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Heineman J.L.,J. Heineman Consulting | Sachs D.L.,Forest Research Consultant | Jean Mather W.,Skyline Forestry Consultants Ltd | Simard S.W.,University of British Columbia
Canadian Journal of Forest Research

Lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) has been extensively planted throughout interior British Columbia, and as a result may be particularly susceptible to climate-induced changes in the range and severity of common damaging agents. We quantified the presence of 14 damaging agents in sixty-six 15-to 30-year-old pine stands. Hard pine stem rusts, primarily western gall rust, were present on every site. We used logistic regression to predict individual agent presence from climatic, location, site, and treatment factors and calculated odds ratios to evaluate whether risk to lodgepole pine increases or decreases as these factors change. Risk of damage from serious agents (stem disease, root disease, and mountain pine beetle) increased with increasing latitude; however, in several of these models, risk also increased as temperature of the coldest month got warmer. We also found evidence that increasing risk of damage from agents that are currently less serious (sequoia pitch moth, pine needle cast, and pine terminal weevil) was associated with warming and (or) increasingly dry climatic conditions. Given the predominance of lodgepole pine in northerly ecosystems and the prediction that climate change effects will increase with latitude, our results suggest the need to consider potential increases in damage from diseases and insects during silviculture planning and timber supply prediction. Source

Mather W.J.,Skyline Forestry Consultants Ltd | Simard S.W.,University of British Columbia | Heineman J.L.,J. Heineman Forestry Consulting | Sachs D.L.,Forest Research Consultant
Forestry Chronicle

Lodgepole pine is extensively planted across western Canada but little is known about development of these stands beyond the juvenile stage. We quantified stocking status and damage incidence in sixty-six 15- to 30-year-old lodgepole pine plantations that had previously been declared free-growing in the southern interior of British Columbia. The stands were located in six biogeoclimatic zones: Engelmann Spruce-Subalpine Fir (ESSF), Montane Spruce (MS), Interior Cedar-Hemlock (ICH), Interior Douglas-fir (IDF), Sub-Boreal Spruce (SBS), and Sub-Boreal Pine-Spruce (SBPS). Freegrowing standards were no longer met on 27% of plantations, with the worst performance (70% no longer free-growing) in the Interior Cedar-Hemlock forests. Natural regeneration was common but it was half the size of lodgepole pine. Biotic damage, especially hard pine stem rusts, was the dominant factor reducing free-growing densities. Stands were at greater risk of reduced stocking where summer precipitation was higher or soil moisture regimes were wetter and where stands had been broadcast-burned prior to planting or received secondary treatments of brushing or pruning. Reforestation policies that encourage widespread planting of lodgepole pine, particularly in areas where lodgepole pine has limited natural occurrence such as in the ICH zone, should be reconsidered given that health problems are extensive and are expected to increase with climate change. Source

Heineman J.L.,J. Heineman Consulting | Sachs D.L.,Forest Research Consultant | Simard S.W.,University of British Columbia | Jean Mather W.,Skyline Forestry Consultants Ltd
Forest Ecology and Management

In southern British Columbia, juvenile trembling aspen is managed primarily as a competitor with conifers rather than for its ecological and economic value. As a result, brushing treatments have been applied on a widespread basis and this practice is likely to continue in the near future. Given the potential for climate change to affect our valuation of aspen, we require a better understanding of factors that affect its development, its competitive ability with conifers and its responses to brushing. We used data from 11 aspen management experiments to examine the influence of climate and site factors on aspen height, cover, and density in 17-24 year-old control stands and 9-16 years after manual cutting or girdling. Models explained 64% and 89% of the variation in aspen height in control and manually brushed stands, respectively, but were poor for girdling. Increasing length of the frost-free period was associated with increasing aspen height in control stands, whereas drier summer conditions on cool aspects favoured height growth of aspen suckers following manual cutting. We also examined the influence of climate and site factors on three simple competition indices that describe the height and density of aspen relative to conifer height, and then tested how well these indices predicted conifer growth. The density of aspen taller than conifers accounted for 39% of the variation in lodgepole pine diameter and the ratio of aspen/conifer height accounted for 33% of the variation in Douglas-fir height, suggesting that aspen competition was only moderately important to conifer growth. Our findings imply that aspen may become more productive with warmer summers provided it is not limited by summer moisture availability and that mixed stand management is a viable option in southern interior stands. © 2010 Elsevier B.V. Source

Baleshta K.E.,Forest Research Consultant | Simard S.W.,University of British Columbia | Roach W.J.,Skyline Forestry Consultants Ltd
Scandinavian Journal of Forest Research

Naturally regenerated paper birch (Betula papyrifera Marsh.) is commonly removed from juvenile interior Douglas-fir (Pseudotsuga menziesii var. glauca [Beissn.] Franco) plantations in southern interior British Columbia, Canada, to increase conifer productivity and create a free-growing stand; however, this practice is expensive and contentious because of possible negative ecological impacts. One solution is to retain an optimal density of birch where growth gains of understory Douglas-fir are balanced against losses to Armillaria ostoyae (Romagn.) Herink and understory plant species diversity. We sought to find this optimal density by comparing four evenly applied birch density reduction treatments (0, 400, 1111, and 4444 retained birch stems ha−1) and an unthinned control (>7300 retained birch stems ha−1). The mortality rate of Douglas-fir due to Armillaria root disease increased non-significantly with thinning intensity. Mean diameter increment of surviving Douglas-fir improved the most where birch was completely removed, with little variation among intermediate thinning treatments. Height growth was unaffected by the thinning treatments. Diversity of cryptogams was significantly greater in the control than where all birch was removed. We suggest that the treatment with 4444 retained birch stems ha−1 provides the best balance for improving Douglas-fir growth while minimizing risk of increased Armillaria root disease and reduced understory plant diversity in young mixed stands. © 2015 Taylor & Francis. Source

Roach W.J.,Skyline Forestry Consultants Ltd | Simard S.W.,University of British Columbia | Sachs D.L.,Forest Research Consultant

Single-species planting of lodgepole pine (Pinus contorta var. latifolia) following clear-cut logging or wildfire has been common throughout interior British Columbia, Canada, but health problems with the species have been documented as it grows beyond the juvenile stage. We examined damage and stocking in twenty-seven 15- to 30-year-old lodgepole pine plantations that were previously declared free growing in the highly productive cedar-hemlock forests in southeastern British Columbia, where lodgepole pine is absent from many primary forests. In order to be free growing, stands must meet minimum tree density, height, damage and brush competition criteria as legislated by the Provincial government. Overall, 44 per cent of lodgepole pine trees had unacceptable damage (causing them to be rejected as crop trees), and as a direct result, one-third of the plantations were no longer defined as free growing because there were insufficient crop trees remaining. Natural regeneration of other tree species partially compensated for the unhealthy pine. Logistic regression and odds ratio analysis associated increasing risk of damage from western gall rust with increasing soil moisture, more northerly aspects and mechanical site preparation, and decreasing risk with pre-commercial thinning treatment. Risk of damage from snow and ice was associated with increasing mean annual precipitation, decreasing longitude and broadcast burning. Risk of bear damage was associated with increasing soil moisture, pre-commercial thinning treatment and broadcast burning. Based on our results, we recommend that single-species planting of lodgepole pine be curtailed in the Interior Cedar-Hemlock zone in southeastern British Columbia. © Institute of Chartered Foresters, 2015. Source

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