Tom's Blog

Saturday, August 20, 2011

Edge effects in prairies

Most of the prairies at Pleasant Valley Conservancy are small (less than 5 acres), which means that they have lots of edges. Anyone doing prairie restoration will tell you that edges are bad, since they increase chances for weed invasion, and have significant negative effects on wildlife. However, you play the hand you've been dealt, so at Pleasant Valley Conservancy we are learning how to cope.

This week Marci and I spent part of the day in the Barn and Cabin Prairies killing Canada goldenrod (Solidago canadensis), one of our most persistent (albeit native) invaders. This is the time of year to deal with this species, since it is just starting to flower, making it easy to recognize.

At first glance, it looked like we had a pretty serious infestation, but once we got into it we realized that all the Canada goldenrod was along the edges. Once we pushed past this tall fringe, we got into a much more diverse prairie, with lots of shorter species.

It is not only the weedy invaders that line the edges. Several of our small prairies have fringes of tall prairie species, such as the Silphiums.

It is not difficult to understand the ecology here. For one thing, plants growing along an edge don't have to deal with competition from that side. Also, they get more favorable light, so they can grow taller.

We used the leaf spritz technique on the Canada goldenrod. This is a procedure that worked well in last year's tests so we are expanding its use. Two or three leaves on each goldenrod stem are gently sprayed (just a few drops) with 20% Garlon 4 in bark oil. Within a day or two the sprayed stem starts to twist, and within a week it is turning brown. In two weeks it is completely dead.

In my tests I had found that if all the stems in a clone are spritzed, the complete clone was killed, and the eradication was permanent.

The nice thing about this technique is that it is very quick and easy, and if one is careful there is no damage to "good" plants nearby. This procedure is slower than mowing but lots less disruptive to the prairie, and if done properly eradicates the whole clone (which mowing does not do).


Blogger Bob said...

Hi Tom,
I've followed your blog for years now and have never commented. First off all, it's great and I really enjoy reading your updates. Your recent post on canada goldenrod control made me think to forward a link to another conservation blog I follow ( If you don't follow it already, you may be interested in the comments concerning sunflower and canada control via parasitization by prairie dodder. You may find interest beyond that specific topic as well. It's one of my favorite conservation blogs. Along with yours, of course.

August 23, 2011 at 7:19 PM  

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