scholarly journals Variable-Retention Harvesting as a Silvicultural Option for Lodgepole Pine

2014 ◽  
Vol 112 (5) ◽  
pp. 440-445 ◽  
Author(s):  
Christopher R. Keyes ◽  
Thomas E. Perry ◽  
Elaine K. Sutherland ◽  
David K. Wright ◽  
Joel M. Egan
Keyword(s):  
Lodgepole Pine ◽  
Variable Retention ◽  
Variable Retention Harvesting

Forest fuels and potential fire behaviour 12 years after variable-retention harvest in lodgepole pine

2016 ◽  
Vol 25 (6) ◽  
pp. 633 ◽  
Author(s):  
Justin S. Crotteau ◽  
Christopher R. Keyes ◽  
Elaine K. Sutherland ◽  
David K. Wright ◽  
Joel M. Egan
Keyword(s):  
Lodgepole Pine ◽  
Structural Complexity ◽  
Fuel Load ◽  
Fire Behaviour ◽  
Forest Fuels ◽  
Fuel Loads ◽  
Variable Retention ◽  
Harvesting Technique ◽  
Trade Offs ◽  
Variable Retention Harvesting

Variable-retention harvesting in lodgepole pine offers an alternative to conventional, even-aged management. This harvesting technique promotes structural complexity and age-class diversity in residual stands and promotes resilience to disturbance. We examined fuel loads and potential fire behaviour 12 years after two modes of variable-retention harvesting (dispersed and aggregated retention patterns) crossed by post-harvest prescribed fire (burned or unburned) in central Montana. Results characterise 12-year post-treatment fuel loads. We found greater fuel load reduction in treated than untreated stands, namely in the 10- and 100-h classes (P = 0.002 and 0.049 respectively). Reductions in 1-h (P < 0.001), 10-h (P = 0.008) and 1000-h (P = 0.014) classes were greater in magnitude for unburned than burned treatments. Fire behaviour modelling incorporated the regenerating seedling cohort into the surface fuel complex. Our analysis indicates greater surface fireline intensity in treated than untreated stands (P < 0.001), and in unburned over burned stands (P = 0.001) in dry, windy weather. Although potential fire behaviour in treated stands is predicted to be more erratic, within-stand structural variability reduces probability of crown fire spread. Overall, results illustrate trade-offs between potential fire attributes that should be acknowledged with variable-retention harvesting.

scholarly journals Limited Effects of Variable-Retention Harvesting on Fungal Communities Decomposing Fine Roots in Coastal Temperate Rainforests

2017 ◽  
Vol 84 (3) ◽  
Author(s):  
Timothy J. Philpott ◽  
Jason S. Barker ◽  
Cindy E. Prescott ◽  
Sue J. Grayston
Keyword(s):  
Community Composition ◽  
Fungal Community ◽  
Fine Roots ◽  
Fine Root ◽  
Plant Litter ◽  
Fungal Communities ◽  
Decomposition Rates ◽  
Fungal Community Composition ◽  
Variable Retention ◽  
Variable Retention Harvesting

