Grazing Intensity Research in the Missouri Coteau of North Dakota


Plant Community Dynamics

Changes in the plant community are monitored by sampling the frequency of occurrence, density per unit area and percent basal cover of all plant species as well as sampling the weight of herbage produced. Frequency data was collected each year of the study. Density was collected on forbs and shrubs in 1988 and 1990 to 2000 and on cespitose (bunchgrasses) from 1992 to 2000. Basal cover was sampled on plant species in 1988, 1990, 1992, 1993, 1996 and 1999 and basal cover of litter and bare ground was sampled in 1996 and 1999. The change in abundance of species between years was determined for each site. The arcsine transformation was applied to frequency and basal cover data to convert it from a binomial distribution to a nearly normal distribution. Analysis of variance was performed to determine if there was a change in species abundance across all sites, which might indicate a response to weather, or if there was a change in response to the different grazing treatments. All tests were performed at the P=0.05 level. Table 9 lists plant species that appear to be favored by no grazing or light grazing. Table 10 lists species that appear to be favored by moderate grazing and table 11 lists species that appear to be favored by heavy grazing. An asterisk marks species in table 11  which appear to be invasive. These are species that have not been found or are extremely rare on the ungrazed or lightly grazed treatments. On silty range sites total plant basal cover has decreased on the ungrazed and lightly grazed treatments between 1992 and 1999 and increased on the extreme and heavy treatments between 1996 and 1999. In addition to the changes listed for plant species, litter has decreased and bare ground has increased on both silty and overflow range sites under heavy grazing.

Table 9. Plant species which appear to be favored by no grazing or light grazing (P < 0.05).
Overflow Range Sites
Bromus inermis
Helianthus rigidus
Rosa arkansana
Tragopogon dubius
smooth brome
stiff sunflower
prairie rose
goat's beard

Silty Range Sites
Artemisia absinthium
Helianthus rigidus
Medicago sativa
Melilotus officinalis
Poa pratensis
Psoralea esculenta
Tragopogon dubius
wormwood
stiff sunflower
alfalfa
yellow sweetclover
Kentucky bluegrass
breadroot scurf-pea
goat's beard


Table 10. Plant species which appear to be favored by moderate grazing 
(P < 0.05).


Overflow Range Sites
Ambrosia psilostachya
Anemone canadensis
Anemone cylindrica
Aster simplex
Campanula rotundifolia
Carex lanuginosa
Galium boreale
Poa pratensis
Sisyrinchium montanum
Solidago rigida
western ragweed
meadow anemone
candle anemone
panicled aster
harebell
wooly sedge
northern bedstraw
Kentucky bluegrass
blue-eyed grass
stiff goldenrod

Silty Range Sites
Agropyron repens
Ambrosia psilostachya
Anemone cylindrica
Artemisia ludoviciana
Bromus inermis
Cirsium flodmanii
Comandra umbellata
Dichanthelium wilcoxianum
Erysimum inconspicuum
Orthocarpus luteus
Psoralea argophylla
Ratibida columnifera
Rosa arkansana
Sisyrinchium montanum
Solidago missouriensis
Solidago mollis
quackgrass
western ragweed
candle anemone
cudweed sagewort
smooth brome
Flodman's thistle
comandra
Wilcox dichanthelium
smallflower wallflower
owl clover
silver-leaf scurf-pea
prairie coneflower
prairie rose
blue-eyed grass
Missouri goldenrod
soft goldenrod


Table 11. Plant species which appear to be favored by heavy grazing 
(P < 0.05).


Overflow Range Sites
Achillea millefolium
Agropyron caninum
Agropyron smithii
Agrostis hyemalis
Androsace occidentalis
Astragalus agrestis
Aster ericoides
Bouteloua gracilis
Carex heliophila
Carex obtusata
Cerastium arvense
Cirsium flodmanii
Conyza canadensis
Erysimum inconspicuum
Euphorbia serpyllifolia
Geum triflorum
Grindelia squarrosa
Juncus interior
Lithospermum incisum
* Medicago lupulina
Oxalis stricta
Penstemon gracilis
Polygonum convolvulus
* Polygonum ramosissimum
Potentilla norvegica
* Potentilla pensylvanica
Ratibida columnifera
Solidago missouriensis
Stipa viridula
Taraxacum officinale
Vicia americana
Viola pedatifida
western yarrow
slender wheatgrass
western wheatgrass
ticklegrass
western rock jasmine
field milk-vetch
heath aster
blue grama
sun sedge
sedge
prairie chickweed
Flodman's thistle
horse-weed
smallflower wallflower
thyme-leaved spurge
prairie smoke
curly-cup gumweed
inland rush
yellow puccoon
black medic
yellow wood sorrel
slender beardtongue
wild buckwheat
bushy knotweed
Norwegian cinquefoil
Pennsylvania cinquefoil
prairie coneflower
Missouri goldenrod
green needlegrass
common dandelion
American vetch
larkspur violet

Silty Range Sites
Achillea millefolium
Agropyron smithii
* Agrostis hyemalis
Androsace occidentalis
Artemisia frigida
Aster ericoides
Bouteloua gracilis
Carex eleocharis
Carex heliophila
Cerastium arvense
Chenopodium desiccatum
Draba nemorosa
Erysimum asperum
Euphorbia serpyllifolia
Grindelia squarrosa
Hedeoma hispidum
* Juncus interior
Koeleria pyramidata
Lepidium densiflorum
*Medicago lupulina
Oxalis stricta
Plantago patagonica
* Polygonum ramosissimum
Potentilla norvegica
Potentilla pensylvanica
Symphoricarpos occidentalis
Taraxacum officinale
Vicia americana
western yarrow
western wheatgrass
ticklegrass
western rock jasmine
fringed sagewort
heath aster
blue grama
needle-leaved sedge
sun sedge
prairie chickweed
narrow-leaved goosefoot
yellow whitlowort
western wallflower
thyme-leaved spurge
curly-cup gumweed
rough false pennyroyal
inland rush
junegrass
peppergrass
black medic
yellow wood sorrel
wooly plantain
bushy knotweed
Norwegian cinquefoil
Pennsylvania cinquefoil
buckbrush
common dandelion
American vetch

* Invaders, these species have not been found, or are extremely rare, on the ungrazed and lightly grazed treatments.

 
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