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The timber producing forest land-base in Alberta, Canada, is decreasing due to the increase in allocation of land to other uses such as agriculture, infrastructure, energy development and conservation areas, while the demand for forest products continues to increase. Tree improvement, first implemented in Alberta in 1975, is one strategy used for increasing forest productivity to meet an increasing demand for fibre and forest products. To quantify the operational impact of tree improvement on white spruce productivity, we collected data from 15-year-old white spruce stands in Alberta: 11 stands planted with seedlings from improved (seed orchard) seedlots and seven stands planted with seedlings from wild (unimproved) seedlots. Eight plots (100 m2 circular plots) within each stand were randomly established for measurement (18 × 8 = 144 plots). Diameter at breast height (DBH), tree height, crown width, and branch diameter for each tree inside the plots were measured. Mixed effects models, with site and plot considered random, were used to evaluate the effect of tree improvement on the growth of white spruce. Basal area per ha of competitor species was used to develop a non-spatial competition index, and to compare the growth of improved and unimproved white spruce response to competition. Individual trees from improved stands showed 17% greater DBH and height compared to individual trees from unimproved stands. Individual trees of improved stands also had a greater height and smaller branch diameter for a given DBH than the trees grown in unimproved stands. Overall, tree improvement increased the site index of white spruce by 2 m while both improved and unimproved stands were similarly, and negatively, affected by competition. The application of tree improvement in white spruce resulted in an increase in growth rate, site index, and quality of timber, which will help offset the increasing demand for forest products. • Impact of tree improvement on white spruce was assessed operationally. • 17% greater growth in DBH and height was observed in improved white spruce. • Site index of improved white spruce was increased by 2 m. • Improved and unimproved stands were similarly affected by competition. [ABSTRACT FROM AUTHOR]

The growing concern of the impact of climate change in forestry has prompted tree improvement programs and regulatory agencies to integrate climate change adaptation in the production and use of tree seed. In support of such adaptation strategies, we conducted a case study for lodgepole pine ( Pinus contorta Dougl.) in Alberta, Canada. We compared the tree height for populations and families planted across 37 progeny and provenance trials when transferred among six physiogeographically and climatically distinct breeding regions. Based on these results we infer how lodgepole populations and families are adapted to current climate conditions and how they might respond to future changes in climate. Interestingly, in almost all regions we found that local populations grew better than introduced sources, suggesting that in the current climate the use of local populations is still an appropriate reforestation strategy with some exceptions. Notably, in cool and wet higher elevation environments (between 1050 and 1650 m), local populations were outgrown by populations originating from warmer lower elevation regions. Moreover, these higher elevation populations were always outgrown when transferred to other regions. A number of transfers among regions were identified that ensure productivity gains under recent climate conditions, and simultaneously represent a short term adaptation measure for warming of about +0.5 °C. Further, we provide a database for selection of families within breeding populations to enhance their resilience to climate change. [ABSTRACT FROM AUTHOR]

Hybrid poplar plantations have the potential to produce a large amount of biomass for the forest industry; however, competition for resources by neighbouring vegetation can severely reduce that potential. Intensive vegetation control of all neighbouring vegetation is potentially costly and an inefficient use of limited resources, thus identifying the characteristics of competing vegetation most detrimental to tree growth is essential for optimizing plantation inputs and yields. Our objectives were to model tree growth losses as a function of neighbouring vegetation composition, abundance, and spatial proximity. We then tested different vegetation control treatments for their effectiveness with different neighbouring vegetation. Field work took place on four operational plantation sites in northeastern Alberta over the course of three years, and commenced at the beginning of the second growing season after plantation establishment. Regression tree and Nonmetric Multidimensional Scaling (NMDS) analyses indicated that perennial grasses in general, and Elytrigia repens in particular, were detrimental to hybrid poplar growth – especially for younger trees. Planting site also played a large role in determining tree productivity, although it is difficult to quantify its influence relative to competition because site and vegetation community differed among sites. Increasing intensity of vegetation control treatments did not increase tree survival rates in any of the sites, but did result in commensurate increases in tree growth on most sites. Intensive vegetation control with herbicides dramatically increased tree growth on sites containing populations of perennial grasses. Using only cultivation as a form of vegetation control was the least effective option, and was ineffective for control of perennial grasses compared to other treatments. These results suggest that control of perennial grasses by means of herbicides over the other forms of competition control tested will have the greatest impact on reducing losses in tree growth due to competition. [ABSTRACT FROM AUTHOR]

