Silvicultural Options Study: plot locations, tree growth, tree regeneration, and understory species abundance

The Silvicultural Options Study (SOS) is a long-term study replicated on three sites (blocks) containing mature second-growth Douglas-fir on the Capitol State Forest, Washington State Department of Natural Resources, near Olympia, Washington. Each site contains six treatment areas that are being managed and regenerated according to standard silvicultural regimes (i.e., clearcut, two-age, patch cutting, group selection, thinning, and non-treated; the latter two regimes represent a deferred final harvest). The six silvicultural regimes were implemented in 1998, 2002, and 2004 at the Blue Ridge, Copper Ridge, and Rusty Ridge sites, respectively, and they include even- and uneven-aged silvicultural regimes assuming a 50-year rotation. The patch and group treatments have a 10-year harvest interval, while the thinning treatment has a 20-year harvest interval. This data publication contains the tree and understory vegetation measurements being taken from a systematic grid of permanent 0.20-acre circular plots, including: (1) tree stem and crown growth (measured December 1996 - May 2019), (2) tree regeneration size and abundance by species and origin (i.e., natural versus planted) (measured January 1997 - November 2009), and (3) visual estimates of cover by dominant understory species (measured December 1997 - November 2009). Initial measurements were taken at 5-year intervals, but later the measurement interval was changed to 10 years. These data are being used to compare forest productivity and stand structure among silvicultural regimes.The long-term Silvicultural Options Study was initiated in 1998 to provide examples of a range of harvest, stand tending, and regeneration practices that could be used to achieve a wide range of management objectives, including improved visual aesthetics and wildlife habitat. The study is serving as the basis for comparing yields and associated costs of alternative silvicultural systems for coast Douglas-fir in western Washington, as well as a visual demonstration area for foresters, planners, and the public. In the study, a silvicultural regime is defined as a planned program of silvicultural treatments covering the entire life of the stand, but it may or may not include a pre-determined date or method of harvest and regeneration (i.e., a “deferred harvest”). Six silvicultural regimes were selected to represent a wide range of management alternatives thought to be biologically, operationally, and economically feasible for regenerating and managing Douglas-fir based on existing knowledge and experience.These data were originally published on 06/08/2022. On 09/15/2023, minor metadata updates were made and diameter at breast height (dbh) values for SOS_tree_growth_data.csv were corrected. In processing, dbh values for all years were rounded to whole numbers. However, only 1996-1997 dbh data were recorded as whole numbers and for all other years dbh was measured to the nearest 0.1 inches. Dbh values are now provided as measured (whole numbers for 1996-1997 and to the nearest 0.1 inches for 1998+).营林方案研究（Silvicultural Options Study, SOS）是一项长期定位试验，于华盛顿州自然资源部管辖的奥林匹亚附近的国会州立森林内的3个样地（区组）上开展，样地内均为成熟的次生花旗松（Douglas-fir）。每个样地均设置6个处理区，按照标准营林制度（即皆伐、双龄级经营、块状皆伐、群团择伐、抚育间伐以及未处理；后两种制度代表延迟最终收获）进行经营与更新。上述6种营林制度分别于1998年、2002年、2004年在蓝岭（Blue Ridge）、铜岭（Copper Ridge）和锈岭（Rusty Ridge）样地落地实施，涵盖了轮伐期为50年的同龄林与异龄林营林制度。块状皆伐与群团择伐处理的收获间隔期为10年，抚育间伐处理的收获间隔期则为20年。本数据集包含通过系统布设的永久0.20英亩圆形样方网格采集的林木与林下植被监测数据，具体包括：(1) 林木茎干与冠层生长数据（监测时段为1996年12月至2019年5月）；(2) 按物种与起源（天然更新与人工栽植）划分的林木更新体尺寸与多度数据（监测时段为1997年1月至2009年11月）；(3) 优势林下物种盖度的目视估测数据（监测时段为1997年12月至2009年11月）。初始监测采用5年间隔，后续调整为10年间隔。本数据集用于对比不同营林制度下的森林生产力与林分结构。这项长期营林方案研究始于1998年，旨在展示一系列采伐、林分抚育与更新经营措施，以助力实现多样化的管理目标，包括提升景观美学价值与改善野生动物栖息地。本研究可为华盛顿州西部沿海花旗松（Douglas-fir）不同营林系统的产量与相关成本对比提供依据，同时也可为林业工作者、规划人员及公众提供可视化的示范区域。在本研究中，营林制度被定义为覆盖林分整个生命周期的系统性营林措施方案，可包含或不包含预先设定的收获与更新日期及方式（即"延迟收获"）。研究团队基于现有认知与实践经验，筛选出6种营林制度，以涵盖花旗松更新与经营中在生物学、作业性与经济性层面均具备可行性的多样化管理方案。本数据集最初于2022年6月8日发布。2023年9月15日，本数据集完成了元数据的小幅度更新，并修正了SOS_tree_growth_data.csv中的胸径（diameter at breast height，dbh）数据。在数据处理环节，所有年份的胸径数据均被取整为整数。但实际上，仅1996-1997年的胸径数据为整数记录，其余年份的胸径测量值均精确至0.1英寸。当前发布的数据已按照原始测量值提供：1996-1997年数据为整数，1998年及以后的数据精确至0.1英寸。