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Ecotonal Dynamics of High-Bush Blackberry
in Eastern Kansas
Thomas A. Eddy
(Stephens 1973). Primo canes remain vegetative t~rough ~he
first growing season and become flower and frUIt bearmg
(floricanes) the second year. Invading strategies of the highbush blackberry were studied during the growing season of
1994. Thirty 5 m line transects were randomly established
along 300 m of the advancing edge of high-bush blackberry
populations on the study area in April. Q~adrats (5 m x.I0 m)
were located perpendicular to the 5 m hne transects In the
direction of movement of the invading blackberries.
Primocanes in the quadrats were counted in April and
August.
High-bush blackberry stem and root dimensions related
to population growth were examined. Two hundred floricanes
and their associated root systems were randomly selected
for measurements of cane length, height, depth to lateral
roots and root sprout intervals.
Patterns of expansion of invading shrubs and acres invaded were determined from aerial photographs and vegetation maps.
Two woody species accompanied the invasion of high-bush
blackberries into prairies on the study site. The frequency of
occurrence of coralberry (Symphoricarpos orbiculatus
Moench) and dwarf sumac (Rhus copillina L.) was determined in 30 quadrats along the front of invasion.
Cultivated patches of grain and forage sorghum have been
planted on scattered areas of the study site annually since
1978. Unplanted strips (2 m to 4 m wide) are frequently left
between the rows of sorghum. High-bush blackberry plants
have established in many of these strips. Twenty m 2 quadrats were established randomly along 100 m of invaded
unplanted strips.
Abstract-An aggressive and bothersome invader in Eastern Kansas is the high-bush blackberry (Rubus ostryifolius Rhbd.). This
study investigated the rates and patterns of invasion of this thorny
bramble from forest border areas into tallgrass prairie on a site in
Elk County, Kansas, that has been unburned and ungrazed since
1978. Blackberry populations advanced a mean distance of5.4 m on
deep loam soil compared to 2.3 m on shallow loam and clay soils with
exposed sandstone rock. Patterns of invasion were broadening
bramble borders along woodland edges and stream's peninsulas of
bramble growth into prairie, and expanding islands of brambles in
open prairie.
The role of fire in maintaining the integrity of the tallgrass prairie ecosystem is well known (Weaver and Rowland
1952; Hulbert 1969; Bragg and Hulbert 1976). Ungrazed
and unburned prairies along forest borders are especially
vulnerable to change. Accumulated plant materials alter
the microclimate which encourages retrogression of prairie
grasses and forbs and their replacement by woody plants.
An aggressive and bothersome invader in Southeast Kansas is the high-bush blackberry (Rubus ostryifolius Rhbd).
This study investigated the rates and patterns of invasion
ofthis thorny bramble from forest border areas into tallgrass
prairie and cultivated fields on a 2,800 acre area in Elk
County, Kansas.
Methods and Materials _ _ _ __
The study site is located in the Chautaqua Hills, an
undulating uplift extending from the Kansas-Oklahoma
border to Woodson County, Kansas (Bare 1979). The hills
are dissected by deep ravines with occasional sandstone
bluffs along the major drainages. Soils are sandy clays and
loams with sandstone outcrops of Pennsylvanian age. The
tallgrass prairie vegetation is interspersed with groves of
blackjack oak (Quercus velutina Lam.) and post oak (Quercus
stellata Wang). A variety of shrubs are associated with the
woodland borders. Fire and grazing have not occurred on the
site for at least a decade. Disturbances include strip thinning of oak groves in 1978, introduction of milo feed patches
for wildlife food and cover, and construction of roadways.
Natural propagation and expansion of high-bush blackberry populations occur by root suckers (primocanes)
Results and Discussion
Primocane numbers in the 30 quadrats along the advancing edge ofthe bramble invasion ranged from 21m to 9/m with
a mean of 4/m. August readings in the 5 m x 10 m quadrats
showed population extensions from 0.5 m to 6.3 m with a
mean of 2.1 m. Populations advanced a mean distance of
5.4 m on deep loam soil compared to 2.3 m on shallow loam
and clay soils with exposed sandstone rock.
Stem and root measurements indicated important aspects
of the growth of the high-bush blackberry. Length of canes
varied from 1.4 m to 0.11 m with a mean length of 0.82 m.
The arching canes were 1.3 m to 0.2 m tall with a mean
height of 0.7 m. Depth of lateral roots ranged from 0.5 cm
to 25 cm with a mean depth of 6.2 cm. Primocanes sprouted
from lateral roots at intervals of 6 cm to 53 cm with a mean
distance between sprouts of 18 cm.
Two woody plant species were associated with the invading blackberries. Fourteen of the thirty 5 m x 10 m plots
contained coralberry and 9 of the plots were occupied by
In: Barrow, Jerry R.; McArthur, E. Durant; Sosebee, Ronald E.; Tausch,
Robin J., comps. 1996. Proceedings: shrubland ecosystem dynamics in a
changing environment; 1995 May 23-25; Las Cruces, NM. Gen. Tech. Rep.
INT-GTR-338. Ogden, UT: U.S. Department of Agriculture, Forest Service,
Intermountain Research Station
Thomas A. Eddy is a Plant Ecologist, Emporia State University, Box 4050,
Emporia, KS 66801.
146
dwarf sumac. These species competed with the grasses and
forbs for light and moisture. Penfound (1964) determined
that coralberry represented 15% of the foliage in ungrazed
pastures in central Oklahoma as compared to 0.8% in ungrazed pastures.
Acres invaded and patterns of expansion by high-bush
blackberry and associated woody species were estimated.
Approximately 315 acres or 12% of the study site have been
invaded since 1978. The three patterns ofinvasion identified
and percent acreage in each type were: (1) broadening shrub
borders along woodland edges and streams (75%), (2) peninsulas of shrub growth into open prairie (15%), and
(3) expanding islands of woody vegetation (10%).
Intrusion of high-bush blackberry into unplanted wildlife
food strips was measured. Density of canes ranged from
141m2 to 431m2 with a mean density of 351m 2 • Primocanes
frequently appeared in the planted strips. If food plantings
are discontinued the cultivated areas will be invaded by
high-bush blackberries in a few growing seasons.
References
-----------------------------------------------------------Bare, J. E.1979. Wildflowers and weeds of Kansas. Lawrence, KS:
The Regents Press of Kansas. 322 p.
Bragg, T. B.; Hulbert, L. C. 1976. Woody plants invasion of unburned Kansas bluestem prairie. Journal of Range Management.
29:19-23.
Hulbert, L. C. 1969. Fire and litter effects in undisturbed bluestem
prairie in Kansas. Ecology. 50:874-877.
Penfound, W. T. 1964. The relation of grazing to plant succession in
the tall grass prairie. Journal of Range Management. 5:256-260.
Stephens, H. A. 1973. Woody plants of the North Central Great
Plains. Lawrence, KS. The University of Press of Kansas. 530.
Weaver, J. E.; Rowland, N. W. 1952. Effects of excessive natural
mulch on development, yield, and structure of native grassland.
Botanical Gazette. 114: 1-19.
147