Simulating Historical Variability in the Amount of Old Forests in the Oregon Coast Range

Abstract: We developed the landscape age‐class demographics simulator ( LADS) to model historical variability in the amount of old‐growth and late‐successional forest in the Oregon Coast Range over the past 3,000 years. The model simulated temporal and spatial patterns of forest fires along with the resulting fluctuations in the distribution of forest age classes across the landscape. Parameters describing historical fire regimes were derived from data from a number of existing dendroecological and paleoecological studies. Our results indicated that the historical age‐class distribution was highly variable and that variability increased with decreasing landscape size. Simulated old‐growth percentages were generally between 25% and 75% at the province scale (2,250,000 ha) and never fell below 5%. In comparison, old‐growth percentages varied from 0 to 100% at the late‐successional reserve scale (40,000 ha). Province‐scale estimates of current old‐growth (5%) and late‐successional forest (11%) in the Oregon Coast Range were lower than expected under the simulated historical fire regime, even when potential errors in our parameter estimates were considered. These uncertainties do, however, limit our ability to precisely define ranges of historical variability. Our results suggest that in areas where historical disturbance regimes were characterized by large, infrequent fires, management of forest age classes based on a range of historical variability may be feasible only at relatively large spatial scales. Comprehensive landscape management strategies will need to consider other factors besides the percentage of old forests on the landscape, including the spatial pattern of stands and the rates and pathways of landscape change.

[1]  R. Neil Sampson,et al.  Assessing Forest Ecosystem Health in the Inland West , 1994, Assessing Forest Ecosystem Health in the Inland West.

[2]  P. Bartlein,et al.  A 9000-year fire history from the Oregon Coast Range, based on a high-resolution charcoal study , 1998 .

[3]  S. Garman,et al.  A Landscape Plan Based on Historical Fire Regimes for a Managed Forest Ecosystem: the Augusta Creek Study , 1998 .

[4]  L. Benda,et al.  Stochastic forcing of sediment supply to channel networks from landsliding and debris flow , 1997 .

[5]  William J. Ripple,et al.  The role of terrain in a fire mosaic of a temperate coniferous forest , 1997 .

[6]  Ajith H. Perera,et al.  Modeling temporal variability of boreal landscape age-classes under different fire disturbance regimes and spatial scales , 1997 .

[7]  P. C. Impara.  Spatial and temporal patterns of fire in the forests of the central Oregon Coast Range , 1997 .

[8]  Ajith H. Perera,et al.  Modelling the effect of spatial scale and correlated fire disturbances on forest age distribution , 1997 .

[9]  William J. Ripple,et al.  Landscape composition and pattern around northern spotted owl nest sites in southwest Oregon , 1997 .

[10]  David O. Wallin,et al.  Comparison of managed and pre-settlement landscape dynamics in forests of the Pacific Northwest, USA , 1996 .

[11]  Peter Lesica,et al.  Using fire history models to estimate proportions of old growth forest in northwest Montana, USA , 1996 .

[12]  C. Whitlock,et al.  Late Quaternary vegetation and climate history near Little Lake, central Coast Range, Oregon , 1995 .

[13]  Fred L. Bunnell,et al.  Forest-Dwelling Vertebrate Faunas and Natural Fire Regimes in British Columbia: Patterns and Implications for Conservation , 1995 .

[14]  E. Johnson,et al.  Old-growth, disturbance, and ecosystem management , 1995 .

[15]  T. Spies,et al.  Growing‐Season Microclimatic Gradients from Clearcut Edges into Old‐Growth Douglas‐Fir Forests , 1995 .

[16]  James R. Sedell,et al.  A Disturbance-Based Ecosystem Approach to Maintaining and Restoring Freshwater Habitats of Evolutionarily Significant Units of Anadromous Salmonids in the Pacific Northwest , 1995 .

[17]  G. Aplet,et al.  Historical Range of Variability: A Useful Tool for Evaluating Ecosystem Change , 1994 .

[18]  C. Trummel.  Privatizing New Zealand's Forests and Managing Public Concern , 1994 .

[19]  W. Baker.  Restoration of Landscape Structure Altered by Fire Suppression , 1994 .

[20]  F. Swanson,et al.  LANDSCAPE PATTERN RESPONSE TO CHANGES IN PATTERN GENERATION RULES: LAND-USE LEGACIES IN FORESTRY , 1994 .

[21]  Thomas A. Spies,et al.  Dynamics and Pattern of a Managed Coniferous Forest Landscape in Oregon , 1994 .

[22]  Species and Ecosystem Viability: Key Questions and Issues , 1994 .

[23]  J. Agee.  Fire Ecology of Pacific Northwest Forests , 1993 .

[24]  J. W. Thomas,et al.  Forest ecosystem management : an ecological, economic, and social assessment. Report of the forest ecosystem management assessment team , 1993 .

[25]  Russell G. Congalton,et al.  Mapping old growth forests on National Forest and Park Lands in the Pacific Northwest from remotely sensed data , 1993 .

[26]  F. Swanson,et al.  Natural Variability: Implications for Ecosystem Management , 1993 .

[27]  K. Waddell,et al.  Area of old-growth forests in California, Oregon, and Washington. Forest Service research bulletin , 1993 .

[28]  W. Baker.  Spatially heterogeneous multi-scale response of landscapes to fire suppression , 1993 .

[29]  T. Spies,et al.  Vegetation Responses to Edge Environments in Old-Growth Douglas-Fir Forests. , 1992, Ecological applications : a publication of the Ecological Society of America.

[30]  D. Booth.  Estimating Prelogging Old-Growth in the Pacific Northwest , 1991 .

[31]  P. Teensma,et al.  Preliminary reconstruction and analysis of change in forest stand age classes of the Oregon Coast Range from 1850 to 1940 , 1991 .

[32]  Frederick J. Swanson,et al.  CONSERVING BIODIVERSITY IN MANAGED FORESTS : LESSONS FROM NATURAL FORESTS , 1991 .

[33]  G. F. Frazier,et al.  A spatial model for studying the effects of climatic change on the structure of landscapes subject to large disturbances , 1991 .

[34]  Frederick J. Swanson,et al.  Fire history and pattern in a Cascade Range landscape , 1990 .

[35]  William L. Baker,et al.  Effect of scale and spatial heterogeneity on fire-interval distributions , 1989 .

[36]  P. Hogeweg.  Cellular automata as a paradigm for ecological modeling , 1988 .

[37]  J. Agee,et al.  Fuel succession in a western hemlock/Douglas-fir forest , 1987 .

[38]  J. Franklin,et al.  Fire and Other Disturbances of the Forests in Mount Rainier National Park , 1982, Quaternary Research.

[39]  C. E. Van Wagner,et al.  Age-class distribution and the forest fire cycle , 1978 .

[40]  James E. Meacham,et al.  Atlas of Oregon , 1976 .