To cross the suburban death moat (aka Good Luck (sucker) Road) into Greenbelt Park, I walked far enough along the road that the drivers and I could see each other and take enough precautions to avoid (for them) excessive deceleration or unsightly dents on their hoods or (for me) severe injury/death. In less than a minute I was in the woods.
Understory/overstory
When I walk through the woods in winter, the mix of signal and noise differs a lot from in other seasons. Mostly it’s gray and brown: leaves, trunks, decomposing vegetation. That’s the “noise,” the background, even more so if the sky is gray. With so much of that background in the understory, anything green pops out at you. Mostly that means holly trees, specifically American holly (Ilex opaca). Bright blue sky made the overstory branches distinct on some of my recent visits, but these fade into nuance when it’s cloudy.
Holly stands out even more up when you get close enough to see the berries. Considering how yummy these berries are for birds and deer, it’s kind of a wonder to find any of them at all.
The North American beech (Fagus grandifolia) also stands out in the winter understory, partly because of its light-gray trunk but more so because it keeps its light-tan leaves all winter long. The saplings really show up; older, taller trees rise into the overstory where you have to look more deliberately for the few leaves that remain after repeated windstorms.
One day after a slight rain, a felled log caught my attention because of its blanket of neon-bright moss, pale green lichen, and white and dark-brown bracket fungus against the subtler shades of composting trunk and leaves.
Not every tree gets that colorful after it dies, though; woodpeckers demolish some snags before they hit the ground.
Downcuts
Throughout the park, like other fragments of undeveloped land in urbanized landscapes, you see signs of fast-moving water. Impervious surfaces (pavement and roofs) shed water fast; for decades, proper management of stormwater equated to “get it away from the development as fast as possible,” from rooftops to gutters to storm drains to watercourses that were themselves often channelized, sometimes with cement, or placed entirely underground. More quantity, especially during storms, + higher speeds, especially during storms = much more powerful scouring action by water moving through river courses. It doesn’t take much pavement to have a big impact. Some cited literature estimates that a catchment area with only 10-20% impervious surface can have twice the surface runoff as a forested landscape with no impervious surface.
Deep Creek and Still Creek both originate east of the Baltimore-Washington Parkway, which runs north-south through the park. The NPS built the southern segment of the BW Parkway from DC to the northern edge of Fort Meade (now home of the NSA) in the early 1950s, joining a state-built segment running south from Baltimore. The construction of the whole 30.8 miles took just 4 years (though the planners started talking about it in the 1920s) and cost only $35 million, not only because of fewer regulations but also because the designers used an abandoned rail right of way for the route and because the federal government already owned most of the land. The engineers cut and filled the land to level out the grades, so the Parkway stands out not only on aerial photos but also on the slope maps.
This isn’t a total tangent, because as far as I can tell, some of the downcutting I saw in Greenbelt Park might result from the Parkway’s runoff. Most of the rest of these streams’ catchment areas lie within the park’s forested area east of the Parkway. The roadbed of the Parkway is about 40′ (yes I measured), but the base of the embankment maxes out at about 230′. If the engineers built it so stormwater could get away as fast as possible, everything falling on the Parkway or the embankment will end up in a stream pretty quickly.
Climate change is bringing frequent and intense rainstorms, a trend most forecasters expect to continue, so these streams will keep on changing. Eventually the park planners will need to build new bridges and boardwalks or even relocate segments of the trail.
The Parkway (plus Kenilworth Ave. on the east and Greenbelt Rd. on the north) also make the Perimeter Trail a noisy walk for half its distance or more. How will new transportation technology change this experience, I wonder? Electric vehicles are quieter for sure, but a lot of the noise comes from wheels on asphalt. Maybe someone I know could even tell me the answer to this but that’s a rabbit hole too far for me today.
But the southern reach of the trail sits far enough away from any road to still the traffic from a roar to a whisper. Down at the streambed, the raindrops, flowing water, and smell of damp earth and moldering leaves helped me imagine what this place might have been like before the pavement.
Peace, all.
Stormwater impacts are very site specific. The B-W Pkwy appears to have the mountable curbing that directs stormwater into drains and concentrates it at the point where it’s dumped into a drainage swale or stream. Fortunately at least here in the Northeast as state tighten the Clean Water Act regulations, practices are changing and the focus is turning to reducing runoff through retention and infiltration of stormwater onsite, treatment for urban runoff pollutants, and slowing the velocity of waters released into the environment. I think with some thought the B-W Pkwy can be retrofitted with improved stormwater infrastructure. A start would be replacement of the mountable curbing with curbing that permits water to flow off the roadway and into grass areas and rain gardens where it can be slowed and allowed to infiltrate into the ground.
I guess I have to come down and take a closer look… 🙂
thanks for these comments and the further info–the Anacostia watershed (which these streams are part of) has been a focus for local, state, & federal attention on nonpoint pollution for decades now, and my sense is that we’re far ahead of a lot of other areas in managing stormwater of new development as well as some retrofitting. There’s an expert on low-impact design from this area who visited URI in the early 1990s, I think, just before I started there, and he won a lot of converts at URI extension. I don’t remember his name though. It would be great to walk Greenbelt Park with you to see it through your eyes, sometime when we coincide here.