Comment on “Modeling of the interactions between forest vegetation, disturbances, and sediment yields” by Erkan Istanbulluoglu et al.

Climate change, forests, fire, water, and fish: Building resilient landscapes, streams, and managers

“…Episodicity clearly has a direct influence on the consequences for fish as does the spatial distribution of synchronous major disturbances. The sediment yield studies have been faulted for failing to include road erosion impacts (Rhodes 2005). The addition of road erosion would likely contribute little to long term sediment yields (Goode and others 2011), however, considering the chronic additions would provide interesting and biologically relevant contrast.…”

Reply to comment by Jonathan J. Rhodes on “Modeling of the interactions between forest vegetation, disturbances, and sediment yields”

“… Rhodes [2005] primarily cites literature relative to the effects of roads on stream peak flows and drainage density. Our model only estimated sediment yield from hillslopes and hollows and did not consider stream transport.…”

“…The paper does not disclose predictions of drainage density under the managed regime, so the statement that the drainage density is underpredicted is incorrect. Also, the papers that Rhodes [2005] cites present a clear hypothesis via mechanistic descriptions and modeling studies to suggest that roads affect peak flows; however, such observational evidence as exists suggests only a mild effect [ Jones and Grant , 1996; Thomas and Megahan , 1998]. Furthermore, there is some question about the complete details of the mechanistic explanation related to topographic effects on interception of subsurface flows [ Luce , 2002].…”

“… Rhodes [2005] brings up some excellent points in his comments on the work of Istanbulluoglu et al [2004]. We appreciate the opportunity to respond because it is likely that other readers will also wonder how they can apply the relatively simple analysis to important policy questions.…”

“…It may be helpful at times for readers to understand the high dimension of the complexity sacrificed in order to obtain the synthesis and the reasons for reducing the complexity in a particular manner. Rhodes [2005] comments on three things: (1) the omission of roads and landings from the analysis; (2) the implicit assumption that fire does not occur with harvesting; and (3) the overestimation of water repellency. We will respond to each of these, clarifying and elaborating on the basis for our modeling choices.…”