Dynamics of Municipal Wastewater Renovation in a Young Conifer-Hardwood Plantation in Michigan
Since the pioneering work of investigators at The Pennsylvania State University who introduced the "living filter" concept in the 196Os, numeious studies have examined the impact of wastewater irrigation upon forest communities. Some industries had undertaken wastewater recycling measures earlier (Rudolph, 1957; Little et al., 1959). but these met with only modest success, owing, in part, to a limited urderstanding of the physical and biological capabilities of the sites involved. A wide variety of forest ecosystems have now been treated with wastewater, among these being red pine (Murphy et al.; 1973), jack pine (Urie, 1973), aspen (Murphy and Bowier, 1975),.oak, birch, and pine (Frost et al., 1973), semiarid chaparral areas (Younger et al., 1973), and a variety of conifer and hardwood species (Sopper and Kardos, 1973). "Old field" planting sites often present a rigorous set of conditions concerning plantation establishment. A well-developed sod layer usually results in vigorous competition for water and nutrients with the newly planted seedlings. This is particularly true for hardwood seedlings, which are somewhat less adept than conifers in competing with grasses and associated vegetation. In this study, seven hardwood and three conifer species were planted in an old field and irrigated with municipal wastewater as part of the Michigan State University:(MSU) Water Quality Management Area. Major objectives were to (1) monitor water quality changes as percolating effluents interact with the living filter, (2) measure changes in the levels of soil nutrients, and (3) assess the growth response and nutrient status of the tree species employed. Corollary goals ilicluded determination of the site's nutrient renovation capacity and detection of possible nutrient toxicity symptoms.