This document summarizes a study on the effects of removing invasive Chinese privet from forest areas. Researchers established test plots where privet was removed by manual felling or mulching, and compared plant and pollinator communities over time in these treatment plots versus control plots with no privet removal. Immediately after privet removal, herbaceous plant cover increased significantly in the treatment plots. Five years later, privet had not returned and plant diversity remained higher in the treatment plots. Bee diversity and abundance also increased substantially in the treatment plots compared to controls, with mulching and felling plots hosting over 4-5 times as many bee species. Common bee species observed utilizing the regenerating plant communities are described.

1. If You Cut It, Will They
Come?
Pollinator Response to Chinese Privet Removal
Scott Horn, Jim Hanula, Jacob Hudson, Mike Ulyshen, and
Yanzhuo Zhang

2. How do a bunch of
Entomologists get involved with
Chinese Privet?

3. Southern Research Station
Insects, Diseases, Invasive Plants
Forest Service
“To provide the basic biological and ecological knowledge and innovative
management strategies required for management and control of native and non-
native insect pests, pathogens and invasive plants in changing forest ecosystems”

4. Insects, Diseases, Invasive Plants
“Yellow star thistle: Volunteers tackle a thorny
problem “
“Garlic mustard is a threat to several
tree species”
“How to stop honeysuckle invasion”
Kudzu That Ate U.S. South Heads North
as Climate Changes

6.  Invasive species are considered one the top
threats to forest ecosystems in North America.
 42% of the decline in native species now listed
as endangered or threatened in the US is a
result of non-native invasive plants, animals or
microbes (Pimentel 2002).
 GA-Exotic Pest Plant Council “Category 1”
 “Exotic plant that is a serious problem in Georgia by
extensively invading and displacing native species”.
 Chinese privet………one of the worst!!
Who has privet on their property???

7.  Used in traditional medicine in China
 Introduced into the US in 1852
 Widely used for hedges and borders
Chinese Privet, Ligustrum sinense

8. Chinese Privet
Invasion Biologist= Invasive Weed Nurseryman= “remarkable ornamental”
Shade tolerant too!
*Same attributes……..different perspective!

9. Playing “Between the Hedges”
For $30 plus shipping and handling, Dawgs fans can order
plants and get their own piece of the hedges in a pot.
The product is officially licensed by the school through the
Collegiate Licensing Corp.
“If you’re an Auburn fan, it’s just a privet,” said Garrison,63,
(owner) “But if you’re a Georgia fan, it’s something special.”

10. Chinese Privet, Ligustrum sinense
 Well established in the Southeast by the 1930’s
 No native natural enemies
 70 Years later……
 59% of Oconee river floodplain infested (Ward 2002)

11. Sandy Creek Nature Center
Athens, GA

12. Privet in the forest is an
ecological nightmare.
Oconee National Forest
Greensboro, GA
State Botanical Gardens
Athens, GA
Private land
Ashland, AL

13. It covers 1-3 million acres of forest land in the
Southeast (and growing!!!)

14. Broad Goals
1. Increase public awareness
2. Lay groundwork for biological control
project
3. Understand impacts of privet invasion
and its control on forest plant and animal
communities

15. Specific Questions
 Which method (manual felling vs mulching)
of Privet control is most effective?
 How does the local plant community
respond when Privet is removed?
 How do pollinators respond once privet is
removed and native plants return?
 How do pollinators in privet cleared areas
compare to communities in areas that have
never had privet (“desired plots”)?
 How do cleared areas change over time?

