Genecology, patterns of adaptive variation and a comparison of focal point seed zone development methodologies for white spruce (Picea glauca)

Abstract

Ecologically based management of white spruce (Picea glauca [Moench] Voss.) requires an understanding of its patterns of adaptive variation. Six common garden trials and a greenhouse trial established in 2002 and 2003 across Ontario were used to assess levels of genetic variation in 127 seed sources from Ontario and western Quebec and relate this variation to local climate. Using this information focal point seed zones were developed. The focal point seed zone methodology determines spatially explicit areas of ecological compatibility for any selected point. This approach will assist in properly matching seed sources and planting sites based on current and predicted future climate conditions. Growth and phonological variables, including height, root collar diameter, survival, budflush timing, and budset timing were measured. Intraclass correlation coefficients were calculated for all traits to determine levels of genetic variation. Levels of between-provenance genetic variation ranged from 0 percent for several of the budflush variables, up to 22 percent of the total amount of variation expressed for 2003 survival at the Englehart field trial. Overall, growth variables showed higher levels of between-provenance variation than phonological variables. Simple linear regressions were used to relate these differences to local climate conditions. Variation was explained by a wide range of temperature and precipitation related variables. Late budset stages, which had r2 values ranging from 0.55 to 0.46, were explained by temperature and precipitation variables related to the growing season. Generally, the primary patterns of adaptive variation followed a southeast to northwest trend across Ontario. A secondary east-west trend was evident in northwestern Ontario. Northern sources flushed earlier and set bud earlier, while southern sources demonstrated superior growth. Results support previous white spruce genecology studies showing superior growth of sources from the Ottawa Valley region of Ontario and Quebec. Two statistical approaches were used to develop focal point seed zones. The first used principal components analysis (PGA) to summarize patterns of variation based on selected variables. Provenance factor scores were then regressed against climate variables and the resulting equations used to model the PC axes. The second approach used canonical correlation analysis (cancorr) to simultaneously find the relationship within and between biological and climate data sets. Standardized climate coefficients from each significant canonical variate were used to model patterns of adaptation. For both methods parallel seed zones were constructed using GIS tools to intersect grids standardized to sample points selected from across the study area. Results showed overall similar trends for the two methods, however, cancorr based zones showed stronger longitudinal trends for northern points and became more fragmented for southern points. Cancorr zones were also more affected by lake shore effect from Lake Superior and Georgian Bay than regression based zones.