Research Highlights: The efficacy of planting for restoration is important for ecosystem managers. Planting efforts represent an opportunity for conserving and managing species during a population crisis. Background and Objectives: Federal agencies have been planting whitebark pine (WBP), an important subalpine species that is late to mature and long-lived, for three decades in the Greater Yellowstone Ecosystem (GYE). These efforts have been met with varying success, and they have not been evaluated beyond the first five years post-planting. Ecosystem managers will continue to plant WBP in the GYE for years to come, and this research helps to inform and identify higher quality habitat during a period of changing climate and high GYE WBP mortality rates. Materials and Methods: We use a combination of field sampling and a water balance model to investigate local biophysical gradients as explanatory variables for WBP performance at twenty-nine GYE planting sites. Results: We found that the WBP growth rate was positively correlated with actual evapotranspiration (AET) and was greatest when cumulative growing season AET was above 350 mm. Growth rate was not strongly affected by competition at the levels found in this study. However, site density change over time was negatively affected by mean growing season temperature and when more than five competitors were present within 3.59 m radius. Conclusions: If they make it to maturity, trees that are planted this season will not begin to produce cones until the latter half of this century. We recommend planting efforts that optimize AET for growth rate objectives, minimize water deficit (WD) that cause stress and mortality, and removing competitors if they exceed five within a short distance of seedlings.

Whitebark pine is difficult to distinguish from limber pine when seed cones are not present. This is often the case because of young stand age, growth at environmental extremes, or harvesting by vertebrate species. Developing an economical genetic identification tool that distinguishes non-cone-bearing limber from whitebark pine, therefore, could aid many kinds of research on these species. Phylogenetic studies involving limber and whitebark pine suggest that chloroplast DNA sequences differ between these species. We therefore wanted to identify chloroplast loci that could differentiate limber from whitebark pine trees by taking an economical approach involving restriction-site analysis. We generated chloroplast DNA barcode sequences sampled from limber and whitebark pine trees that we identified using attached seed cones. We searched for nucleotide differences associated with restriction endonuclease recognition sites. Our analyses revealed that matK and the psbA-trnH spacer each readily amplified and harbored multiple DNA-sequence differences between limber and whitebark pine. The matK coding sequence of whitebark pine has a BsmAI restriction site not found in limber pine. The psbA-trnH spacer of limber pine has two PsiI restriction sites, neither of which is found in whitebark pine. DNA-sequence and restriction-site analysis of the psbA-trnH spacer from 111 trees showed complete congruence between visually and genetically identified limber (n = 68) and whitebark (n = 43) pine trees. We conclude that restriction site analysis of the chloroplast psbA-trnH spacer and matK involves both minimal technical expertize and research funds. These findings should be of value to foresters interested in species identification and distribution modeling, as well as the analysis of fossil pine pollen, given that gymnosperms transmit chloroplast DNA paternally.

Research and management issues related to pine forests, snowpack and refugia are relevant to mountainous ecosystems globally. For this study, we investigated local snowpack longevity as an explanatory variable for whitebark pine performance (survival rate, growth rate and condition). We used Sentinel-2 imagery to monitor local snowpack longevity. This new imagery is spatially and temporally more appropriate than other publicly available satellite imagery, and early results indicate that Sentinel-2 imagery can be successfully used for this purpose. Sites were selected based on a multi-decade management effort by federal agencies to plant whitebark pine in the Greater Yellowstone Ecosystem. Relative to initial planting records, present-day field sampling affords an opportunity to evaluate whitebark pine performance over time. Featured photo from Figure 3 in report.