One of the challenges of maintaining vegetation around the Cynwyd Trail is invasive species that have become prevalent in some areas. A conventional way to deal with areas that have lots of invasive plants is to destroy all the vegetation in the area and start over. This is very labor intensive except in very small areas and risky if not done carefully. When all vegetation is destroyed, the area becomes highly susceptible to colonization by new invasive plants. Invasive species are generally adapted to disturbance, so they do well without competition. Another disadvantage of destroying all plant life in an area is the disruption it causes for insects and other animals the depend on plants for food and shelter. Therefore, we are trying some strategies that consider the process called succession. In natural systems, the rapid colonizer plants (which are often fast-growing annuals that make lots of seed) would gradually be replaced by other plants like shrubs, clump-forming grasses, and a variety of plants that can compete with the colonizing plants. This can take many years. We are seeking to speed up the timetable by planting robust plugs (seedlings with strong roots already in place) in the midst of some of the invasive species that we think might be susceptible to competition. Some of these areas are labeled by QR-coded signs out on the trail.
Mugwort (Artemesia vulgaris) is a common invasive species on the trail. You can learn more about it from this video. We noticed that when mugwort is cut back by weed-wacking in June, Panicum virgatum (switchgrass) plants that were lurking underneath were able to grow over the top of the mugwort. So we are trying this strategy with other warm-season native grasses, like sideoats grama (Bouteloua curtipendula). The mugwort was weed-wacked several times during the growing season, lastly in mid-August, just before the plugs were planted.
Another common non-native invasive is garlic mustard (Alliaria petiolata). You may have helped us control garlic mustard in the spring; this video explains how to do that. Garlic mustard tends to grow in rich soil in partly shady areas. It is biennial; seeds make small plants the first year and tall flowering stalks in the second year. This plant succeeds in large part by making compounds in the soil that prevent other seeds from germinating. So we are trying to break the cycle by planting some plugs (things like wood aster, foam flower, packera, and spring grasses and sedges). We will still need to keep cutting the second year garlic mustard so it doesn't make more seeds, but hopefully now there will be some nice plants mixed in.