The animal unit has been a multiple-use concept in the natural resource sciences. This paper examines the animal unit as an example of a general process of concept design, a process involving multiple options for definingthe concept, and multiple objectives and multiple applications for the concept in range management science. Based on this analysis, the animal unit is abstracted as a unit of energy demand independent of interactive considerations of forage or environment. The proposed definition optimizes the utility and universality of the concept by minimizing confounding in the concept's most important applications. The result is a simplified concept that can be used to explicitly express animal equivalences, and can be used in a web of more complex, interactive concepts and models involving human objectives, natural resources, and livestock. The animal unit and animal-unit equivalent are relatively simple examples of synthetic concepts involving communication that are central to the identity of range management science.
{"title":"Entropy, concept design, and animal-unit equivalence in range management science","authors":"D. L. Scarnecchia","doi":"10.2307/4003962","DOIUrl":"https://doi.org/10.2307/4003962","url":null,"abstract":"The animal unit has been a multiple-use concept in the natural resource sciences. This paper examines the animal unit as an example of a general process of concept design, a process involving multiple options for definingthe concept, and multiple objectives and multiple applications for the concept in range management science. Based on this analysis, the animal unit is abstracted as a unit of energy demand independent of interactive considerations of forage or environment. The proposed definition optimizes the utility and universality of the concept by minimizing confounding in the concept's most important applications. The result is a simplified concept that can be used to explicitly express animal equivalences, and can be used in a web of more complex, interactive concepts and models involving human objectives, natural resources, and livestock. The animal unit and animal-unit equivalent are relatively simple examples of synthetic concepts involving communication that are central to the identity of range management science.","PeriodicalId":16918,"journal":{"name":"Journal of Range Management","volume":"75 1","pages":"113-116"},"PeriodicalIF":0.0,"publicationDate":"2004-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86269767","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pensacola bahiagrass (Paspalum notatum Flgge) swards pretreated with fertilizer nitrogen rates of 0 and 66-99 kg N ha-1 year-1 were exposed to repeated, severe defoliation (i.e., removal of all laminae) of every day (D1), every 2 days (D2), and every 4 days (D4). Responses of the grass were monitored in terms of tiller survival, lamina production and changes in the mass of the stubble-stolon-root system, in an effort to investigate the effects of nitrogen rate and defoliation frequency on defoliation tolerance, to examine differences in survival ability of tillers among tiller age cohorts, and to evaluate contribution of the stubble-stolon-root system to defoliation tolerance. With the progress of defoliation treatments over 12 weeks, the swards degraded with decreasing tiller density, lamina production, and mass of stubble and stolons. Defoliation tolerance in terms of tiller survival was influenced only by defoliation frequency (D1 approximately D2 < D4), with no significant effect of nitrogen fertilizer rate. There were no differences in survival ability of tillers among age cohorts formed before the defoliation treatments, suggesting that all tillers in bahiagrass were able to share energy and nutrients in connecting stolons under severe defoliation. It was confirmed that stolons play a key role in defoliation tolerance in bahiagrass as the main storage organ supporting aboveground parts, whereas the contribution of roots seems nil. DOI:10.2458/azu_jrm_v56i6_hirata
施用施氮量分别为0和66 ~ 99 kg N / h -1 -1 -1年的百叶草(passacola bahigrass, Paspalum notatum Flgge)，每天(D1)、每2天(D2)和每4天(D4)进行多次严重落叶(即去除所有叶层)处理。通过对分蘖存活、叶片产量和茬口-匍匐茎质量变化的监测，探讨施氮量和刈割频率对叶片脱落耐受性的影响，考察不同分蘖年龄群体间分蘖存活能力的差异，评价茬口-匍匐茎系统对叶片脱落耐受性的贡献。在12周以上，随着落叶处理的进行，禾草分蘖密度、叶片产量、残茬和匍匐茎质量逐渐下降。分蘖成活方面的落叶耐受性仅受落叶频率的影响(D1约为D2 < D4)，施氮量对分蘖成活无显著影响。在落叶处理前形成的年龄群中，分蘖的存活能力没有差异，说明在严重落叶处理下，百海草各分蘖在连接匍匐茎上能够共享能量和养分。结果表明，匍匐茎作为百喜草地上部分的主要贮藏器官，在百喜草的耐落叶性中起关键作用，而根系在百喜草耐落叶性中的作用为零。DOI: 10.2458 / azu_jrm_v56i6_hirata
