Monroe State Forest:  Dunbar Brook and Parsonage Brook   Robert Leverett   Sep 30, 2004 06:49 PDT  Lee:    ...On another topic, I'm wondering if you would be willing to give a quick summary of the forests you saw this past Monday in Monroe State Forest along Dunbar and Parsonnage Brooks. For the Ents out there who want to attend the Oct 22nd and 24th event in Monroe State Forest, a preview of what they would see from a true expert would be highly valuable. I have tended to over-focus on the individual trees of Dunbar because until you gave your interpretation, I was pretty confused about what I was looking at on both the north facing ridge and along Parsonnage Brook (the last place we visited). Bob Re: Request of Lee   Lee E. Frelich   Sep 30, 2004 09:45 PDT  Bob: Yes, here is my report on the two forests. Dunbar Brook: Dunbar brook has a large primary forest remnant on steep slopes with many large boulders, dominated by sugar maple, yellow birch, and white ash, with some beech, hemlock, red maple, basswood and white pine. The forest experienced some major blowdown probably about 30 years ago (an exact date can be determined by coring some of the pole-sized trees that survived and will show a release from suppression). The blow down was most severe at mid slope, indicating that the wind hit the slope at an acute angle (i.e. it was neither parallel to nor at right angles to the valley and adjacent ridge). This produced turbulence at mid slope and patches of blowdown of varying size from a few trees to nearly an acre. The heavily hit stands have an abundance of young synchronously-released trees (total age of these trees may vary by a century or more because they were suppressed for varying amounts of time before the storm), with scattered larger trees that survived the storm. These larger trees are more abundant in boulder-filled draws that run perpendicular to the ridge, where they had better anchorage and where slightly less exposed, being rooted 5-10 feet lower than surrounding trees. Many of the large survivor trees show evidence of branch and crown breakage from the storm. The developmental stage of these stands has been variously described as a mature-sapling mosaic, multi-aged pole stand or disturbed stand with mature remnants. Some stands were not hit as hard by the wind and have a larger component of large trees with classic multi-aged forest stage of development. Most of the original northern hardwood forests from Minnesota to New Hampshire went back and forth from mature sapling mosaics to old multi-aged stands in response to wind storms of varying intensity. Therefore this stand provides an ideal exhibit of how northern hardwoods respond to the type of natural disturbance that is thought to have perpetuated northern hardwoods for the last several thousand years. The successional status of the stands varies little, since the released understory reflects the late-successional composition of the overstory. Species that are mid-tolerant of shade, such as white ash, yellow birch, and red maple, are common in old multi-aged stands because some of the gaps there are large enough and have enough light to support growth of those species, even if stands are not hit by storms such as the one that hit Dunbar Brook a few decades ago. Therefore, primary forest remnants are a mixture of shade-tolerant and mid-tolerant species, and this mixture forms the so-called climax species composition. There is a rich moss flora and a lot of species of wildflowers including nodding trillium. Hemlock is starting to form a neighborhood fairly high up on the slope, where there is a cluster of several large trees that vary in age, with multi-aged saplings surrounding them. Once this patch becomes consolidated, it could maintain itself until the climate changes. I envision it as similar to the initial phase of hemlock patch development in Sylvania, MI that occurred 3000 years ago. Parsonnage Brook: On Parsonnage Brook, there is a much different type of primary forest dominated by hemlock and red spruce, that originated after a severe stand-levelling disturbance, probably wind, during the mid to late 1800s. As with Dunbar Brook, the canopy has synchronous release but the total tree age varies because suppressed trees released by the storm were various ages. What is different here with respect to the disturbance, is that it was much more intense, and nearly levelled the stand, leaving only a handful of mature survivors. The stand was probably dominated by sapling-sized trees at the time the surrounding stands were logged, and is the likely reason that stand is still in primary condition. At this point, the first few gaps large enough to recruit new saplings into the canopy are starting to form (i.e. the stand is reaching the end of the stem exclusion stage and ready to enter the transition to uneven aged condition). This stand is dominated by late-successional species now and was right after the disturbance, at which time it would have been an example of a young late-successional stand. The disturbance did not cause any succession, which is defined as directional change in species composition. This stand has very thick duff, which is a consequence of the high C:N ratio of the leaf litter of hemlock and red spruce, which is decomposed at a slow rate, allowing a lot of accumulation. There may be remnants of logs from the previous canopy buried in the duff, now in category 5 of decay. This stand has analogs in the highlands of the Porcupine Mountains, MI, where there are a few hemlock stands (mixed with white spruce and white cedar in that case) surrounded by hardwoods. Lee   Home