Pre-commercial thinning (PCT) and fertilization are two silvicultural practices designed to accelerate the growth of timber that also generate a variety of understory vegetative compositions and overstory stand structures in second-growth forests. Snowshoe hares (Lepus americanus), mule deer (Odocoileus hemionus), and moose (Alces alces) commonly occur in young stands. This project was designed to test the hypotheses that (1) large-scale PCT and repeated fertilization at 15 years after treatment, and (2) large-scale PCT at 15-20 years after the onset of treatments, would enhance relative habitat use by hares, mule deer, and moose in managed stands compared with mature/old-growth stands. Study areas were located near Summerland, Kelowna (TFL 49), Gavin Lake, Kamloops, and Penticton in south-central B.C. Each of the first three study areas had nine treatments: four pairs of stands thinned to densities of ~250 (very low), ~500 (low), ~1000 (medium), and ~2000 (high) stems/ha with one stand of each pair fertilized five times at 2-year intervals, and an unthinned stand. The other two study areas had three young pine stands thinned to densities of ~500 (low), ~1000 (medium), and ~2000 (high) stems/ha, with an unthinned young pine and oldgrowth pine stand for comparison. Relative habitat use by the three mammalian herbivores was measured by fecal pellet and pellet-group counts in 2008, 15 and 20 years after start of treatments in the two studies. Understory vegetation and coniferous stand structure were measured in all stands. Relative habitat use by snowshoe hares started to fit the predicted pattern with higher activity in the unthinned and high density (1290 to 1580 stems/ha) stands. This trend was further accentuated by the increase in understory conifers in lower-density (. 4 1000 stems/ha) stands, both fertilized and unfertilized, that provided essential cover for hares. This change in stand structure presumably increased their degree of habitat use at 15 compared to 10 years since the onset of PCT and fertilization treatments. Relative habitat use by mule deer appeared to be enhanced in very low-density (~250 stems/ha) stands; with comparable levels of use in the other managed stands (500-2000 stems/ha) and old-growth stands. There were no significant relationships between mule deer and habitat components of abundance or diversity of understory vegetation, nor with fertilization. Deer habitat use declined with an increase in conifer structural diversity that may have been related to preference for open stands. Relative habitat use by moose also tended to be enhanced in managed stands, particularly very low-density, and generally greater than in unthinned or old-growth stands. Fertilization further enhanced this response with positive habitat relationships for moose and abundance of herbs and shrubs.
Sullivan, Thomas P.. 2009. Long-Term responses of Mammalian Herbivores to Stand Thinning and fertilization in young Lodgepole Pine forest 15-year remeasurement. Forest Investment Account (FIA) - Forest Science Program. Forest Investment Account Report. FIA2009MR244
Topic: FLNRORD Research Program
Keywords: Forest, Investment, Account, (FIA), British, Columbia
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