{"title":"Responses of bahiagrass to nitrogen and defoliation.","authors":"M. Hirata, W. Pakiding","doi":"10.2307/4003935","DOIUrl":"https://doi.org/10.2307/4003935","url":null,"abstract":"Pensacola bahiagrass (Paspalum notatum Flgge) swards pretreated with fertilizer nitrogen rates of 0 and 66-99 kg N ha-1 year-1 were exposed to repeated, severe defoliation (i.e., removal of all laminae) of every day (D1), every 2 days (D2), and every 4 days (D4). Responses of the grass were monitored in terms of tiller survival, lamina production and changes in the mass of the stubble-stolon-root system, in an effort to investigate the effects of nitrogen rate and defoliation frequency on defoliation tolerance, to examine differences in survival ability of tillers among tiller age cohorts, and to evaluate contribution of the stubble-stolon-root system to defoliation tolerance. With the progress of defoliation treatments over 12 weeks, the swards degraded with decreasing tiller density, lamina production, and mass of stubble and stolons. Defoliation tolerance in terms of tiller survival was influenced only by defoliation frequency (D1 approximately D2 < D4), with no significant effect of nitrogen fertilizer rate. There were no differences in survival ability of tillers among age cohorts formed before the defoliation treatments, suggesting that all tillers in bahiagrass were able to share energy and nutrients in connecting stolons under severe defoliation. It was confirmed that stolons play a key role in defoliation tolerance in bahiagrass as the main storage organ supporting aboveground parts, whereas the contribution of roots seems nil. DOI:10.2458/azu_jrm_v56i6_hirata","PeriodicalId":16918,"journal":{"name":"Journal of Range Management","volume":"12 1","pages":"608-615"},"PeriodicalIF":0.0,"publicationDate":"2003-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76519436","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The fragmented, weak identity of range science has been disadvantageous to the institutions and individuals involved with it. This paper addresses a complex, interrelated group of issues related to range science, the Journal of Range Management, and the Society for Range Management. Beginning with the longstanding conception of the art of range management, it presents a concept of range management science that has multiple implications for the Society for Range Management and its flagship publication, the Journal of Range Management. The paper presents a strategically designed identity for range management science as a synthetic science, i.e., a science of synthesis, and examines the elements of diversity, synthesis, and communication that are the essence of that identity. It encourages a diverse, inclusive, synergistic character for, and offers many suggestions related to the philosophy and conduct of, the science, the Journal, and the Society. The harmonious vision of range management science that it presents is designed to give the science a strong, coherent, marketable identity. The vision is dynamic in that it can readily accommodate evolving changes. That vision is designed to make the diversity of the science and the Society work for us, rather than against us, by establishing a philosophical environment where the kind of scientific, institutional, informational, and professional synergies we need can flourish.
{"title":"Viewpoint: Empowering diversity: Envisioning, designing, and developing range management science","authors":"D. L. Scarnecchia","doi":"10.2307/4003929","DOIUrl":"https://doi.org/10.2307/4003929","url":null,"abstract":"The fragmented, weak identity of range science has been disadvantageous to the institutions and individuals involved with it. This paper addresses a complex, interrelated group of issues related to range science, the Journal of Range Management, and the Society for Range Management. Beginning with the longstanding conception of the art of range management, it presents a concept of range management science that has multiple implications for the Society for Range Management and its flagship publication, the Journal of Range Management. The paper presents a strategically designed identity for range management science as a synthetic science, i.e., a science of synthesis, and examines the elements of diversity, synthesis, and communication that are the essence of that identity. It encourages a diverse, inclusive, synergistic character for, and offers many suggestions related to the philosophy and conduct of, the science, the Journal, and the Society. The harmonious vision of range management science that it presents is designed to give the science a strong, coherent, marketable identity. The vision is dynamic in that it can readily accommodate evolving changes. That vision is designed to make the diversity of the science and the Society work for us, rather than against us, by establishing a philosophical environment where the kind of scientific, institutional, informational, and professional synergies we need can flourish.","PeriodicalId":16918,"journal":{"name":"Journal of Range Management","volume":"121 1","pages":"558"},"PeriodicalIF":0.0,"publicationDate":"2003-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80405161","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2003-11-01DOI: 10.2458/azu_jrm_v56i6_pylypec
B. Pylypec, J. Romo
