【正文】 freshly prepared wood chips and old sawdust. An excavator equipped with a site preparation rake was used to till the soils to a depth of m. Organic amendments were subsequently added to the plots, and either left as a mulch or incorporated into the surface m of the soil. Nitrogen was applied to all plots at a rate of 225 kg N ha1, which represents about onethird of the 500177。 Soil conservation。re hazard on the adjacent cutblock, and wellrotted sawdust from an old sawmill site. These materials are typical of soil amendments that may be available at remote rehabilitation sites. The chips had typical particle size of m ? m ? m,while the sawdust particles had all dimensions smaller than m. . Treatments Treatments were carried out in the summer of 1994 using an excavator equipped with a fivetooth site preparation rake. Soils were tilled to a depth of m, and anic amendments were subsequently shoveled onto the plots to obtain an even distribution of the material. Amendments were either left as a mulch or subsequently incorporated into the surface m of the soil. Pine seedlings (PSB 313) were planted at 1 m spacing on all plots. A legume seed mix was applied in the summer of 1995, but very poor establishment of the legume cover crop occurred due to dry and legume cover has been maintained at a low level throughout the experiment. All plots, including controls, were fertilized in the summer of 1995, using a bination of urea (4500) and a plete NPK fertilizer (181818). Nitrogen was applied at a rate of 225 kg N ha1, which represents about onethird of the 500177。ne soil anic matter content. In contrast, sawdust incorporation would be expected to result in similar changes to total C concentration, but the C would appear in the fine soil fraction sooner,because the initial particle size is much smaller for sawdust than for wood chips. As expected, Fig. 2 shows that the plots where sawdust was incorporated into the surface had higher anic matter levels in the surface mineral soils than other treatments. Concentrations of other nutrients in surface mineral soils were variable, and did not show obvious trends arising from the treatments. . Tree survival and early growth Seedlings on plots with tillage alone produced the most volume over the 3 year period (Fig. 3). Trees growing in plots where sawdust was used as an amendment tended to have more volume after 3 years than trees growing where wood chips were used as the amendment. Heavy applications of wood chips left as a surface mulch resulted in the lowest volume growth after 3 years. Survival rates were over 90% for all treatments (Fig. 4). The silty soils were prone to frost heave, and high mortality rates and seedling damage due to frost heave were observed on control and tilled only plots on a wet area of one landing where seepage water was present, while lower rates were observed for adjacent plots that had received anic amendments. Although data on soil moisture content are not presented here, several effects of the treatments on soil moisture status and availability to tree roots could be considered as causing the observed growth response. Lower soil moisture contents may result from better drainage from areas with raised surfaces, resulting in warmer soil temperatures and increased aeration of the root zone. During dry periods,increased soil anic matter contents of soils treated with sawdust or chip incorporation may improve soil moisture retention and provide moisture for mulches can also enhance moisture retention,although mulches also insulate the surface and may result in lower temperatures. Several