Abstract: Trees from three hybrid poplar clones (one Populus balsamifera × P. simonii clone and two P. deltoides × P. × petrowskyana clones), were grown for 3 years in an agricultural field and fertilized at planting with 27 combinations of nitrogen (N), phosphorus (P) and potassium (K) fertilizers. Fertilizers used were granular ammonium nitrate (34.5–0–0) at three levels (0, 8 and 16g/tree), triple-super-phosphate (0–45–0) at three levels (0, 12.5 and 25g/tree), and potassium sulfate (0–0–50) at three levels (0, 8 and 16g/tree). Growth responses to N fertilization were negative during the first growing season: N fertilization reduced growth, net assimilation rate (A), stomatal conductance (G s), and increased the abundance of 13C in the leaves. These results might be related to the soil pH at the site which ranged from 7.7 to 8.1, and to the dry conditions that prevailed during the first growing season. Leaf N concentrations were unaffected by the fertilization level. Conversely, N fertilization decreased leaf P concentrations, which were in turn positively correlated with growth and negatively correlated with carbon isotopic composition (δ13C). There were clonal differences in δ13C that varied between the first and second growing seasons in relation to the relative growth rates of the clones. Growth responses to fertilization at planting were nil or slightly positive during the second and third growing seasons. These results indicated that ammonium nitrate was unsuitable for fertilizing these hybrid poplar clones at planting, and that further study is required to test fertilization at planting with nitrate-N versus ammonium-N sources under these field conditions. [Copyright &y& Elsevier]

Balsam poplar (Populus balsamifera L.) can easily be grown when planted as dormant, unrooted cuttings. The first part of this research project consisted of a greenhouse study to identify the best combination of pre-planting treatments to maximize rooting of hardwood cuttings for large-scale greenhouse propagation. Eighty-four treatment combinations were tested on 10 cm-long cuttings, including seven soaking lengths of time (0, 1, 2, 3, 4, 5 and 14 days), three dips (none, powder and liquid rooting hormone), two collection dates (fall and spring), and two cutting selections (average trees and a superior clone).Secondly, we tested the performance of unrooted cuttings on typical forestry sites lacking natural regeneration, using 30 cm-long cuttings and full-length whips (>60 cm). Three pre-planting treatment combinations were used (soaking for 1 or 3 days, or 3 days with a dip in rooting hormone). Other factors tested were two collection dates (fall and spring), two cutting selections (average trees and a superior clone), two storage methods (stored as full whips or cut to size), and two cutting locations (basal or top 30 cm of stools). [Copyright &y& Elsevier]

• Aridity exerted minimal to no selective pressure on wood density. • Wood density therefore did not reflect an ability to tolerate drought. • Wood quality is best assessed past cambial ages of 10 for spruce and 8 for pine. • Transition age out of juvenile wood production was not a heritable trait. • Five spruce and six pine families had above average wood density and volume. Climate driven tree mortality threatens the current performance and productivity of the temperate boreal forests. For economically important tree species, progeny trials provide an opportunity to assess variability in wood quality and growth traits and their associations with climatic stressors, such as water availability. Data from 3,152 34-year-old white spruce and lodgepole pine progeny, representing 120 half-sib families, were used to test the selective pressure of aridity on wood density and wood microfibril angle, two attributes that contribute to wood performance. Tree increment cores were further evaluated for correlations between time of transition out of juvenile wood production and the environment. Aridity at seed point of origin had minimal to no selective pressure on overall wood density or microfibril angle in the breeding populations represented in this study. Aridity at the progeny test sites had a greater effect on spruce wood density, however, similar effects on pine could not be assessed as sites were too climatically similar. Transition out of juvenile wood production was not found to be influenced by genetic differences across families in either species examined. These determinations are pivotal for breeding programs which seek to use heritable and economically important traits to select for adaptability in a changing climate. [ABSTRACT FROM AUTHOR]

• We adjusted and compared two available age-age correlation equations. • We explored a new method for age-age correlation prediction. • The adjusted age-age correlation equations were incorporated into the growth and yield projection system (GYPSY). • Phenotypic age-age correlation was a good substitute for genetic age-age correlation. • White spruce has a higher age-age correlation than lodgepole pine for a given age of selection and rotation. Tree improvement is considered an effective method to address the shrinking forest land-base in Alberta, Canada. It is also of great necessity to quantify the potential harvest from deployment of improved trees. However, the growth and yield models currently used in Alberta were originally developed based on growth measurements and projections from fire origin stands, and therefore, there is no widely accepted method to recognize the impact of managed stands, and even less information available to properly incorporate genetic gain in volume from tree improvement into managed stand models. Furthermore, there are considerable challenges associated with acceptance of an appropriate age-age correlation when selecting trees at a young age and projecting their anticipated increase in volume at rotations as long as 80–110 years. White spruce (Picea glauca (Moench) Voss) and lodgepole pine (Pinus contorta Dougl.) are the most important commercial tree species in Alberta, and the focus of this study. Based on the most recent and comprehensive datasets from progeny trials from both species, two available age-age correlation equations, one developed by Lambeth (1980) and another by Rweyongeza (2016), were compared and adjusted. This study also explored a new method for age-age correlation prediction based on a sigmoid parabolic branch (SPB) equation. The results show that the adjusted Lambeth equations, with re-estimated parameters for white spruce and lodgepole pine in Alberta, are the most robust for both species and should be further incorporated into the growth and yield models, based on cross-validation results at a relatively young age (7–31 years for white spruce and 6–30 years for lodgepole pine). The phenotypic age-age correlation shows no significant deviation from the genetic age-age correlation for white spruce and lodgepole pine in Alberta. The stand volume generated from the growth and yield projection system (GYPSY) using an age-age correlation from the adjusted Lambeth equations shows that white spruce has a higher age-age correlation and therefore, a higher percentage improvement in volume per hectare compared to lodgepole pine regardless of rotation age. [ABSTRACT FROM AUTHOR]

