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Beaver Are Back!

Beaver (Castor canadensis) have been an intermittant presence at the Lilly ARBOR since the forest restoration project was initiated seventeen years ago. There is plenty of evidence of past beaver activity. Many an oak, green ash, and white mulberry growing near the river (and some not so near) show clear signs of having been gnawed by the large aquatic rodents - a short stump with an angled, pointed top is indicative of the presence of beaver. There is a method to the madness: gnawed stumps often resprout, providing tender young stems as a future food resource for the beaver. This behavior - the clipping/removal of the plant's main stem - is known as "coppicing" and promotes growth of new sprouts and lateral stems. Beaver are notorious for such activities, and there are areas within the ARBOR - beaver grottos - that show extensive evidence of coppicing behavior. 


(Left) A beaver grotto in plot 4 shows coppicing of mulberries. (Right) This green ash (Fraxinus pennsylvanica, tree #8169) has been attacked by beaver at least twice. The more elevated trunk damage likely occurred during a winter when significant snowfall allowed the beaver to gnaw further up the trunk. Photos by VR Schmalhofer.


The low survival rate of certain tree species that were planted as part of the ARBOR restoration project may have been due, at least in part, to beaver. Willows and poplars are favored food plants of beaver, and these trees have not done well at the ARBOR. Ten willows of the 136 that were planted still live (~ 7% survival rate). Cottonwoods (a type of poplar) fared even worse: only two of 85 planted remain alive (~ 2% survival rate).

Beaver damage that occurred many years ago to tree #7034, a cottonwood (Populus deltoides). Photo by VR Schmalhofer.


Beaver incursions into the ARBOR appear to have diminished in recent years. According to Coach Harger (a frequent traveler along the White River trail) beaver have been more active in the Fall Creek area and other regions of the White River north of the ARBOR. That has changed though. Beaver are back in the ARBOR and making their presence known in a BIG way. Since the beginning of November, two significant instances of beaver damage have occurred. Following the November 6 flooding, tree #4134 (green ash) suffered severe bark removal, while a nearby mulberry sapling was clipped. Between November 15-17, tree #6148, a double-trunked green ash was bark-stripped and partially felled. 


Extensive gnawing of tree #6148 (green ash) has resulted in the felling of half of the double-trunked tree. Photos by VR Schmalhofer.



(Left) Tree #4134 (green ash) has had its lower bark stripped, while a nearby white mulberry (Morus alba) sapling has been clipped. (Right) The mulberry was dragged away and stripped of bark. Photos by VR Schmalhofer. 



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