Breakout Session: Research

 

Participants: Mary Brophy, Su Fanok, Erik Kiviat, Elizabeth Kolb, Jennifer Forman Orth, Beth Reichheld, Paul Salon, Donna Vogler

 

I have tried to mention nearly everything discussed with the name of the discussant(s) but I apologize if I have left out anything or anyone. Material in brackets is my editorial comments. – Erik Kiviat

 

Kiviat: Summarized data on knotweed stand characteristics and associated biota from two unpublished manuscripts by Kiviat, Jenn Grieser, and Gretchen Stevens. In two well-developed stands on the Batavia Kill in Greene County, New York, vegetation statistics (median [observed range]) were: canopy cover 87 (70-93%), litter cover 85 (55-97%), shoot density 7 (2-14 per square meter), aboveground dry mass 545 (72-2154 grams per square meter), , and associated vascular plant species richness 2 (0-10 per 25 square meter plot). Basal stem diameter was a better predictor of shoot biomass than shoot height. Well over 300 species of animals and plants have been found in knotweed stands in New York, New Jersey, and Massachusetts. Flower-visiting insects were especially prominent. The negative or positive impacts of knotweed upon other species are very poorly understood.

 

What are the data gaps?

 

Kolb: Roads and stream corridors are often together, presenting a problem [for spread of knotweed]. NYS DOT will do trials with Waipuna (not foam) to kill invasive plants on roadsides.

 

Vogler: Protect refugia for native species.

 

What is the best way to monitor spread of Japanese knotweed? What are the rates of spread?

 

Fanok: Rebar marking outer stems to monitor spread.

 

Kolb: Use GPS?

 

How does knotweed alter soils?

 

Vogler: Is patchiness a function of establishment or habitat quality?

 

Fanok: Delaware River – more on insides of meanders.

 

Brophy: What plants prevent knotweed rhizome extension?

 

Salon: Saw where a dense sedge was apparently excluding knotweed [which species of sedge?]. Knotweed overruns willow plantings used for bioengineering. Does GCSWCD treat knotweed before doing streambank work?

 

Reichheld: No.

 

Fanok: Do healthy native communities keep knotweed out?

 

Kiviat & others: Rivers have natural and anthropogenic disturbances that promote knotweed invasion.

 

Salon: Would like to remove knotweed and do competitive plantings. Salix exigua, a native invasive species – would it compete with knotweed? Knotweed not good as a riparian buffer strip (for removing nutrients and silt)?

 

Kolb & Salon: What is knotweed doing to soil biogeochemistry, soil biota, etc.?

 

Fanok: Allochthonous support of coldwater fishery [i.e., plant detritus falling into stream as food for invertebrate prey of trout]?

 

All: A high priority for research is the effects of knotweed on streambank stability.

 

Fanok: Impacts of flow regime and its alteration on invasibility [of streambanks by knotweed]? Where are we on the invasion process [sorry, I don’t remember what that means- EK]? What is the role of reproduction by seed in the large scale dynamics of knotweed?

 

Kiviat: Research agenda, based on today’s discussions:

 

Impacts of knotweed on sedimentation (erosion, deposition) and geomorphology

 

Negative and positive impacts on other animals and plants – habitat function, quality of biodiversity

 

Test better management methods especially competitive planting. Find out what really happens following management (and what the nontarget impacts of management are).

 

4. Role of seedlings in invasion and population dynamics.

Greene County Soil & Water Conservation District

Stream Stewardship Program

 

Japanese Knotweed