16. Why study pollinators?
 They provide important ecosystem services (pollination)
 roughly 1/3 of all food crops need cross-pollination, as do 90% of wild plants for their
survival
 This leads to an estimated economic value in the U.S. (2003) of between 18-27
billion dollars
 Natural areas near agricultural fields can serve as a refuge and possibly increase
crop pollination……so healthy forests might =higher crop yields
 Declining worldwide

18. Why Bees and Butterflies?
 Bees are the real pollination powerhouses—considered the most
efficient (repeatedly visit a plant species on a given foraging trip,
ensuring pollination) # of Bee Species in United States?
Birds = 785 Mammals = 430
 Butterflies (larvae) important part of the food chain serving as prey
for other species and probably the most important insect
“ambassador” (think monarch)
 Disturbance creates winners and losers in forests
 Question we always get: How does “X” affect insects??
 Useful bio-indicators for forest and ecosystem health

19. Where did we work?
59% of Oconee River
Floodplain infested
with privet

20. What did we do?
 Four Treatment
Locations
 Three, 5-acre plots
at each location
 Mulch
 Felling
 Control
 Three “desired”
plots
(*15 Total Plots)

21. Treatment #1
Manual Felling
Advantages: Lower cost ($250/acre), lower environmental impact, easier to treat stumps

22. Treatment #2
Mulching
Advantage: removes ALL debris, cleaner “look”
Cost: $500/acre

23. Gyrotrac Mulcher

25. Treatment #3
Control
$*%@!

26. Treatment #4
Desired Plots

27. Follow-up Treatments
 Initial treatments (2005) alone
didn’t kill all the privet
 Foliar application of 2%
glyphosate in late fall or early
winter of 2006
 Maximum impact on privet with
minimum impact on native
vegetation

28. Foliar Application
Before – November, 2006 After – January, 2007

29. Foliar application worked!
(% Privet in Herbaceous Layer)
10 months after initial treatment
0
5
10
15
20
25
30
M
ulch
Felling
Control
0
5
10
15
20
25
M
ulch
Felling
Control
22 months after initial treatment
“Hit the reset button”…………. 99% reduction in privet

30. Biomass and Nutrient Measurements
 Established random transects on felling plots and
measured amount of residue per square meter to
estimate biomass
 19.9 tons (dry wt.) of privet per acre
 Process subsamples for nutrient content analysis to
estimate nutrients tied up by privet
 Privet contains 250 lbs N per acre
*Indicates just how much privet is altering these floodplain systems!

31. Plant sampling methods
 Plants sampled at beginning of project (evaluate
immediate impacts) and then again 5 years post-
treatment (determine “sustained restoration”)
 Established 3 transects across
each of the 15 plots
 Line intercept method
 Presence/absence
 Plant species
 Plant height
 Shrub cover

32.  Pollinators sampled at beginning of project and
then again 5 years post-treatment
 Sampled for one week in each month from
March-September (7 sampling periods)
 Five subplots were established and equally
distributed in each of the 15 plots
 Each subplot had 2 pan traps (blue, yellow)
Pollinator sampling methods

33. What is “Pan trapping”
 Widely accepted collection
technique
 Simple and inexpensive
 More time efficient and less
biased than sweep netting
 Collects pollinators during all
activity times
 Major downside = Might not
attract all pollinators equally
*Flower mimic

34. Results—Immediate Plant Response
*non-privet herbs
• Plant diversity
increased, but
not significantly
• Percent of
herbaceous
plant cover
significantly
increased
<20% control
>40% felling
>60% mulch
• Mulch plot herb
cover similar to
“Desired” plots
good news!
• Early colonizers

35. Results—Immediate Plant Response

36. Results—Immediate Plant Response

37. Results—Immediate Plant Response

38. Plants that showed up Post-removal
 Herbs/vines
 Pokeweed
 Fireweed
 Winged stem
 Nettle
 Violets
 Aster spp.
 Greenbrier
 Muscadine
 Elderberry
 Sedges
 Poison Ivy
 J. Stiltgrass
 Trees/shrubs
 Boxelder
 Sweetgum
 Red maple
 Sycamore
 Redbud
 Red mulberry
 Loblolly pine
 Hophornbeam
 Ironwood
 Slippery elm

39. Results—5 yr. Plant Response
January 2012
• Very little privet has returned
• “sustained restoration”
• Boxelder has moved in

40. Results—5 yr. Plant Response

41. NMS Ordination for Herbaceous Plants 2007 and 2012
sites are plotted so distances between them in
the graph reflect the ecological differences
between them
• Mulch and
Felling plots
from both
2007 and 2012
are
ecologically
similar
• Removal
technique had
little effect on
plant
community
between the
two
• Both treatment
plots moving
towards the
“desired” plots
(our goal!)
• Desired plots=
native grasses

42. Unexpected Outcome
A rare plant, yellow fumewort (Corydalis flavula), was discovered on our removal
plots at the State Botanical Gardens. This plant occurs in only 4 counties in
Georgia-this was a new county record.
Maybe not so rare?? Just losing ground…….

