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CISMA Call Agenda

1:30pm Introductions

Rose Godfrey & Sherry Williams

1:35pm Technical Presentation

Exploring the link of Mexican Petunia and Soil Nutrient Dynamics by Candice Prince

2:05pm CISMA Updates:

FCIWG by Jessica Spencer

2:20pm Shout outs

2:30pm End

Technical Presentation

Exploring the link between Mexican Petunia and soil nutrient dynamics

By Candice Prince

Exploring the link between Mexican Petunia and soil nutrient dynamics.

Candice M. Prince, PhD student

Adrienne M. Smith, PhD candidate

Carrie Reinhardt Adams, Associate Professor

Florida Cooperative Invasive Management Area (CISMA) Webinar

January 28th, 2015

Outline

• Background info on Mexican Petunia Origin

Impacts

Management

• Is there a link between Mexican Petunia invasion and soil characteristics?

Mexican Petunia (Ruellia simplex)

• Native to Central and South America (Hupp, 2007)

• Introduced to Florida in the 1930’s as an ornamental

• Established in 6 southeastern states and Hawai’i

Credit: Early Detection & Distribution Mapping System

Mexican Petunia (Ruellia simplex)

Credit: JayJayC Credit: Folia

• Popular ornamental due to showy flowers that bloom year-round Economic output for Florida nurseries $12 million (Wirth et

al. 2004)

• Tolerant of wide range of conditions Makes it easy for gardeners, but contributes to invasiveness

• Commonly planted, spreads to natural areas via seed and rhizomes

Wild-Type vs. Sterile Cultivars

• When Mexican Petunia was first introduced, only wild-type plants available for production (Reinhardt Adams et al. 2014b)

• Sterile cultivars (‘Purple Showers,’ ‘Mayan Purple,’ ‘Mayan White,’ etc.) have recently been developed

UF/IFAS Assessment of Non-Native Plants in Florida’s Natural Areas lists ‘Purple Showers’ as “Not a Problem Species”

However, still concerns about vegetative spread

Credit: Keona Nolan

Mexican Petunia (Ruellia simplex)

• Listed in 2011 as a Category I invasive by the Florida Exotic Pest Plant Council (FLEPPC)

Alters native plant communities by displacing native species and changing ecological functions

Florida wetlands – may impact watershed hydrology (Reinhardt Adams et al. 2014)

• Forms dense monoculture in understory

Mexican Petunia (Ruellia simplex)

• Aggressively invades urban-bordered floodplain forests

Grows in narrow strips along disturbed riparian zones

• Prefers periodically flooded, shaded places but also grows well in sun and upland habitats (Hupp, 2007)

• Abundant seed producer, and grows easily from stem and rhizome sections

Management • Mechanical

• Herbicides

• Biological

• Prevention

Management

• Mechanical – hand-pulling, mowing

Difficult due to rhizomes

• Herbicides

• Biological

• Prevention

Management

• Mechanical – Difficult due to rhizomes

• Herbicides – Success with glyphosate (Reinhardt Adams et

al. 2014a)

Multiple applications recommended for adequate control

• Biological

• Prevention

Management

• Mechanical – Difficult due to rhizomes

• Herbicides – Multiple applications of glyphosate

• Biological – Melanagromyza ruelliae (Huey et al., 2007)

Insect which feeds on Mexican Petunia

Not enough research, feeds on native Ruellia caroliniensis

• Prevention

Management

• Mechanical – Difficult due to rhizomes

• Herbicides – Multiple applications of glyphosate

• Biological – More research required

• Prevention – Both of initial invasion and reinvasion Requires understanding the mechanisms behind Mexican

Petunia invasion

How can we inform management?

• Need to understand mechanism of Mexican Petunia invasions

• Potential mechanism: Areas receiving urban runoff might be susceptible due to nutrient enrichment (King and Buckney, 2000)

Relatively infertile, sandy soils easily invaded when exposed to nutrient runoff (Lake and Leishman, 2004)

• Mexican petunia might exhibit greater use efficiency of P

and N than native FL species (Wilson et al, 2004)

Suggests invasion may be connected with soil nutrient dynamics

• Greater understanding of soil characteristics needed to target invasion

Mexican Petunia and soil characteristics

• Preliminary testing (2012) showed differences in soil characteristics between invaded and uninvaded sites (Prince,

unpublished data)

Significantly higher pH and NOx at sites with Mexican Petunia

• Reported cases of invasive species causing nutrient enrichment (Ehrenfeld et al., 2001)

Alterations in litter chemistry or net primary production

Creates positive feedback loop promoting further invasion

• Unclear if the presence of Mexican Petunia is due to nutrient enrichment from runoff, or if the plant itself is changing the environment

