Potential for pH to Limit
Oriental Bittersweet Invasion in MN
Celastrus orbiculatus
Heather Pagelkopf
August 14, 2013
Botanic Description
• Deciduous climbing woody vine
• Up to 66’ long
• Large root system sends up new
shoots
• Flowers borne on axillary cymes
(clusters along length of vines)
• Bright ripe fruit bright red with
yellow capsules
Botanic Description
Celastrus orbiculatus
INVASIVE
Celastrus scandens
NATIVE
• Ripe fruit capsules yellow with red • Ripe fruit capsules orange with red
berries containing > 5 seeds
• Flowers found on axillary cymes
berries containing <1 seed
• Flowers found on terminal panicles
Infests forests,
grasslands and
urban areas
o
Shades out and
smothers lowlying plants
o
Girdles limbs
and trunk,
eventually causing
tree death if phloem
is damaged
o
o Weighs down
limbs and trunk,
causing breakage
Reduces
number of native
Celastrus scandens
through
competition and
hybridization
o
Invasive Properties
 Extensive root system
– regenerates
asexually
 Hybridization with
native C. scandens
 Faster growth than
native liana

Up to 3 m annually
Invasive Properties
 Exhibits “sit and wait”
growth strategy

Tolerance to wide range
of light intensities
 Abundant seed
production
 High rates of
germination and
establishment
Possible Limits to MN Invasion
~ 4.1 to 7.9
~ 4.6 to 7.1
Soil Preferences

Origin data hard
to obtain

Literature suggests
circumneutral soil
preference
(6.5 to 7.5)
Minneapolis
Infestations in MN:


Winona – 6.56
Red Wing – 6.81
St. Paul
Red Wing
Winona
What Soil pH is Preferred for Growth?
Research Questions:
Is high pH a limiting factor for C. orbiculatus
distribution, or has bittersweet simply not yet spread
to regions with high pH?
What soil pH values in Minnesota will be suitable for
Celastrus orbiculatus seedling vigor?
 Pre-Germinated Seeds taken from
Winona, MN in Nov. 2012
 Transplanted into Ebb and Flow
Hydroponic Rockwool System
Three pH Nutrient Solutions:
6.5, 7.2, and 7.9
 Watered and drained every weekday with
solutions and flushed with deionized
water when EC of drained solution > 3.5
millimhos/cm

Seedling Deaths:
(After 27 Days)
 pH 6.5 = 8
 pH 7.2 = 32
 pH 7.9 = 61
Chlorosis:
 pH 6.5 – very green
 pH 7.2 – slightly chlorotic
 pH 7.9 - chlorotic
Chi-Square Analysis of Seedling Deaths
•
•
pH 6.5
pH 7.2
pH 7.9
Total:
χ2= 53.947; df = 2
α < 0.001
Alive
Dead
142
8
(116.33) (33.67)
118
32
(116.33) (33.67)
89
61
(116.33) (33.67)
349
101
Total
150
150
150
450
Parenthesis indicate expected values.
 We cannot conclude that
seedling death and pH treatment
are independent of one another.
 Therefore pH is somehow
affecting seedling vigor.
 Our study suggests a relationship between soil
Implications
and Further
Analysis
pH and seedling vigor. Regions of MN with
soil pH higher than 7.2 will likely cause some
decline in seedling vigor if C. orbiculatus
establishes there.
Continued Analysis:
 Comparison of leaf chlorophyll levels
 Comparison of root and shoot biomass
Other Future Study:
 Replicated trial using narrow range of pH
(e.g 7.5, 7.6, 7.8, and 7.9)
 Similar trial using soils obtained from
different regions of MN with varying soil pH
Thank You!