Twenty year responses of white spruce to mechanical site preparation and early chemical release in the boreal region of northeastern British Columbia

Abstract

The effects of six mechanical site preparation treatments, two stock-type treatments, and early chemical release on survival and growth of planted white spruce (Picea glauca (Moench) Voss) were studied in the BWBSmw1 biogeoclimatic zone of northeastern British Columbia. After 20 years, spruce height and diameter were larger in all mounding treatments than in the control. Early results suggested better spruce performance on large than small mounds, but after 20 years, growth was equally good on small mounds as on mounds with 20 cm mineral capping. Spruce planted on hinge positions in the Bräcke patch and blade scarification treatments did not survive or grow well. Early chemical release improved spruce growth equally as well as the mounding treatments. Twenty year spruce survival averaged 71% in the 14 and 20 cm mound treatments, 60% in the early chemical release treatment, and ≤35% in the Bräcke patch and blade scarification treatments. A large stock type was also planted in untreated ground and, after 20 years, had similar survival and growth as the standard stock type. Differences in survival had a large effect on basal area at age 20 years. Trend analysis showed that treatments diverged into two distinct groups with regard to spruce size during the 20 year span of the study.Résumé : Les effets de six traitements de préparation mécanique de terrain, de deux traitements avec différents types de plants et de l'application précoce d'un herbicide chimique ont été étudiés sous l'angle de la survie et de la croissance de plants d'épinette blanche (Picea glauca (Moench) Voss) dans la zone biogéoclimatique BWBSmw1 du nordest de la Colombie-Britannique. Vingt ans après l'application des traitements, la hauteur et le diamètre des épinettes étaient plus grands dans tous les traitements de mise en buttes que dans le traitement témoin. Les résultats préliminaires indiquaient que la performance de l'épinette était meilleure sur les grandes buttes que sur les petites, mais après 20 ans, la croissance s'est avérée aussi bonne sur les petites buttes que sur les buttes recouvertes de 20 cm de sol minéral. Les épinettes plantées à des positions charnières des parcelles scarifiées au Bräcke et des parcelles scalpées n'ont pas eu de bons taux de survie ou de croissance. L'application précoce d'un herbicide chimique a eu pour effet d'augmenter la croissance de l'épinette autant que dans le cas des traitements de mise en buttes. Le taux moyen de survie de l'épinette après 20 ans était de 71 % dans les traitements de mise en buttes de 14 et 20 cm, de 60 % dans le traitement d'application précoce d'herbicide chimique et inférieur ou égal à 35 % dans les traitements de scarifiage au Bräcke et de scalpage. Des plants de grande taille ont aussi été plantés sur un terrain non traité et avaient après 20 ans des taux de survie et de croissance semblables à ceux des plants standard. Une analyse de tendance a montré que les traitements se divisaient en deux groupes en ce qui concerne la taille des épinettes au cours de la période de 20 ans pen...

Longer-Term Volume Trade-offs in Spruce and Jack Pine Plantations Following Various Conifer Release Treatments

“…Increases in volume ranged from 5% to 11 800% in the Pacific Northwest, from 15% to 5800% in the southeast, and from 50% to 5500% in northern forests. These results and those from more recent longer-term work (~20 years post treatment) in British Columbia (e.g., Boateng et al 2006Boateng et al , 2009 concur with those of Stewart et al (1984) who documented that virtually every study where competing vegetation has been effectively controlled resulted in increased survival and/or growth of conifers. The exception to these results is where other factors (e.g., harsh climate, insects, disease) that are not remediated The Forestry Chronicle Downloaded from pubs.cif-ifc.org by 34.216.127.252 on 05/12/18…”

“…Hearnden et al (1992) further observed that such plantations may not provide the same quantity of conifer fibre as the original stands due to competition from aspen (Hearnden et al 1992). Since that time, results of several experimental studies have been published for northern conifers (e.g., Boateng et al 2006Boateng et al , 2009. examined 23 of the oldest (i.e., ≥10 years of post-treatment growth measurements) conifer release studies in North America that included control (untreated) plots.…”

Early vegetation control for the regeneration of a single-cohort, intimate mixture of white spruce and aspen on upland boreal sites – 10thyear update

“…Research and operational experience have shown that fairly rigorous vegetation management is required to counter the natural propensity of upland boreal sites to regenerate aspen following harvest (Wood and von Althen 1993, Cole et al 2003, Pitt and Bell 2005, Boateng et al 2006 and that unintentional, intimate mixedwoods are often the result of conventional conifer regeneration efforts (Navratil et al 1991, Pitt et al 2004a2004b, Pitt andBell 2005). In 2000, we worked with a coalition of forest industry partners to formulate and test a practical regeneration strategy for a singlecohort, intimate mixture of spruce and aspen that would capitalize on the natural propensity of these sites to regenerate aspen following harvest.…”

Early performance of planted hybrid larch: effects of mechanical site preparation and planting depth

“…Indeed, soil scarification is recognized to increase soil temperature and moisture, and favour organic matter mineralization especially in boreal ecosystems (Prévost 1992). Seedling growth and survival are enhanced, as biotic and abiotic conditions are positively modified (Grossnickle and Heikurinen 1989), which can lead to increased timber supply in the long-term (Boateng et al 2006). Under non-optimal conditions, seedlings suffer various stresses that can negatively affect their physiology and growth (Margolis and Brand 1990;Grossnickle 2005Grossnickle , 2012.…”