Abstract
1. An extensive area of Mixed Prairie in the loess hills of central Nebraska was studied to ascertain the degree of degeneration that had resulted from long periods (60-70 years) of grazing. 2. The topography is mostly that of steeply rolling and hilly land. The soils, derived from loess, have A horizons varying from 6 to 20 inches in depth, carbonate accumulations in the thick B horizons, and C horizons of deep, mellow loess. Water from the 23.5 inches of precipitation penetrates the soil to 5 feet or more. 3. Ungrazed hilltops and upper slopes were covered mostly with short grasses. Ravines and ravine banks supported a post-climax vegetation of tall and mid grasses derived from True Prairie. Typical climax Mixed Prairie of taller grasses with an understory of short grasses occupied the long mid slopes. 4. Each-type of vegetation demarked different environments or pasture sites. Various degrees of deterioration of the vegetation in each site were revealed in four range-condition classes-excellent, good, fair, and poor. 5. In lowland the chief grasses which decreased under grazing were Andropogon gerardi and other tall grasses. In excellent range A. gerardi composed 58% of the perennial grasses, but decreased to 29%, and then to 3%, and finally in poor pasture to 1%. Conversely, short grasses (Bouteloua gracilis and Buchloe dactyloides) increased from 10 to 82% from excellent to fair pasture, and then decreased to 53% in poor range. Poa pratensis and Bouteloua curtipendula were other increasers. 6. Basal area of grasses increased with lowland range deterioration from 15% in excellent pasture to 51% in fair range, but it was only 21% in poor range. Organic mulch steadily decreased, as vegetation degenerated, from 8540 pounds per acre in excellent range to 634 pounds in poor pasture, and yield of perennial grasses from 2.44 tons per acre to only 0.27 ton. 7. On hillside sites Andropogon gerardi, Bouteloua curtipendula, and Poa pratensis all decreased from their respective 8, 10, and 3% composition of the vegetation to less than 1% in fair range. Bouteloua gracilis maintained a high percentage composition (50-75) throughout. Buchloe dactyloides increased from 5 to 45% in fair pasture and then decreased. 8. Basal area on hillsides increased from excellent pasture (27%) to fair range (43%) and then decreased to 18%. In the same sequence, yields of perennial grasses were 1.44, 1.33, 0.92, and 0.41 tons per acre. A yield of 5900 pounds per acre of mulch in excellent range decreased to 281 pounds in poor pasture. 9. On hilltop sites there were no tall and few mid grasses to decrease. The two short grasses composed 95% of the basal area in excellent pastures and 92% in poor ones. Here degeneration consisted largely of the fragmentation of the more or less continuous cover of excellent range to one with much bare interspace. 10. Basal area of grasses increased under grazing from 36 to 49% and then, in poor range, decreased to 20%. Mulch was reduced from 3980 pounds per acre to only 281 pounds in poor range. Yields of grasses were moderate in excellent and good range (about 1.28 tons per acre) but low (0.65 and 0.41 ton) in fair and poor range. 11. The same species of forbs often grew in different sites, but some were more or less confined to a single site. Each pasture type had a characteristic group of forbs which consistently decreased with degeneration of prairie, as Amorpha canescens, Lygodesmia juncea, and Ratibida columnaris. 12. Chief forbs that increased with deterioration of grassland were Vernonia baldwinii, Aster multiflorus, Ambrosia psilostachya, and Cirsium undulatum. Among forbs that invaded degenerated grassland were Verbena stricta, Grindelia squarrosa, and, in poor pastures, Helianthus annuus and many other weedy annuals. 13. Of 148 ranges examined, only 5% were in excellent condition, 18% were in good condition, fair ranges composed 49%, and distinctly poor ranges were 28% of the total.
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Claims 20
Claim · model-written summary
Ungrazed hilltops and upper slopes were mostly covered by short grasses.
Verbatim
e0“Ungrazed hilltops and upper slopes were covered mostly with short grasses.”
Claim · model-written summary
Ravines and banks supported tall and mid grass vegetation.
Verbatim
e0“Ravines and ravine banks supported a post-climax vegetation of tall and mid grasses derived from True Prairie.”
Claim · model-written summary
Typical Mixed Prairie occupied long mid slopes.
Verbatim
e0“Typical climax Mixed Prairie of taller grasses with an understory of short grasses occupied the long mid slopes.”
Claim · model-written summary
Lowland Andropogon gerardi composition declined across range deterioration.
- Taxon
- A. gerardi
Andropogon gerardie0 - Outcome
- composede0
- Direction
- decreasede0
- Value
- 58%e0
- Qualifier
- 29%, and then to 3%, and finally in poor pasture to 1%e0
- Setting
- poor pasturee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In excellent range A. gerardi composed 58% of the perennial grasses, but decreased to 29%, and then to 3%, and finally in poor pasture to 1%.”
