Ten Years of Monitoring Illustrates a Cascade of Effects of White Pine Blister Rust and Focuses Whitebark Pine Restoration in the Canadian Rocky and Columbia Mountains

Brenda Shepherd,Natalie Stafl,Brad Jones,Cyndi Smith,Jed Cochrane,Jane Park,Robert Sissons

doi:10.3390/f9030138

Brenda Shepherd, Natalie Stafl + Show 5 more

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https://doi.org/10.3390/f9030138

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Journal: Forests	Publication Date: Mar 14, 2018
Citations: 21	License type: CC BY 4.0

Affiliation: Parks Canada, Alberta Environment and Protected Areas

Abstract

Whitebark pine forests are declining due to infection by white pine blister rust and mountain pine beetle, combined with the effects of climate change and fire suppression. The Canadian Rocky and Columbia Mountains represent a large portion of the whitebark range; a vast area, exemplifying the need for knowledge about whitebark pine stands to target restoration. The aim of our work was to identify variables predicting live tree infection, seedling infection, canopy kill, mortality, and regeneration across this region, and present the results in spatially-explicit formats to assist land managers with restoration. Live tree and seedling infection by white pine blister rust increased over the last decade and cascading effects of the disease are intensifying, including canopy kill and mortality. We show that large diameter trees are more likely to be infected, and the highest infection rates are in southern and western areas. The conditions for seedling infection are more strongly influenced by fine-scale climatic conditions than for trees. Areas with low regeneration are: (1) the dry east slopes where live tree infection is low; and (2) where live tree infection rates are high, suggesting that canopy kill and mortality are influencing regeneration. Results highlight where to target restoration and coordinate across boundaries.

Highlights

We examined natural regeneration to better understand the relationships between regeneration and blister rust infection in the region, and to identify areas that may benefit from restoration treatment by thinning or prescribed fire, and/or seedling planting
We report the predictive performance of the cross-validated model using the Area Under the Curve (AUC) of the receiver-operating characteristic (ROC) plot for binary responses and the root mean square error (RMSE) for beta and negative binomial response variables
Blister rust infection of whitebark pine is highly variable across the Canadian Rocky and Columbia

Summary

Introduction

Current white pine blister rust (Cronartium ribicola J.C. Fisch) infection and mountain pine beetle (Dendroctonus ponderosae Hopk.) impacts, combined with the effects of climate change and fire suppression, have placed whitebark pine (Pinus albicaulis Engelm.) in an endangered status in Canada, and as a candidate species for listing under the United States Endangered Species Act [1,2]. Additional research on the effectiveness of early restoration efforts and strategies across the species’ range will accelerate science-based management and recovery of the species. The range-wide restoration strategy for whitebark pine [9], recovery strategy for whitebark pine in Canada [8] and recovery plan for Alberta [10] highlight principles and possible actions to guide restoration. These include thinning competing tree species, collecting putatively blister rust-resistant seeds, screening seed stock for natural resistance, planting rust-resistant seedlings, and using prescribed fire to emulate the natural disturbance regimes that benefit whitebark pine regeneration [9]

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