ABSTRACT Fine root litter is the principal source of carbon stored in forest soils and a dominant source of carbon for fungal decomposers. Differences in decomposer capacity between fungal species may be important determinants of fine-root decomposition rates. Variable-retention harvesting (VRH) provides refuge for ectomycorrhizal fungi, but its influence on fine-root decomposers is unknown, as are the effects of functional shifts in these fungal communities on carbon cycling. We compared fungal communities decomposing fine roots (in litter bags) under VRH, clear-cut, and uncut stands at two sites (6 and 13 years postharvest) and two decay stages (43 days and 1 year after burial) in Douglas fir forests in coastal British Columbia, Canada. Fungal species and guilds were identified from decomposed fine roots using high-throughput sequencing. Variable retention had short-term effects on β-diversity; harvest treatment modified the fungal community composition at the 6-year-postharvest site, but not at the 13-year-postharvest site. Ericoid and ectomycorrhizal guilds were not more abundant under VRH, but stand age significantly structured species composition. Guild composition varied by decay stage, with ruderal species later replaced by saprotrophs and ectomycorrhizae. Ectomycorrhizal abundance on decomposing fine roots may partially explain why fine roots typically decompose more slowly than surface litter. Our results indicate that stand age structures fine-root decomposers but that decay stage is more important in structuring the fungal community than shifts caused by harvesting. The rapid postharvest recovery of fungal communities decomposing fine roots suggests resiliency within this community, at least in these young regenerating stands in coastal British Columbia. IMPORTANCE Globally, fine roots are a dominant source of carbon in forest soils, yet the fungi that decompose this material and that drive the sequestration or respiration of this carbon remain largely uncharacterized. Fungi vary in their capacity to decompose plant litter, suggesting that fungal community composition is an important determinant of decomposition rates. Variable-retention harvesting is a forestry practice that modifies fungal communities by providing refuge for ectomycorrhizal fungi. We evaluated the effects of variable retention and clear-cut harvesting on fungal communities decomposing fine roots at two sites (6 and 13 years postharvest), at two decay stages (43 days and 1 year), and in uncut stands in temperate rainforests. Harvesting impacts on fungal community composition were detected only after 6 years after harvest. We suggest that fungal community composition may be an important factor that reduces fine-root decomposition rates relative to those of above-ground plant litter, which has important consequences for forest carbon cycling.

scholarly journals Dispersed Variable-Retention Harvesting Mitigates N Losses on Harvested Sites in Conjunction With Changes in Soil Microbial Community Structure

2021 ◽  
Vol 3 ◽  
Author(s):  
Carolyn Churchland ◽  
Per Bengtson ◽  
Cindy E. Prescott ◽  
Sue J. Grayston
Keyword(s):  
Community Structure ◽  
Microbial Community ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Soil Microbial ◽  
Clear Cut ◽  
Clear Cutting ◽  
Variable Retention ◽  
Dispersed Retention ◽  
Variable Retention Harvesting

As an alternative to clear-cutting, variable-retention harvesting is now standard forest management practice on the coast of British Columbia and in temperate forests globally, due to the benefits associated with maintaining mature forest species and forest structural diversity. Although there is some evidence that variable-retention harvesting, particularly single-tree (dispersed) retention will mitigate the impacts of clear-cutting on soil microbial communities and nutrient cycling, findings have been inconsistent. We examined microbial community structure (phospholipid-fatty acid), and nutrient availability (PRSTM probes) in a large (aggregated) retention patch and over three harvesting treatments: dispersed retention, clear-cut and clear-cut edge 2 years after harvest. Unlike previous studies, we did not observe elevated nitrate in the harvested areas, instead ammonium was elevated. Availability of N and other nutrients were surprisingly similar between the dispersed-retention treatment and the retention patch. The microbial community, however, was different in the clear-cut and dispersed-retention treatments, mostly due to significantly lower abundance of fungi combined with an increase in bacteria, specifically Gram-negative bacteria. This was accompanied by lower δ13CPDB value of the Gram-negative PLFA's in these treatments, suggesting the decline in mycorrhizal fungal abundance may have allowed the dominant Gram-negative bacteria to access more of the recently photosynthesized C. This shift in the microbial community composition in the dispersed-retention treatment did not appear to have a major impact on microbial functioning and nutrient availability, indicating that this harvesting practice is more effective at maintaining generic microbial functions/processes. However, as Mn levels were twice as high in the retention patch compared to the harvested treatments, indicating the other “narrow” processes (i.e., those performed by a small number of specialized microorganisms), such as lignin degradation, catalyzed by Mn peroxidase, which concomitantly removes Mn from solution, may be more sensitive to harvesting regimes. The effect of harvesting on such narrow nutrient cycling processes requires further investigation.

Twelve-year dynamics of alien and native understorey plants following variable retention harvesting in Nothofagus pumilio forests in Southern Patagonia

2019 ◽  
Vol 449 ◽  
pp. 117447 ◽  
Author(s):  
Rosina Soler ◽  
Sabine B. Rumpf ◽  
Stefan Schindler ◽  
Guillermo Martínez Pastur ◽  
Marcelo Barrera ◽  
...  
Keyword(s):  
Nothofagus Pumilio ◽  
Variable Retention ◽  
Southern Patagonia ◽  
Variable Retention Harvesting ◽  
Understorey Plants
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