43. Results-Bee Richness
Richness
Control Mulch Felling Desired
MeanSpecies/plot
0
20
40
60
80
2007
2011
b
a
a
A
B
B
2007
2012
2007
• Bee diversity
went up almost
5x on mulch
and 4x on
felling plots
• Even surpassed
Desired plots—
extra sunlight?
2012
• Trend continued
for 5 year
assessment—
mulch and
felling plots
significantly
more diverse
than control

44. Results-Bee Abundance
Abundance
Control Mulch Felling Desired
MeanBees/plot
0
200
400
600
800
1000
2007
2011
a
b
b
A
B
B
2007
2012
2007
Control 33/plot
Felling 383/plot
Mulch 658/plot
Dramatic results!
2012
• After 5 years
bee numbers
remained
significantly
higher on privet
removal plots
• Change in plant
cover led to a
sustained
change in the
bee community

45. Results-Bee Abundance
Mulch Control

46. Common bees collected
10,000 bees
120 species

47. Sweat Bees
Halictidae: Augoclora pura
 Most common bee
collected
 One of the bright green
“sweat bees”
 Nests are made in rotting
wood
 Can have multiple
generations in one year
(unlike most bees)
 Forage on a wide range
of plants

48. Sweat Bees
Halictidae: Lasioglossum spp.
 Another “Sweat Bee,
usually smaller in size
and not as bright in color
 One of the most diverse
Genera of bees (280
species in North America.
 Ground Nesters (~ 70%)

49. Small Carpenter Bees
Apidae: Ceratina spp.
 Excavate nests in pithy centers
of dead stems:
 Sunflowers, elderberry,
sumac, and blackberry
 Series of brood cells with the
dividing walls made up of
chewed pith and saliva
 Female dies in the winter but
remains at the entrance to block
nest access--protecting her
offspring.
 One reason to protect
“weedy” areas

50. Mason Bees
Megachilidae: Osmia spp.
 Use mud to seal their nests
(“mason” bees)
 Mostly a Spring bee
 Economically important
 Blue Orchard bees pollinate
almonds, apples, plums, peaches
and cherries.
 More efficient than honey bees
 300 blue orchard bees can
do the work of 90,000 honey
bees!!
 In the wild use old beetle holes or
other holes in wood.
 Readily attracted to artificial nests
 Ventral Pollen collecting apparatus

51. Mining Bees
Andrenidae: Andrena spp.
 Common “Yard” bee
 Ground nester that prefers open
sunny areas like yards and fields
 Solitary bee, however many nest
in large aggregations
 Mostly a Spring bee (cold tolerant)
 Important pollinator of apples,
blueberries, cranberries, and even
onions.

52. Long-Horned Bees
Apidae: Melissodes spp.
 Active in the Summer and
Fall
 Close association with
Asters
 Important pollinator of
wild and hybrid
sunflowers

53. Bumble Bees
Apidae: Bombus spp.
 Only social native bee (live in
colonies)
 One of the largest bees and
only confused with carpenter
bees
 Important “Buzz-Pollinator”
 Many species have seen steep
declines

54. Cuckoo Bees
Apidae: Nomada spp.
 Cowbird of the bee world
 Lack pollen carrying
apparatus
 Adults feed on nectar only
 Very few hairs and wasp-
like in appearance

55. So what about the butterflies??
 We captured over 3000
Butterflies during the study
 35 different species

56. Results-Butterflies
Richness
Control Mulch Felling Desired
0
5
10
15
20
2007
2011
a
b
b
A
B
AB
2007
2012
2007
• Richness went
up more than 2x
on felling plots
and almost 4x
on mulch plots
• Richness on
mulch plots
same as desired
plots
2012
• Butterfly
communities
strongly
responded to
plant restoration
over the long
term (same as
bees)
Larval host plants?

