Thursday, February 18, 2021

Recreational Trails and Resilience

The Friends of Herrontown Woods and other stewards of natural lands in Princeton have been asked to give input to the state bike/ped office and the Federal Highway Administration about trail resilience in these times of rapid change. I decided to put my feedback into a blog post. We steward trails at Herrontown Woods and Autumn Hill Reservation in Princeton, NJ--about 220 acres total. Fit into the categories we were asked to address, here is some of what we've learned over time:

Trail vulnerability and resilience to natural hazards

Climate change is impacting our trails in multiple ways. Trees still pull water out of the soil during the growing season, making most trails reasonably dry during the summer and fall. In the past, winters were cold enough to freeze the ground in the winter. Now, with warmer winters, trails can get wet from rains in the fall and remain wet and muddy until the trees awaken again in late spring. 

Trails are becoming more vulnerable to erosion, give the more intense, longer, and more frequent rains, and the reduction in freezing in winter. Trails on a slope can become like streams as they catch runoff from the surrounding ground and convey it downhill. This makes water bars, which serve to divert runoff from trails, all the more important to build and maintain. 

As ash trees killed by the introduced Emerald ash borer become brittle over time, they will fit in the category of natural hazards. We've been fortunate to be able to take some down in the vicinity of our botanical garden, but it would be impossible to cut down all of them in the forest. They can serve as useful snags for wildlife, at least.

Designing trails for climate change and future conditions

We ground-truth potential new trail routes during the wettest times of the year. This has become all the more important as weather becomes more extreme. It's the only way we can know whether a particular route will be usable year-round. A route that looks dry during the summer may be impassable in the spring, when vegetation has yet to pull moisture out of the soil. This is the problem with having trail consultants spend a couple days in a preserve, and then make recommendations about trail routes. Ongoing observation is really helpful.

In some of our soils, it is the roots that maintain the firmness of the soil. We've been deceived at times by a seemingly dry route that, when it becomes a trail with lots of foot traffic, becomes muddy due to the breakdown of the underlying root structure that had been holding the soil together. 

No trail can be perfectly designed. We fortunately have a source of local "native" stepping stones that we can lay down on particularly muddy patches, and we use some boardwalking. Over time, we hope this will keep trails passable even as rain increases. 

Trails providing ecosystem services

Trails provide access to areas to cut invasive species or do other stewardship work. If invasive species are controlled along trails, the trails become essentially a corridor of restored habitat. Interestingly, trails can sometimes provide the necessary combination of disturbance and additional light necessary for some wildflower to grow that would otherwise get smothered by leaves or shade in off-trail areas.  

On the downside, trails can intrude on habitat, and also provide a route by which invasive plants like stiltgrass can penetrate into otherwise uninvaded areas of the preserve. 

Use of trails during emergencies (evacuation routes, emergency vehicle access, fire suppression, etc.)

We invited the the local rescue squad to do a practice rescue in our preserve. It was very helpful in acquainting them with the lay of the land. We also showed them areas where accidents could potentially happen, and are working on a better map of the preserve showing access points. 

Trails can serve as potential fire breaks, whether for fire suppression or for prescribed burns. We have yet to use fire as an ecological tool in the preserve, but fire often has a positive and historically important role in open spaces if prescribed and carried out appropriately.

Use of recreational trails during public health emergencies

We've seen a dramatic increase in trail use this past year, as well as an increase in volunteers to help at our preserve. Though hikers tend to be conscientious about wearing masks, some will want to avoid encounters along narrow trails. That gets us looking at how we could provide at least one trail that is wider than others. 

Nature has served as an indispensable balm, refuge, and recreational outlet for people during the pandemic. The pandemic has made nature preserves ideal for those who love not only plants and wildlife, but socializing safely with people as well. 

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