Regeneration of Black Walnut to Sustain Production on Forested, Deep-Alluvial Soils Along a Creek

Final Report for FNC07-659

Project Type: Farmer/Rancher
Funds awarded in 2007: $5,170.00
Projected End Date: 12/31/2008
Region: North Central
State: Missouri
Project Coordinator:
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Project Information


Our family has 15 acres of annual crops, 97 acres of CRP, 220 acres of pasture with typically 65 head of cattle and 383 acres of timber. Typical of farms with meandering creeks, we discontinued farming the small, irregular fields along the creeks as current farm machinery cannot economically operate. Grazing by cattle has also been restricted from most of the bottomland.
As mentioned above, we had 97 acres of cropland enrolled in CRP. Other than the ten acres in this test site, we have conducted timber stand improvement on all of the forested bottomland on the entire farm.

The overall objective was to renovate the existing stand of timber that had naturally reforested a tract of land along a creek on our property after grazing had been discontinued about 35 years ago. Two levels of site preparation were compared and replicated two years to see how much disturbance would be necessary to increase the density of population of black walnut in the mixed stand of timber.

Stand density of black walnut trees growing in an uneven aged reforestation setting. Before starting any treatments of renovation, there were about six walnut trees per acre on the ten acre site. Existing walnut trees were geo-referenced and mapped. These trees varied from just a couple inches in diameter up to 26. I was told that black walnut trees are shade intolerant and need full sunlight to grow as seedlings and young trees. So, it was useless to direct seed or transplant walnut seedlings into an existing dense growth of mixed timber. Thus, two levels of renovation or canopy removal were compared.
Site prep level 1 consisted of girdling with a chain saw all cull brush and low-valued trees while saving only existing walnut, northern red oak, white oak, and black cherry. Herbicide treatment was applied to the frill (chainsaw kerfs) to kill the culls. The dying and dead trees remain standing for a couple years but theoretically should allow filtered light to reach the ground in hopes of supporting volunteer walnut seedling growth.
Site prep level 2 consisted of cutting all stems of low-valued trees at ground level and treating the stumps with herbicide while saving the existing walnut, oak, and cherry. We salvaged all marketable cull trees (sycamore and soft maple) to evaluate the initial economic return while trying to give a chance for more walnut to thicken the stand of mixed timber. The remaining tops were pushed into wildlife habitat piles so that the ground surface was relatively clean except for the widely spaced existing trees we wanted to keep.
The ten acre area was subdivided into four segments to give us two replications of the two treatments for two years. In some ways, level 1 of site preparation is easier. But it seems rather wasteful to kill sycamore and soft maple that are 20 to 40 inch diameter at breast height and let it rot in the woods. In the near future, such biomass could be utilized by the biofuel power plants.
Verbalized nuts under screen in three spots totaling 48 nuts in Site prep level 1 and the same number of nuts I three spots in Site prep level 2. The purpose of doing this was to see if there was a notable difference in emergence percentage and growth rate of seedlings in the two environmental conditions.
Fifty nuts were direct seeded under screen in each of the four treatment blocks during the fall of 2007. Additionally, hundreds of verbalized nuts were dumped in piles in random areas in each of the four blocks in the spring of 2008. During the fall of 2009, hundreds of nuts were dumped in random areas in each of the four blocks. All of these efforts were done to augment the ultimate stand of walnut trees with the aid of gray and fox squirrels on site.
An assessment was made in December, 2009 as to the population of volunteer walnut emerging throughout the replicated study. This was done by counting walnut seedlings at four randomly selected points within each of the four blocks (2 levels of site prep x 2 year replication). Each point of observation consisted of a radius of 30 feet or 1/15 acre.

Ben and Arnold Bruggeman, Bruggeman Milling in Dubuque, IA – they traveled down to buy veneer quality sycamore, soft maple, and walnut. None of the walnut logs were off this ten acres but were from farms downstream on this same Auxvasse Creek. We wanted to see if the color of the heartwood from this immediate area could meet the color standards in the veneer industry. All logs met their standards.
Dr. Hank Stelzer, MU Ext Forester – emphasized the value in keeping in the stand any white and red oak along with the cherry and walnut for diversity sake.
Mr. Doug Wallace, NRCS State Forester – he confirmed the Haymond silt loam classification of the land and that it is “very-well suited” for raising the best black walnut.
Josh Stevens, MO Dept of Conservation – he was very supportive of the project and was very curious as to which scenario of site preparation would produce the most volunteer walnut seedlings.
Bob Burk, Walnut Foundation Chairman – was also very supportive of the idea of this project and the scenario of letting young walnut saplings compete with a dense and diverse set of other species resulting in naturally pruned walnut that are straight and tall … which is exactly what the veneer millers want.
Dr. Mark Coggeshall, MU Walnut Geneticist – was impressed with a couple of the existing walnut trees (12-16” Diameter Breast Height) as to their straightness as influenced by genetics that possess a dominant terminal growth form. We shot off and collected a few terminals from the 70’ crown for him to include in his nursery of grafted walnut to serve as potential seed stock for the MO Dept of Conservation to raise seedlings in the future.

