Ecological adaptations in Douglas-fir (Pseudotsuga menziesii var. glauca) populations

Abstract

SUMMARYGrowth, phenology and frost tolerance of seedlings from 50 populations of Douglas-fir (Pseadotsuga men ziesli var. glauca) were compared in 12 environments.Statistical analyses of six variables (bud burst, bud set, 3-year height, spring and fall frost injuries, and deviation from regression of 3-year height on 2-year height) showed that populations not only differed in mean performance, but also reacted differently to the environmental gradient. Most of the populationenvironment interaction was attributable to heterogeneous regressions of population means on environmental means. For all variables except growth rate, the variance of heterogeneous regression coefficients was explained by convergence of regression lines to a common point on the environmental gradient. Consequently, mean values for populations were significantly correlated with regression coefficients. Thus, main effects of populations in those single environments that induced the greatest mean differences reflected the interaction.Multiple regression analyses associated adaptive differentiation of populations with geographic and ecologic characteristics of the seed source. Differentiation was controlled primarily by elevation and secondarily by latitude.Whereas longitude was a minor factor, habitat types accounted for no differentiation beyond that associated with elevation, a factor closely correlated with habitat types. From these results it is recommended that seed for reforestation should not be moved more than 140 m elevation, l6 degrees latitude, or 27 degrees longitude in northern Idaho and eastern Washington.

Ecological adaptations in Douglas-fir populations. II. Western Montana

“…Regression model 1 (table 2) indicated that (1) genetic variation was related to elevation; (2) geographic patterns of variation followed a grid that was oblique to latitude and longitude; and (3) habitat types were related to neither dependent nor independent variables. A lack of association between habitat types and genetic variation in western Montana corresponds with results for Douglas-fir populations from northern Idaho (Rehfeldt 1979a) and for Pinus ponderosa from southern Idaho (Rehfeldt 1980). …”

“…Interactions of genotype and environment were detected for only bud burst and height. While accounting for little variance, these interactions, like those detected for north Idaho populations (Rehfeldt 1979a), resulted from mean differences not associated with changes in the ranking of populations.…”

“…Variation in growth, phenology, cold hardiness, and first-year flushing of western Montana populations formed an intercorrelated network of traits to which only bud burst was unrelated (table 5). This network, like that for northern Idaho populations (Rehfeldt 1979a), seems keyed to adaptation to the cold. Populations that set buds early were also characterized by a low proportion of seedlings that flushed twice, a low growth rate, a short height, but a high tolerance to freezing.…”

“…glauca), the growth potential and cold hardiness of populations depends on geographic origin: populations from northern Idaho tend to be faster growing and less hardy than those from western Montana which in turn are faster growing and less hardy than populat'ions fro~ southern Idaho (Rehfeldt 1979b). Within northern Idaho alone, differences among populations are closely related to the elevation, latitude, and longitude at the seed origin (Rehfeldt 1979a).…”

Seed zones and breeding zones for sugar pine in southwestern Oregon.

“…An alternative to extensive, long-term field testing is to map patterns of genetic variation in the native stand from short-term tests at a single site (Campbell 1986, Langlet 1945, Rehfeldt 1983, Squillace 1966. Two main assumptions are implicit if genetic maps are used to devise provisional zones: (1) genetic variation among populations reflects natural selection by an environment that varies across locations; and (2) the greater the genetic difference among populations, the greater the risk in transfers of seedlings between origins of populations.…”