Claim · model-written summary
Short grasses increased from excellent to fair pasture and then decreased in poor range.
Verbatim
e0“short grasses (Bouteloua gracilis and Buchloe dactyloides) increased from 10 to 82% from excellent to fair pasture, and then decreased to 53% in poor range.”
Claim · model-written summary
Lowland grass basal area rose through fair range but was lower in poor range.
Verbatim
e0“Basal area of grasses increased with lowland range deterioration from 15% in excellent pasture to 51% in fair range, but it was only 21% in poor range.”
Claim · model-written summary
Organic mulch declined with degeneration in lowland.
- Outcome
- Organic mulche0
- Direction
- decreasede0
- Value
- 8540 pounds per acree0
- Qualifier
- 634 pounds in poor pasturee0
- Setting
- poor pasturee0
Not reportedTaxon
Verbatim
e0“Organic mulch steadily decreased, as vegetation degenerated, from 8540 pounds per acre in excellent range to 634 pounds in poor pasture”
Claim · model-written summary
Perennial grass yield declined in lowland.
Verbatim
e0“yield of perennial grasses from 2.44 tons per acre to only 0.27 ton.”
Claim · model-written summary
Three hillside grasses declined to less than one percent in fair range.
- Taxon
- Andropogon gerardi, Bouteloua curtipendula, and Poa pratensis
.jpg?width=60)
Poa pratensisAndropogon gerardi
Bouteloua curtipendulae0 - Outcome
- composition of the vegetatione0
- Direction
- decreasede0
- Value
- less than 1%e0
- Setting
- hillside sitese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“On hillside sites Andropogon gerardi, Bouteloua curtipendula, and Poa pratensis all decreased from their respective 8, 10, and 3% composition of the vegetation to less than 1% in fair range.”
Claim · model-written summary
Bouteloua gracilis maintained high composition on hillsides.
- Taxon
- Bouteloua gracilis
Bouteloua gracilise0 - Outcome
- percentage compositione0
- Direction
- maintainede0
- Value
- 50-75e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Bouteloua gracilis maintained a high percentage composition (50-75) throughout.”
Claim · model-written summary
Buchloe dactyloides increased to fair pasture and then declined.
- Taxon
- Buchloe dactyloides
Bouteloua dactyloidese0 - Outcome
- Buchloe dactyloidese0
- Direction
- increasede0
- Value
- 5 to 45%e0
- Qualifier
- then decreasede0
- Setting
- fair pasturee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Buchloe dactyloides increased from 5 to 45% in fair pasture and then decreased.”
Claim · model-written summary
Hillside basal area rose from excellent to fair range and then fell.
Not reportedTaxon
Verbatim
e0“Basal area on hillsides increased from excellent pasture (27%) to fair range (43%) and then decreased to 18%.”
Claim · model-written summary
Hillside perennial grass yields declined across range condition classes.
Verbatim
e0“yields of perennial grasses were 1.44, 1.33, 0.92, and 0.41 tons per acre.”
Claim · model-written summary
Hillside mulch yield declined from excellent to poor range.
Not reportedTaxon
Verbatim
e0“A yield of 5900 pounds per acre of mulch in excellent range decreased to 281 pounds in poor pasture.”
Claim · model-written summary
Short grasses dominated hilltop basal area in both excellent and poor pastures.
Verbatim
e0“The two short grasses composed 95% of the basal area in excellent pastures and 92% in poor ones.”
Claim · model-written summary
Hilltop grass basal area increased under grazing and then fell in poor range.
Verbatim
e0“Basal area of grasses increased under grazing from 36 to 49% and then, in poor range, decreased to 20%.”
Claim · model-written summary
Hilltop mulch declined in poor range.
Not reportedTaxon
Verbatim
e0“Mulch was reduced from 3980 pounds per acre to only 281 pounds in poor range.”
Claim · model-written summary
Grass yield on hilltops was lower in fair and poor range.
Verbatim
e0“Yields of grasses were moderate in excellent and good range (about 1.28 tons per acre) but low (0.65 and 0.41 ton) in fair and poor range.”
Claim · model-written summary
Characteristic forbs declined with prairie degeneration.
- Taxon
- Amorpha canescens, Lygodesmia juncea, and Ratibida columnaris
Ratibida columnifera
Lygodesmia juncea.JPG?width=60)
Amorpha canescense0 - Outcome
- characteristic group of forbse0
- Direction
- decreasede0
- Setting
- prairiee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.JPG?width=500)
Verbatim
e0“Each pasture type had a characteristic group of forbs which consistently decreased with degeneration of prairie, as Amorpha canescens, Lygodesmia juncea, and Ratibida columnaris.”
Claim · model-written summary
Most examined ranges were fair or poor.
Not reportedTaxon
Verbatim
e0“Of 148 ranges examined, only 5% were in excellent condition, 18% were in good condition, fair ranges composed 49%, and distinctly poor ranges were 28% of the total.”