Alan E. Harvey

The effects of thinning and similar stand treatments on fire behavior in Western forests.

Graham, Russell T.; Harvey, Alan E.; Jain, Theresa B.; Tonn, Jonalea R. 1999. The effects of thinning and similar stand treatments on fire behavior in Western forests. Gen. Tech. Rep. PNW-GTR-463. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 27 p. In the West, thinning and partial cuttings are being considered for treating millions of forested acres that are overstocked and prone to wildfire. The objectives of these treatments include tree growth redistribution, tree species regulation, timber harvest, wildlife habitat improvement, and wildfire-hazard reduction. Depending on the forest type and its structure, thinning has both positive and negative impacts on crown fire potential. Crown bulk density, surface fuel, and crown base height are primary stand characteristics that determine crown fire potential. Thinning from below, free thinning, and reserve tree shelterwoods have the greatest opportunity for reducing the risk of crown fire behavior. Selection thinning and crown thinning that maintain multiple crown layers, along with individual tree selection systems, will not reduce the risk of crown fires except in the driest ponderosa pine (Pinus ponderosa Dougl. ex Laws.) forests. Moreover, unless the surface fuels created by using these treatments are themselves treated, intense surface wildfire may result, likely negating positive effects of reducing crown fire potential. No single thinning approach can be applied to reduce the risk of wildfires in the multiple forest types of the West. The best general approach for managing wildfire damage seems to be managing tree density and species composition with well-designed silvicultural systems at a landscape scale that includes a mix of thinning, surface fuel treatments, and prescribed fire with proactive treatment in areas with high risk to wildfire.

Impacts of soil compaction and tree stump removal on soil properties and outplanted seedlings in northern Idaho, USA

Intensive timber harvesting and site preparation are becoming more common as demand for timber-based products increases. On some harvested sites in the western United Staes of America and Canada, stump removal is used to ameliorate root disease problems. Soil compaction and nutrient loss could become a problem on some sites after harvesting, site preparation, or stump removal. In a non-replicated, randomized block experiment, two levels of soil compaction (none and severe) and a stump extraction treatment were examined on an ash-cap soil in northern Idaho. These treatments were planted with Douglas-fir (Pseudotsuga menziesii var. glauca [Beissn.] Franco) and western white pine (Pinus monticola Dougl. ex D. Don) seedlings. Soil compaction increased post-harvest bulk density 15–20% to a depth of 30 cm. Stump removal decreased surface soil bulk density, but it increased at the 30- to 45-cm depth to levels equal to the soil compaction treatment. One year after outplanting, seedling top weights were similar am...

Decaying organic materials and soil quality in the Inland Northwest: A management opportunity

Organic debris, including wood residue, is important to the development and function of. forest soil. Organic matter stores nutrients and moisture plus it provides important habitats for microbes beneficial to tree growth. To protect long-term forest soil productivity, organic horizons and their parent materials should be maintained.

A comparison of dinitrogen fixation rates in wood litter decayed by white-rot and brown-rot fungi

Nitrogen fixation rates, as estimated by the acetylene reduction technique, were determined in conifer wood litter being decayed by brown- and white-rot fungi. Average ethylene production rates were significantly higher in white-rotted wood (15.1 nmol g−1 day−1) than in brown-rotted wood (2.3 nmol g−1 day−1). This difference may be related to a higher soluble sugar content in white-versus brown-rotted wood. The nitrogen-fixing bacteriumAzospirillum was not detected in any of the decaying wood samples examined. Greater nitrogen additions from nitrogen-fixing bacteria may be a factor in the more rapid white-rot decay of hardwood litter, as compared to the slower brown-rot decay of conifer wood.

Nitrogen-fixing bacteria in Douglas-fir residue decayed byFomitopsis pinicola

SummaryColonizing populations of nitrogen-fixing bacteria were measured in various decay stages of Douglas-fir logs infested withFomitopsis pinicola. Numbers of nitrogen-fixers and N-fixation rates in the wood increased as decay progressed. These increase in bacterial populations and N-fixing activity appeared related to increases in wood moisture content. Bacteria resemblingClostridium pasteurianum, Clostridium butyricum, andKlebsiella/Enterobacter spp. were isolated from the various wood decay stages.

Site preparation alters soil distribution of roots and ectomycorrhizae on outplanted western white pine and Douglas-fir

This report documents root and ectomycorrhizal development on container-produced (1-0), outplanted, western white pine and Douglas-fir seedlings growing in site-prepared forest soils typical of the Inland Northwestern US. The following site preparations were used: 1) mounding organic and surface mineral horizons; 2) mounding with subsequent physical removal or chemical control of competing vegetation; 3) scalping to reduce competing vegetation; and, 4) a control or no post-harvest disturbance. Treatments were applied on relatively harsh and moderate sites in northern Idaho. Most ectomycorrhizae on the seedling population were found in the mineral substrates that dominated planting sites. However, compared to mineral substrates, highest seedling ectomycorrhizal tip counts were recorded in organic matter, particularly decayed wood or mixtures containing decayed wood. Strong ectomycorrhizal development was characteristic of western white pine. It supported highest ectomycorrhizal activity in organic substrates on the harshest treatments (scalps). Douglas-fir showed even stronger relative increases of ectomycorrhizae in organic substrates on harsh treatments. Three of the four common ectomycorrhizal morphological types were concentrated in mineral substrates with all treatments. A treatment-induced change of behavior was shown by the principal pine type. It occurred at highest numbers in organic substrates of the mound with competing vegetation treatment and in mineral substrates with the control. If relative availability to seedling roots was considered, organics (especially decomposed wood) were generally equal or superior to mineral substrates for supporting ectomycorrhizal activity on planted seedlings.

Site preparation alters biomass, root and ectomycorrhizal development of outplanted western white pine and Douglas-fir

This report documents impacts from manipulations of native forest soils and competing vegetation on development and ectomycorrhizal formation of outplanted western white pine and Douglas-fir in the Inland Northwest. Treatments were: 1) mounding surface horizons with competition left in place, 2) mounding surface horizons with subsequent physical or chemical control of competing vegetation, 3) scalping for control of competing vegetation, and 4) a control, or no postharvest disturbance. Treatments were applied on a low-altitude, relatively harsh site and on a higher altitude, more moderate site. Wich established seedlings, mounding with no competition control generally produced small seedlings (5–15g; both species) with low numbers of ectomycorrhizal short roots (21). Mounding with competition control produced large seedlings (20–48g) with moderate numbers of short roots (25). Scalping produced small seedlings (8–16g) with high numbers of short roots (41). The control also produced small seedlings (8–13g) but with a moderate number of short roots (27). Douglas-fir produced more short roots on the harsh than the moderate site. Western white pine produced high root to shoot ratios (above 0.60) in the mound with competition on the harsh site. Douglas-fir produced very high root to shoot ratios (above 1.0) in both the mound with no competition of the harsh site and in the mound with competition of the moderate site. Throughout, western white pine produced more ectomycorrhizae more rapidly than Douglas-fir. Ectomycorrhizal development and root and shoot weight of both conifers were adversely affected by competing vegetation.