Stock type in intensive silviculture: A (short) discussion about roots and size

Abstract

I present an overview of some main issues related to the role of stock type in the intensive silviculture of conifers. The aim of my analysis is to answer some aspects of the question of whether or not foresters involved in intensive silviculture in eastern Canada should be concerned with stock type selection. When artificially establishing a forest stand, stock type selection can interact with other treatments to influence plantation success and productivity. Of particular importance are seedling size and root system characteristics. Research has demonstrated the greater intrinsic growth potential and competitive ability of larger seedlings as compared to standard stock sizes. These results also illustrate the multiplier effect of planting large spruce (Picea spp.) seedlings, combined with a release treatment to reduce competing vegetation. The larger size of bareroot seedlings compared to container seedlings has often been seen as improving their competitive potential, although mortality of such stock has been higher. However, recent nursery practices are increasing the size of containerized seedlings and improving the quality of bareroot stock. The issue is now more dependent on practical reforestation considerations than on field performance. Other considerations, such as seedling genetic potential and seedling nutritional status can be raised. The production of seedling characteristics specifically for growth performance is essential to intensive plantation management, but plantation success requires both proper stock type selection and appropriate silviculture. IntroductionWith population growth, the steady increase in per capita consumption of wood, and increased concern about the protection of natural forests, intensive forestry will play an increasingly important role in sustaining the wood supply in the future (Cossalter and Pye-Smith 2003). In eastern Canada and elsewhere, intensive silviculture generally involves resorting to plantation forestry (Bell et al. 2000). Several issues are related to the use of high-yield plantations, one of which is the use of proper seedling types to optimize plantation productivity. Stock type has the potential to influence plantation success, and hence forest productivity. This is especially true during the establishment and early growth stages. In this paper, I discuss the question of whether or not foresters involved in intensive silviculture in eastern Canada should be concerned with stock type selection. Although it is based on published scientific literature, my brief analysis is not a literature review. It points out some aspects related to stock type that I believe are important for the intensive silviculture of conifers in eastern Canada.The concept of "stock type" rings different bells for foresters, depending on their background and experience. In the context of this paper, the focus is from a silviculture-centred point of view. From this perspective, stock types differ with every change in the combination of species, genetic potential and cultural practices...

Comparing large containerized and bareroot conifer stock on sites of contrasting vegetation composition in a non-herbicide scenario

“…The principal vegetation management alternative comprises early planting of large stock seedlings followed by mechanical release treatments (Thiffault and Roy 2011). Although large containerized seedlings (containers [300 cm 3 ) are preferred to large bareroot seedlings in most situations due to ease of handling (Thiffault 2004), questions remain regarding the potential stock type 9 release interactions on sites characterized by different abiotic conditions or levels of biotic competition. We found only slight growth differences and response to mechanical release between large containerized and bareroot white spruce (Picea glauca (Moench).…”

Optimization of environmental factors affecting initial growth of Norway spruce seedlings

“…Soil inversion is the site preparation method that has shown to create the most optimal conditions for seedling establishment in field (Örlander et al 1998). The choice of seedling type has also shown to be important and it depends on the type of site preparation method used as well as on the climatic conditions at the regeneration area (Thiffault 2004, Johansson et al 2007. Containerized seedling types usually show a lower rate of growth check than larger bare-root seedlings (Nilsson et al 2000), supposedly due to differences in root system morphology.…”

Living without herbicides in Québec (Canada): historical context, current strategy, research and challenges in forest vegetation management

“…As a result, nurseries in Québec now produce an array of seedling sizes that vary from * 15 cm in height for very small seedlings, to *60 cm in height for large seedlings, with many intermediate dimensions. Based on the concept of an ''optimum'' seedling (South and Mitchell 1999), which should minimise overall reforestation costs while achieving specific establishment objectives, the choice of seedling size for any given reforestation project is based on site fertility (Thiffault 2004 ; Fig. 4), which is an indicator of its potential to be invaded by species that are recognised to offer aggressive competition for light.…”