Bulkley Valley Research Centre - Science in the Public Interest

Assessment of off-site tree plantations in the Northern Interior Forest Region

Project Reference Number: 2010-07

Project Status: Complete

Led by: Phil LePage, Research Silviculturist, Ministry of Forests and Range, Smithers

Funder: Ministry of Forests and Range, Tree Improvement Branch

One of the core assumptions underlying British Columbia’s reforestation program is that the climate and environment are stable and therefore the tree species that were removed during harvest will be suitable for the next rotation. Global climate change, and the rate at which it is occurring locally, has put this assumption in serious doubt. across B.C., we are seeing increased instances of plantation failures that are likely associated with atypical climatic conditions (e.g. severe drought), as well as climate-driven alterations to forest disease levels and insect populations (e.g. Dothistroma and mountain pine beetle). In order to ensure the viability and sustainability of our forest resources and the communities and industries that rely on them, we need to determine not only the continued suitability of the species currently being used for reforestation, but also the potential of other “non-local” or “off-site” species to survive and grow. For the purposes of this proposal, “off-site” refers to tree species that are native to B.C. but not native to the area under study. Several research projects have investigated and modelled the fitness of tree species under warming temperatures due to climate change (Hamman and Wang, 2006; MoFR, 2006; Nitschke and Innes, 2007), but there is little field-based information available on the actual long-term performance of off-site tree species. Assisted migration and provenance trials are the usual approach to addressing this issue and they are valuable; however, because B.C.’s tree species are typically slow-growing and very long-lived, these types of experiments will take many years or even decades to provide detailed long-term survival and growth information. Our climate is changing more rapidly than our tree species can adapt, so it is critical that we take advantage of all available information to assist us in planning for, and adapting to, this change.

Over the last fifty years, the BC Ministry of Forests and Range (MoFR) and local forest companies in the northwest part of the province have established a network of operational non-local or off-site plantations, typically as small inclusions in operational blocks. These plantations have not been maintained or visited on any regular schedule; however, a preliminary survey in 2009 found that many still exist. Given the age of these plantations, they offer a unique and unparalleled opportunity to examine the survival, health, and growth of tree species that were established well outside of their known ranges and preferred climatic envelopes. Although these plantations were not specifically established as assisted migration or genecology trials, the condition of these trees will provide extremely valuable insight into how well the species have coped, not only with an atypical climate to start with, but also one that has continued to change over the last several decades. Off-site species known to have been planted outside their natural ranges include: Interior Douglas fir (Pseudotsuga menziesii var. glauca (Mirb.) Franco), Coastal Douglas fir (Pseudotsuga menziesii var. menziesii (Mirb.) Franco), Western larch (Larix occidentalis Nutt.), and Ponderosa pine (Pinus ponderosa Dougl. ex Laws).

The objective of this project is to examine how established plantations of off-site tree species have survived and grown over the last 50 years in northwest B.C. This information can then be compared with data for the local species in order to establish some baseline data for developing assisted migration guidelines. (e.g. How well is western larch doing in the ICHmc2 compared to lodgepole pine?) This project is a logical continuation of previous modelling efforts to understand and quantify the adaptability of tree species in a changing climate.

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