A Walk in the Woods

paved walkways, parking lots, and impervious roofs send watersluicing down the steep hill, gouging the trails, and cutting gullies.And that, Claire points out, started in 1988. Now, there’s even morecampus development to shed water.Arboretum volunteers and College grounds crews have beenfighting these trends. Roger points along the high edge of the slopeto beams staked as check dams, and more beams lie across the trailsas speed bumps and diverters for the runoff.He pauses to nudge a beam that has slippedaskew, and I see a miniravine, a few inchesdeep, snaking around the beam’s edge. Soilsaving on such a steep hillside demandsconstant vigilance.As we follow the path behind LangMusic Building, we come to a megaravine.If I clambered down its muddy sides,squeezing among the tree limb and brusherosion barriers that crews have built, Iwould disappear below ground level. I’m notexactly a towering hulk, but an erosion gullydeep enough to swallow even a nonhulkseems too deep to me. As for power ofrunoff, I’m now convinced.Working our way down to the water, we find a good illustrationof another menace to the Crum: aliens.Roger gestures westward across the creek to another of hisprime pedagogical spots. He has led students to this groveof trees and points out there’s basically onespecies. No other trees mingle, and virtuallynothing grows underneath. What causesthis distribution? Roger asks the students.“The students guess that it’ssomething like a toxic waste dump,”he says. Rarely does someone figureout we’re standing among botanicalbullies. The trees, Norway maples,are spreading throughout NorthAmerica, crowding out other specieswith the ruthlessness of a sci-fi alieninvasion. And no, Roger says, no one hasdemonstrated how Norway maples manageto do this, though his students havedone some great projects testing ideas suchas killer shade.Claire also worries about invasive species.She’s organized a SWAT team of volunteers whowork their way through key parts of the Crumduring winter, wrestling out Norway maples.To appreciate the volunteers’progress as wellas the challenge theyface, Claire adviseswalking down to theCrum’s edge in fall.There’s a lot of nostalgiaand affection for thesewoods. But there’s alsothe attitude that we havemore urgent problems,and the Crum cantake care of itself.Native maples flare bright yellow early in the season, but Norway’sstay green for weeks longer. The near side of the Crum with most ofthe College buildings, where crews have labored for several years,looks calendar fall-colorful. The far side, however, sports so manystill-green Norway maples, it could be a woodland in a differentseason.Norway maples top Roger’s list of most alarming aliens, but headds others (see “Threats to the Crum,”page 23). Already, these as well as less virulenttakeover artists have, to some degree,infiltrated about half the woodland acreage,he warns. Instead of the rich mosaic of plantcommunities now patchworked over thelandscape, the woods could end up dominatedby fewer species or, to use Roger’s words,“simplified and impoverished.”Roger has led the way into CrumMeadow, and, after so much talk aboutmenaces to the Crum, it’s a pleasure to hearwhat treasures remain. Roger gestures acrossthe water toward roughly four acres he callsTrillium Slope. Alien species are creeping in,but the slope still offers a glimpse of whatpre-European woodland probably looked like in southeasternPennsylvania. In spring, before the trees leaf out, native wildflowersburst out to take advantage of their few weeks of full sun, anddozens of trilliums dot the slope. Of greateco-historical value it may be, but it alsosounds lovely.He gestures toward othergreat spots to show to students,including a realAmerican chestnut on the farside of the creek. It’s asprout of one of thegiants that perishedwhen a blight sweptthrough the country earlierthis century, and thesprout’s prognosis doesnot look promising. Fewpeople still alive have had achance to meet a living chestnut tree, evena doomed one.We stroll by the Scott Arboretum’s array of some300 hollies, which Claire has called “one of the arboretum’smost significant collections.” I still hear debate among alumniabout the location, but the trees certainly look fat,flossy, and happy to be there. Then we follow apath roughly parallel to the creek, toward one ofthe wild spots that Roger has put on his gemslist, the marshy hollow that had anear-miss with a bridgebuilder’sback hoe.Out here on a sunnyM A R C H 2 0 0 119