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  • Author: Y. A. El-Kassaby x
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Abstract

The maintenance, protection, and conservation of forest genetic resources for economic, ecological and social benefits are daunting tasks. Understanding how reforestation materials are spatially and temporally deployed across the landscape is an integral component of forest genetic resources management. To improve the current understanding of how reforestation materials are deployed in British Columbia (BC), we developed a geographical information systems (GIS) method to track seed deployment across silviculture openings. Generally, reforestation materials can originate from either natural stand (wild seed collections) or orchards’ seed sources (improved seed); the latter are produced within the framework of specific tree improvement program designed for a particular species within a well-defined seed deployment area, commonly known as Seed Planning Zone (SPZ). In this paper, we present a GIS-based method for evaluating seed deployment patterns for interior spruce (Picea glauca and Picea engelmannii and their natural hybrids) within the Prince George SPZ. The evaluation period (1970-2004) is associated with wild stands and improved seed availability and the dynamic of each seed source proportionate contribution followed three distinct phases; namely, developing (1970-1987), immature (1988-1994), and mature (1995-2004) with a progressive increase of orchards’ seed use over time. The developed method is scalable across SPZs of the same species or multiple species, thus providing the means to: 1) temporally and spatially monitor improved and natural stands seed deployment over the landscape; and 2) identify areas of concerns where a particular seed source is over-represented which might pose an increased genetic vulnerability. The present study revealed that the current interior spruce orchard’s seed use within the Prince George SPZ is expected to exceed the provincial goal of performance target of 75% by 2014. Additionally, areas of excessive use of one seed orchard seed were identified.

Abstract

Acorn production was surveyed for eight consecutive years (2000-2007) in a 94-clone Sawtooth oak (Quercus acutissima) seed orchard established in 1992. Acorn production commenced in 2000 and peaked in 2005 and was characterized by a 3-4 years interval. Sixty out of the orchard’s 94 clones were consistent producers across the study period. Acorn production’s Pearson productmoment and Spearman rank correlation coefficients were significant and consistently positive over the eight years study period. Parental cumulative reproductive output, represented by parental balance curves, slightly varied among mast years and showed steady improvement (less distortion) over years. Effective population size (Np) was high in moderate and good acorn production years; however, departure from clonal equal contribution was observed throughout the study period. Parental effective population size was estimated under various scenarios of male fecundity (pollen production is: 1) proportional to clone size, 2) equal to female contribution, and 3) equal across all clones) resulted in high Np and low group co-ancestry under equal male fecundity scenario while moderate Np size and group co-ancestry were observed when male fecundity was assumed to be proportional to clone size (i.e., ramet number).

Abstract

The effects of seed pre-treatment (stratification/prechilling) and simulated aging on germination parameters (germination capacity, speed and value and peak value) were evaluated for several seedlots originating from seed orchard clones of lodgepole pine (Pinus contorta var. latifolia DOUGL. ex LOUD.) and white spruce (Picea glauca (MOENCH) VOSS). Region of origin and stratification had little effect on white spruce, while stratification enhanced germination speed and completeness of lodgepole pine. Broad-sense heritability for germination parameters ranged from 70 to 97% (unstratified) and from 81 to 96% (stratified) for pine, and from 95 to 97% (unstratified) and from 93 to 97% (stratified) for spruce. Simulated aging (short-term storage at high temperature and relative humidity, approximating the physiological effects of long-term storage) resulted in rapid deterioration of white spruce, with very little germination after six days of aging. Lodgepole pine germination increased during the first several aging treatments relative to the control, but germination capacity decreased following twelve days of aging, and was very low after 18 days. White spruce was nondormant and responded primarily to moisture conditions, whereas pine was strongly influenced by maternal effects. These results can be incorporated for more efficacious nursery production practices for commercial reforestation seedling production as well as ex-situ gene conservation strategies.

Abstract

Genetic analysis of height and form at age 12 years of 697 yellow cypress (Callitropsis nootkatensis [D. Don] Oerst.) clones tested across seven sites in coastal British Columbia (BC) were explored in populations: Population 1 - No Pedigree and Population 2 - Reconstructed Pedigree. Genetic variances were statistically significant but generally higher σ̂g 2 was observed for Population 2. Height and form were under low to moderate genetic control as indicated by clonal repeatability and estimates were relatively similar between populations. For example, average Ĥ2 in Population 2 was 0.31 for height (range: 0.18-0.45) and 0.22 for form (range: 0.06-0.32). While average Ĥ2 in Population 1 was 0.25 for height (range: 0.19-0.35) and 0.18 for form (range: 0.09-0.27). The reconstructed pedigree in Population 2 allowed partitioning the genetic variance (σ̂g 2) into component parts of additive (σ̂a 2), specific combining ability (σ̂s 2 ), and clone (σ̂c 2 ); however, general lack of structure within the population resulted in variance components to be estimated with little precision for additive and specific combining ability. The majority of genetic variation was associated with clone for both traits. For example, σ̂c 2 accounted for 57.6% and 62.5% of the total genetic variance for height and form, respectively. Growth and form responses of clones across test environments were relatively stable and overall type-B genetic correlations were in excess of 0.8 for both traits implying clones selected for production populations should respond favorably across the seed planning zone for yellow cypress in coastal BC.

Abstract

Spatial environmental heterogeneity are well known characteristics of field forest genetic trials, even in small experiments (<1ha) established under seemingly uniform conditions and intensive site management. In such trials, it is commonly assumed that any simple type of experimental field design based on randomization theory, as a completely randomized design (CRD), should account for any of the minor site variability. However, most published results indicate that in these types of trials harbor a large component of the spatial variation which commonly resides in the error term. Here we applied a two-dimensional smoothed surface in an individual-tree mixed model, using tensor product of linear, quadratic and cubic B-spline bases with different and equal number of knots for rows and columns, to account for the environmental spatial variability in two relatively small (i.e., 576 m2 and 5,705 m2) forest genetic trials, with large multiple-tree contiguous plot configurations. In general, models accounting for site variability with a two-dimensional surface displayed a lower value of the deviance information criterion than the classical RCD. Linear B-spline bases may yield a reasonable description of the environmental variability, when a relatively small amount of information available. The mixed models fitting a smoothed surface resulted in a reduction in the posterior means of the error variance (σ2 e), an increase in the posterior means of the additive genetic variance (σ2 a) and heritability (h 2 HT), and an increase of 16.05% and 46.03% (for parents) or 11.86% and 44.68% (for offspring) in the accuracy of breeding values, respectively in the two experiments.

Abstract

Clonal differences in fertility (expressed as the number of female and male strobili) were determined for three consecutive years (2002-2004) in a clonal seed orchard of sugi (Cryptomeria japonica D. Don) in Korea. Fertility varied among clones and among years producing three-year averages of 196 and 652 for female and male strobili per ramet, respectively. Correlation between female and male strobilus production was positive over the three years and statistically significant in 2003, a good flowering year. Based on the observed fertility variation, the status numbers (Ns, measure of genetic diversity) were calculated and varied from 25.6 to 31.7 among the three studied years. On average (pooled), relative status number was 86% of the census number (N). Variation in female fertility was higher than that in male fertility, and this variation was reflected on female and male parents’ status numbers. Pooled Ns estimated from the three years was higher than that for any single year, implying that genetic diversity would increase when seeds collected from different years are pooled.