past century. To examine the current
 dispersal capacity of yellow-cedar at its leading range edge, and
 potential for the species’ leading edge to stay ahead of its trailing
 edge, we characterized recent yellow-cedar stand development near Juneau,
 Alaska, and surveyed the spread of yellow-cedar seedlings just beyond
 existing stand boundaries. 3. Despite suitable habitat beyond stand edges,
 stand expansion appears limited in recent decades to centuries. Large
 quantities of seed are germinating within stands and just beyond
 boundaries, but seedlings are not developing to maturity. Furthermore,
 ~100-200-year-old yellow-cedar trees are located abruptly at stand
 boundaries, indicating stand expansion is in a period of stasis with a
 last pulse at the end of the Little Ice Age climate period. 4. Vegetative
 regeneration is common across stands and may be an adaptive strategy for
 this long-lived tree to persist on the landscape until conditions are
 favorable for successful seedling recruitment, leading to an overall
 punctuated migration and colonization of new landscapes. 5. Synthesis.
 Species ranges do not always respond linearly to shifting climatic
 conditions. Instead, successful colonization of new habitat may be tied to
 episodic, threshold-related landscape phenomena, dispersal ability, and
 competition with existing plant communities.
description: Full_Stand_Stem_Map_DataTree species, location, health, plant community, and associated environmental data. These data were used to create stem maps of adult trees (&gt; 1.39m in height) in three leading edge yellow-cedar (Callitropsis nootkatensis) stands in our study area near Juneau, Alaska, USA. The three stands are the "BCBP: Bridget Cove Beaver Pond", "DM: Dan Moller Trail", and "RS: Roadside" stands shown in Figure 1. These data were also used in Figure 5 to compare the diameter distributions of yellow-cedar trees in the fully stem mapped stands to the yellow-cedar trees in plots located only at the edges of stands.Plot_Stem_Map_DataTree and seedling species, location, health, plant community, and associated data for 29 plots spanning boundaries of leading edge yellow-cedar (Callitropsis nootkatensis) stands near Juneau, Alaska. These data were used to create stem maps of adult trees (&gt; 1.39m in height) and individuals of yellow-cedar (Callitropsis nootkatensis) regeneration (seedlings and vegetative layering). Plots were located at stand edges to monitor stand development and spread. The eight stands are the "BCBP: Bridget Cove Beaver Pond", "CL: Cedar Lake", "DM: Dan Moller Trail", "EG: East Glacier", "MCT: McMurchie Cat Trail", "RBC: Ready Bullion Creek", "RS: Roadside", and "TH: Tee Harbor Ridge" stands shown in Figure 1. These data were used in Tables 3 and 4, Figures 3, 4, and 6, Supplemental Table S1, and Supplemental Figure S1.Juneau_Yellow_Cedar_Stand_LocationsThese data represent the locations of eleven leading range edge yellow-cedar stands in our Study Area located near Juneau, Alaska, USA. Coordinates here are for the geographic mean center of patches of trees and lone trees (separated from each other by 30 m or more) that make up stands. Geographic Information Systems (GIS) shapefiles for stand boundaries and lone trees are also included on the data archive. A companion manuscript, Krapek, J., Hennon, P.E., D'Amore, D.V., and Buma, B. "Despite available habitat at range edge, yellow-cedar migration is punctuated with a past pulse tied to colder conditions." Diversity and Distributions, 2017 describes stand mapping methodology in detail.Juneau_YellowCedar_StandsThis is a shapefile containing the location of patches of yellow-cedar trees in yellow-cedar stands in our Juneau Study Area. The geographic coordinates of patches are also listed in the "Juneau_Yellow_Cedar_Stand_Locations.csv" file in this data package and are shown in Figure 1. A companion manuscript, Krapek, J., Hennon, P.E., D'Amore, D.V., and Buma, B. "Despite available habitat at range edge, yellow-cedar migration is punctuated with a past pulse tied to colder conditions." Diversity and Distributions, 2017, describes yellow-cedar stand and patch mapping methodology in detail.Juneau_Lone_YellowCedar_TreesThis is a shapefile containing the location of lone yellow-cedar trees in our Juneau Study Area. The geographic coordinates of lone yellow-cedar trees are also listed in the "Juneau_Yellow_Cedar_Stand_Locations.csv" file in this data package and are shown in Figure 1. A companion manuscript, Krapek, J., Hennon, P.E., D'Amore, D.V., and Buma, B. "Despite available habitat at range edge, yellow-cedar migration is punctuated with a past pulse tied to colder conditions." Diversity and Distributions, 2017, describes stand and lone tree mapping methodology in detail.