Aquatic Ecosystem Response to Timber Harvesting for the Purpose of Restoring Aspen

Abstract

The removal of conifers through commercial timber harvesting has been successful in restoring aspen, however many aspen stands are located near streams, and there are concerns about potential aquatic ecosystem impairment. We examined the effects of management-scale conifer removal from aspen stands located adjacent to streams on water quality, solar radiation, canopy cover, temperature, aquatic macroinvertebrates, and soil moisture. This 8-year study (2003–2010) involved two projects located in Lassen National Forest. The Pine-Bogard Project consisted of three treatments adjacent to Pine and Bogard Creeks: (i) Phase 1 in January 2004, (ii) Phase 2 in August 2005, and (iii) Phase 3 in January 2008. The Bailey Project consisted of one treatment adjacent to Bailey Creek in September 2006. Treatments involved whole tree removal using track-laying harvesters and rubber tire skidders. More than 80% of all samples analyzed for NO3-N, NH4-N, and PO4-P at Pine, Bogard, and Bailey Creeks were below the detection limit, with the exception of naturally elevated PO4-P in Bogard Creek. All nutrient concentrations (NO3-N, NH4-N, PO4-P, K, and SO4-S) showed little variation within streams and across years. Turbidity and TSS exhibited annual variation, but there was no significant increase in the difference between upstream and downstream turbidity and TSS levels. There was a significant decrease in stream canopy cover and increase in the potential fraction of solar radiation reaching the streams in response to the Pine-Bogard Phase 3 and Bailey treatments; however, there was no corresponding increase in stream temperatures. Macroinvertebrate metrics indicated healthy aquatic ecosystem conditions throughout the course of the study. Lastly, the removal of vegetation significantly increased soil moisture in treated stands relative to untreated stands. These results indicate that, with careful planning and implementation of site-specific best management practices, conifer removal to restore aspen stands can be conducted without degrading aquatic ecosystems.

Regional Differences in Stream Water Nitrogen, Phosphorus, and Sediment Responses to Forest Harvesting in the Conterminous USA

“…The average age for the harvested forests in this study followed the trend west > south > north (Tables 2–5), and studies have shown the importance of age of forest materials on decomposition rates (Troendle et al, 2010; Jones et al, 2013). Mature conifer forests have also been reported to use more water than mature aspen forests, leading to less nutrient export (Jones et al, 2013).…”

“…The average age for the harvested forests in this study followed the trend west > south > north (Tables 2-5), and studies have shown the importance of age of forest materials on decomposition rates (Troendle et al, 2010;Jones et al, 2013). Mature conifer forests have also been reported to use more water than mature aspen forests, leading to less nutrient export ( Jones et al, 2013). Stream flow response was also reported to be affected by species composition and the percentage change in vegetation density in the western region (Troendle et al, 2010), and in the eastern coastal plain ( Jayakaran et al, 2014), with a potential to affect nutrient and sediment exports.…”

Effects of Streamside Buffers on Stream Temperatures Associated With Forest Management and Harvesting Using DHSVM-RBM; South Fork Caspar Creek, California

“…For example, the Washington State Department of Natural Resources outlines riparian management strategies to restore conifer dominated riparian areas (Bigley and Deisenhofer, 2006). Additional studies in Lassen National Forest seek to restore aspen stands for habitat and ecosystem services (Jones et al, 2013). Furthermore, there has been documented success at releasing suppressed conifers in riparian areas using patch cutting and thinning in parts of Oregon (Emmingham et al, 2000;Maas-Hebner et al, 2005).…”