Pump Hollow Natural Area

About Pump Hollow Natural Area

Location: Pump Hollow Natural Area, T 26N, R 3E, Sections 30 & 31
Size: 940 acres
Landowner: USDA, U.S. Forest Service (USFS), Mark Twain National Forest, Poplar Bluff District

Species of invasives managed forThere are a few very small populations of multiflora rose (Rosa multiflora) within the natural area.  The biggest threat that is attempting to be managed is Japanese stiltgrass (Microstegeum vimineum).

History of land and invasives management: The land was likely acquired by the USFS in 1939 when it was part of the original Clark National Forest.  In 1976, the Clark and Mark Twain National Forests were combined and the Clark was absorbed by the Mark Twain NF.  Pump Hollow was designated as a state natural area in February 2015.  Before designation, the forest service had a systematic botanical survey completed.  This survey was conducted by a private contractor and consisted of a spring and a fall visit in 2012.  During these visits, both invasive plants and rare/threatened species were mapped and identified. The area also had a more general survey in the late 1980’s and again in 2008.  It was not until the 2012 survey that invasive species had been found in the area.

Results of management: Unfortunately, Microstegeum vimineum is highly aggressive.  It surprised land managers by how quickly it spread in just 2-3 years.  In June of 2016 the forest was able to establish resources that could start working on removal.  Because of the areas sensitivity, the forest tried to avoid the use of herbicides or contractors.  Six AmeriCorps crew members were tasked with hand pulling, bagging, and removing 5 island populations of Microstegeum vimineum.  Frustratingly, the 5 mapped populations had now merged and become generally 1 much larger population.  The crew was able to fill and haul out over 30, 50 gallon trash bags from the area over multiple days of laborious work.

Current invasives management: After realizing the daunting task that was hand pulling this population, the forest determined that hand pulling alone would not eradicate J. stiltgrass.  Pulling and hauling debris is too labor intensive, it demands too many personnel, and it has to be done during a brutally harsh time of year for the plants to be mature enough to pull.

The forest is adapting to the hand pulling struggle and attempting to try herbicide application using a Sideswipe®Pro herbicide applicator or similar product.  This device wets the plants evenly and eliminates the fear of drift and overspray.  This is extremely important due to the potential water threat.  Herbicide type will be appropriately determined and mixed according to labels and cautions.

Other information: This natural area features acidic seeps (a rare wetland natural community type) and a high-quality Ozark headwater stream and its surrounding watershed of restorable pine-oak woodlands.  The area supports 10 plant species of conservation concern, most of them associated with the rare seeps.  The area supports at least 258 native plant species and fish and invertebrate species associated with good quality headwater streams.

Japanese stiltgrass (Microstegium vimineum) invasion

Above: Invasive stiltgrass prefers the edges of water more than full submersion. It is not directly in the seep’s flowing water, but is in the background on the right hand side of this picture.

Japanese Stiltgrass invasion in Pump Hollow Natural Area

One of the infestations before the crew pulled thousands of plants. Note the large log in the background on the left.

Eradicated invasive plants at Pump Hollow Natural Area

The same area as above (note large log, standing snag was brought down for safety concerns). Each single plant can produce 100-1,000 seeds/year and those seeds can remain viable for 3 years. Though complete eradication was not achieved, hundreds of thousands of potential seeds were removed in this pulling effort.

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