Comparing timber marking versus operator select to thin open longleaf pine stands

Brett Lawrence , Jeremy Stovall, Matthew McBroom

Introduction: Open longleaf pine stands in the southeast U.S. are often marked prior to thinning to ensure quality residual trees are left. We present a case study where operator select thinning was applied in a longleaf pine forest where the optimization of water resources was a major goal. Longleaf pine stands were in Trinity County, Texas, U.S.A. Stands were overstocked and had a dense, shrubby understory from years of fire exclusion. 

Objectives: Our main objective was to compare the outcomes of operator select versus timber marking, and whether they were different when attempting to create specific stand structure. Additionally, we worked closely with loggers to manage brush in place of traditional forestry mulching. 

Methods: Fourteen inventory plots were sampled pre-thinning, with half marked and the other half left unmarked and harvested by operator select methods. Following timber harvest thinning, we conducted a comparative analysis of marked and unmarked plots.

Results: We measured no significant difference in basal area, trees per hectare, quadratic mean diameter, or volume at marked and unmarked plots. Also, QMD increased across all plots, longleaf dominance increased, woody vegetation decreased significantly, and we saw some herbaceous groundcover reestablishment. Our results indicate that close monitoring and feedback with loggers allowed us to circumvent an estimated $194.94 US per hectare cost for timber marking and $1,123.82 US per hectare for traditional mulching services. This amounted to an estimated $923.29 US per hectare reduction in project cost to create open longleaf pine structure. 

Conclusions: Operator select may be a viable option for initial entry in unmanaged and highly stocked longleaf pine stands of varying age. For our case study, it was a cost-effective approach for creating our desired stand conditions.

Implications for Practice: Where open stand structure is a targeted outcome in longleaf pine forests, operator select thinning can yield similar and satisfactory results in place of timber marking. When tasking logging operators to also manage brush during thinning, significant costs savings can be realized by circumventing the cost of timber marking and forestry mulching.