Developing a Planning and Assessment Tool for Predicting Riparian Vegetation Response to Management

Conclusions from this study follow.

A number of characteristics were examined to determine which influenced vegetation types. Several factors co-varied to an extent that many were unnecessary. Ground cover, for example, co-varied with the moisture availability zone and distance above the channel. Soil texture did not seem to impact shrub recruitment independently from the effects of water availability and ground cover. The range of soil textures was narrow, especially in the Sycan, and possibly, with a survey more refined that this one, it may be possible to predict shrub distribution on that basis.

As any good research project does, this study reveals more questions to be answered. Additional transects, especially in Beatty Gap and above, would help guide restoration in those areas, and determine if processes in those smaller channels followed the more wetland-like patterns of the lower Sprague, or the more fluvial patterns of the Sycan. Soil moisture measurements were very helpful in determining whether lack of water or dropping water were limiting shrub recruitment, but lead to the question of gas exchange in saturated sites. What are the controlling factors in sites saturated at near surface layers? Saturation doesn’t seem to limit shrub growth in the Sycan, but does in the Sprague.

Further research into the timing of willow seed fly and spring temperatures, compared with stream flows would greatly benefit estimates of rates of recovery for woody vegetation. Knowing whether favorable seedling germination events occur every other year or every 10 years could change priorities for active vs. passive restoration approaches.

Extrapolating water zones to the larger floodplain surface (possible with the LiDAR data) could reveal the areas most likely to support shrubs, least likely to support shrubs, and those areas that could with a little bit of intervention. Also, this type of geospatial analysis could illustrate the areas most at risk of further invasion of reed canary grass.

The Sprague River is an extremely low gradient, valley bottom river with fine grained, highly erodable soils, in which robust riparian plant communities function to maintain the integrity of the river banks. In systems like this, riparian vegetation is the key component to successfully restoring appropriate form and function to the river and its floodplain, and therefore to successfully reducing non-point nutrient and thermal loading to the river. If we do not provide landowners and managers with the tools to accurately predict the response of riparian vegetation to various management alternatives, we diminish the efficiency and effectiveness of the restoration dollars spent here. Results of this effort will be immediately disseminated throughout the Sprague River restoration community, as were our previous efforts with LiDAR and bathymetry. This project is designed to enhance the overall success of restoration actions done by the restoration community in the Sprague, by enabling better decisions about how and where to put particular types of on-the-ground restoration.
A variety of assessments, research and monitoring projects, and active restoration and enhancement projects are either planned or ongoing in the Upper Klamath Basin. This project intends to help in the development of prioritizing projects. The Tribes Habitat Enhancement Biologist will facilitate the dissemination of information collected during this project and assist in enhancing coordination and collaboration, and ultimately making enhancement efforts of many entities more effective.