Rockefeller State Park Preserve

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#1)  Rockefeller State Park Preserve

Postby Erik Danielsen » Sat Aug 12, 2017 8:39 pm

On Tuesday August 8, I traveled just a couple dozen miles north of the Bronx to Rockefeller State Park Preserve in Westchester County with a Wildmetro assemblage to document old trees and their associated habitats. The entire preserve consists of over 1400 acres donated by the Rockefeller Family. As far as I can tell, pretty much the entire preserve has experienced one or another degree of human intervention over the last few centuries, from agriculture (mainly pasture) to woodlot laced with carriage roads to full estate-style landscaping. In fact, the entire trail system of the park consists of paved carriage roads, though mechanized vehicles (including bicycles) are now prohibited.

The first section we visited was the Rockwood Hall area, a section right along the Hudson and just barely contiguous with the rest of the preserve. This is mainly an open environment with some old estate landscaping including stoneworks and some specimen plantings of now-very-large european beech trees I did my best to ignore. More interesting to me were the scattered large oaks. All of these (with perhaps one exception I'll point out) likely date to a point in the 1880s when the Rockefellers hired Olmsted to landscape this section, and he did us the service of sticking with native species. A ravine at the north end has a higher diversity of mostly native species in its forest but all seems to be no older than that point in time, so it's likely there was some human involvement in the establishment of what now looks like a mostly natural (aside from the abundant black locust) forest.

Trees likely to date to the Olmsted period are getting very close to the 150 years old mark, and the soils and climate of the lower hudson valley have enabled rapid growth. Measurements and photographs will tell the story best:
Measurements from the Rockwood Hall section.
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The large Black Oak

The big Red Oak of Rockwood Hall, which seems to be locally well-known. Just a touch shy of our current NYS champion contenders, and moreso for having lost a large section of its crown a couple years ago.

However, I'd like to point out one tree in particular- the second largest red oak, even at 18.1'cbh that would normally suggest an open-grown tree, has a remarkably straight and columnar trunk. I strongly suspect that this tree was already present and established in a grove of other forest-grown trees when Olmsted did his work in the 1880s, and that that grove may have been left until then due to the very steep nature of that particular spot. This being the tree he left (if that is an accurate narrative), it may well be the oldest tree present.
The columnar 18.1'cbh Red Oak likely to predate the rest of the large trees.

The very tall black oak is also forest-grown, but may originate from the period of the rest of the Olmsted work. It's located in the forested ravine section and keeps company with tulips in the 120s and 130s.
Measurements from the sections described in the following paragraphs.
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Following this section, I headed alone to the central portion of the preserve following some tips from a friend who's one of the preserve managers. I was not able to check out all the suggested "big tree" areas he pointed out on the map, but with my available time in mind I headed for the 13 Bridges Trail, where he had noted that mature hemlocks could still be found lining the trail. Based on that and the trail's topography (tracing the bottom of the Gory Brook ravine), it seemed like a good bet for tall trees. Entering on the Pocantico River trail a solid tuliptree and northern red oak in second-growth hardwoods were promising, but the trail headed north and uphill into less vigorous forest before finally turning south and heading into the ravine, where I was immediately struck by the tallest Hemlock I'd see at this site. Right beside it was a nice tall Red Hickory.
The tallest Hemlock, a nice double but suffering from the adelgid.

Continuing down the 13 Bridges Trail I measured another tall Hemlock (these are badly hit by the adelgid) before heading uphill, off-trail, in search of good viewpoints into additional tall trees. There are many here, but I didn't get anything else with a good window to measure so I just kept going up. Eventually I hit a point on the slope that became a little more open and was dominated by very large, impressive chestnut oaks, just below a rim that crested to an unexpected grassy bald. After examining the bald for any interesting open-grown trees I headed back down into the ravine to find the trail again, encountering a couple very tall tulips (I think this site will definitely join the 150 list after leaf-off) and a nice beech which I probably didn't find the top of. White Ash, other Hickories, red and white oaks, and sugar maple are all likely to join the species measured in putting up very good numbers after leaf-off.
New NYS max height Scarlet Oak.

The trail crosses beneath route 117 and branches; I took the Eagle Hill trail east and measured another tall tulip and a nice bitternut hickory in its vicinity. There are many tall tulips in this section that are dense enough to be unmeasureable in leaf, and I have reason to believe there are at least a couple more "tuliptree cathedral" spots in the preserve. The day's final surprise came as I rejoined the Pocantico River trail and headed north, before crossing 117: a Scarlet Oak looming above the trail, missing half of its crown, that significantly exceeds the species' previous NYS maximum.

This preserve seems to offer significant potential for additional tall-tree forest, and with a large portion of its acreage still in active pasture and haying operation will likely yield additional superlative radiant trees as well (we may need to get permits for accessing those portions).

