Simulation of a fire-sensitive ecological threshold: a case study of Ashe juniper on the Edwards Plateau of Texas, USA |
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Authors: | Samuel D. Fuhlendorf Fred E. Smeins William E. Grant |
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Affiliation: | aDepartment Rangeland Ecology and Management, Texas A &; M University, College Station, TX 77843-2126, USA;bDepartment Wildlife and Fisheries Sciences, Texas A &; M University, College Station, TX 77843-2126, USA |
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Abstract: | A model was developed to represent the establishment of a fire-sensitive woody species from seeds and subsequent survival and growth through five size classes. Simulations accurately represent structural changes associated with increased density and cover of the fire-sensitive Ashe juniper (Juniperus ashei, Buckholz) and provide substantial evidence for multiple steady states and ecological thresholds. Without fire, Ashe juniper increases and herbaceous biomass decreases at exponential rates until a dense-canopy woodland is formed after approximately 75 years. Maintenance of a grass-dominated community for 150 years requires cool-season fires at a return interval of less than 25 years. When initial cool-season fires are delayed or return intervals are increased, herbaceous biomass (fuel) decreases below a threshold and changes from grassland to woodland become irreversible. With warm-season fires, longer return intervals maintain grass dominance, and under extreme warm-season conditions even nearly closed-canopy stands can be opened with catastrophic wildfires. |
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Keywords: | Fire Juniper Succession Thresholds |
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