Municipal wastewater renovation, growth and nutrient uptake in an immature conifer-hardwood plantation
The impact of wastewater applications upon a variety of forest ecosystems has received widespread attention in the United States over the past 20 years. During this period the efforts of many researchers have improved our under- standing of the species composition and site characteristics which are appropriate for wastewater irrigation in various forest types (Smith and Evans 1977).A 1977 symposium sponsored by Pennsylvania State University treated the topic of wastewater discharge effects upon various sites.Sixteen papers deait specifically with research conducted on forestlands (Sopper(Ed.), In press). When tree plantations are established upon "old field" sites, plants in the well developed Ap horizon frequently compete vigorously with the newly planted seedlings for water and nutrients. Cultural treatments, such as wastewater irrigation, whichsupplement supplies of water and nutrients, greatly enhance seedling survival and plantation growth if competition from weeds is controlled. This is especially true for hardwood seedlings which are often less tolerant than conifers in competing with grasses and associated vegetation. In 1974, three conifer and seven hardwood species were planted in an old field and irrigated with municipal wastewater: Objectives were (1) to determine the site's ability to renovate applied wastewater and thus provide a high quality groundwater recharge and (2) through monitoring seeding growth and nutrient uptake, to assess each tree species' suitability for plantation establishment on old field sites under wastewater irrigation. Site responses to wastewater applications are described over four growing seasons, 1974 to 1977.