Hike highlights the ever-changing natural landscape of the Mill Brook Preserve

Julie Seyfert-Lillis and Tom O’Dowd lead a hike on the Mill Brook Preserve in New Paltz. (Photo by Lauren Thomas)

The creation of the Mill Brook Preserve may have placed a gem in the crown of New Paltz, but it’s a gem that is being constantly polished and beautified. Executive director Julie Seyfert-Lillis led a walk this past Sunday to highlight the ever-changing natural landscape of the 126-acre preserve. Self-educated “tree guy” Tom O’Dowd also accompanied the group of preserve supporters during the event, dubbed “Tracks and Trees.”

“This place is changing all the time,” said Seyfert-Lillis, as she walked down one of the newly-blazed trails. Some of those changes are more dramatic than others: a bridge had been washed downstream, forcing participants to ford Mill Brook — also known as tributary 13 of the Wallkill River — to continue deeper into the woods.


Nearly all of the preserve was farmland decades ago, and evidence of cultivation can be seen if one knows where to look. Second-growth forest is characterized by many trees of about the same age growing straight upward, as the former fields are succeeded by larger plants. Older trees, planted by farmers beside open space or simply left unmolested by them, sent their branches out much more widely than those which grew up in tight copses. Some of them can be seen growing in rows far straighter than any natural process would allow.

Seyfert-Lillis spends considerable time in the preserve, and welcomed the opportunity to share her discoveries with others. While the preserve is open to the public, infrastructure to plumb its heart is still being established, and at the moment it may seem more welcoming to native non-human species. A more adventurous soul, Seyfert-Lillis is willing to pull on boots ready for slogging through muddy patches to see what, for example, the beavers have been up to of late.

Beavers are an iconic animal of the Mill Brook Preserve. In 2003 the then-owner of part of this property got considerable backlash for killing beavers he said were causing “significant tree destruction” on his investment property, despite the fact that he received approval from state officials for the cull. Now, beavers are free to build lodges and dams wherever they please within preserve limits, and their actions shape the environment around them.

After building a new dam away from the largest pond and setting up housekeeping, the beavers have altered where frogs and other amphibians choose to breed as well. Tracks through the forest show where the large rodents pull felled trees toward their public works projects. Beavers eat some trees and use others for their building.

Other animals also make their marks, and they can be significant. One tree on the preserve is riddled with holes nearly large enough to fit one’s head into, made by a pileated woodpecker searching for insects. The bugs being sought tend to grow in trees already dying, meaning that the woodpecker itself does not cause that destruction. Dead trees are critical to any forest; they support ants and other insects, woodpeckers and other animals which eat bugs, and provide nesting places for still more.

Nevertheless, death does stalk the Mill Brook Preserve in notable ways. The hemlock forest is being shaded to the point where most of those trees are in the twilight of their lives; oaks are expected to succeed them in time. Ash and elm trees are plagued by invasive pests, and invasive plants like the choking bittersweet vine are evident in many areas. Removing such threats will take a huge number of hours of work over many years, if it’s even possible.

Three trails are now largely marked through the preserve, with another still being mapped. The specific routes may have to be altered by volunteer trail stewards again and again; as the banks of the titular brook shift, trails must be relocated to accommodate these natural changes. Rather than memorize particular landmarks, hikers will be better off recognizing the trail markers, which are usually a simple rectangle of latex paint on a tree. One should be visible from the last, and when the trail turns, two rectangles are painted one above the other, with the upper offset in the direction of the turn.

Ironically, the best way to preserve this land is believed to be by intruding more to allow human access. Putting up educational signs and benches is considered to be a deterrent against, for example, dumping furniture. The reasoning is that if people see and appreciate nature, they will protect it from poor treatment by their fellows. To that end, work to make Mill Brook Preserve a pleasant place to visit continues, although it’s not clear if anyone thought to ask the beavers their opinion on that.