For this message the author Erik Danielsen has received Likes - 3:
a_blooming_botanist, bbeduhn, Rand
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#2)  Re: Rockefeller State Park Preserve

Postby dbhguru » Sun Aug 13, 2017 9:17 am


  Your trip reports are information rich, and through your efforts, we're now getting a much better picture of what grows in that corner of New York state. I pay a lot of attention to how different species perform relative to one another and your data is adding greatly to what I already knew. Will you be putting your tree measurements in our VA Tech database? Need help doing that?

Robert T. Leverett
Co-founder and Executive Director
Native Native Tree Society
Co-founder and President
Friends of Mohawk Trail State Forest
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#3)  Re: Rockefeller State Park Preserve

Postby Erik Danielsen » Sun Aug 13, 2017 9:55 am

Bob, I'll definitely be getting them into the VA tech DB. It shouldn't be any trouble, I'm just on the road a lot so my "office time" comes in brief windows. I'll probably do an upload once I hit 75 or 100 trees for this project, which shouldn't be long.
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#4)  Re: Rockefeller State Park Preserve

Postby Larry Tucei » Tue Aug 15, 2017 10:39 am

Erik-  Fabulous trees! Its amazing how large a tree can become in a century and a half.  When reading William Bartram's stuff his description of trees 10' in dia. were everywhere.  It would have been a site to behold.  Your post reminds me of Congaree National Park where the largest trees in the eastern U.S. grow.    Larry
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#5)  Re: Rockefeller State Park Preserve

Postby Erik Danielsen » Wed Aug 23, 2017 3:25 pm

New measurements as discussed in the following post. Note the 16'+ cbh white oak is a double.
Rockvisit2.jpg (60.23 KiB) Viewed 94 times

I returned to Rockefeller State Park Monday August 21st to continue surveying trees and to have a nice atmosphere for experiencing the partial eclipse. It was a nice day, alternating between hiking and looking around with some of the preserve staff and slowing down to focus on taking measurements where it was appropriate (and feasible, given the canopy density in parts). The first set of measurements were of a number of open-grown oaks in fields above Swan Lake and along the border with the Stone Barns Center for Agriculture. Black Oak seems to be the most common species in these pastoral settings at Rockefeller, along with some white and red and an anomalous Swamp White Oak. The largest Black Oak will become the new NY state champion, slightly exceeding the tree in the Rockwood Section I reported in the original post.
New State Champion Black Oak, along the border with the Stone Barns Center.

The canopy over the trails provided a nice eclipse experience.

After the eclipse had passed, I hiked down into the area south of the 13 Bridges Trail where I had left off last time, along the Pocantico River Trail. Here, not far from the tall Scarlet Oak I reported last time, is a trail intersection where I found a new even taller Scarlet Oak, along with a nice Sycamore, tall Elm, and new Shagbark Hickory state maximum (unless Elijah's gotten a taller one since I last checked). Continuing down the Pocantico River Trail yielded more nice sycamores and a tall Green Ash. This section has a nice transition zone from upland hardwoods to riverine forest that's very diverse and produces a lot of tall trees, many hickories, oaks, tulips, etc. Peering up into the leafy canopy I'm sure I'm missing some of the best trees and their tops.
Nice tall elm center in this photo, with the first sycamore above to its right.

125.5' shagbark hickory

119' Scarlet Oak- there are plenty of northern red and black oaks with fuzzy traits in the same stand, so it was convenient to have an epicormic branch down low to inspect buds and confirm ID.

The trail follows the river around to where it intersects with the Gory Brook, at which point I headed north. To my right was a steep ascending slope with one anomalous large open-grown double white oak and many tall sugar maples along with hemlock, white oak, and chestnut oak, and to the left the slope descended to terrace above the brook. A single Sycamore growing at the edge of the tulips down on the terrace caught my eye, and turned out to stretch to 135'. Below it in the dense tulips it was impossible to do any real measuring, but what small windows I could find indicated trees exceeding 140' and the other hardwoods scattered throughout are undoubtedly tall as well. This terrace extends a good way and the tulips get thicker and older further north. I think this section will yield the tallest trees in Rockefeller.
Large Double white oak on a naturally open ridgetop, unfortunately now being overrun by invasives.

The tall Sycamore looming above the terrace forest.

After just two low-intensity visits with the canopy in full leaf, the RHI for Rockefeller already stands at 124.6. I'm very impressed and from what I've seen but been unable to satisfyingly measure expect that this site might have a shot at 130 with the leaves off. Together with the interesting open-grown habitat and specimens, Rockefeller State Park Preserve Belongs up there with the Dutchess County sites as a Hudson Valley big tree hotspot. I can only imagine how much else this region has left to discover.
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