Status and Trends of Silvicultural Practices in Minnesota

This article describes the kind and extent of silvicultural practices applied in Minnesota. We surveyed land managers with respect o silvicultural systems and practices employed uring 1996. Results were compared to corresponding information from 1991. The study obtained input from ownerships covering approximately 50% of the acreage and timber volume harvested in the state. The statewide harvest volume increased 8%from 1991 to 1996, and the estimated acreage subject o harvesting increased 1%. An increased emphasis on thinning was a significant factor in the rise in total acreage harvested. From 1991 to 1996, clearcutting (> 5 ac) decreased from 89 to 85% of the acreage harvested. Residuals were left on 77% of the acreage clearcut, a level nearly twice as high as in 1991. Reliance on natural versus artificial regeneration increased by 7% since 1991. At the same time, artificial regeneration efforts showed greater emphasis on site preparation rather than later release, especially on land owned by forest industry. Overall,forest management trends in Minnesota are moving toward a more intensively managed but also more diverse forest across ownerships. North. J. Appl. For. 16(4):203-210. In 1990, Minnesota initiated a Generic Environmental Impact Statement (GEIS) on timber harvesting and forest management (Jaakko P6yry Consulting Inc. 1994). Part of that study collected and summarized basic information about silvicultural practices in Minnesota (Jaakko POyry Consulting Inc. 1992a). A broad assessment of silvicultural practices and trends can help policy-makers, forest managers, the forest industry, and others concerned about forest ecosystems (Fajvan et al. 1998). This study provides an update on silvicultural practices since the GEIS study. A comparison of the 1996 information with silvicultural practices in 1991 is a basis for investigation of current trends in forest management. History of Silviculture Practices Silviculture practices are determined in part by the forest composition (see Leatherberry et al. 1995). Forest composition is very dynamic and influenced by historical developments (Steams 1997), including climate pattems (Clark 1990), natural disturbances (Heinselman 1996), and harvesting and forest management activities (e.g., Larson 1972). In the early 1800s, Minnesota's forest area was 31.5 million ac and was dominated by conifers. White pine was the species most heavily logged between 1880 and 1910 (Jaakko POyry 1992b, NOTE: Klaus J. Puettmann is the correspondence author, and he can be reached at (612) 625-3733; FAX (612) 625-5212, E-mail: kpuettma• forestry.umn.edu. The authors gratefully acknowledge the assistance of numerous individuals who provided review and feedback on the design of the study questionnaires. We also thank all survey respondents and Drs. Charles Blinn and Helen Whimey-Mclver for their help in data collection and analysis. Larson 1972). Later, logging of white pine declined and then moved to other species, particularly other conifers and the larger hardwoods. The forest harvest reached a low point in the mid1930s and remained roughly stable until the 1960s. Since then, the trend in forest harvesting has been gradually upwards. Early land speculation and settlement led to much of the state falling into private ownership, primarily farmland. This began to change first with the establishment of the National Forests and then State Forests early in this century. In the 1930s and 1940s, large-scale tax forfeiture occurred, and public agencies acquired privately owned lands that were no longer viable as farmland. Importantly, lands considered viable for agriculture at one time usually had a higher productivity level, compared with federal lands, as most of these never supported agriculture. Private owners generally retained the most productive agricultural land (and timberland) concentrated in south, central, and northwestern Minnesota, while land with lower agricultural productivity was forfeit. At first, state and county agencies did not have the personnel or funding at the time to manage the tax forfeited lands that came under their jurisdiction. Consequently, many of these acres gradually reverted to forest naturally. Portions of individual farms, in total comprising large acreages, also reverted to forest. This new forest was largely even-aged hardwoods and had a large component of aspen, a pioneer species. Most hardwood stands originated since the 1920s with the initiation of organized fire control. Many conifer stands originated from residuals after earlier logging of softwoods. The age class distribution of conifers is less concentrated than hardwoods because of earlier harvesting and steadier markets