Invasive plant removal method determines native plant community responses

Abstract

Summary 1.Restoration of habitats invaded by non-native plants should include both the removal of invasive plants and re-establishment of native plant communities. To develop appropriate restoration strategies and quantify the effects of invasions, experiments that evaluate multiple removal methods and native community responses to those removal methods are needed. 2. We evaluated the response of native plant communities to removal of the invasive grass Microstegium vimineum (Japanese stiltgrass) in eastern forests in the USA. At eight field sites in southern Indiana, we applied three common removal treatments and compared native community responses among treatments and to untreated reference plots. 3. After 2 years of treatment, native community responses to Microstegium removal varied significantly among methods and plant functional groups in autumn 2006. Graminoid richness was greater when the invader was removed with hand-weeding, while graminoid biomass was lower in plots treated with post-emergent herbicide compared to reference plots. Forb richness was greater with hand-weeding and post-emergent herbicide compared to plots treated with post-emergent plus pre-emergent herbicides or untreated plots. Forb biomass was greater across all removal treatments. Overall native community diversity was 24% greater when the invasion was removed with handweeding and 21% greater with post-emergent herbicide compared to reference plots. No positive response in plant diversity occurred with post-emergent plus pre-emergent herbicide. 4. By spring 2007, graminoid percentage cover was greater with hand-weeding but not with herbicide treatments compared to untreated plots. However, forb cover was greater across all removal treatments compared to plots where the invader was not removed. The density of native tree seedlings was 123% greater in post-emergent herbicide treated plots than in untreated plots, indicating that the invasion was inhibiting tree recruitment. Synthesis and applications.Our results demonstrate that multiple techniques can be used to control invasive plants but that the responses of native plant communities vary among removal methods. Further, greater native plant diversity and biomass following removal shows that invasions were suppressing native plant communities. Management of plant invasions should consider not only the effectiveness of removal methods but also how different methods influence native plant responses.

Performance and reproduction of an exotic invader across temperate forest gradients

“…5). These results are consistent with other researchers that report decreased M. vimineum growth and reproduction in drought and shade (Claridge and Franklin 2002, Cole and Weltzin 2004, 2005, Glasgow and Matlack 2007, Marshall and Buckley 2008a, Eschtruth and Battles 2009a, Flory and Clay 2009a v www.esajournals.org 2010, Droste et al 2010, Flory 2010, Huebner 2010a, Schramm and Ehrenfeld 2010). Yet, as noted, these associations cannot fully decouple cause and effect in M. vimineum establishment.…”

“…Since arriving in the U.S. in the early 1900s (Fairbrothers and Gray 1972), it has spread throughout the eastern U.S. and midcontinental states. It invades roadsides, trails and waterways, along with associated forest understories and wetlands, displacing native vegetation (Cole and Weltzin 2004, Flory and Clay 2009a. Warren et al (2011) synthesized published research on M. vimineum habitat distributions and hypothesized that the plant is limited by shade, drought and heavy aboveground leaf litter cover.…”

Community level impacts of Microstegium vimineum on arthropod community structure and foodweb dynamics in a temperate deciduous forest.

“…This annual C 4 grass (Poaceae), also known as Japanese Stiltgrass, was accidentally introduced to the US in the early 1900s as packing material (Fairbrothers and Gray, 1972;Barden, 1987), and is a prevalent invader throughout the eastern U.S. It is considered a species of concern due to its ability to thrive in the understories of deciduous forests, often outcompeting native forbs and grasses Civitello et al, 2008;USDA, 2008;Flory and Clay, 2009;Adams and Engelhardt, 2009;Flory, 2010). Microstegium vimineum is an early spring germinating annual that reaches peak biomass in late summer, produces a high volume of seed in early fall and leaves behind a dense mat of litter (Barden, 1987;Hunt andZaremba, 1992, Redman, 1995).…”

“…Microstegium vimineum is an early spring germinating annual that reaches peak biomass in late summer, produces a high volume of seed in early fall and leaves behind a dense mat of litter (Barden, 1987;Hunt andZaremba, 1992, Redman, 1995). Microstegium vimineum has been shown to significantly impact plant community composition, reducing native plant diversity and biomass which could have serious effects on arthropod community structure (Barden, 1987;Civitello et al, 2008;Flory and Clay, 2009;Adams and Engelhardt, 2009;Simao et al, 2010). Individual arthropods were identified to the family level using Johnson and Triplehorn (2005), and were assigned to a trophic group (carnivore, herbivore, omnivore and detritivore) and guild (parasite, parasitoid, predator, concealed chewer, free-living chewer, free-living sap feeder, pollinator, scavenger/shredder) using feeding information found in Marshall (2009) and Gratton & Denno (2005).Samples were then sorted by sampling method, family, site and date, and placed in a drying oven (40°C) for 48 h and weighed.…”

“…Microstegium vimineum is an annual and early spring germinator that reaches peak biomass in late summer, produces high volumes of seed in early fall, and leaves behind a dense mat of litter (Barden 1987, Hunt and Zaremba 1992, Redman 1995. While M. vimineum has been shown to significantly impact plant community composition by reducing native plant diversity and biomass, its impacts on herbivorous insects and their invertebrate predators appear to be highly variable and context dependent (Barden 1987, Civitello et al 2008, Flory and Clay 2009, Adams and Engelhardt 2009, Simao et al 2010.…”