Tree Growth Field Trial at Monocacy NRMA

-Submitted by: Mike Kay
Forester, Maryland Forest Service

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Beginning in the spring of 2004 a Tree Growth field trial program has been in effect at the Monocacy Natural Resources Management Area (NRMA) in Southern Frederick County.  The purpose of the study is to conduct four popular methods of growing seedlings and measures certain parameters such as cost of establishment, maintenance cost, seedling survival, condition of trees, and growth and development of the seedlings.

The four methods of seedling planting were: 

• Planting trees at a 10’ x 10’ spacing or (436 trees per acre) in a deer fence enclosure (Area A)
• Planting trees at a 10’ x 10’ spacing (436 trees per acre) placing 4.5’ tall tree shelters on 50% of the trees (Area B)
• Planting trees at a 5’ x 10’ spacing (871 trees per acre) without any protective devices (Area C)
• Planting trees at a 20’ x 20’ spacing (109 trees per acre) placing 4.5’ tall tree shelters on 100% of the trees (Area D).

A 12-acre upland site, which had been in agriculture, was chosen for this project.  We established 1-acre plots with each tree growing strategy and duplicated the plots so there was an A1, A2, B1, B2, C1, C2, D1, D2.

The field had been in a soybean crop so it was pretty clean when we began our field trial.  In March of 2004 we planted a cover crop of 25 lbs. of oats and 5 lbs. of white clover.  A commercial tree-planting contractor used the machine planting method to plant the trees.  We planted black walnut, red oak, and green ash in distinct rows for this study.

After planting was complete, we selected individual trees to monitor over the duration of the study, and established long-term monitoring plots.  We planned to inventory about 10% of the trees in the plantation.   The height and diameter of each tree in the survey point was then measured and recorded.  Plans were made to measure height, diameter, and survival of each survey point in the fall of 2004, 2005, 2006 and 2007.

Once the plots were established and trees measured we enclosed areas A1 and A2 with deer fencing.  We installed tree shelters on 50% of the trees in the deer fence area to gauge the difference in growth and development of seedlings with or without shelters in this area.  The planting contractor installed tree shelters a few days before the trees we measured and the deer fence was installed.

Individual costs of establishment were calculated and costs of maintenance will be identified and calculated over the life of the project. Regular maintenance practices are in place at the field trial.  So far, maintenance has entailed mowing the site twice per season in June and late September, removal of bird netting when trees reach the top of the tree shelter, spot spraying thistle, fixing shelters that we knocked over by deer, and repairing a section of deer fencing in the winter of 2005.

This is an ongoing project and plenty of changes are likely to occur.  Nonetheless some preliminary results (2 years into the study) are worth noting.

Survival:  Tree survival has been good, averaging 85-93% survival for all plots, and all planting scenarios.

Averaged tree height growth readings (as measured on green ash) were as follows:

Tree Condition:  Most of the unprotected trees had deer feeding damage and some had damage inflicted by the 17 year cicada that impacted this site during the spring of 2004.  Unprotected walnut showed the least amount of damage,  presumably because deer find it distasteful.  The oaks suffered most from the cicada,  and many died back to the ground only to resprout in 2005.  The trees growing in shelters had some deer damage as deer nipped them back to the top of the shelter.  The trees inside the deer enclosures showed no deer damage but the cicada impacted the unsheltered trees.

The 17-Year cicada damaged this green ash as the female
laid her eggs in the stem, the ash and walnut seemed
to grow out of the damage but many red oak were
killed back to the ground

Cost of plantings:  The cost of establishment and maintenance has been tabulated for the various planting scenarios and are as follows:

A section of deer fence needed to be
repaired during June, 2005

Discussion:  Some observations may be stated two years into this study, but as previously stated, nothing should be concluded this early in the process.  It appears that survival is consistent throughout the site no matter what method of seedling planting was used.  Nonetheless, deer have browsed any unprotected seedlings, and this could stunt growth and lead to a multistemmed tree as individuals loose their “apical dominance”.  It will be interesting to see if trees can outgrow the deer damage. 

Deer fencing is the most expensive option and the most maintenance intensive compartment we have been dealing with.  However, trees growing in these enclosures are significantly taller and have a more natural shape than the unprotected sites.  Deer fencing establishment costs would be significantly lower if larger areas were fenced.  The clover cover crop has held up well and provides little cover for mice and voles, which can be very destructive in young tree plantings. 

The perennial white clover cover crop helps
enrich the ground by trapping Nitrogen and
provides little cover for mice
and voles. (Oct 2005 photo)

Trees growing in shelters outside the deer fence area are nearly 3’ taller than those growing without shelters.  The 20’ x  20’ and 10’ x 10’ areas have a very similar cost  and growth.  The main difference is the 10’ x 10’ area has nearly 250 more trees growing in it on an acre basis.  The 10’ x 10’ should have better stocking and attain a closed forest condition before the 20’ x 20’ compartment does.

We will continue to maintain this area and record pertinent information for two more growing seasons.  After that time we will compile and evaluate data and prepare a report which we hope will assist land managers, natural resource professionals, and private landowners in designing tree planting systems to fit their budgets and needs.

Dr. Hailu Sharew inspects a seedling during the fall of 2004

Bryan wonders when I will put the camera
down and give him a hand

This project is a combined effort of numerous agencies, organizations, and individuals whose support has made it a reality.  Funding for the project came from Frederick County Government, the U.S Fish & Wildlife Service, and the MD DNR Forest Service.  The cover crop was provided by and planted by the MD Wildlife Division (Hi Donnie).  Parkton Woodland Services were very patient with us as they planted the trees and installed the shelters.  Trident Enterprises (Deer Busters) were very helpful in designing the deer fencing system and gave us a good deal on the materials.  Bryan Seipp of the Potomac Conservancy  helped us to design the inventory methodology and was able to lend us a 10 person Americorps Crew to assist with taking the initial measurements, install the survey points, and help install the deer fencing.  Also lending their assistance were The Potomac Project, Frederick County Division of Public Works, Community Commons, Frederick County Forestry Board, and members of the MD Forest Service Western Region.  Special thanks go out to Dr. Hailu Sharew, MD Forest Service for his assistance in designing the project. Darrell McCartney of the Frederick County Forestry Board also deserves special thanks for his tireless work .  You’re the man Darrell!