Effects of Summer Weather Modification (Irrigation) in Festuca Idahoensis-Agropyron spicatum Grasslands

1978 ◽  
Vol 31 (4) ◽  
pp. 264 ◽  
Author(s):  
D. Collins ◽  
T. Weaver
Keyword(s):  
Weather Modification ◽  
Festuca Idahoensis ◽  
Agropyron Spicatum

scholarly journals Responses of Nematodes to Ungulate Herbivory on Bluebunch Wheatgrass and Idaho Fescue in Yellowstone National Park

1994 ◽  
Vol 18 ◽  
pp. 126-130
Author(s):  
Evelyn Merrill ◽  
Jon Hak ◽  
Nancy Stanton
Keyword(s):  
Root Growth ◽  
Yellowstone National Park ◽  
Root Biomass ◽  
National Park ◽  
Growing Season ◽  
Belowground Biomass ◽  
Winter Range ◽  
Bluebunch Wheatgrass ◽  
Festuca Idahoensis ◽  
Agropyron Spicatum

Above- and belowground biomass of Idaho fescue Festuca idahoensis and bluebunch wheatgrass Agropyron spicatum and nematode densities under these plant species were sampled during the growing season inside and outside a 2-year old exclosure on Crystal Bench in Yellowstone National Park. Early in the growing season, grazed plants of both species had lower shoot and root biomass than ungrazed plants. Standing biomass of grazed plants was equal to ungrazed plants at the end of the growing season. Densities/g root biomass of phytophagous and bacterial feeding nematodes were higher under grazed than ungrazed plants of both plant species only early in the growing season. Foliar concentrations of nitrogen in grazed plants were higher than ungrazed plants but there was no difference in root nitrogen between grazed and ungrazed plants. The effects of ungulate grazing on the Northern winter range of Yellowstone National Park has recently received considerable attention (Frank 1990, Coughenour 1991, Singer 1992, Wallace submitted). Early interest in this topic centered around the question to cull or not to cull elk in the Park. However, as the concepts of "maintaining ecological processes" (Houston 1982) and "ecosystem management" (Keiter 1991) have gained acceptance in Park management, understanding the dynamics and interactions of a broader array of herbivores inhabiting the Park have become increasingly important. In this paper, we describe the results of a study which focused on the effects of aboveground herbivory on nematode density and trophic structure. Root-feeding nematodes are major herbivores in other grassland systems and may consume twice as much biomass as aboveground consumers (Ingham and Detling 1984, Stanton 1988). Houston (1982) reported that nothing is known about the effects of nematodes on the native grasses of the northern range especially in combination with aboveground grazers. We hypothesized that if spring grazing is intense, grazed plants would initially show a decline in root growth and phytophagous nematodes. Cessation of root growth is a common response of plants to grazing and may occur within the first 2-24 hours (Hodgkinson and Baas Becking 1977). Evidence to date supports the idea that phytophagous nematode densities are highest under moderate levels of grazing and low under heavily grazed and ungrazed plants (Stanton 1983, Stanton et al. 1984, Seastedt 1985, Seastedt et al. 1988). Because senescing roots, subsequent to grazing, provide increased substrates for decomposers, we also hypothesized that microbial activity and nitrogen mineralization should increase (Stanton et al. 1984). As a result, we expected to detect an increase in microbial feeding nematodes. As root regrowth occurred, we expected phytophagous nematodes to increase. However, we predicted that populations would not reach levels found under ungrazed plants because plants in grazed areas experience higher levels of nitrogen mineralization (Holland and Detling 1990) than ungrazed plants and may produce proportionally fewer numbers of root hairs (nutrient absorption organs) which serve as feeding sites for nematodes. Because of reduced densities of phytophagous nematodes and increased mineralization rates under grazed plants, we expected grazed plants to recoup their losses rapidly. The net result we predicted would be no detectable differences in aboveground or belowground biomass during years of normal rainfall. Thus, our study addressed 3 null hypotheses. First, root and shoot biomass of grazed and ungrazed plants will be similar at the end of the growing season. Second, density of phytophagous and microbial feeding nematodes will not differ between grazed and ungrazed plants. Finally, nitrogen concentration of roots and aboveground foliage will not be higher in grazed than in ungrazed plants. We focused our attention on bluebunch wheatgrass Agropyron spicatum and Idaho fescue Festuca idahoensis because of their importance as winter range forages and because Mueggler (1975) reported that bluebunch wheatgrass was more sensitive and recovered more slowly to heavy clipping than Idaho fescue.

Possible Effects of Weather Modification (Increased Snowpack) on Festuca Idahoensis Meadows

1977 ◽  
Vol 30 (6) ◽  
pp. 451 ◽  
Author(s):  
T. Weaver ◽  
D. Collins
Keyword(s):  
Weather Modification ◽  
Festuca Idahoensis

scholarly journals Responses of Nematodes to Ungulate Herbivory on Bluebunch Wheatgrass and Idaho Fescue in Yellowstone National Park

1991 ◽  
Vol 15 ◽  
pp. 231-234
Author(s):  
Evelyn Merrill ◽  
Nancy Stanton
Keyword(s):  
Yellowstone National Park ◽  
National Park ◽  
Ecological Processes ◽  
Winter Range ◽  
Ungulate Herbivory ◽  
Bluebunch Wheatgrass ◽  
Ungulate Grazing ◽  
Northern Winter ◽  
Festuca Idahoensis ◽  
Agropyron Spicatum

The effects of ungulate grazing on the Northern winter range of Yellowstone National Park has recently received considerable attention. Early interest in this topic centered around the question to cull or not to cull elk in the Park. However, as the concepts of "maintaining ecological processes" (Houston 1982) and "ecosystem management" (Keiter 1991) have gained acceptance in Park management, understanding the dynamics and interactions of a broader array of herbivores inhabiting the Park will become increasingly important. In 1990, we studied the responses of Idaho fescue (Festuca idahoensis) and bluebunch wheatgrass (Agropyron spicatum) and their associated nematode communities to ungulate herbivory.