• Objective: Quantify differences in invaded and uninvaded soils, and explore the role Mexican Petunia plays in creating these differences

• If Mexican Petunia is shown to modify soil nutrient dynamics, research can be focused into productive avenues for control and restoration

May also be possible that changes to soil dynamics facilitates further invasion (both of itself and other species)

• If we do not observe changes in soil characteristics, other factors (i.e., nutrient runoff) may play a role in the invasion process

Presence of Mexican Petunia may be an indicator of soil degradation from stormwater runoff

• Methods: 1) field soil analysis, 2) greenhouse study

Area of Study • Two sites: Paynes Prairie Preserve State Park and Hogtown

Creek in Gainesville, FL

Mexican Petunia invaded riparian wetlands

History of stormwater runoff

Hogtown Creek

Paynes Prairie

Paynes Prairie

Hogtown Creek

Methods: Part 1 Field soil analysis

Sampled in August, 2013

7 samples of top 5 cm

(spaced 1.5 m apart) of soil from uninvaded and invaded areas of both sites

Evaluated for: P, K, Ca, Mg, TKN, NOx, Fe, Al, pH, and organic matter

Results – Part 1 Field Soil Analysis

Status K (ppm) Mg (ppm) Al (ppm) pH TKN (ppm) OM (%)

Invaded 49.6 231.0 375.4 7.3 2403.0 0.9

Uninvaded 85.1 362.6 668.3 6.3 3822.7 2.0

1. Hogtown Creek soil analysis (only significant differences are shown)

2. Paynes Prairie soil analysis (only significant differences are shown)

Status Ca (ppm) Mg (ppm) Fe (ppm) pH TKN (ppm) OM (%)

Invaded 11041.0 594.2 243.3 7.6 3541.3 2.5

Uninvaded 3134.7 309.7 247.0 7.2 1859.3 1.0

• Similarities across sites (higher pH in invaded sites) indicate possible modifications from Mexican Petunia The same relationship with pH was found in preliminary

testing in 2012 (Prince, unpublished data)

Increase in pH can be caused by litter chemistry of invasive species, or by a preferential uptake of nitrate by the exotic plant (Ehrenfeld et al. 2003)

• Differences (e.g. opposing trends in OM) suggest site-level constraints to the invasion Most of the tested nutrients exhibited opposing trends,

suggesting Mexican Petunia may be limited in ability to modify soil

Results – Part 1 Field Soil Analysis

Methods: Part 2 Greenhouse Experiment

• Greenhouse experiment: September 2013 – February 2014

• Soil from uninvaded areas at both sites used to fill 80 trays

For each site:

10 trays – Mexican Petunia

10 trays – Soft Rush (Juncus effusus)

10 trays – Pinebarren Goldenrod (Solidago fistulosa)

5 trays – unseeded and weeded control

5 trays – unseeded and unweeded control

• Above and belowground biomass harvested at conclusion of experiment

• Soil analyzed for nutrients, pH, and organic matter

• Failure of Soft Rush and Pinebarren Goldenrod to germinate limited interpretation

• Still able to test differences between Mexican Petunia colonization and natural recolonization

Mexican Petunia Pinebarren Goldenrod Soft Rush

Weeded Control Unweeded Control

Average number of individuals, as well as aboveground and

belowground biomass, in each treatment.

Treatment Site Number of

Individuals

Aboveground

Biomass (g)

Belowground

Biomass (g)

Unweeded Hogtown

Creek 17 ± 5 3.0 ± 1.7 3.9 ± 1.4

Unweeded Paynes

Prairie 33 ± 16 2.7 ± 0.9 4.9 ± 1.5

Mexican

Petunia

Hogtown

Creek 5 ± 2 3.4 ± 1.9 6.1 ± 3.6

Mexican

Petunia

Paynes

Prairie 5 ± 3 1.2 ± 0.7 3.3 ± 1.3

• Biomass nearly twice as high for

Mexican Petunia in Hogtown Creek

soil • Suggests that we may see more

changes/greater magnitude of changes

in soil characteristics in Hogtown

Creek soil

Results: Part 2 Greenhouse Experiment

Results: Part 2 Greenhouse Experiment 1. Significant differences in soil nutrients between treatments for plants grown in

Hogtown Creek soil.

Status NOx-N (ppm) TKN (ppm) OM (%)

Mexican Petunia 3 (B) 3895 (AB) 15.2 (AB)

Unweeded 7 (AB) 4270 (A) 18.8 (A)

Weeded 10 (A) 3192 (B) 13.7 (B)

2. Significant differences in soil nutrients between treatments for plants grown in

Paynes Prairie soil.

