Baker Riparian - USBAK001 Olson, Diana; Heyerdahl, E.K.; Harley G.L. Dating method: crossdated Sample storage location: Idaho Tree-Ring Lab at the University of Idaho in Moscow Idaho Reference: Harley, G.L., E.K. Heyerdahl, J.D. Johnston, and D.L. Olson. (in press) Riparian and adjacent upland forests burned synchronously during dry years 2 in eastern Oregon (1650-1900 CE), USA. International Journal of Wildland Fire. Abstract: Riparian forests link terrestrial and freshwater communities and therefore understanding the landscape context of fire regimes in these forests is critical to fully understanding the landscape ecology. However, few direct studies of fire regimes exist for riparian forests, especially in the landscape context of adjacent upland forests or studies of long-term climate drivers of riparian forest fires. We reconstructed low-severity fire history from tree rings in 38 1-ha riparian plots and combined them with existing fire histories from 104 adjacent upland plots to yield 2633 fire scars sampled on 454 trees. Historically (1650-1900), low-severity fires burned more frequently in upland than riparian plots, but this difference was not significant (p = 0.15). During more than half the fire years at both sites, fires were extensive and burned synchronously in riparian and upland plots, and climate was significantly dry during these years. However, climate was not significantly dry when fires burned in only one plot type. Historically, entire riparian zones likely burned in these two study sites of the Blue Mountains during dry years. This study suggests that riparian and upland forests could be managed similarly, especially given the projected increases to fire frequency and intensity from impending climate change. Reference: Heyerdahl, E.K., L.B. Brubaker, and J.K. Agee. 2001. Spatial controls of historical fire regimes: A multiscale example from the Interior West, USA. Ecology. 82:660-678. doi.org/10.1890/0012-9658(2001)082[0660:SCOHFR]2.0.CO;2 Abstract: Our objective was to infer the controls of spatial variation in historical fire regimes. We reconstructed a multicentury history of fire frequency, size, season and severity from fire scars and establishment dates of 1426 trees sampled on grids in four watersheds (~64 plots over ~1620 ha each) representative of the Blue Mountains, Oregon and Washington, USA. The influence of regional climate, a top-down control, was inferred from among-watershed variation in fire regimes, while the influence of local topography, a bottom-up control, was inferred from within-watershed variation. Before about 1900, fire regimes varied among and within watersheds, suggesting that both top-down and bottom-up controls were important. At the regional scale, dry forests (dominated by ponderosa pine), burned twice as frequently and earlier in the growing season in southern than in northern watersheds, consistent with longer and drier fire seasons to the south. Mesic forests (dominated by subalpine fir or grand fir) probably also burned more frequently to the south. At the local scale, fire frequency varied with different parameters of topography in watersheds with steep terrain but not in the watershed with gentle terrain. Frequency varied with aspect in watersheds where topographic facets are separated by significant barriers to fire spread, but not in watersheds where such facets interfinger without fire barriers. Frequency varied with elevation where elevation and aspect interact to create gradients in snow-cover duration and also where steep talus interrupts fuel continuity. Frequency did not vary with slope within any watershed. The presence of both regional- and local-scale variation in the Blue Mountains suggests that top-down and bottom-up controls were both important and acted simultaneously to influence fire regimes in the past. However, an abrupt decline in fire frequency around 1900 was much greater than any regional or local variation in the previous several centuries and indicates that twentieth-century fire regimes in these watersheds were dramatically affected by additional controls such as livestock grazing and fire suppression. Our results demonstrate the usefulness of examining spatial variation in historical fire regimes across scales as a means for inferring their controls. Reference: Olson, Diana L. Fire in Riparian Zones : a Comparison of Historical Fire Occurrence in Riparian and Upslope Forests in the Blue Mountains and Southern Cascades of Oregon. Masters Thesis. University of Washington, 2000. https://alliance-primo.hosted.exlibrisgroup.com/permalink/f/39bnvb/CP71101804880001451 Abstract: Conversion of historically low-severity fire regime forests to high-severity fire regimes, combined with concerns about the protection and restoration of riparian zones, requires a greater understanding of the historical role of fire within riparian zones. Where fire suppression has converted low-severity fire regimes to high severity, increased detrimental effects are likely in today's riparian ecosystems within the drier forest types. The objectives of this study are: 1) to determine whether historical fire frequencies differ between riparian and corresponding upslope areas, and 2) if they differ, to determine whether fire frequency differences vary by stream size and general forest type (dry or mesic). This study is limited to comparing fire frequencies between riparian and upslope forests through the use of fire scars. NOAA/IMPD web landing page for this fire history site is available at: https://ncdc.noaa.gov/paleo/study/28891 NOAA/IMPD DIF and JSON metadata records for this fire history site are available at: https://www1.ncdc.noaa.gov/pub/data/metadata/published/paleo/dif/xml/noaa-fire-28891.xml and https://www1.ncdc.noaa.gov/pub/data/metadata/published/paleo/json/noaa-fire-28891.json FHX filename: usbak001.fhx IMPD code: USBAK001 Name of site: Baker Riparian Site code: BAK Contributors: Olson, Diana; Heyerdahl, E.K.; Harley G.L. Latitude: 44.77594 (WGS84) Longitude: -117.98694 (WGS84) Mean elevation: 1450 (meters) Country: United States State: Oregon Region: Blue Mountains First year: 1329 AD Last year: 1998 AD Species name: Abies grandis [ABGR], Larix occidentalis [LAOC], Pinus ponderosa [PIPO], Pseudotsuga menziesii [PSME] Funding agency names and grant numbers: UDSA Forest Service, Pacific Northwest Research Station through cooperative agreements PNW-97-5082-1-CA and PNW-93-0479 with the University of Washington Comments: This site was sampled by Diana Olson as part of her masters thesis research to reconstruct historical fire regimes in riparian areas of Oregon. Ring-boundary fire scars were assigned to the preceding calendar year. Information on plot location, elevation, aspect, etc. are provided in Olson 2000. usbak001-tree-info.csv provides species and status for fire-scarred trees. Fire History Graphs: Fire History Graphs illustrate specific years when fires occurred and how many trees were scarred. They are available in both PDF and PNG formats. The graphs consist of 2 parts, both of which show the X axis (time line) at the bottom with the earliest year of information on the left and the latest on the right. The Fire Index Plot is the topmost plot, and shows two variables: sample depth (the number of recording trees in each year) as a blue line along the left Y axis, compared with the percent trees scarred shown as gray bars along the right Y axis. Below, the Fire Chronology Plot consists of horizontal lines representing injuries by year on individual sampled trees. Symbols are overlain that denote the years containing the dendrochronologically-dated fire scars or injuries. The sample ID of each tree is displayed to the right of each line. The Composite Axis below represents the composite information from all individual series. The symbols used to represent the fire scars or injuries, and the filters used to determine the composite information, are shown in the legend. These graphs were created using the Fire History Analysis and Exploration System (FHAES). See http://www.fhaes.org for more information.