# Assisted Migration Field Tests in Canada and Mexico: Lessons, Limitations, and Challenges
## 3 Field Tests Examined  
### Canada. Pinus albicanulis  
Materials and Climate Data  
_Pinus albicanulis_ (whitebank pine) is a high-elevation species foundational to treeline ecosystems in mountainous areas of western Canada and the United States. It has been listed as endangered under Canada's Species at Risk Act as populations are in steep decline over much of its range, primarily due to the introduced pathogen causing white pine blister rust (_Cronarium ribicola_), but also from mountain pine beetle (_Dendroctous ponderosae_), fire suppression, and climate change. A species distribution model (SDM) projected a loss of climatically favorable habitat over most of its range in the USA under future climate scenarios [52]. A separate SDM also identified potential climate refugia in northwestern British Columbia (BC) outside of the current species range that already have contemporary climates suitable for this species and are projected to remain favorable to the end of this century (Figure 1) [53]. The apparent underfilling of the potential contemporary range of this species is typical of many North American tree species [54]. A field experiment was initiated in 2007 to (1) test the climate suitability projections of the latter model, and (2)evaluate the potential for assisted migration to establish populations of this species outside of the current range in areas predicted to be habitable [53].  
Briefly, seed from six provenances of _Pinus albicans_ was directly sown into common gardens in eight subalpine locations in BC, including sites within the current species range, sites north of the range predicted to be climatically suitable in 2055, and sites north of the species range predicted to be unsuitable in 2055 (Figure 1). Seeds rather than seedlings were sown to test whether sites were within the species ecological niche without circumventing life history stages. Half the seeds planted were extracted from cones and sown in fall 2007, untreated, while half were subject to a maturation and dormancy-breaking treatment, then sown in the spring of 2008. Data on seedling germination, survival, and growth were collected in 2008, 2009, 2010 (see [53]), and in 2017 ([PERSON], [PERSON], [PERSON] and [PERSON], in prep.). iButton temperature recorders were placed at the soil surface at each common garden location and provided records of air temperatures in the absence of snow, as well as duration of snowpack. In alpine treeline environments, microclimate varies greatly with microsite, so data regarding slope, soil depth and type, and surrounding vegetation were collected at each common garden location. Multinomial logistic models were used to analyze germination and survival data, while general linear models were used to analyze growth data. Predictor variables tested in models included provenance climate estimates for temperature and precipitation (obtained from ClimateBC), temperatures and snowmelt dates at common garden sites (from iButtons), and planting microsite characteristics.  
Figure 1: Location of _Pinus albicans_ provenances and common garden locations for the assisted migration experiment, with current and 2055 predicted _Pinus albicans_ ranges shown (from [53]).