As the leaves on the trees begin to turn, another fall mast survey has wrapped up on Duck Creek. I was surprised to look back and see that we started publishing these mast surveys for Duck Creek five years ago. Accordingly, you all have come to expect this information and have made inquiries about the status of this year’s acorn crop. Instead of just giving you the annual report, I thought I’d also compare it with the previous four years.
There is a saying that goes, “one can’t see the forest for the trees”, which means that someone is too focused on the details to see the big picture. However, with bottomland forests this is typically not the case, but the exact opposite. You could say most of the time “one can’t see the trees for the forest”. People often see the timber, but don’t realize the differences among the trees. Species of red oaks in the bottoms, which include cherrybark, pin, and willow oak, are less flood tolerant than other trees like, overcup oak, maple, sweet gum, tupelo, or cypress. Because of these differences, you will find the healthier red oaks at higher elevations in the floodplain, which aren’t flooded as early in the fall. The “wetter” species commonly occur in lower positions where water begins to collect first as the water table begins to seasonally rise in the fall.
One of the challenges in managing natural resources is not only the variability across space, but also the variability that occurs over time. Since trees live a long time, they don’t put the same effort into reproduction every year. To ensure that the family genes are passed on, an old tree has plenty of time to make sure that one little nut germinates and begins to grow up in the understory to replace it one day. This is why we can’t expect to have a bumper crop of acorns year in and year out. Sure, the trees will produce nuts in most years, but the density is highly variable. As a rule, foresters that manage these slow-growing communities have to be patient because they aren’t going to see results overnight or even within a year or two. Sometimes they have to wait ten or twenty years to see if things work out like they had planned.
Throw in the spatial and temporal variation along with the weather and you’ve got a dandy mess to try and make some sense out of. In the past five years we’ve had almost everything you can imagine ranging from tornados and straight-lined winds, late spring freezes, summer floods, to droughty falls. Unlike ducks that can migrate to where the resources are available, trees have to stay put, try to survive the rough patches, and flourish when conditions are right.
When looking at the 2013 mast production at Duck Creek, nothing really jumps out and grabs you except the fact that there were very few trees that were a complete bust. Only two percent of pin oaks and eight percent of overcup had few to zero acorns. Among the hardwood species and individual trees the density and distribution of acorns varied. Cherrybark oak may have been the most notable because even though 89% fell in the light crop category, many of these were on the line of being considered a medium crop.
When looking at the past five years it is kind of interesting to see how the acorn production has varied among species over time. Overcup oak had a banner year in 2009. Last year would have been similar if it hadn’t been for two wind storms that knocked down a lot of the overcup acorns prior to becoming mature. Cherrybark oak mast production was strong in 2010 and 2011, but was down last year. Also in 2011, pin oak acorn production was the strongest within this five year window. Finally, in 2012, we saw the best Willow Oak mast production from this dataset.
While this short span of data doesn’t tell us why one species did better than other, it does help us rein in our expectations from one year to the next and gives us an idea of the variability that occurs among species and across years. Thanks for tuning in over the years and showing interest in what is going on up in the tree tops. Hopefully, this will give you something to think about as you hear the acorns plunk into the water beside you as you hunt the forest this fall.