Provenance variation in Christmas tree characteristics in subalpine fir (Abies lasiocarpa) planted in Denmark and Iceland

A field test with 26 provenances of subalpine fir and corkbark fir was established at three sites in Denmark and one site in Iceland in 1999. Survival, growth and Christmas tree quality were assessed after 10 growing seasons in Denmark and 12 in Iceland. Provenances showed significant differences for all measured traits. The western-most subalpine fir provenances from Washington state and British Columbia showed the overall best results in Denmark with the highest survival (after 15 years), fastest growth in height and highest Christmas tree quality and profitability as well as both good postharvest needle retention and high resistance to pests. The corkbark fir provenances also showed high Christmas tree quality and the lowest frequency of fork formation, but corkbark fir provenances also exhibited the poorest postharvest needle retention. In Iceland, the corkbark fir provenances generally showed the highest survival rate and Christmas tree quality. The White River provenance from British Columbia is recommended for use in Denmark. The Mount Taylor provenance from the Cibola National Forest in New Mexico is recommended for use in Iceland.     

Damage by Neonectria neomacrospora and Adelges piceae in provenance trials of subalpine fir (Abies lasiocarpa) in Denmark

Field trials of Abies lasiocarpa were undertaken with the aim of assessing the potential for Christmas tree production in Denmark. Twenty‐six provenances originating from Alaska to New Mexico were tested. Damage by the insect Adelges piceae and the fungus Neonectria neomacrospora was recorded for the first time 8 and 12 years after the initial planting. Damage from N. neomacrospora increased rapidly in the period 12–15 years after planting. Trees from the northern provenances and humid climates exhibited less damage than those from southern ones. Previous attack by A. piceae had a minor effect on N. neomacrospora infection. Greenhouse tests showed that detached shoots from healthy Abies lasiocarpa can be used to rank provenances for resistance to N. neomacrospora, but results varied according to host subspecies.     

Weed control measures in Christmas tree plantations of <Emphasis Type="Italic">Abies nordmanniana</Emphasis> and <Emphasis Type="Italic">Abies lasiocarpa</Emphasis> on agricultural land

Abies nordmanniana and Abies lasiocarpa, established for Christmas tree production in southwestern Norway (58°44′N, 5°38′E), were treated with different weed control methods, including chemicals, use of black plastic mulch, grass or clover as ground cover, living mulch and mechanical hoeing. Ground cover with black plastic mulching resulted in the best growth and quality in A. lasiocarpa; the least favourable treatment was when grasses were allowed to grow close to the trees. Unless measures were taken to remove this competing vegetation, the ground cover grew over the trees, smothering 94% of them. A. nordmanniana plants grew to the same height on plots with no weed control as on plots with thorough weed eradication. Stem diameter decreased on plots with ground vegetation compared to seedlings grown in the weed-free environment. The use of Trifolium repens as ground cover decreased height growth by 30% compared to thorough weed control. Both grasses and clover sown as living mulch, damaged the trees more than did natural weed vegetation.     

Patterns of phenotypic and genetic variability show hidden diversity in Scottish Arctic charr

Abstract –  This study examined the degree and pattern of variability in trophic morphology in Arctic charr ( Salvelinus alpinus L. ) at three spatial scales: across 22 populations from Scotland and between and within two adjacent catchments (Laxford and Shin) in northern Scotland. In addition, the variability at six microsatellite loci between and within the Laxford and Shin systems was determined. Habitat use by charr differed significantly between populations. The pattern of variability in trophic morphology, known to influence foraging ability in charr, showed a very high degree of between-population variation with at least 52% of population pairs showing significant differences in head shape. Trophic morphology and genetic variation was also high over small geographical scales; variation being as high between charr from lakes within the same catchment, as between adjacent catchments. The pattern of both phenotypic and genotypic variation suggests a mosaic of variation across populations with geographically close populations often as distinct from each other as populations with much greater separation. Very low levels of effective migrants between populations, even within the same catchment, suggest that this variation is being maintained by very low straying rates between phenotypically and genetically distinct populations, even when there is no apparent barrier to movement. We conclude that the genetic and phenotypic integrity of charr populations across Scotland is high and that this adaptive radiation constitutes a 'hidden' element of diversity in northern freshwater systems. Two consequences of this are that the population (rather than the species) makes a more rational unit for the consideration of conservation strategies and that the habitat requirements and therefore management needs may differ significantly between populations.