Conducting site prep level 1 was less manual labor and potentially less dangerous while doing it than while felling large timber (maximum of 41 inch at the cut and over 100 feet high). The open areas looked neater and it was obvious that a lot of work had been done.
For this study, I sold the salvaged logs to log buyers. During the first year, I salvaged sycamore valued at $563/acre. During the second year, I salvaged sycamore and soft maple valued at $700/acre.
Regarding Step 3 from above, 12 seedlings have emerged from the 48 nuts placed under screen in the shaded level1. In contrast 18 of 48 emerged in the sunny area of level 2 site prep. While this may not be significantly different, it is of interest to compare the height of seedlings grown under the two levels of canopy clearing. The seedlings in level 1 average 39 inches while only 15 in level 2. The taller seedlings are etiolated (spindly in diameter) as they have been stretching up for more sunlight while growing under the filtered sunlight because of the standing dead trees above them. In contrast, the seedlings in the open area are shorter but do not have much more stem diameter. The ground-cover competition is much greater in the cleared sunny area. Annual and perennial grasses are much more prevalent and these are known to be more competitive than broadleaf forbs found more in level 1 of site prep.
Regarding Step 5 from above, there appears to be an adequate number of walnut seedlings volunteering in all areas of the study and we fully expect many more to emerge within the next couple of years as natural reforestation is a gradual process. Volunteer seedlings exist in both replications of both levels of site prep. As described above, walnut seedlings were counted in randomly selected 1/15th acre points. The following table shows the two levels of site preparation, two replications of the treatments, number of seedlings in the 1/15th sample points, and population expressed on a per acre basis.

The results to date are very encouraging. To begin with, this ten acre test area had 64 walnut or 6.4 per acre. That is typical of naturally reforested tracts that have been idled in the last half century. The density is spatially variable as a function of proximity to walnut seed trees to propagate seedlings during the early stages of reforestation. An about 35 per acre. Trees in such a population would be about 35 feet apart and would have adequate space for maximum crown development.
In this setting, we welcome some diversity in the final stand by having some oak and black cherry. So, a final stand of 20 to 30 walnut per acre plus some oak and cherry would be optimum. The counts are conservative in that it is very possible that not all small seedlings were recognized among the heavy ground cover in all areas of the test.
In some localized areas of the test site, the volunteer walnut seedlings are already thicker than can ultimately exist in the final stand. An example is the count of 32 shown in the table. That converts to 480 per acre. A couple of walnut “seed trees” are nearby and we are seeing the results of squirrels hiding nuts during the last couple of years.
The following photo shows an example in the densely populated area. Pink ribbons are tied to walnut seedlings.
The next photo shows the mixture of other hardwood species that will be competing with the walnut and force the walnut saplings to grow straight and naturally prune as they shed their side branches.

We learned that both levels of site preparation will facilitate an increase in the population of walnut trees in previously idled land along our creeks. Site prep level 1 is easier, faster, and really does not cost much to do. Girdling of all cull trees and treatment with herbicide can be
done best during the dormant season. Amount of time is a function of the density of undesirable. .Felling all undesirable trees, limbing, and pushing into wildlife habitat piles is much more
time consuming, much more dangerous work, and it requires a tracked dozer rather than a rubber
tired tractor because of all the honey locust thorns. In so doing however, most timbered areas
will yield several hundred dollars worth of salvageable logs that offset the cost of doing the
work. In the near future, significant amounts of such biomass could be sold to biofuel energy
Prior to regeneration or rejuvenation of stagnant, low-valued timber sites along creek
bottoms, it would be advisable to bring in large amounts of nuts a year before killing or removing cull trees and brush. Assuming there are squirrels present, they will eat some but hide more than they find later resulting in a new flush or stand of walnut seedlings ready to take advantage of more sunlight reaching ground level.
Another issue is paw paw and buckeye in these sites. I did not want to kill them as I
wanted them as an understmy in the final composition. In level 1 of site prep, the large stems
were cut but not treated with herbicide. They re-sprouted profusely and aggressively cover much
of the ground area and are giving too much competition to walnut seedlings and probably have
prevented some from surviving. In hind site, the biggest ones should have been treated with
herbicide while assuming a few smaller ones would have eventually formed the desired
In level 2 of site prep, the paw paw and buckeye were essentially scraped off while the
brush was pushed into the wildlife habitat piles. In so doing, they were killed or severely set
back so that they are not dominating the ground cover so quickly.
Other invasive species that are disgusting in some ways are multiflora rose and black
berry briars. They make it difficult for man to move through the area but it seems that walnut
seedlings compete fairly well with them. Most interesting is that especially the multiflora rose
provide protection against deer browsing and rubbing during mt season. These sun-loving
species will thin out as tree canopies develop and shade them out. The paw paw and buckeye are
more shade tolerant and can ultimately become the ground cover.

• Callaway County SWCD Annual Meeting-A presentation was given to the! 50
attendees that explained the purpose of the project and progress to date.
• Following the meeting, 12 landowners, 1 NRCS, and I MU Extension attended a field
tour of the site.
• Two presentations have been given to the National Walnut Council summer meetings
with 200-250 in attendance and an optional tour was available during the 2008 meeting
• Two presentations have been given to the Walnut Council Foundation Board as it also contributed to this research/demonstrational trial.
• A couple neighbors have viewed the site.
• Eight USPS, NRCS, and MU Foresters have been on site.


Participation Summary
Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.