Forest Regeneration Strategies at the Arnot

[Brett Chedzoy]

Many of you have visited Cornell's Arnot Teaching and Research Forest over the past year and noticed some big changes, namely several large regeneration harvests aimed at replacing aging stands with new ones that are as good or better as the old ones in terms of future quality and value.  For those of you who won't make it back there anytime soon but are interested in following the progress, I'll provide periodic updates here.

[Michael L Ashdown]

Slash wall openings for access fences and gates.

                 When I was approached for suggestions on how to secure the openings in the slash walls my first thought was that the fencing needed to overlap the slash far enough to prevent any possible gaps between the fence and the slash that might look accessible to deer. I also thought the fence should be flexible and able to conform to the irregular shape of either the inside or the outside of the actual pile of slash.  My second thought, which may have been an erroneous assumption, was that the fence needed to be as inexpensive as possible.  There was also the thought that for one of the openings I was going to have to carry the fence in to the site from the landing.  All these things considered I suggested the 7.5 ft. tall plastic mesh fence (Tenax C-flex; mesh dimensions are approx. 1.77" x 1.97") that we have been using for research deer exclosures for many years. This fence is flexible and can be attached to the slash and support post using nylon cable (or zip) ties. 

Initially for the gate opening I proposed an 8 ft. metal T-post driven in near the edge of the slash wall on at least one side of the opening.  The thought being a section of mesh could overlap the slash wall next to the post as described above and end at the T-post.  Then start another piece of fence along the wall on the other side of the opening and ending at the T-post with enough extra that the fence could be wrapped around a straight, small diameter, hardwood sapling. This would support the “swinging” part of the gate so it could be wired or tied to the T-post. 

This simple design works well and each gate in the slash wall openings at Arnot has some form of this system in place.  However, there are complicating circumstances and needs that have led to adaptations and improvements to the basic design.  

[Michael L Ashdown]

New wildlife issues with the plastic gates.
There have been some new wildlife creating issues with the plastic fence gates on the 74 acre harvest slash wall.

Granted I have not noticed any issues caused by turkeys or porcupines. However these other 2 critters have created some.

This pesky woodchuck has pushed the camera out of line with the gate and he and/or gray squirrels continue to chewed holes in the plastic.

This black bear thankfully climbed up the slash next to the gate and went over the plastic that overlaps the logs. When I went in to reposition the camera toward the gate on Tuesday the plastic on one side of the gate was hanging funny and the zip-ties had been popped off the logs. I am relieved that it was most likely the bear in the picture that had done the damage even though I am quite sure a deer could not have done the damage where it occurred.

[Michael L Ashdown]

Some pictures from last Fall to show wildlife diversity around the slash walls

BobcatCoyote

Red fox

[Michael L Ashdown]

Complications:
The first issue with using this plastic fence is that it needs support. For the smaller exclosures we built years ago we simple used T-post at about an 8 ft. interval. More recently we attached the plastic mesh to high tensile wire stretched around the exclosure perimeter using lower quality standing trees as corner post. Most of the openings in the slash walls are narrow enough (10 to 12 ft.) that extra support is not needed. However the 74 acre harvest was left with approximately 65 feet of opening at the landing. There is also a gas line right-of-way that has a 20 to 25 ft. opening at one crossing. These are too wide for the plastic without some type of support. At the landing opening it was simple enough to put appropriately spaced T-post after designating a 16’ gate opening for future equipment access.

Across the gas line right-of-way however support post cannot be driven. The suggestion was made that a rope could be stretched across opening level with the top of the fence for support. Rope could also be easily untied to allow unimpeded access for equipment working on the gas line right-of-way. That is, if the rope is tied in a location easily reachable. To accomplish this a ~1/4 inch diameter rope was tied to a tree on one side of the opening above the planned height of the plastic fence. Starting at about ¼ of the distance across the opening the rope was threaded through the top of the plastic mesh to about the ¾ distance. A screw eye or screw hook was put into the tree on the far side of the opening above the planned fence height over which the support rope was placed. A screw eye was put low down on the tree to provide the easily reachable tie off point for the rope. The problem with using rope to support the fence is that no matter how tight it is pulled it will still sag noticeably when stretched across any span of 10 foot or more. Therefore the point of the initial tie off and the support screw hook has to be quite a bit higher than the fence is intended.
Another issue at the wide gas line opening was contour. The ground level in the center right-of-way opening is higher than the edges. This aggravated the rope sag situation so that in the end the fence in the center of the opening was less intimidating to a deer that might have a strong desire to be on the other side of the fence. This may have been an issue later in the fall.

An interesting observation of deer behavior is that when confronted with fencing they are more inclined to search for places to crawl under or through a fence than to go over it. With that in mind I was trained to make sure that the fence is secured at ground level and therefore I will almost always set the fence so approximately 1 foot of the fence folds and lays on the ground. This allows for pieces of slash to be laid on that flap with the intent that deer will not be able to push under the fence. This also holds the fence from blowing in the wind, getting suspended by slash or brush and thus leaving an opening for deer. By doing this with 7.5 ft. tall fencing the end result is a 6.5 ft. fence. Combine that with sag in long along large opening and high spots and pretty soon the fence is barely 6 ft. tall. Not really enough height to deter deer from accessing an area they know has a good source of food or blocks off a long used part of their home range.

