Bamboo on the Run
Like many natural areas in the mid-Atlantic region, Wissahickon Valley Park suffers from habitat degradation due to invasive plant species. Most of these species originate from area garden centers and nurseries and are planted in yards and open spaces adjacent to the park.
Plants regenerate in several ways, including seed dispersal, roots, rhizomes, and shoots. Seed dispersal provides the most far-reaching regeneration method and is the primary way invasive plants become established in the park. Seeds are dispersed by birds, animals, wind, water, and . . . humans. This is particularly relevant in relation to non-native ornamental plants. A lovely specimen in your yard can quickly “escape” and find root elsewhere and, under the right conditions, become an invasive plant, usurping native species and the organisms that rely on them for survival.
While in the park, you may have noticed several impenetrable stands of bamboo. There are several popular ornamental bamboo species sold in the region. Two common species are golden bamboo (Phyllostachys aurea) and arrow bamboo (Pseudosasa japonica). While some bamboo spreads vegetatively into the park from adjacent private property, some arrives through seed dispersal. Either way, once established, it spreads rapidly by rhizomes.
BAMBOO AT HERMIT LANE
Alongside and extending downslope behind the Hermitage Mansion on Hermit Lane, bamboo from neighboring yards became established in a sunny opening created by a couple of fallen canopy trees. By the spring of 2016, the bamboo had taken over nearly three quarters of an acre of land.
Depending on the species, there can be a number of effective ways to control invasive plants. Choosing a method depends on a variety of interrelated factors such as cost, labor, terrain, equipment, and ultimate goals. The best way to remove bamboo is to remove the rhizomes located about 12-18 inches underground. However, this site presented challenges because the bamboo was located under tall canopy trees. Removing the rhizomes meant severing the thousands of feeder roots the trees depend on for water and mineral uptake. This type of root damage can lead to decline and eventual death for trees.
WHAT TO DO?
For this patch of bamboo, FOW is employing a series of mechanical methods to first remove the aboveground stalks and shoots. Since late winter, FOW staff and 42 volunteers have worked 336 hours cutting and hauling the material to the Philadelphia Parks & Recreation recycling center. We have experimented with loppers, hedge trimmers, and mowers; every method has been labor-intensive. As of this writing, we have completed cutting the stalks and shoots on half the site.
Based on our experience thus far, we have decided to use hedge trimmers to complete the initial cut. Working in teams of two, one person will cut stalks of bamboo, while the other clears and stacks the material to be hauled away. Once we have cleared the area, we will return to mow the new shoots every six to eight weeks depending on their rate of growth. In this way, we hope to exhaust the energy reserves in the rhizomes, leading to their ultimate eradication.
An additional method, especially practical for smaller patches, is to dig a two-foot trench around the patch and either prune the new rhizomes as they grow into the trench or install a plastic root barrier. This is a very effective way to contain the spread of the plant and is an appropriate first step toward removal of small patches.
HOW YOU CAN HELP AT HOME
- Do not plant bamboo!
- If you have bamboo on your property, remove or contain it.
- Replace it with native species.
There are many native plant options you can choose from that not only provide a visual barrier but support habitat. Finally, if you see bamboo for sale at your local garden center, please request that they stop carrying it and educate their customers on the beauty and benefit of native species.
INSTEAD OF BAMBOO
American Holly (Ilex opaca)
by Peg Shaw, Project Manager