Do Red Maples Hide Bogs?

When I was pursuing a Ph.D. at New York University in the late 1980s I was casting about for a dissertation topic and had settled on a project that came about as a result of my being exposed to ground-penetrating radar and pollen analysis. My advisor Jim Mellett had been a vertebrate paleontologist for most of his career, but had begun using the radar machine to begin a second leg of his professional life as a forensic scientist. Cal Heusser, another member of my committee, had been a Quaternary palynologist for his entire career and had done pioneering work in the higher latitudes of both hemispheres.

 

Bog with deciduous and coniferous trees at the edge.

Bog with deciduous and coniferous trees at the edge.

Bogs are not very common below a particular latitude because the conditions that make them abundant—a flat landscape with a drainage deranged by glacial moraine—is not often encountered. During the 10,000 years since the retreat of the ice sheets from the mid-latitudes most of the morainal “dams” that backed up water in valleys had been broken by erosion, leaving water to enter at the upslope side of a pond and depart by the downslope route. Bogs require—among several criteria—that water leave only by evaporation. Bogs can also go away when they fill with sediment and water simply drains across the area they once covered.

It was the latter that particularly interested me. I thought perhaps the present sites of some “red maple swamps” could once have been bogs. The low oxygen conditions at the bottom of bogs insure the preservation of pollen and the sediment record is often continuous. Perhaps there were “lost bogs” under some maple swamps that would provide local climate records of the early Holocene where none presently were known.

Red maple swamp in Maine.

Red maple swamp in Maine.

The ground-penetrating radar is able to distinguish differences in density in sediment layers. I hoped to be able to find the closely packed predominantly vegetative peat layers buried below the mineral-rich shallower layers that had covered them. A series of transits across a maple swamp would determine whether it was candidate for coring and bringing up pollen-laden peat.

Red maples (Acer rubrum) often grow around the edges of bogs because they are tolerant of a wide range of physical environmental conditions. They are called variously “swamp maple” or “water maple” (among other vernacular names) because they thrive in both saturated conditions, but they are also happy on rocky ridges where many trees cannot find purchase. They also grow along side other maples in more moderate conditions, but in less hospitable places they can form nearly solid stands.

Compared to sugar (A. saccharum) and black (A. nigrum) maples red maple is a smaller, less long-lived tree; it does not dominate the canopy where these trees are present in the forest. It is not an understory tree like striped maple (A. pensylvanicum) and is more common along watercourses where it can be found with silver maple (A. saccarhinum) and box elder (A. negundo).

Red maple flowers.

Red maple flowers.

Red maple lives up to its name: the leaf buds and petioles, the flowers, and the samaras (seeds) are all tinged with red. In the fall the foliage is often a brilliant scarlet, while sugar maple tends to be a reddish orange and several other maples are yellow-leaved in autumn. These characteristics (and its tolerance of difficult conditions) have made it a popular street tree and ornamental in designed landscapes. Several cultivars have been developed. (It should not be confused with the marooned-leaved cultivars of Norway maple.)

It seemed likely to me that red maple swamps would be the next successional step as a bog filled in. They are often already present around the margins of existing bogs, their windblown samaras allow them to distribute themselves relatively rapidly, and they don’t mind “wet feet.”

But I didn’t pursue this research project. Instead I decided to “take a master’s” and leave the biology program to join a geology Ph.D. program in Massachusetts, where I ended up studying Pliocene climate using microfossils in deep-sea sediments. I did hear that Mellett did have a subsequent student who did independently arrive at the same idea. However, I never learned her name or was able to read anything she published on the topic.

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