Spacing and provenance effects on the performance of shore pine (Pinus contorta var. contorta): 20-year test results

Spacing and provenance effects on the performance of shore pine (Pinuscontorta var. contorta) at a frost-prone site in coastal British Columbia were investigated with respect to mortality, growth, stem defects, and disease and insect damages in a trial with six seed sources that were assigned to seven spacing regimes from 749 to 2990 stems per hectare. Twenty-year test results indicate that mortality was low (2.3% on average) and not significantly influenced by spacing. However, spacing effects on the other traits were significant. Increasing planting density reduced the proportion of stem defected and disease- and insect-damaged trees, slowed diameter and stem volume growth of individuals, and stimulated height growth. Height growth responded to planting density earlier than diameter growth, but diameter growth became more affected as trees grew. The total volume per hectare increases with planting density, but the rate of increase declined as the test proceeded. Response to planting density was homogeneous among provenances with respect to all the traits investigated. However, large and significant regional and provenance differences in mortality, growth, and disease and insect susceptibility were detected. Northern and outer coast provenances demonstrated higher mortality, slower growth, and larger proportions of disease- and insect-damaged trees. Clearly, determining appropriate spacing levels and selecting suitable seed sources are both important for the success of reforestation with shore pine at difficult sites.

Shore pine and Douglas-fir height and volume development on low productivity sites

Stem analysis of 14 cast coast Vancouver Island mixed stands of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) and shore pine (Pinuscontorta Dougl. ex Loud. var. conforta) indicated that shore pine was taller and contained more volume per tree up to 80 years of age than Douglas-fir. Shore pine–Douglas-fir mixed stands could significantly increase fibre yields from these sites if pine were utilized as a thinning crop.

Chemosystematic studies in the genus Pinus. III. The leaf oil terpene composition of lodgepole pine from the Yukon Territory

The leaf terpenes of 95 lodgepole pines from the Yukon and Northwest Territories, as well as those of 30 typical shore pines from more southerly locations, were analyzed by gas–liquid chromatography. The terpene patterns of the northern trees were compared with the known patterns of lodgepole pine from the Rocky Mountains (types B and C) and that of the shore pine (type A). Many trees from northern locations (including nunataqs that were refugia during the last ice age) had the type A terpene pattern of the shore pine and a few had the rare type C or intermediate (A–B, B–C) patterns. The implications for further lodgepole pine population studies by means of leaf oil terpenes analysis are discussed.

Field evaluation of ecological differentiation of dwarf mistletoe on shore pine and western hemlock

Hemloclc dwarf mistletoe (Arcenthobiiuntsugense (Rosend.) G. N. Jones) principally infects western hemlock (Tsugaheteropliylla (Raf.) Sarg.), but it is also damaging to shore pine (Pinuscontorta Dougl. ex Loud.) growing in coastal British Columbia. Stands of varied composition were studied in the Home Lake area of Vancouver Island to compare the levels of infection in shore pine and western hemlock. Infection of shore pine occurred whether or not infected hemlock trees were present in the stand. Observations and measurements from these field studies support indications from earlier artificial inoculation trials that two ecological races of A. tsugense exist.

EcologyDevelopment of Dwarf Mistletoe (Arceuthobium) Infections on Western Hemlock, Shore Pine, and Western Larch

Newly dispersed seeds, established infections, and individually tagged shoots of hemlock dwarf mistletoe on western hemlock and shore pine, and established infections and individual shoots of larch mistletoe on western larch were examined periodically for up to 7 years, Infections on hemlock first appeared as swellings, some of which were visible during the first year after seed dispersal. Aerial shoots appeared in the second year. By the end of the third year most infections exhibited both swellings and aerial shoots. On all three hosts, mature mistletoe fruit were produced occasionally in the fourth year but generally not until the fifth year. Most female aerial shoots bore at least one crop of flowers during their existence, however, only half produced mature fruit. Aerial shoots varied in their life span from less than 1 year up to 7 years. The average was 2 to 3 years. One female shoot on larch bore five successive crops of flowers. The fastest longitudinal growth of mistletoe endophytic system occurred on western larch and the slowest was on shore pine. All infections were nonsystemic in that the endophytic system was largely confined to the swollen portions of the hosts.