Maples and the Adirondacks: Searching for Growth Decline Reasons
The idea that there might be a decline of sugar maples--that provider of maple syrup, heart-stoppingly red fall foliage and economic and ecological importance for the eastern United States and Canada--is not new. But as pancake lovers and others will agree, the trees are a key tree to watch. A report recently published in the journal Ecosphere looked at when the decline of Acer saccharum began and the particulars of it.
The research team, from SUNY College of Environmental Science and Forestry (ESF), analyzed hundreds of maple growth rings across the Adirondacks, in northern New York state. They learned that the decline in growth began for many of the maples after 1970.
"Given their relatively young age and favorable competitive status in these forests, these sugar maples should be experiencing the best growth rates of their lives. It was a complete surprise to see their growth slow down like this," said Daniel Bishop, who was a graduate student working on his master's thesis at ESF during the study, according to a release. "But our data tells a clear story. We can detect the start of a region-wide downturn after 1970, with a large proportion of the trees continuing this trend over recent years."
Aside from the many reasons that sugar maple is culturally important in North America, the tree also helps to encourage soil fertility, is a nutritious source of food for wildlife, and increases plant and soil biodiversity.
Bishop was expanding on an earlier study that examined acid rain impacts on sugar maples in the Adirondacks. That study had demonstrated poor health and lower regeneration of those maples in forests hit hard by acid rain.
In Bishop's work, which looked at the growth rings of hundreds of sugar maples in the Adirondacks and analyzed them with climate data from the same time period as the acid-rain study, the release confirmed.
"The last few decades have brought warmer and wetter conditions to the Adirondacks, which are typically good for plant growth," said Dr. Colin Beier, who teaches ecology at ESF and was the supervisor for Bishop's thesis work, in the release. "Meanwhile, there have been big strides in reducing acid rain, which is especially damaging to sugar maple. Given these changes, we would expect these trees to be thriving, but they are not."
While no conclusive evidence was found in the recent study that acid rain or climate change caused the growth decline, Beier said in the release that this does not cross out the possibility that either of them influenced the tree stress. Either of them could have left the trees more susceptible to insect attack or other factors, said Beier in the release.
"Time will tell if slower growth is a harbinger of something more serious for sugar maple," said Beier in the release. "But given the ecological, economic and cultural importance of this tree, the stakes could be high. We need to sort out whether these declines are more widespread, the reasons why they are occurring, and what their implications might be for our ecosystems and local economies."
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