Science Findings, Issue 107. Growing Trees Where Trees Grow Best: Short-Term Research Sheds Light on Long-Term Productivity

摘要

In 1999, the Fall River Long-Term Site Productivity study began in coastal Washington to investigate how intensive management practices affect soil processes and forest productivity. By comparing conventional harvests to more intensive wood removal treatments, researchers are answering long-standing questions about how residual organic matter influences future growth. Also, by using herbicides to control competing vegetation, they are quantifying the influence other vegetation has on tree growth. Finally, they are measuring soil properties and tree growth on plots where the soil was not compacted during harvest and comparing results to those on plots that were either compacted by logging equipment or compacted and subsequently tilled to restore physical properties. Several interesting findings have emerged after 8 years of measurements: Nitrogen pools in these soils are so high that conventional clearcutting and whole-tree plus coarse-woody-debris removal only reduced the total site nitrogen pool by 3 percent and 6 percent, respectively. Thats a very small percentage reduction that is unlikely to affect long-term productivity. Vegetation control reduced competition for water during the dry growing season and doubled above-ground tree biomass at age 5 compared to the plots where vegetation was not controlled. Soil compaction did not reduce tree growth. These findings suggest that this site is very resilient to intensive forest management.