Stand dynamics after variable-retention harvesting in mature Douglas-fir forests of Western North America.

Abstract

Variable-retention has been proposed as a way to mitigate the effects of timber harvest on biological diversity, particularly lateseral species (FRANKLIN et al., 1997). In the context of silvicultural systems, variable retention harvests represent a regeneration cut because the primary objective is to regenerate the stand without clearcutting. In its implementation, variable-retention bears strong resemblance to the classical system of shelterwood with reserves (MATTHEWS, 1991). Past experience with traditional systems, therefore, can help with the design of new treatments that target specific structural objectives, such as multiple cohorts and layers of trees, or control growth rates of understory trees by varying overstory density. The objectives that motivate variable retention, however, are generally more complex than those implicit in classical systems or that their variants (MITCHELL and BEESE, 2002), and little experience has accrued on ecological responses to different levels or spatial patterns of overstory retention. Even if habitat requirements of key species are known, a coarse-filter approach(HUNTER et al., 1988) that yields a diversity of vegetation structures over time and space (SEYMOUR and HUNTER, 1999) remains the most promising way to avoid erosion of forest biodiversity. Achieving this goal, however, requires understanding how forest stands will respond to a wide range of silvicultural treatments applied at spatial scales that accommodate the organisms of interest, are operationally feasible, and yield information relevant to forest management and policy.

Citation

Maguire, D.A.; Mainwaring, D.B.; Halpern, C.B. 2006. Stand dynamics after variable-retention harvesting in mature Douglas-fir forests of Western North America. Allg. Forst- u. J.-Ztg. 177(6/7): 120-131