Variable retention is a new approach to harvesting and silvicultural systems that was developed by ecologists in the Pacific Northwest region of North America to address a wide array of forest management goals. Variable retention recognizes that natural disturbances, such as fire, wind or disease, nearly always leave some standing structure from the original forest. This structural complexity plays an important role in forest ecosystem function and biological diversity. A new "retention silvicultural system" was defined that leaves trees distributed throughout harvested areas. This system facilitates retention of structural features of old-growth forests, such as live and dead trees of varying sizes, multiple canopy layers, and coarse woody debris. Weyerhaeuser's British Columbia Coastal Group will use the variable retention approach for all harvesting by 2003. More than 75% of the company's coastal harvesting in British Columbia used variable retention in 2001. Company guidelines describe the amount, type, and spatial distribution of retention for groups and individual trees. An adaptive management program is monitoring the amount and type of structural attributes retained in relation to the original forest.Key words: old-growth forests, variable retention, silvicultural systems, biodiversity, landscape zoning La conservation variable est une nouvelle approche aux systèmes de récolte et de sylviculture que des écologistes de la région du Nord-Ouest du Pacifique, en Amérique du Nord, ont mis au point pour atteindre un vaste ensemble d'objectifs pour l'aménagement forestier. La conservation variable reconnaît que des facteurs naturels de perturbation tels que le feu, le vent ou la maladie laissent presque toujours sur leur passage une structure résiduelle de la foret antérieure. Cette complexité structurelle joue un rôle important dans la fonction d'écosystème de la forêt et dans sa diversité biologique. On a défini un nouveau « système sylvicole de conservation » qui laisse subsister des arbres distribués sur les parterres de coupe. Ce système facilite la conservation des caractéristiques structurales des vieilles forêts telles que des arbres vivants et morts de tailles variables, des étages multiples du couvert et des débris ligneux grossiers. Chez Weyerhaeuser, le groupe « BC Coastal » appliquera cette approche à toute la récolte, dès 2003. Pour plus de 75 % de la récolte pratiquée dans la zone côtière de la Colombie-Britannique, cette société employait la conservation variable en 2001. Les lignes directrices que s'est données la compagnie décrivent, pour des groupes d'arbres et des arbres individuels, la quantité, le type et la répar-tition spatiale de la conservation. Un programme d'aménagement adaptatif permet de contrôler la quantité et le type de caractères structuraux conservés relativement à ceux de la forêt antérieure.

Sustainability is now woven throughout forest management and policy. Criteria and indicators (C&I) provide a means of defining the concepts of sustainability in the context of forest management and establishing goals to gauge progress. There have been no major research initiatives to determine the implications of climate change for C&I. We evaluated the 46 indicators of the 2003 Canadian Council of Forest Ministers framework. Indicators were evaluated for their relationships with climate, relationships with other indicators, robustness and utility under climate change, and future prospects, including abandonment, improvement, or continued use. An evaluation framework was developed to analyze indicator linkages, direct and indirect climate-change influence, and potential modifications. 12 indicators were considered unaffected by climate change. The remaining 34 indicators were considered to be influenced by climate change. No modification seemed warranted for 23 of these indicators, while modifications for the remaining 11 indicators were recommended. Six new indicators were identified for monitoring forests sustainably under climate change. The difference between action and state indicators had implications for the influence of climate change on indicator effectiveness. State indicators were more prone to declines in their tracking ability, while action indicators were often unaffected, or even improved under climate change, as measured by several key traits of indicator effectiveness. The most prevalent theme in the evaluations was a decline in indicator predictability. We suggest moving from predominantly retrospective analysis to a balance of retrospective and prospective analysis, given that monitoring is inherently backward-looking and the threats and uncertainties of climate change are impending.

2Over the past several decades, federal incentive programs have encouraged the restoration of bottomland forests throughout the West Gulf Coastal Plain (WGCP) and the Lower Mississippi Alluvial Valley (LMAV). Programs such as the Conservation Reserve (CRP) and Wetlands Reserve (WRP) Programs have been marginally successful (Stanturf et al. 2001). Foresters and contractors often follow conventional tree planting procedures that are well established for upland sites, but prove problematic in bottomlands. High water tables, soil drainage and compaction, overland flooding and diverse soil properties make species selection difficult. Slight changes in topography and soil structure often have a dramatic effect on survival and growth of planted oak seedlings (Hodges and Schweitzer 1979). This project documented the survival and growth of six-year old seedlings that were established on a bottomland site in 2004, located at the West Tennessee Research and Education Center, Jackson, Tennessee. The purpose was to determine how soil drainage as indicated by mottling (specifically, the point of 50 percent gray color throughout the soil profile) affects the survival and growth of bottomland oak species. The findings suggest that practitioners plant Nuttall, pin and overcup oaks in poorly drained soils. As the drainage improves, begin mixing in willow oak. In the best drained soils (if they exist), finish by including water, swamp chestnut, swamp white, Shumard, cherrybark and bur oaks. Potential species diversity should expand as the soil drainage improves.

Variable retention (VR) refers to a strategy that is designed to retain biological legacies, such as large old trees, snags, and downed logs, at harvest to create and/or maintain structurally complex stands with a range of silvicultural systems. The retention system is a new silvicultural system (Forest Practices Code – Operational and Site Planning Regulations) designed for use under a VR strategy (Mitchell and Beese 2002). By retaining certain structural elements, habitat carrying capacity can be maintained and connectivity can be conserved over the landscape. The planning and implementation of VR is a complex process, with many potential risks that must be understood if one is to successfully achieve multiple management objectives. With the implementation of the retention system in coastal British Columbia, researchers have generated much information and learned many lessons. This Stand Establishment Decision Aid (SEDA) is intended to provide general guidance and points to consider when implementing the various structures (aggregated or dispersed) that are associated with the retention system in British Columbia's coastal forests. Additional information related to retention and variable retention can be found in the Resource and Reference list at the end of this document. It is important to note that the list provided in this reference section is not exhaustive and more information is available, but not necessarily cited. Reference material that is not available on-line can be ordered through libraries or the Queen's Printer at: http://www.qp.gov.bc.ca.