Variable species establishment in response to microhabitat indicates different likelihoods of climate-driven range shifts

Climate change is causing geographic range shifts globally, and understanding the factors that influence species’ range expansions is crucial for predicting future biodiversity changes. A common, yet untested, assumption in forecasting approaches is that species will shift beyond current range edges into new habitats as they become macroclimatically suitable, even though microhabitat variability could have overriding effects on local population dynamics. We aim to better understand the role of microhabitat in range shifts in plants through its impacts on establishment by Q1) examining microhabitat variability along large macroclimatic (i.e., elevational) gradients, Q2) testing which of these microhabitat variables explain plant recruitment and seedling survival, and Q3) predicting microhabitat suitability beyond species range limits. We transplanted seeds of 25 common tree, shrub, forb, and graminoid species across and beyond their current elevational ranges in the Washington Cascade Ra..., Study site
We utilized the large macroclimatic and elevational gradients of the Cascade Range in Washington, USA to transplant seeds along each of 2 large transects spanning ~1200 m on the West and East side of the Cascade Crest on the traditional lands of the Nlaka’pamux, Nooksack, Okanagan, and Methow peoples. Both transects are characterized by topographically complex terrain and differ substantially in their macroclimatic characteristics. The West transect (Mount Baker National Forest) is warmer and wetter than the East transect (Okanagan National Forest). Both transects are characterized by montane to subalpine species common in the Pacific Northwest, with an abundance of cedars, firs, heathers, and understory forbs and graminoids. We selected 15 sites along each of the 2 transects (n = 30 sites) using satellite images of accessible areas, and identifying areas (i.e., blocks) that had both low and high tree canopy openness. In the field, we established two blocks per site (n = 60 b..., , # Variable species establishment in response to microhabitat indicates different likelihoods of climate-driven range shifts

[https://doi.org/10.5061/dryad.rv15dv4gn](https://doi.org/10.5061/dryad.rv15dv4gn)

## Description of the data and file structure

Made available here are compiled data on yearly germination/seedling census and microhabitat variables, and R scripts used to analyze the effects of microhabitat on germination and seedling survival. These data and R scripts were used in Chardon et al. 2024. Variable species establishment in response to microhabitat indicates different likelihoods of climate-driven range shifts. Ecography. Files are listed under their parent folder.

**Compiled Data: these data files are used in the R scripts below, which load these data files as listed**

data/abbreviations.xlsx: description of all variables and species abbreviations, with datasets each variable is (1) or is not (0) used in

data/census_sdlg.RData: yearly seedling survival + microhabi...