We developed allometric equations for small-diameter woody species growing on mixed forest marginal lands, which are potential sources of biomass for bioenergy. Eleven species of trees and shrubs were sampled from a site located in eastern Canada. Equations derived in this study generally performed better than equations from the literature. Also, fixed-area plots (FAP) and line-intersect sampling (LIS) methods using both random or systematic selection of sampling units were compared to determine which method required the lowest number of measurements to estimate stand biomass for the same precision. The fixed-area plots method was successfully used to estimate relatively accurately oven-dry biomass per hectare. Results indicated that potentially harvestable woody biomass (oven dry basis) varied between 33-41 and 12–13 t ha −1 for the most and least productive marginal sites respectively. On the most productive site, LIS estimates (between 20 and 42 t ha −1 ) were usually lower than those obtained using different FAP sampling methods (i.e. systematic or random, small (50 m 2 ) or large (100 m 2 ) plots), but similar on the more open sites (between 10 and 14 t ha −1 ). Small FAP resulted in a plot without measurements in one case. Moreover, estimates based on small FAP were generally higher, even if not significantly different from larger plot estimates. We therefore suggest using FAP with 100 m 2 plots to estimate small-diameter woody biomass on marginal lands with dense vegetation, while LIS, even if promising for open stands, needs further evaluation before recommendation. [ABSTRACT FROM AUTHOR]

Short-rotation intensive culture (SRIC) for bioenergy production is at its pre-commercial stage in Canada. To be economically viable, these types of plantations need an accurate examination of actual yields, which requires precise and efficient estimation methods (i.e., specific allometric equations and sampling methods). At six SRIC plantations from three Canadian provinces (Quebec, Ontario and Alberta), 6 willow and 10 poplar clones were sampled and clone allometric equations were developed to estimate plant biomass. A stem selection approach was successfully used to develop plant allometric equations, reducing the number of stems to be measured by up to 81% in coppiced plantations relative to traditional stem equations. Clone-specific equations were more accurate than equations for groups of clones, but the difference in terms of RMSE% was generally small (less than 5%). Using extensive measurements of all the plants inside a plantation and a simulation approach, we also compared five sampling methods (simple random sampling, stratified sampling, systematic sampling, random and systematic cluster sampling) to estimate total biomass inside the plantation. Simple random sampling and stratified random sampling were the most efficient methods (i.e., increased precision for equal sample size) for the estimation of average plant biomass, survival and total plantation biomass. Stratified random sampling (based on the position inside the plantation) made it possible to reduce the sample size as compared to simple random sampling, but only at higher levels of precision (e.g., 25 less plants at 5% precision). Applications of sampling using remote sensing techniques and GIS are briefly discussed. [ABSTRACT FROM AUTHOR]

Morphological characteristics of poplar and willow clones were determined in order to identify main characteristics leading to superior growth under increased plant competition with low or high nitrogen (N) availability. Seven hybrid poplar ( Populus spp. including one hybrid aspen) and five willow ( Salix spp.) clones were grown under greenhouse conditions for 13 weeks at three spacings (20 × 20, 35 × 35, and 60 × 60 cm) and two N levels (20 and 200 mg kg −1 ). The decrease in spacing from 60 to 20 cm reduced leaf area by 50% but clones had similar aboveground biomass per tree under all spacings, with increasing their height per unit leaf area. More productive clones had greater leaf area (+102%), leaf area per unit plant biomass (+12%) and lower root-to-shoot ratios (−27%) compared to less productive clones. There were positive relationships between leaf area and above-ground biomass per tree for both more and less productive clones. Compared to low N level and 60 cm spacing, trees growing in high N level and 20 cm spacing reached similar root collar diameter, crown width, and leaf area values and even greater height, suggesting that an addition of N could help mitigate negative effects of tree competition. [ABSTRACT FROM AUTHOR]