Historical fire regimes in ponderosa pine forests of the Colorado Front Range, and recommendations for ecological restoration and fuels management

At the request of The Nature Conservancy and the Front Range Fuels Treatment Partnership, the authors of this article are developing brief summaries of the current state of our scientific understanding of historical fire regimes in the forested landscapes of Colorado's Front Range. The area of interest extends from EI Paso and Teller Counties, near Pikes Peak, to Larimer County and the Colorado-Wyoming border. This article focuses on forests in which ponderosa pine is a dominant or co-dominant species. A subsequent article will deal with forests of lodgepole pine, spruce, and fir. M. Kaufmann and T. Veblen have conducted extensive studies of ponderosa pine forest ecology in the southern Front Range (mainly the Cheesman Reservoir area) and the northern Front Range (mainly in and around Boulder County), respectively. This research has led to substantial agreement about the historical role of fire in shaping these forests, and we emphasize these points of agreement in this article, in the section entitled "Things We Know with Relatively High Confidence." Some disagreements and uncertainties also have arisen, and we identify these..

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Disturbance patterns in southern Rocky Mountain forests

The pattern of landscape diversity in the Southern Rocky Mountains has been described as resulting from two superimposed vegetation pat- terns: the distribution of species along gradients of limiting factors, and patterns of disturbance and recovery within the communities at each point along the environmental gradients (Romme and Knight 1982). The previous chapter (D. H. Knight and W. A. Reiners, this volume) has emphasized the first pattern whereas this chapter emphasizes the role of natural disturbance in creating landscape patterns. Although human impacts on fundamentally natural disturbances such as fires and insect outbreaks are included, other chapters treat disturbances of exclusively human origin such as logging and road construction

Insights from recent fires into juniper savanna dynamics at Wupatki National Monument, Arizona, USA

We tested the hypothesis that recurrent fires may limit juniper expansion into southwestern semiarid grasslands and savannas. Seven large fires at Wupatki National Monument, Arizona, burned 38% of the grasslands and dynamic savannas between 1995 and 2017. Mortality of one-seed junipers (Juniperus monosperma) was >50% among smaller trees (2 m tall), and 0% in trees >4 m tall. Herbaceous vegetation recovered within 2 to 3 years postfire. This suggests that fires may have limited juniper expansion historically and that fire may be an option for controlling juniper expansion and restoring grassland/savanna ecosystems today.The Rangelands archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information

Historical and Modern Fire Regimes in Piñon-Juniper Woodlands, Dinosaur National Monument, United States

Twentieth-century fire exclusion has produced unnatural and undesirable changes in vegetation structure and dynamics of many rangelands of western North America, but not all kinds of ecosystems have been so affected. A comparison of the historical and modern fire regimes, especially in peripheral populations that can be particularly vulnerable to climatic change, can help guide fire management planning with information on the degree to which a local area has been altered by past fire exclusion. Historical fire rotations in piñon-juniper (Pinus edlis Engelm.-Juniperus spp. L.) woodlands vary widely across woodland types, hence management applications should be specific to local historical and modern fire characteristics. We asked if the modern fire rotation is similar to or longer than the historical fire rotation before arrival of Euro-American settlers on the northern woodland boundary in northwestern Colorado and northeastern Utah. This study was initiated by managers from Dinosaur National Monument (DINO) concerned that lack of 20th-century fire may have allowed unnatural expansion of piñon-juniper woodlands into grasslands and shrublands. Fire history analysis using dendrochronology methods suggests a historical (pre-1900) fire rotation of ca. 550 yr, comparable with or longer than many other woodlands on the Colorado Plateau. In contrast, analysis of digital fire records reveals that the fire rotation between 1981 and 2010 was substantially shorter than historical; if only natural fires are considered, the piñon-juniper fire rotation was 364 yr, and if anthropogenic fires were included, the fire rotation was 233 yr. This shorter fire rotation supports a previously documented contraction in woodland extent in DINO during the past 90 yr. Our data support reducing the amount of fire in the landscape to preserve the integrity of the natural vegetation of this and other piñon-juniper woodlands, especially under projections of warmer and drier future climates. © 2017 The Society for Range Management. Published by Elsevier Inc. All rights reserved.The Rangeland Ecology & Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information

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