Length and Timing of Grazing on Postburn Productivity of Two Bunchgrasses in an Idaho Experimental Range

1998 ◽  
Vol 8 (1) ◽  
pp. 15 ◽  
Author(s):  
SC Bunting ◽  
R Robberecht ◽  
GE Defosse
Keyword(s):  
Growing Season ◽  
Grazing Management ◽  
Plant Mortality ◽  
Grazing Tolerance ◽  
Regeneration Period ◽  
Postfire Regeneration ◽  
Defoliation Treatment ◽  
Management Policies ◽  
Festuca Idahoensis ◽  
Agropyron Spicatum

Plant mortality and productivity in semiarid grasslands may be affected by the length of time grazing is excluded during the postfire regeneration period. The degree of grazing tolerance for the semiarid bunchgrass species, Festuca idahoensis and Agropyron spicatum, exposed to fire, and how the variation in grazing tolerance was affected by the length of time allowed for undisturbed plant regeneration after fire, were central questions addressed in this study. We examined the degree of plant mortality and productivity that resulted from the interaction of fire and grazing. Plants exposed to fire alone, i.e., without subsequent defoliation, exhibited low plant mortality, although culm production was reduced relative to unburned plants. An early-season-defoliation treatment after fire resulted in the plant mortality as high as 50% for Festuca and 70% for Agropyron bunchgrasses. Plant height and the number of vegetative and reproductive culms were also most affected by this defoliation treatment. These detrimental effects were lessened when defoliation was delayed by one growing season after the fire. Although our results suggest that one growing season seems to be enough for both species to recover after the fire, more studies will be necessary to confirm these trends, and induce changes in current grazing management policies.

The Relative Sensitivity of Two Bunchgrass Species to Fire

1995 ◽  
Vol 5 (3) ◽  
pp. 127 ◽  
Author(s):  
R Robberecht ◽  
GE Defosse
Keyword(s):  
Fire Severity ◽  
Biomass Productivity ◽  
Relative Sensitivity ◽  
Fire Exposure ◽  
Quantitative Index ◽  
Above Ground Biomass ◽  
Plant Mortality ◽  
Precise Control ◽  
Festuca Idahoensis ◽  
Agropyron Spicatum

The response of two bunchgrass species, Festuca idahoensis and Agropyron spicatum, to fire was examined under three levels of fire severity. The fire treatment was applied with an instrument system that allowed precise control over the intensity and duration of fire, and full documentation of the temperatures experienced in various regions of each plant during the fire and postfire cooling phases. A quantitative index of fire exposure, or severity, for each plant was obtained by integrating the temperature curve for the meristematic crown region over the fire and postfire cooling periods. No significant plant mortality was observed at any fire severity level. Although tissue damage in newly initiated culms was observed for Festuca, this did not significantly affect culm or biomass productivity. Culm production was initiated earlier and more rapidly in Festuca than Agropyron, and within 60 days after fire exposure the total number of culms produced in Festuca was nearly that of unburned plants. Above ground biomass for both species was significantly less than that of unburned plants at the end of this 60-day period. Agropyron exhibited significantly less culm and biomass production at a moderate fire severity, whereas high fire severity was required for this reduction in Festuca. Contrary to previous studies, Festuca thus appears less sensitive to fire injury than Agropyron.

scholarly journals 100 Years of Progress in Cloud Physics, Aerosols, and Aerosol Chemistry Research

2019 ◽  
Vol 59 ◽  
pp. 11.1-11.72 ◽  
Author(s):  
Sonia M. Kreidenweis ◽  
Markus Petters ◽  
Ulrike Lohmann
Keyword(s):  
Radiative Forcing ◽  
Cloud Microphysics ◽  
Climate System ◽  
Mitigation Strategies ◽  
Climate Projections ◽  
Weather Modification ◽  
Theoretical Understanding ◽  
Aerosol Cloud ◽  
Chemistry Research ◽  
Aerosol Cloud Interactions

Abstract This chapter reviews the history of the discovery of cloud nuclei and their impacts on cloud microphysics and the climate system. Pioneers including John Aitken, Sir John Mason, Hilding Köhler, Christian Junge, Sean Twomey, and Kenneth Whitby laid the foundations of the field. Through their contributions and those of many others, rapid progress has been made in the last 100 years in understanding the sources, evolution, and composition of the atmospheric aerosol, the interactions of particles with atmospheric water vapor, and cloud microphysical processes. Major breakthroughs in measurement capabilities and in theoretical understanding have elucidated the characteristics of cloud condensation nuclei and ice nucleating particles and the role these play in shaping cloud microphysical properties and the formation of precipitation. Despite these advances, not all their impacts on cloud formation and evolution have been resolved. The resulting radiative forcing on the climate system due to aerosol–cloud interactions remains an unacceptably large uncertainty in future climate projections. Process-level understanding of aerosol–cloud interactions remains insufficient to support technological mitigation strategies such as intentional weather modification or geoengineering to accelerating Earth-system-wide changes in temperature and weather patterns.

On Certain Ratio Statistics in Weather Modification Experiments

Technometrics ◽  
1979 ◽  
Vol 21 (3) ◽  
pp. 283-289 ◽  
Author(s):  
A. W. Davis
Keyword(s):  
Weather Modification
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