Dear Stump:
After a timber harvest, there is typically a flush of Raspberries or Blackberries. How does this fit into the natural order of succession? A lot of people complain about them and want to know what to do about it. I don’t know for sure but I think they act as a nurse crop as a new generation of trees come to life to replace the old trees. What are your thoughts?
As a very wise friend used to say to me… Is it a problem or is it an opportunity. As someone who has spent a great deal of time trying to navigate my way through dense, prickly, unforgiving thickets of raspberry and blackberry I completely understand why some folks don’t like to see these plants takeover the understory following a harvest. When thinking about any plant I like to think about it in terms of its competitive advantages. What competitive advantages does it have that gives it an edge over other species that allows it to succeed where they fail?
Blackberries and raspberries are native throughout the state of Wisconsin. The UWSP Herbarium lists over 50 species that can be found here. They prefer moist, well drained loamy sands to clay loam soils and are found in forest communities that range from lowland forest to upland forest and from Pine Barrens and Oak Savanna to boreal forest. So pretty much everywhere except excessively wet or excessively dry sites. Although, I suspect that you can probably find them there as well but in limited numbers and as poor and sad reflections of what you might find on better quality sites.
So, they can grow pretty much anywhere and everywhere but why do they seem to take over stands after a harvest. The answer is simple… Blackberries and raspberries love full sunlight. As you think about this statement think about where you have seen them, where they are causing you the most trouble, and where your favorite berry picking patches are. You find them in forest openings, along forest or trail edges or in areas of your woods where dappled or direct sunlight penetrates to the forest floor for a significant part of the day. Blackberries and raspberries competitive advantage is to grow, and grow quickly, into areas where there is full to partial sunlight. When an opening in a forest occurs they grow into it and they are completely unwilling to share their space. They form thickets and spread rapidly by vegetative propagation (when the vines get so heavy that they come into contact with the ground they put out roots and new plants spring up from there) creating colonies that are so dense that they shade out the ground and prevent anything else from growing there. A pretty nifty trick!
But is it a problem you should worry about? I say NO. It is an opportunity. I understand, believe me I have the shredded jeans to prove it, that many people don’t like to see these plants take over parts of their woods. I understand that it means additional maintenance and reduces your ability to walk through and enjoy your woods. But there are also many benefits to consider as well. I love my mom’s blackberry pies. Although, I hated picking the berries as a child. Actually, I am still not fond of picking them but you gotta do the work if you want to eat the pies. There are dozens of wildlife species that feed on the berries and leaves, which is a problem if you like pie. (They are also good if you like them with a little sugar and cream. Okay, now I am just making myself hungry…) But mainly they are terrific if you like to grow high-quality hardwoods.
Competition is a good thing. I have had the opportunity throughout my career to work with high-quality hardwoods and I have seen many landowners and foresters try many different things but one thing that I have seen consistently is that competition improves the growth and quality of high-quality hardwood trees. I have seen landowners who can grow red oak six feet tall in one year by maintaining high levels of competition. I have seen and measured the impact of competition on red oak seedlings and growth is greatly improved where there is competition. I have worked with other land managers who have come to the same conclusion and were growing black walnut under high levels of competition and were seeing improved growth and quality. Competition is a good thing!
I know that this runs counter to how we think about and manage our woodlands. We spend so much time and energy trying to keep individual trees alive that we forget how our forests formed in the first place. Competition is good. It weeds out the genetically poor stock, it forces the seedlings to grow straight and tall, and makes it difficult for predators to feed on or destroy them. Frankly, it is a lot easier to let the bramble do this work for you than putting in drip irrigation systems, tree shelters, deer fencing, mowing, and applying pesticides. You might get the same results at the end of the day but your costs in time, labor, and money are astronomically higher and you have also managed to keep all of the genetically poor stock in place; which more often than not will thrive under all the tender, loving care you have given your stand and will only further destroy your hopes of quality wildlife habitat or future income.
So… leave the bramble alone. Learn to love it. Learn to love it for the berries. Learn to love it for the wildlife habitat. Learn to love it for improved forest stands that you can grow. And most importantly, learn to love it for the extra time you can now spend watching your woodlands instead of weeding your woodlands, for the money you can save and the money you will make, and most importantly for the pies.