Implementing a winter 2013-14 seed tree harvest in a mature pine stand to regenerate a mix of red and white pine following a winter harvest with a low cost per acre and no site preparation.
The objective was to regenerate a stand comprised of at least 70% red pine/white pine, the rest other species. Climate change and threats from insects and disease were considered in this stand which shaped the decision to have a mixed over a monotypic stand and provide some flexibility into the future.
Pre-treatment stand description and condition
Stand establishment and management history:
The stand was thinned in August/September of 2003 with conventional logging equipment; 80 ft2/acre was removed. Just before the 2013-14 seed tree harvest, stand density was variable, with BA ranging from 20 to 160 ft2 throughout the stand and averaging 68 ft2. This 2003 treatment did produce about 1,800 seedlings per acre of mixed species, based on a 2012 regeneration survey. However, as noted below, much of this regeneration was killed during the 2012 seed tree harvest.
Pre-treatment species composition:
The distribution of both stocking and species in the overstory was highly variable throughout this stand. However, red pine was dominant throughout. Other scattered associates included: white pine, white spruce, black spruce, balsam fir, trembling aspen, red maple, paper birch, jack pine, and tamarack. The red pine and white pine were mostly dominant in the canopy and somewhat uniformly distributed across the stand. All other species were co-dominant or suppressed with a patchy distribution. The paper birch, jack pine, and tamarack were only present in the understory.
Pre-treatment forest health issues:
Hares, red squirrels, spruce budworm, white pine blister rust, white pine weevil. For hares and red squirrel, the solution is to maintain a predator- or raptor-friendly environment by reserving snags in order to make hares and red squirrels vulnerable. White pine blister rust (WPBR) is an issue that must be considered but viable stands can still be grown despite the presence of WPBR. Pruning the bottom third of the live crown can limit its spread and pruning can typically take place when the tree reaches about 5 feet in height.
Maintain a mix of red and white pine to mimic pre-settlement native land cover types.
The prescription for the 2013-14 seed tree harvest was as follows: Harvest all white pine and red pine marked with yellow paint, all white spruce and black spruce less than 14” DBH and 7 sticks (must meet both diameter and height criteria), and all merchantable tamarack, balsam fir, and red maple. In addition, fell all tamarack, balsam fir, and red maple greater than 2” DBH. Reserve all unmarked white pine and red pine and all healthy white spruce and black spruce greater than 14” DBH and 7 sticks (must meet both diameter and height criteria). Conduct sale operations on frozen or dry soil conditions only. Since there was adequate stocking of regeneration (estimated at about 1,800 seedlings per acre in 2012), there was no post-harvest management planned; the amount of regeneration is deemed more than enough to withstand browse pressure as well as mortality from white pine blister rust. However, this stand will be monitored in the case the prescription needs to be adjusted or release work is needed.
Figure 1. The horizontal structure of the stand. Recall that red pine and white pine stocking were 71% and 86%, respectively.
Figure 2. The seed trees of the site. About 20 BA/acre of red and white pine were left.
Figure 3. Future competitors side by side. Spruce mix had about 21% stocking. There are some gaps in the understory throughout the site that are not covered up with ferns.
What actually happened during the treatment
This was a winter season (November 2013-January 2014) conventional harvest using full tree skidding with chipping. The seed tree harvest removed over 100 ft2/ac of black spruce, white spruce, white pine, and red pine. Black and white spruce were only removed if their DBH was less than 14” and if they had fewer than 7 sticks.
This winter full-tree harvest killed most advanced regeneration that originated from the 2003 treatment. Full tree harvest was used because that's the equipment that the operator had available and the prescription did not specify protection of the advanced regeneration. Residual BA of mature red and white pine seed trees ranged from 10 to 30 ft2/acre across the site.
Some biomass was removed and went to Sappi. All non-hazardous snags were reserved.
Table 1: Seedling stocking by species from a 2018 survey, four growing seasons after the 2013-14 seed tree harvest.
Plans for future treatments
New regeneration was released from competition in 2016 through spraying. Following release, the plan is to let the stand grow and monitor patches of empty space for growth, monitor for forest health issues, and evaluate the impact of hazel, honeysuckle, and raspberry on regen. There are no plans at this time to budcap or control deer browse.
Costs and economic considerations
Cost of stock, planting, & survey: $350/acre
Cost of release: $110/acre
This case study was developed with support from the United States Department of Agriculture's National Institute for Food and Agriculture (USDA-NIFA), Renewable Resources Extension Act (RREA). Project #MIN-44-E02, principal investigator Eli Sagor, University of Minnesota.
Climate Adaptation Considerations
Uncertain future climate conditions were one consideration in planning for regeneration from a variety of species, rather than single-species, stand. A diverse stand can help to maintain stocking if one species fares poorly in the future.
Summary / lessons learned / additional thoughts
More of a 50/50 mix between red and white pine would be ideal but wouldn’t change anything about the treatment. Would have preferred a summer only harvest for more ground scarification but circumstances didn’t allow for it. Overall happy with the results.
Lane got his passion for silviculture over the course of achieving his B.S. and M.S. in forestry from the University of Minnesota. He has worked at the Sustainable Forests Education Cooperative since early 2022. Lane is also currently pursuing a PhD at the University of Minnesota; his specialization and research interests include both silviculture and soil health and structure, particularly as they relate to the aspen cover type.