Status K (ppm)

Mexican Petunia 53 (B)

Unweeded 61 (AB)

Weeded 103 (A)

• Few significant differences found None of the soil differences that were found were consistent

between field sites

May be partly due to initial differences in field soil composition

Conclusions

• Mexican Petunia is not likely to be an ecosystem engineer Would have seen more significant differences in soil from both sites

May be able to remove plants without making soil amendments for restoration

• Possible that site level-factors such as urban stormwater runoff play a role in facilitating Mexican Petunia invasion Would explain why more differences were found in the field soil analysis

than the greenhouse experiment

Consistent with other studies that have found links between nutrient enrichment and invasion on infertile soils

• May be able to use presence of Mexican Petunia to indicate areas of soil degradation from stormwater runoff Problems with stormwater runoff may need to be addressed before

restoration can successfully occur on invaded sites

• Possible that more differences may have been seen if the experiment lasted longer and/or was during the growing season

May take longer than five months for Mexican Petunia to build up enough belowground biomass to impact soil nutrient dynamics

• If true, then if invasions are addressed early in the colonization process it may be sufficient to remove plants without making any soil amendments

Early Detection, Rapid Response Programs

• Recommend repeating the experiment over a greater timeframe, with modification to promote greater germination

Conclusions

Acknowledgements

• Gregory E. MacDonald (University of Florida)

• Leah Cobb Lee (University of Florida)

• Christine Wiese (University of Florida)

• This work was funded by:

The Weed Science Society of America (WSSA)

USDA Tropical and Subtropical Agricultural Research Program (TSTAR)

References • Ehrenfeld JG, Kourtev P, Huang W. 2001. Changes in soil functions following invasions of

exotic understory plants in deciduous forests. Ecological Applications 11:1287-1300

• Huey LA, Steck GJ, Fox AM. 2007. Biological notes on Melanagromyza ruelliae (Diptera: Agromyzidae), a seed feeder on the invasive Mexican petunia, Ruellia tweediana (Acanthaceae). The Florida Entomologist 90(4):763-765

• Hupp KVS. 2007. Investigating the determinants of local scale distribution of Ruellia tweediana (synonym R. brittoniana) in natural areas. Gainesville (FL): University of Florida. 108p

• King SA, Buckney RT. 2000. Urbanization and exotic plants in northern Sydney streams. Austral Ecology 25:455-461

• Lake JC, Leishman MR. 2004. Invasion success of exotic plants in natural ecosystems: the role of disturbance, plant attributes and freedom from herbivores. Biological Conservation 117:215-226

• Reinhardt Adams C, Wiese C, Cobb LC. 2014a. Effect of season and number of glyphosate applications on control of invasive Mexican petunia (Ruellia simplex). Ecological Restoration 32: 133-137.

• Reinhardt Adams C, Wiese C, Lee LC, Wilson SB, Smith AM, Freyre R. 2014b. Managing Mexican petunia (Ruellia simplex C. Wright) in the home landscape. University of Florida EDIS Publication #ENH1237

• The Nature Conservancy (TNC). Florida: Stopping the spread of invasive species. Retrieved from: http://www.nature.org/ourinitiatives/regions/northamerica/unitedstates/florida/howwework/combating-invasive-species-in-florida.xml

• Wilson SB, Wilson PC, Albano JA. 2004. Growth and development of the native Ruellia caroliniensis and invasive Ruellia tweediana. HortScience 39(5):1015-1019

• Wirth FF, Davis KJ, Wilson SB. 2004. Florida nursery sales and economic impacts of 14 potentially invasive landscape plant species. Journal of Environmental Horticulture 22: 12-16.

CISMA Update

First Coast Invasive Working Group

By Jessica Spencer

FCIWG in 2014

• Quarterly meetings were held on 3/26, 6/19, 9/18 and 12/3

• 3 Volunteer workdays – 2/20 at Tree Hill Nature Center

– 9/9 at Jax Equestrian Center

– 11/21 at Spanish Pond

• 8th Annual Air Potato Round-up, held on 3/1 in association with NISAW.

FCIWG Education & Outreach

• Confirmation of 1st Brazilian pepper population in Georgia (6/20)

• Outreach booth at St. Augustine Earth Day (4/26) & Green Lion Festival (10/4)

• Invasive Grasses & Aquatics Workshop with Colette Jacono (10/30)

• Assisted Coastal Georgia CISMA with Tamarix control efforts (12/1)

Shout Outs

What’s happening?

What’s happened?

What’s about to happen?

Shout Outs

NISAW February 22-28 2015 FISP Winter Meeting February 10th 2015 CISMA resources on CISMA page of FISP website FISP Youtube channel…coming soon! Doodle poll to be sent to CISMA Leads

Next Month’s Call

Wednesday, February 25th 2015

Mexican Red Squirrel by Tony Pernas

Shout out by Misty Spada

CISMA update one of the following:

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