57. Results-Butterflies
Abundance
Control Mulch Felling Desired
0
50
100
150
200
250
2007
2011
a
b b
A
B
C
2007
2012
2007
Control 22/plot
Felling 92/plot
Mulch 157/plot
• Mulch plot again
was very similar
to desired plots
in the number of
butterflies
caught
2012
• The trend
continued
demonstrating a
positive
response to
privet removal
and to the
return of native
plants.

58. Clouded Skipper
 Most commonly collected butterfly by
far
 Only species in a mostly tropical
genus
 Larvae feed only on grasses
 Active late spring to fall
 Common along streams and in open
hardwood forests

59. Zabulon Skipper
 Sexually Dimorphic
 Larvae feed only on grasses
 Active late spring to fall
 Similar to Clouded Skipper--common
along streams and open hardwood
forests

60. Carolina Satyr
 Active Spring through Fall
 Multiple generations
 Larvae feed only on grasses
 Adults prefer to feed on sap and
rotting fruit

61. Eastern Tiger Swallowtail
 State Butterfly of Georgia
 Multiple generations
 Larvae feed on numerous plants
 Yellow poplar, basswood, black
cherry, birch, willow, magnolia, ash
 Distinct looking larvae

62. NMS Ordination
for Bees and
Butterflies 2007
and 2012

63. Summary
 Reduces the number of native trees
 Reduces the number of native shrubs
 Reduces herbaceous plant species and number
 Reduces bee diversity and abundance
 Reduces butterfly diversity and abundance
Chinese Privet…..

64. Is There Light at the End of the
Privet Tunnel?

65. Long-term Hope?
 3 million acres in the Southeast
 Eradication with mechanical and herbicide
treatments not practical on such a large scale
 Biological control offers the best long-term
option
 No native Ligustrum species in U.S.

66. Exploration in China

67. Lacebug
Leptophya hospita
*Testing completed and petition
submitted to APHIS
*Zero tolerance/Release looks unlikely

68. More Biological Control options?
• Pros and Cons to any management strategy
• INTEGRATED PEST MANAGEMENT……..Have to use all tools in our toolbox!

69. “Native Americans ran the continent as
they saw fit.………..
If there is a lesson it is to think like the
original inhabitants of these lands and we
should not set our sights on rebuilding an
environment from the past but concentrate
on shaping a world to live in for the
future.”
From:
1491: New Revelations of the Americas
Before Columbus
By Charles C. Mann

70. Thanks

71. Scott Horn
Email: shorn01@fs.fed.us
Phone: 706-559-4249
http://www.srs.fs.usda.gov/staff/648
https://www.researchgate.net/profile/Scott_Horn
Contact Information

72. ONLINE WILDFLOWER SEED SOURCES
 American Meadows
https://www.americanmeadows.com/
 Roundstone
http://roundstoneseed.com/

73. Great information on Bees and
Butterflies
www.butterfliesandmoths.org
www.xerces.org

74. TIPS FOR INCREASING POLLINATORS
 Plant Wildflowers and Flowering Trees and Shrubs
– Focus on plants that flower during different seasons (i.e. diversify your
landscape)
– Try to use native plants whenever possible
 Provide nesting habitat (bee blocks or exposed soil areas)
– Leave dead wood in place (or create it!)
 Leave weedy/unmown areas
 Open up your forests (let the light in!)
 Reduce insecticide use

75. BEST METHODS TO KILL PRIVET
 When should I spray?
– Fall and Winter (once other plants are dormant)
 What methods should I use?
– Cut stump Foliar spray
20% Glyphosate or Triclopyr (+ surfactant) 2% Glyphosate
*cut and spray immediately *spray until runoff