#ArticleAlert: #Riparian #vegetation as an indicator of riparian condition: Detecting departures from historic condition across the North American West
The bread and butter of what many applied ecologists do is detecting change, often at plot, transect, stand or reach scales. In many cases, small-scale, experimental trials allow scientists to identify processes responsible for a given change in an ecosystem. This is the tradition of basic science: reducing noise and variability by studying phenomena at very small scales. Ideally, this reductionist approach helps ecologists to understand very specific processes.
However, most landscape planning, like that undertaken in large watersheds, occurs at, well, at the landscape scale. My dissertation advisor, the good Dr. Joe Wheaton, worked hard to impart on me how the people making fish, wildlife, and habitat planning decisions can use small-scale, experimental confirmation of their instincts on how rivers, floodplains, and forests change in response to disturbance, climate change, etc. But...what we and they need to understand such large landscapes with such diverse habitats and ecosystem processes, are tools that match the scales of large study areas. One thing I got out of leaving my ecologist comfort zone and working with a geomorphologist who studied in geography departments, is that spatial context and extent are everything when addressing applied problems, even at fine scales. So, logically, some scientists should work to create landscape-scale tools that help managers to understand the broad patterns within their study areas.
Enter Joe and his lab's efforts to create landscape-scale tools for watershed planning. These network models often buffer a stream network (like NHD or NHD+) and then attribute it with information based on disturbance, vegetation, hydrology, climate or potential for some process to occur. With the leadership of Joe and geospatial analyst, Wally Macfarlane, these network modeling efforts have been underway for years. The most prominent is probably BRAT, which you may have read about here. Gilbert's recent V-BET is another landscape tool for identifying valley bottoms to stratify geomorphic and biological sampling along rivers.
In the latest round of tools, Wally, Joe, and several other players on the team presented the Riparian Condition Assessment Tool, a Landfire-based network tool for mapping where riparian vegetation has changed from historic vegetation classes to new, novel classes. The resulting network model is projected within valley bottoms determined in V-BET and added to an NHD stream segment. This way landscape planners and watershed managers can assess how much of an area's riparian vegetation has changed from disturbance, hydrologic alteration, management history (logging, grazing), or other processes. It is a spatially-explicit, first-cut model of how riparian vegetation has been degraded over time that can be used in applied management
I should note that RCAT maps changes between historic vegetation and current vegetation, and provides GIS layers for land managers. It does not explain which process led to a change in riparian vegetation. It is also susceptible to limitations that arise from the source data, as discussed here.
The data is great for:
- Stratifying field sampling based on riparian vegetation degradation.
- Triage analyses that identify healthy riparian areas that may be a conservation priority.
- Identifying heavily-degraded areas that may be a waste of restoration effort and instead finding areas that may be targets for restoration based on their site potential.
- Being used as a predictor variable in distribution models of aquatic organisms or riparian biodiversity (birds, insects, etc.).
- Generating hypotheses on how flow alteration, grazing, wildfire, drought, etc. have shaped current riparian vegetation.
Macfarlane, W.W., J.T. Gilbert, M.L. Jensen, J.D. Gilbert, N. Hough-Snee, P.A. McHugh, J.M. Wheaton, S.N. Bennett. In Press. Riparian vegetation as an indicator of riparian condition: detecting departures from historic condition across the North American West. Journal of Environmental Management. http://dx.doi.org/10.1016/j.jenvman.2016.10.054