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Tree species growth rates and susceptibility to insects and diseases in the southern ICH under current and possible future climatic conditions
Vyse, Alan
About 80 million tree seedlings are planted every year in the Southern Interior Region. The choice of tree species used in each planting operation is based on site conditions, species selection guidelines, expectations of relative species performance, and the potential impacts of insects, disease and factors such as frost and drought. In the past, foresters were able to assume that species choices could be made under the assumption that climate would not change. This assumption is no longer valid (Ministry of Forests and Range 2006). There are currently no mechanisms for evaluating species choice in the light of climate change. While models predicting the future distribution of climates associated with BC tree species based on bioclimatic envelope modelling are available (Hamann and Wang, in press), we do not know if, how or when species ranges will shift, or if they can successfully be shifted through careful choice of species for reforestation programs. We do not even understand what ultimately limits current species range. By studying species growth and health in multi-species trials, we can assess likely factors limiting ranges such as abiotic stresses (e.g., frost or drought) during seedling establishment, insects, diseases, ability to reproduce or interspecific competition. If trials are planted outside of the native range of species, we can compare the results to predictions from bioclimatic envelope models and evaluate opportunities to move species to new climates in the short term. This information will inform efforts to move species north in anticipation of climate change. For example, if species are limited by frost at the seedling stage, then there will need to be substantial warming before they should be planted in colder locations than they naturally occur. But if reproduction is the critical factor limiting range, then range expansion in a forestry context could proceed without high risks. The interactions between climate, insects and diseases are complex, and there is much to be learned from older species trials. Several long term species trials were established in the Southern Interior in the mid-eighties. The original purpose of these trials was to compare species growth performance under a range of local climatic conditions. A total of nine species were planted in the trials (ponderosa pine, lodgepole pine, white pine, Douglas-fir, interior spruce, western red cedar, western larch, paper birch and hybrid poplar). Ponderosa pine and white pine have both been planted beyond their natural range in the trials. Species growth rankings have changed over time and further changes are expected. The trials have all been measured at least once since establishment, and in one case, every five years. Forest insects, pathogens and climatic factors play a significant role in the dynamics of young stands, but detailed comparisons of individual and interactive pest impacts by host species, on a site and landscape level, have not previously been made before in BC. The experimental projects we propose to re-measure offer such an opportunity. A number of biotic and abiotic forest health factors have been identified over 15 years: Cooley spruce gall adelgid (Adelges cooleyi) on Engelmann spruce; western larch needle cast (Hypodermella laricis); Warren?s root collar weevil (Hylobius warreni), Northern pitch twig moth (Petrova albicapitana), Comandra blister rust (Cronartium comandrae), western gall rust (Endocronartium harknesii), and pine needle cast (Lophodermella concolour) on lodgepole pine; and blister rust (Cronartium ribicola) on western white pine. The species trials have also suffered through two prolonged summer droughts which affected western redcedar and paper birch most strongly. One of the most significant forest health concerns in these species trials is Armillaria root disease caused by the fungus Armillaria ostoyae. A. ostoyae is endemic throughout the ICH in the southern interior of B.C. causing ...
Report Number
Interim Report

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