PRODUCTIVITY OF POPULUS IN MONOCLONAL AND POLYCLONAL BLOCKS AT 3 SPACINGS

Four Populus clones were grown at three spacings (0.5, 1.0, and 1.5 m) in monoclonal plots and in polyclonal plots with all clones in intima te mixture. After the third year, many individual tree and stand trait s differed significantly by clone, spacing, deployment method, and the ir interactions. Differences among clones in growth and stem form were greater in polyclonal than in monoclonal plots, and differences in pe rformance between deployment methods were greater in the denser spacin gs. Monoclonal stands had greater uniformity in tree size than polyclo nal stands. Total aboveground oven-dry woody yield averaged 48.0 Mg.ha (-1) in the 0.5-m spacing and decreased as spacing increased. Some clo nes differed in yield from other clones in both monoclonal and polyclo nal plots. Assuming that equal numbers of plants from the same clones were planted, the manner of deployment did not affect productivity; th at is, although there were clonal differences in yield, mean yield of the four clones in monoclonal plots (44.3 Mg.ha(-1)) did not differ fr om the yield of polyclonal plots (43.1 Mg.ha(-1)). Comparative yields (yield in polyclonal plots/yield in monoclonal plots) differed substan tially, however, and the increases or decreases in comparative yield d iffered with spacing and clone. Production and inventory were less eve nly balanced among clones with polyclonal than with monoclonal deploym ent.