Changes in climate can dramatically influence landscape morphology by altering the frequency and severity of disturbance events such as wildfire and post-fire erosion. This study evaluates fire-related sedimentation along an ecosystem gradient to investigate 1) how climate influences the timing, frequency, and magnitude of fire over Holocene timescales and 2) the contribution of fire-related sedimentation from steep tributary basins to long-term (10³-10⁴) sediment yields in the Salmon River drainage. The Middle Fork Salmon River (MFSR) watershed is located in the Northern Rocky mountains of central Idaho and encompasses a range of ecosystems including subalpine pine and spruce forests (~3,000 -1,700 m), montane Douglas-fir and ponderosa pine-dominated forests (2650 - 1130 m) and sagebrush steppe (~ 1,800 - 900 m). Over 40% of the drainage area of the MFSR has burned in the last 30 years resulting in many large fire-related debris flows. Fire reconstructions from ¹⁴C dating of charcoal macrofossils in alluvial fan sediments indicate that times of synchronous fires across upper and lower ecosystems during the Holocene occurred ~700-1000, 1400-1600, 2800-3000, 6000-6800, 8000-9000 cal yr BP. On millennial timescales, dry conditions of the mid-Holocene are associated with relatively low fire frequency, few fire-related debris flows, and increased sheetflooding events potentially caused by decreased vegetation density and increased fire resistant species (e.g. Douglas fir). In contrast, millennial-scale cool/wet conditions of the late Holocene, combined with severe annual to decadal-scale droughts, are associated with increased fire frequency and large fire-related debris flows. During the last 2000 yrs, fire-related debris flows from eight sub-basins are estimated to contribute ~119 ± 21 T/km²/yr of sediment to the MFSR. This estimate accounts for ~50% of long-term (6500 yr) sediment yields (Kirchner et al. 2001). Fire-related deposits compose >70% of total alluvial fan thickness in cool/wet forested ecosystems and >30% of the total thickness in dry/warm less vegetated basins emphasizing the importance of vegetation density to fire-related sediment delivery.