Soil-Site Factors Associated with Ecological Land Types in Northeastern Wisconsin and Their Influence on Survival and Growth of Red Pine (Pinus resinosa AIT.) Seedlings on Hardwood Conversion Sites
Trobaugh, John R.
University of Wisconsin-Stevens Point, College of Natural Resources
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Hardwood conversion to red pine (Pinus resinosa Ait.) is actively being conducted on the Padus, Pence, and Vilas Ecological Land Types (ELT's) in northeastern Wisconsin. Before clearcutting, 10 plots were located on each ELT and selected soil-site characteristics were sampled. Discriminant analysis showed that some of these characteristics were effective in discriminating between the three ELT's. The "U" or "jackknife" method of error estimation produced correct classifications of 83.3%, 66.7%, 56.7%, and 41.2% for the following data sets: soil and understory vegetation variables, soil variables only, understory vegetation variables only, and post-cut understory vegetation variables, respectively. In the spring after clearcutting each of the 30 plots were planted with 20 2-0 bare root red pine seedlings. After one growing season there were no significant differences in seedling survival or average height growth on the three ELT's. Average diameter growth on the Vilas was significantly higher when compared with the Pence, and the Padus was intermediate. The level of competing vegetation was evaluated at the end of the-first growing season and no significant differences were found at that time. On a six plot subsample, seedling characteristics (diameter, height, and needle water tension) and site characteristics (soil water tension, soil temperature, total soil nitrogen, and ammonium and nitrate concentrations) were measured on July 3, 7, 30, and August 13, 1985. Multivariate analysis of variance on a repeated measures design showed that first year seedling growth parameters were significant with respect to time but not ELT. Analysis of seedling water tension and site characteristics showed that the sandiest soil (Vilas) had the poorest water relations and lowest nitrogen levels, but this was not reflected in first year growth. This study has shown that there were soilsite differences between the Padus, Pence, and Vilas ELT's, but that one growing season was not sufficient time to produce clear differences in seedling survival, growth, or the level of competing vegetation.