Notes: GIS Applications in Fire Ecology & Management Lesson 7 - PDF document

NR406 Notes: GIS Applications in Fire Ecology & Management Lesson 7 Understanding Landscape Dynam ics and VDDT Landscape succession disturbance dynamics in Sagebrush-Juniper Ecosystem s Bunting S.C., E.K. Strand and J.L. Kingery. 2005. Landscape characteristics of sagebrush steppe/juniper woodland mosaics under varying modeled prescribed fire regimes. Tall Timbers Fire Ecology Conference Proceedings, October 2005, Bartlesville, Oklahoma. NR406: GIS Applications in Fire Ecology and Management Notes: Ow yhee Plateau in southw estern I daho Ow yhee Plateau in southw estern I daho The study are for this analysis encompasses 4 6th order watersheds on the Owyhee Plateau in southwestern Idaho. These watersheds are dominated by sagebrush steppe (Artemisia spp.) and western juniper (Juniperus occidentalis) vegetation at different successional stages. Infrequent components in the juniper dominated landscape are aspen stands, mountain riparian and rocky river canyons, ceanothus shrub fields and wet meadows. Altogether western juniper woodland dominates approximately 3.6 million ha in the northwestern portion of the Great Basin and southern Columbia Basin (Miller et al. 2005). Hurry Back Creek Landsat 5 imagery, July 1992 NR406: GIS Applications in Fire Ecology and Management Notes: Landsat satellite im age Landsat satellite im age 116 ° W Long, 43 ° N Lat The four watersheds are here delineated over a Landsat Current Elevation 800-2500 m Creek Precip. 250 – 1000 mm satellite image displayed in false color infrared color combination. In this color display the juniper areas appear in red while the sagebrush appropriately appears in the sage color. 130,000 ha Smith Creek Expansion of juniper (Juniperus spp.) and singleleaf pi ň yon (Pinus monophylla) is of particular concern in many areas of the Great Basin in the western United States. Juniper has over Red Canyon the past 130 years been expanding into the sagebrush steppe, Creek altering the species composition, fire fuels, and wildlife habitat of the region, with sometimes irreversible alterations of ecological processes such as fire regimes, hydrologic cycling and soil erosion rates (Burkhardt and Tisdale 1976; West 1988; Miller et al. 2005). Currently, pi ň yon and juniper woodlands cover over 30 million hectares in the West of which 3.6 million hectares is western juniper (Miller et al. 2005). Suggested causes for the encroachment of western juniper are fire suppression and heavy herbivory, which could facilitate juniper establishment through secondary effects. The resulting low fine fuel loads due to high forage utilization would decrease fire occurrence (Bunting 1993, Miller et al. 1995) and increase sagebrush seedling establishment (Ellison 1960, Tisdale 1969).

NR406: GIS Applications in Fire Ecology and Management Notes: Structural Stage Classification Structural Stage Classification A structural stage classification was developed along the • Herbland sagebrush/juniper successional gradient with the following • Open shrubland classes: herbland, open shrubland, closed shrubland, stand • Closed shrubland initiation woodland, young woodland, mixed-aged woodland, • Stand initiation woodland (Phase I) and mature woodland. The stand initiation woodland, young • Young woodland (Phase II) woodland, and mixed-aged woodland corresponds to a similar • Mixed-age woodland (Phase III) classification into phases presendted by Miller et al. (2005). • Mature woodland NR406: GIS Applications in Fire Ecology and Management Notes: Succession in a W estern Juniper Com m unity Succession in a W estern Juniper Com m unity We mapped succession of western juniper in the four watersheds using aerial photography and classification of landsat imagery. Picture 1 shows grassland after a fire – the first successional stage Mountain big Stand initiation juniper Grassland after fire Picture 2 shows the Sagebrush steppe stage sagebrush steppe (Phase 1) Picture 3 shows the stand initiation juniper or Phase 1 according to Miller et al. (2005) Picture 4 shows the open young juniper or Phase 2 Change in understory cover (Bunting et al. 1999), species composition (Bunting et al. 1999, Miller et al. 2005) and fire Open young juniper Young multistory juniper Mature juniper woodland behavior (Bunting, Yanish) begin to occur in this phase. (Phase 2) (Phase 3) Miller et al. (2005) has shown that these changes begin to occur at 15% juniper cover. Picture 5 shows the young multistory juniper or phase 3 And Picture 6 shows the mature juniper woodland. NR406: GIS Applications in Fire Ecology and Management Notes: Sm ith Creek Cover Types Sm ith Creek Cover Types This is the structural stage map of one of the 4 watersheds, Smith Creek.

NR406: GIS Applications in Fire Ecology and Management Notes: Dom inant PVTs Dom inant PVTs The dominant potential vegetation types (habitat types) in the • Western juniper/ Mtn. big sagebrush/ Idaho area are: fescue Western juniper/Mtn. big sagebrush/Idaho fescue • Western juniper/ Low sagebrush/ Idaho fescue Western juniper/Low sagebrush/Idaho fescue • Western juniper-Curlleaf mtn.- Western juniper-Curlleaf mtn.-mahogany/Mtn. Snowberry mahogany/ Mtn. snowberry NR406: GIS Applications in Fire Ecology and Management Notes: Other PVTs Other PVTs Less common vegetation types in the area are: • Low sagebrush Low sagebrush • Chokecherry-Snowbrush Chokecherry-Snowbrush • Aspen woodlands Aspen woodland • Meadow and riparian Meadow and riparian NR406: GIS Applications in Fire Ecology and Management Notes: Vegetation Dynam ics Developm ent Tool – VDDT Vegetation Dynam ics Developm ent Tool – VDDT Diagram for Western juniper / Mountain big sagebrush steppe Succession for western juniper / mountain big sagebrush steppe is here displayed in a flow diagram. This type of flow diagram can be implemented in the computer simulation 1-10 yr 11-55 yr 56-75 yr software VDDT (Vegetation Dynamics Development Tool) A Herb B Shrub C Phase 1 available from ESSA Technologies Wildfire (p = 0.02) (http://www.essa.com/downloads/vddt/). VDDT is a Windows- Wildfire (p = 0.02) based computer tool that provides a modeling framework for simulating the role of various disturbance agents and 361 yr + 106-360 yr 76-105 yr Mature management actions in vegetation change. F Wdland E Phase 3 D Phase 2 Each box in the diagram represent a stage in the juniper succession. (p = 0.001) (p = 0.01) (p = 0.002) Succession Fire transition Succession progress via a time-step function – green arrows. The red arrows represent a fire disturbance. Disturbance is modeled as stochastic functions, the probabilities for a disturbance are written on the red arrows (P=0.02 means that this transition will on average occur every 50 years, p=0.1 would mean every 10 years). In this simulation wildfire and prescribed fire are the only disturbances in our model. We calibrated the model by entering starting data from 100 years back in time and then ran the model forward to the present time. Input parameter were adjusted in such a way that we ended up with the present distribution of successional classes within the landscape.