Silviculture and planted species interact to influence reforestation success on a Kalmia-dominated site – a 15-year study

Abstract

Successful regeneration following harvesting or natural disturbance is a fundamental prerequisite for sustainable forest management. However, some regenerating stands have poor juvenile growth rates, which compromise sustainable management objectives. In particular, the presence of some ericaceous species that proliferate after forest disturbance, such as Kalmia angustifolia, can slow succession of boreal stands to the point that ecosystem retrogression is induced. We used data from a silvicultural field trial established in central Newfoundland to evaluate how various combinations of silvicultural treatments (trench scarification, herbicide application, fertilization at planting) influenced growth of three conifer species planted on a Kalmia-dominated cutover. Ground-level diameter (GLD), height, diameter at breast height (DBH), and percent Kalmia cover were assessed at the end of 15 growing seasons after planting. We detected several interactions between silvicultural treatments and planted conifer species. Globally, height and estimates of foliar biomass of all conifer species responded positively to scarification. Fifteen-year height in both scarified and unscarified treatments was in the order Picea mariana < Pinus banksiana < Larix laricina. Black spruce and jack pine height increased when Kalmia was controlled with herbicide, but height of tamarack was not. The use of herbicide significantly increased 15-year GLD and volume index of all three conifer species, but only black spruce responded positively to fertilization at planting. Our results confirm that species-specific responses to silvicultural treatments are to be expected when managing Kalmia-dominated sites. Although chemical vegetation management has great silvicultural potential, our results suggest that mechanical site preparation can also be effective in promoting early conifer seedling growth that leads to rapid canopy closure. It is anticipated that canopy closure will lead to exclusion of Kalmia later in the rotation through natural successional pathways.Key words: Kalmia angustifolia, vegetation management, scarification, herbicide, fertilizer, black spruce, jack pine, tamarack RÉSUMÉ L' établissement réussi de la régénération forestière après les perturbations naturelles ou la coupe forestière est un élément critique de l'aménagement forestier durable (AFD). Toutefois, certains peuplements présentent une faible croissance juvénile, ce qui compromet l'atteinte des objectifs d' AFD. En particulier, la présence d' espèces éricacées qui prolifèrent avec les perturbations, telles le Kalmia angustifolia, peut ralentir la succession forestière de peuplements boréaux au point d'induire une rétrogression de l' écosystème. Nous avons utilisé les données issues d'un dispositif sylvicole établi au centre de Terre-Neuve (Canada), pour évaluer comment différentes combinaisons de traitements sylvicoles (scarifiage à disques, application d'un herbicide, fertilisation au moment de la mise en terre) influencent la croissance de trois espèces de coni...

Managing Understory Vegetation for Maintaining Productivity in Black Spruce Forests: A Synthesis within a Multi-Scale Research Model

“…Furthermore, scarification is expected to limit Kalmia expansion by creating barriers to rhizome extension [37]. We confirmed the efficacy of mechanical soil preparation on various ericad-dominated sites [30,32,33,38,39]. For example, five years after planting in northeastern Qué bec, black spruce seedlings in scarified plots exhibit height and diameter gains of near 100% compared to seedlings planted in unscarified plots [32].…”

Growth and nutrition of black spruce seedlings in response to disruption of Pleurozium and Sphagnum moss carpets in boreal forested peatlands

“…Furthermore, these results suggest that the exposure of mineral soil or its mixing with organic substrates is not necessary to improve seedling growth conditions. However, as it has been shown in several experiments, mixing organic substrate with mineral soil could have an even greater effect on seedling growth (Prévost and Dumais 2003;Thiffault et al 2010).…”

An Overview of The Efficacy of Vegetation Management Alternatives for Conifer Regeneration in Boreal Forests

“…Research indicates that MSP improves microsites for pine (Sutton and Weldon 1993;Bedford and Sutton 2000;Macadam et al 2001;Thiffault et al 2004Thiffault et al , 2010Fu et al 2007), spruce (Sutherland and Foreman 2000;Sutton et al 2001;Prévost and Dumais 2003;Thiffault et al 2004Thiffault et al , 2010Boateng et al 2006;Fu et al 2007;Wiensczyk 2008), and eastern larch (Thiffault et al 2004(Thiffault et al , 2010. However, light MSP may stimulate suckering of aspen (Appendix 1, and Frey et al 2003a).…”