Learning and Stewardship on Princeton High School Grounds

Detention basins don't call attention to themselves, but this one found its way onto the front page of the Town Topics a few weeks ago. Located between the Performing Arts Center and the athletic fields at Princeton High School, its flora and fauna have become an object of study and stewardship for environmental science students. 

The main purpose of a detention basin is to catch runoff, in this case from tennis courts and a parking lot, and slowly release it to reduce downstream flooding and pollution. Most basins are mowed, but they can also be turned into meadows full of diverse native plants. 

Last year, the Princeton Public Schools hired the Friends of Herrontown Woods (FOHW) to oversee stewardship of native plants in two PHS basins, and to work with teachers and students. A student writeup in the Princeton Public Schools District News describes FOHW's collaboration with PHS Environmental Science students and teacher Jim Smirk to turn the basin into a native wet meadow. 

Journalist Don Gilpin followed up on that with a front page article in the Town Topics about the project. During eight sessions this spring, students combined the physical and the intellectual. Along with collecting data in the basin, the students are weeding out invasive species and planting natives. Our "Iwo Jima" photo shows the students lifting a tool shed into place that will also collect rainwater for watering plants. The shed was built from scavenged materials by FOHW volunteer Robert Chong. The rainbarrels were donated by Jenny Ludmer of Sustainable Princeton. 

The students divided the basin into a grid, with each student adopting one of the units. Each student then used a 3' square quadrat to study plant diversity within each unit. 

The sessions provided a rare opportunity for students to focus in on the individual plants that comprise our green world and begin to distinguish one plant from another. 

The cool, wet weather was perfect for planting and weeding. For some, this may have been their first encounter with a shovel, and the combination of grit and finesse required to give a plant a new home in the earth.

It was easy to identify the abundant native beardtongue blooming in the basin, harder to distinguish plants without flowers. Using the pattern of leaf veins as a clue, students learned to confidently weed out the non-native narrow-leaved plantain in their plots while leaving the beardtongue to grow. 

The outdoor learning the students are getting, ranging from applied analytical skills to plant identification, including how to safely and effectively use garden tools, will serve them well in life. As I said in the Town Topics article, many of them will have their own homes and yards someday, and if they become familiar with complex native habitats on school grounds, maybe they’ll dig up some of the lawn in those yards and plant natives.

Seven Native Shrubs Offer a Progression of White Blooms in Spring

Why do gardens and nature diversify over time?  Since most flowers last only a week or two, any gardener seeking a steady progression of blooms will naturally seek out new additions to fill the gaps. This spring, I noticed a different sort of steady progression: of blooming trees and shrubs in nature's garden at Herrontown Woods. No gardener put this steady progression together.

Flowering dogwood (Cornus florida) put on a show in late April.

Blackhaw viburnums (Viburnum prunifolium) dotted the understory with white pompoms for the first few days of May, their period of bloom shortened by the heat.

Alternate-leaved dogwood (Cornus alternifolia) followed in the second week of May, with scattered blooms in the shade,

and abundant blooms in the sun.

Arrowwood Viburnum (Viburnum dentatum) in the lowlands sustained flowers through cool days in the second half of May, 

along with maple-leaved Viburnum (Viburnum acerifolium) up on the ridge.

In the last week of May, abundant disks of elderberry (Sambucus canadensis) flowers began an extended residency.

Still to come is silky dogwood (Cornus amomum), 

which will look remarkably like its predecessors when it blooms.

There are many examples of how native plants that have co-evolved behave in an egalitarian way. Though there are exceptions, they tend to "play well with others," sharing the ground rather than bullying their way to dominance. Might this sharing have a collective advantage that benefits them all?

People trying to understand why invasive species can be detrimental will rightly point out that many invasive plants provide abundant flowers for pollinators. But if one species comes to dominate, its week or two of blooms will be preceded and followed by precious few flowers, leaving pollinators little to sustain them through the season.

An interesting experiment would be to monitor what sorts of insects pollinate the progression of blooms generated by native dogwoods and Viburnums. Have their visually similar blooms evolved to attract the same sorts of pollinators? If so, they could be thought of as a sort of tag team, collectively sustaining the needed pollinators through the season. 

Springtime Chow Down on Local Flora

Springtime, and the woods is full of fresh green foliage. With such tenderness and delectability in abundance, it's not surprising that very hungry caterpillars and other insects respond by chowing down. 

Earlier this spring, the tent caterpillars got busy in the Barden at Herrontown Woods defoliating the  black cherry trees. In the photo are one of many new "tents," and the brown, droopy remains of the previous year's.

Last year's black cherry chow down was particularly extravagant, resulting in near total defoliation that ultimately extended to the neighboring pin oak. In the process, the caterpillars built lavish highways of silk, the better to navigate over the cherry's rough "black potato chip" bark. Once the communal caterpillars had had their way with the trees, they individually wandered off to pupate, and the trees grew a second set of leaves. This relationship seems to keep the black cherry trees perpetually stunted, but still healthy enough to grace the Barden grounds. 

Another woody plant burdened by the overwrought appetites of native caterpillars is the Hearts a Bustin (Euonymus americanus). Because deer browse was preventing this native shrub from growing to maturity in the wild, we transplanted some into cages in the Barden at Herrontown Woods. For years, they thrived, but this year the webworm larvae of the American ermine moth (Yponomeuta multipunctella) showed up to chow down. As with the black cherry trees, the Hearts a'Bustin' shrubs are having to be way more generous than seems fair. 

Interestingly, the Hearts 'a Bustin' we have growing in sunnier locations are thus far sustaining less damage from the insects. Perhaps the extra sunlight strengthens their defenses.

More modest in their appetites are caterpillars found on ferns. Deer tend to avoid eating ferns, and insects may find them less edible as well.

Early in the process of creating what became the Barden, we discovered a pussy willow growing there. This spring, some of its leaves were getting "windowpaned" by larvae of the imported willow leaf beetle (Plagiodera versicolora). Like kids that won't eat the crust of bread, the larvae leave the leaf veins uneaten.

Oaks sustain a tremendous variety of insects, among them the wasp Callirhytis seminator. The wasp lays its egg on the oak, simultaneously injecting a chemical that causes the oak to create a growth called a Strawberry Oak Gall, or Wooly Sower Gall. The gall conveniently provides food for the wasp larva.

These are but a few examples of the varied ways plants support the local insect population, which in turn provides sustenance for birds.

Related post: Balance and Imbalance in Nature