Quantifying the ecological benefits of lakeshore restoration in northern Wisconsin

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Down woody material (DWM) is an important ecosystem component that performs many critical functions. Soil temperature and moisture can affect plant growth and survival. Residential development along lakeshores has increased dramatically in the past few decades in northern Wisconsin. Human development can have a dramatic effect on the presence of woody material in terrestrial and aquatic ecosystems. Shoreline restoration projects have occurred in the past few years in the region, but with little or no evaluation of success. In 2007 a collaborative lakeshore restoration research project was initiated on two lakes in Vilas County, Wisconsin. I investigated the benefits of the addition of DWM as part of these restoration projects. I randomly assigned three coverage treatments (0%, 25%, and 50%) of DWM on 3 m × 3 m experimental plots (n = 10 per treatment). I monitored soil temperature and volumetric soil water content at a depth of 10 cm. Three soil temperature variables daily mean, daily maximum, difference in daily high and low, and percent change in moisture content following a watering event were compared among treatments. All plots were planted with two native shrub species and five native understory herbaceous species; change in plant canopy volume was compared among treatments. The mean maximum soil temperature, mean difference in daily high and low soil temperature, and percent change in soil moisture content were significantly lower in the 25% and 50% DWM plots. Plant canopy volume growth for snowberry (Symphoricarpos albus) and Barren strawberry (Waldstenia fragaroides) was significant 2 greater in the 25% and 50% DWM plots. I conclude the addition of DWM had a significant positive effect on soil temperatures, soil moisture, and plant volume growth for two species of native plants used for restoration projects. Introduction Down woody material (DWM) is vital to the function and structure of healthy terrestrial and aquatic ecosystems. DWM can come in many forms including standing and fallen dead trees, large branches, and is often abundant in natural forests, streams (Harmon et al. 1986), and lake ecosystems (Christensen et al. 1996, Marburg et al. 2006). Input mechanisms of DWM into a system include wind throw, insects, diseases, and beaver (Castor canadensis) activity which can display an aggregated spatial pattern (Harmon et al. 1986) adding complexity to the forest floor and below ground heterogeneity (McComb 2008). Many people consider DWM to be a waste of wood fiber and a fire hazard which can lead to multiple and sometimes conflicting values. However, DWM performs many crucial ecological functions such as habitat, energy flow and nutrient cycling, influencing soil and sediment transport and storage (Harmon et al. 1986), and providing nursery sites for germination of plants (Gray and Spies 1997, Rasmussen and Whigham 1998). In addition, DWM provides organic matter to the soil, enhances infiltration capacity of water runoff, creates microclimates (Harmon et al. 1986, Reid et al. 1999), moderates flow of organic matter from terrestrial ecosystems into aquatic systems (Bormann and Likens 1979, France et al 1998, Hagan and Grove 1999), and is a critical factor influencing interactions between terrestrial and aquatic ecosystems (Harmon et al. 1986).