[Michael L Ashdown]

Compromised

For some time after the deer trapped inside the 74-acre slash wall at the time of closure had been removed there was no sign of deer inside. However, October 25th, 2017 as the fall rut got going tracks were found inside that exclosure again. On further inspection both of the gas line right-of-way plastic fences had been compromised. The north side gate had been ripped and pushed out and away from the slash wall and the intended gate fence line. This evidence suggested that a deer had desperately wanted to get out of the slash enclosure. The south right-of-way gate showed damage indicating something large like a deer had gotten tangled in the plastic fence and struggled to get free. What I concluded from the types of damage was one or more deer ran into or tried to jump over the south right-of-way gate during a rut caused chase. Then after being enclosed looked for the quickest way out.

Because of these incidents and pictures of deer constantly checking the large landing gate I decided this large slash exclosure needed taller gate opening fences. Both right-of-way gate openings have whole or cut off standing trees at the edge. These allowed a high tensile wire to be stretched across at a height above 10 feet. A 10 ft. clearance would allow unimpeded access to most equipment that might need to go through those openings. From this wire a 5 ft. tall piece of the same plastic mesh fence was suspended overlapping the original 6 to 7 ft. gate fence. At the large landing site gate the post on either side of the 16 ft. vehicle access gate are 10 ft. and therefore quite a bit taller than the plastic mesh (~8.5 ft. out of the ground or 1.5 to 2 ft. above the plastic). Using brackets purchased at Tractor Supply Company that are designed for constructing angle brace, T-post fence corners the west side gate post was braced to withstand the tension of a high tensile wire stretched from it to the tree at the end of the slash wall. Again, a 5 ft. piece of fence was suspend from the wire and over lapped the original fence. These extra pieces of fence were attached to the support wires with hog-rings applied with auto-loading pliers. On the right-of-way gates they were not attached to the main gate so those gate could be opened as originally designed.

The damage done to these gate fences was a reminder that the black mesh may be hard for deer to see especially if they are running away from danger or in the case of rut, amorous bucks. For this reason more effort was made to attach flagging to the plastic where deer would be likely to see it.

[Michael L Ashdown]

Human access:

One of the problems with excluding deer with fences or slash is providing access for humans. More correctly stated; providing fast, easily opened, and easily closed gates for humans. The originally planned gates while simple and effective, they are time consuming when trying to enter and exit the exclosure. This was not a problem on small research plots that are only accessed once a year for measuring plants. It is an issue when there are frequent, educational site visits or multiple day research projects conducted.

Another concern is that when self-guided visitors to the property access the excluded areas they may not have the same incentive to re-tie the gates tightly as those who built it. That is if they bother to close the gate at all. In fact when I asked the staff at the Cornell Botanical Gardens about the deer exclosure gates around the Mundy Wildflower Garden a un-asked-for suggestion came back recommending simple, self-closing gates when dealing with visitors.

Self-latching swinging gates would be nice but they can be expensive and there are problems with them especially in a woods setting. Besides, most of the slash wall openings will have only the occasional researcher or hunter seeking entrance so the gates do not need to open all the way the majority of the time.

One option would be to leave a gap in the plastic fence that a human could slide through with another piece of fence draped over the gap to hide it from the deer. However, the main fence still needs to be supported on either side of the gap which is an issue with our gate fence design. At the one slash wall gate where this was done, a slice or gap was cut in the main gate fence leaving the top and bottom connected. To suspend the cover flap fence high tensile wire was stretched between the trees on each side of the opening leaving more than 10 ft. of clearance like was done on the gas line right-of-ways. A 5 ft. tall section of fence long enough to fold over the wire and still have enough for a flap on ground was suspended on end from the wire and secured with hog rings. Like on the other fences pieces of slash were laid on the bottom to keep the flap in place. By centering the access gap under the flap there should be approximately 2.5 ft. of overlap on either side of the opening.

One problem encountered with this idea was that once the plastic fence was cut there was a curling memory in the plastic. On this fence the edges of the cut curled downhill away from the flap. Another problem was the flap fence would not lay tight to the fence with the cut opening even though it was on the uphill side. To prevent the gaps from getting larger they were tide shut with pieces of flagging. Flagging being the only thing available to tie with at the time of construction. In hindsight flagging was not a bad choice to tie up the gaps because it can be easily ripped apart if the knots won’t come out. Overall, this is not an ideal construction but if the flap does cover the cut opening enough the fence should still keep deer out for a while even if the gaps do not get retied by someone exiting the exclosure.

[Michael L Ashdown]

The little bandits found the bait pile put out for a new camera set. 

[Brett Chedzoy]

In addition to lots of wildlife diversity, we're also seeing some neat plants that are hard to find anywhere else on the forest, like this American spikenard (Aralia racemosa)

[Brett Chedzoy]

Lush vegetation inside the slash walls at the end of the second growing season

[Brett Chedzoy]

We recently started another regeneration harvest adjacent to the 75-acre wall in the above pictures to utilize the existing wall on one side.  Some of the harvest will be cut to a seed tree residual density, while other areas of mixed quality poletimber are being thinned and patch cut (small clearcuts) to remove low-quality groups of trees and allow a new age cohort to develop in the absence of deer pressure.  The feller-buncher can be seen in the background.