The Effect of Logging and Slash‐Burning on Soil Structure

Abstract

The effects of logging and slash‐burning on soil structure were investigated on three Reddish Brown Latosol soils in the Coast Range of Western Oregon. Soil samples of the surface 2 inches were collected at 50‐foot intervals along randomly located transects within the clear‐cut areas. Soil samples were also collected in the adjacent uncut timber. The condition of the surface soil was noted at 10‐foot intervals along the transects and was recorded as follows: lightly burned, severely burned, disturbed and unburned, or undisturbed. Sixty soil samples from each clear‐cut sampling area were analyzed in the laboratory for mechanical composition, organic matter content, and water stable aggregates. The soil surface conditions after logging and slash‐burning were as follows: lightly burned 44.7%, severely burned 8%, unburned 30.1%, and undisturbed 17.2%. Severe burning was the only treatment that had any significant effects upon soil structure, particle size distribution and soil organic matter content. Analysis of variance revealed that there was a significant decrease in the amount of clay present in the severely burned soils as compared with the soils under undisturbed timber. A 20.6% decrease in the degree of aggregation and a 61.1% decrease in organic matter content were also noted in the severely burned soils as compared with soils in the undisturbed timber. Other treatments had no significant effects upon the soils of the logged area. Since only 8% of the soil surface was severely burned, it is concluded that logging by the high lead method and slash‐burning in the fall after rainfall has occurred have had no appreciable detrimental effects upon soil structure in the area studied.

Impacts of Fire and Fire Surrogate treatments on forest soil properties: a meta‐analytical approach

“…Changes in surface soil permeability or porosity may occur as the result of the volatilization of organic compounds that had served to cement soil aggregates (Dyrness and Youngberg 1957). This can result in reduced porosity as impacted aggregates crumble and plug large soil pores (Moehring et al 1966).…”

How wildfires affect soil properties. A brief review

“…High-intensity fires may cause thermal fusion of clay-size particles, increasing silt and sand percentages (Dyrness and Youngberg, 1957;Nishita and Haug, 1972; due to thermal changes in aluminosilicates and iron oxides and hydroxides (Betremieux et al, 1960;Giovannini et al, 1990). Also, post-fire increased erosion rates may select coarser particles or aggregates and favor the loss of fine materials.…”

Natural and cultural history of beargrass (<em>Xerophyllum tenax</em>)

“…Although canopy openings, increased light levels, and higher soil temperatures resulting from logging could potentially benefit beargrass growth and reproduction (Brockway et al 1983, Maule 1959, Vance et al 2001) most studies have found that logging-related activities result in both short-and long-term reductions in beargrass densities (Shebitz et al 2009a). In a short-term Oregon Cascade Range study examining plant cover and composition (1) prior to clearcut logging, (2) after logging but before broadcast slash burning, and (3) during each of five growing seasons following burning, beargrass disappeared immediately after clearcut logging, remained absent after burning, and reappeared only in trace amounts 4 years later (Dyrness 1965). Clearcutting followed by broadcast burning strongly decreased the abundance of beargrass in a study conducted in high-elevation old-growth Douglas-fir forests of the Oregon and Washington Cascade Ranges.…”