Long-term ecosystem responses from the Coram woody biomass and residue utilization study

This data publication includes long-term ecosystem datasets generated from the Forest Residues Utilization Research and Development Program's study at the Coram Experimental Forest, which is nested within the Flathead National Forest in northwest Montana. This multi-disciplinary study was developed in 1973 and implemented in 1974 by scientists in the Forest Service Rocky Mountain Research Station (then, Intermountain Forest and Range Experiment Station) in the cool, western larch-mixed conifer forest of the northern Rocky Mountains ecoregion. Four utilization treatment levels (a combination of biomass utilization level and residue burning treatment) were applied within each of three silvicultural harvests (clearcut, shelterwood, and group selection) with 2 replications. In addition to conventional timber removal, the four utilization levels were specified to (1) cut understory, remove residue, and broadcast burn; (2) cut understory, leave residue, and broadcast burn; (3) cut understory, remove residue, and do not burn; and (4) do not cut understory, remove residue, and do not burn. These experimental harvests and prescribed burning took place in 1974-1975, and data were collected between 1973 and 2013. There are four core sets of data included in this publication: tree, shrub, plantation, and forest floor. A suite of tree (including natural and planted) measurements were taken in 2012 such as height, diameter at breast height, live crown base height, species, and seedling counts. In 1973, 1976, and 1978 non-tree woody vegetation (shrub) data such as crown diameter, height, density, and species were measured. In 2012 shrub basal diameter (of root crown) was also recorded. Plantation data such as vigor, crown position, tree height, diameter at breast height, crown length and width, etc. were recorded up to 10 times between 1977 and 2013. In 2013, forest floor depth and mineral soil materials were also measured.As identified in the project's 1973 study design, a major problem that has been confronting forestry is how to more efficiently harvest and utilize timber without creating unacceptable impacts on the forest environment. This study was designed to address two related needs. The first was to improve recovery and utilization of the total wood resource, leaving less material as residue. Experts in the 1970s predicted substantial increases in demand for wood and wood fiber-based products, especially softwood housing construction materials. Today, these predictions still stand and include demand for renewable woody residues for power and heat generation or recalcitrant carbon storage. Harvesting practices that facilitate more complete utilization of the available wood resource in the northern Rocky Mountains can contribute significantly to meeting this demand. The second need was to reduce the adverse aesthetic and environmental impacts of timber harvesting and other on-site activities. Utilization standards and logging practices may leave large amounts of residue (small trees, cull and broken logs, tops, and dead timber) on the ground following harvesting operations. These residues can contribute to the forest's nutrient reservoir, reduce erosion, protect seedlings, and provide wildlife cover. In the quantities that frequently occur, however, they create a fire hazard, inhibit regeneration, detract from area esthetic values, and represent waste of a scarce fiber resource. Harvesting practices that improve the economic feasibility of using more of this material can remedy a major source of undesirable impacts on the area. The project addressed a need for silvicultural prescriptions and skyline harvesting systems that can be combined to achieve improved utilization within realistic environmental economic, and management constraints. These data were collected to test the long-term effects of various silvicultural alternatives in the western larch-mixed conifer forest type, especially as they pertain to forest regeneration and dynamics, ecosystem structure and composition, and forest productivity and nutrient loss.These data have been used to summarize short-term effects of forest utilization treatments in 1980-1981 (see Forest Service General Technical Reports listed as cross-references below) as well as to investigate the long term ecosystem effects in the context of the 21st century forest management (see Jang and others between 2015 and 2018, listed as cross-references).本数据集收录了在蒙大拿州西北部弗拉特黑德国家森林（Flathead National Forest）境内的科拉姆实验林（Coram Experimental Forest）开展的森林残留物利用研发项目研究中生成的长期生态系统数据集。该项多学科研究于1973年立项，1974年由美国林务局落基山研究站（Forest Service Rocky Mountain Research Station，时称山间森林与牧场实验站）在北落基山生态区的凉性西部落叶松混交针叶林内实施。在3种营林采伐方式（皆伐、护养伐、团状择伐）下各设置4种利用处理水平（生物量利用水平与残留物焚烧处理的组合），每种设置均设2次重复。除常规木材采伐外，4种利用处理方案分别为：(1) 刈割林下植被、清除残留物并全面焚烧；(2) 刈割林下植被、保留残留物并全面焚烧；(3) 刈割林下植被、清除残留物且不焚烧；(4) 不刈割林下植被、清除残留物且不焚烧。上述实验性采伐与计划火烧（prescribed burning）实施于1974至1975年间，数据采集周期为1973年至2013年。本数据集包含4类核心数据：林木数据、灌丛数据、人工林数据以及林地表层（forest floor）数据。2012年完成了一套涵盖天然林与人工林的林木测量工作，测量指标包括树高、胸径（diameter at breast height）、活枝下高（live crown base height）、树种以及幼苗数量。1973年、1976年及1978年开展了非树木木本植被（灌丛）数据采集，测量指标包括冠幅、高度、密度以及树种；2012年还补充记录了灌丛的根颈基径数据。人工林数据（包括生长势、冠层位置、树高、胸径、冠长与冠宽等）的采集工作在1977年至2013年间累计开展了10次。2013年还完成了林地表层厚度与矿质土壤组分的测量。正如该项目1973年的研究设计所明确的，林业领域长期面临的核心难题之一是：如何在不对森林环境造成不可接受的负面影响的前提下，更高效地采伐与利用木材。本研究旨在解决两项相关需求：其一，提升全木材资源的回收与利用水平，减少残留物残留量。20世纪70年代，业内专家曾预测木材及木质纤维制品（尤其是软质木材住宅建材）的需求将大幅增长；时至今日，该预测仍未过时，且新增了对可再生木质残留物用于发电、供热或难降解碳封存的需求。在北落基山地区，采用能够更充分利用现有木材资源的采伐方式，可对满足上述需求起到显著推动作用。其二，降低木材采伐及其他现场作业对景观美学与森林环境带来的负面影响。按照现行利用标准与采伐作业规范，采伐后往往会在林地遗留大量残留物（幼树、劣等与破损原木、梢头木以及枯立木）。这些残留物可作为森林养分库的组成部分，减少土壤侵蚀，保护幼苗，并为野生动物提供栖息场所；但当残留物存量过高时，会引发火灾隐患、阻碍森林更新、降低区域景观美学价值，并造成稀缺纤维资源的浪费。通过优化采伐作业方式，提升该类残留物的利用经济性，可有效缓解上述对区域环境的诸多不利影响。本项目旨在研发可在现实环境、经济与管理约束下实现更高资源利用率的营林作业规程与索道采伐系统。本数据集的采集目的是，探究西部落叶松混交针叶林内不同营林方案的长期效应，尤其是其对森林更新与动态变化、生态系统结构与组成、森林生产力以及养分流失的影响。本数据集曾被用于总结1980-1981年森林利用处理的短期效应（详见下文交叉引用的《林务局通用技术报告》），同时也被用于在21世纪森林管理的框架下探究生态系统的长期效应（详见2015-2018年Jang等人的相关研究，已列入交叉引用列表）。