The effects of early spring burning on current year standing crop, litter, and total standing crop (current year standing crop plus litter) were examined in Festuca- and Stipa-Agropyron-dominated communities in central Saskatchewan over an 11-year period in a paired design with burned sites compared to adjacent control sites that were not burned. In Festuca communities current year standing crop was reduced in the first and third years (P = 0.010) after burning. Burning Stipa-Agropyron-communities tended to reduce current year standing crop, but the differences were not significant (P < 0.050) compared to control. Increasing precipitation stimulated current year standing crop after burning Festuca (P < 0.001, r2 = 0.33) and Stipa-Agropyron (P < 0.001, r2 = 0.55) communities. Litter and current year standing crop were correlated (R2 = 0.24, P = 0.002) for Festuca indicating beneficial and detrimental effects of litter on production at low and high amounts, respectively. Litter and current year standing crop were not correlated (P = 0.964) for Stipa-Agropyron. In both communities total standing crop increased until about the eighth year after burning while the mass of litter appeared to reach a plateau around 11 years. DOI:10.2458/azu_jrm_v56i6_pylypec
{"title":"Long-term effects of burning Festuca and Stipa-Agropyron grasslands.","authors":"B. Pylypec, J. Romo","doi":"10.2458/azu_jrm_v56i6_pylypec","DOIUrl":"https://doi.org/10.2458/azu_jrm_v56i6_pylypec","url":null,"abstract":"The effects of early spring burning on current year standing crop, litter, and total standing crop (current year standing crop plus litter) were examined in Festuca- and Stipa-Agropyron-dominated communities in central Saskatchewan over an 11-year period in a paired design with burned sites compared to adjacent control sites that were not burned. In Festuca communities current year standing crop was reduced in the first and third years (P = 0.010) after burning. Burning Stipa-Agropyron-communities tended to reduce current year standing crop, but the differences were not significant (P < 0.050) compared to control. Increasing precipitation stimulated current year standing crop after burning Festuca (P < 0.001, r2 = 0.33) and Stipa-Agropyron (P < 0.001, r2 = 0.55) communities. Litter and current year standing crop were correlated (R2 = 0.24, P = 0.002) for Festuca indicating beneficial and detrimental effects of litter on production at low and high amounts, respectively. Litter and current year standing crop were not correlated (P = 0.964) for Stipa-Agropyron. In both communities total standing crop increased until about the eighth year after burning while the mass of litter appeared to reach a plateau around 11 years. DOI:10.2458/azu_jrm_v56i6_pylypec","PeriodicalId":16918,"journal":{"name":"Journal of Range Management","volume":"19 1","pages":"640-645"},"PeriodicalIF":0.0,"publicationDate":"2003-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85109336","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2003-11-01DOI: 10.2458/AZU_JRM_V56I6_MERRILL
E. Merrill, P. J. Colberg
Wet meadows are some of the most productive communities in the northern Rocky Mountains, USA but are also among the most sensitive to grazing by native ungulates and domestic livestock. These meadows typically are inundated with floodwater in spring and early summer but are relatively dry in summer. To determine the interactive effects of clipping and flooding on plant recovery after clipping, we subjected plants of tufted hairgrass (Deschampsia caespitosa (L.) Beauv) to 6-week and 10-week waterlogging treatments in combination with 1 and 2 clipping events, with and without dung amendment in a greenhouse experiment. The experiment was designed to mimic early and late growing-season patterns of herbivory by native and domestic herbivores on a dominant species of wet meadows of this region. Waterlogged plants produced a higher percentage of roots at the surface, elongated stems to the first axial leaf, increased the proportion of tillers that flowered, but increased aboveground yield and tiller height only with the addition of dung. Root biomass declined with waterlogging when dung was not added, and a second defoliation exacerbated the negative effects of waterlogging on roots. Defoliation with short-duration waterlogging increased shoot nitrogen (N) concentration and N yield/root biomass, while continuous waterlogging reduced shoot N concentration of aboveground biomass. Dung amendment did not reverse this effect. Although extended flooding in combination with moderate rates of defoliation did not reduce aboveground biomass of Deschampsia caespitosa, it aggravated total root loss, caused shifts to a shallower root distribution, and altered N concentration of aboveground biomass for herbivores. DOI:10.2458/azu_jrm_v56i6_merrill
{"title":"Defoliation, waterlogging and dung influences allocation patterns of Deschampsia caespitosa.","authors":"E. Merrill, P. J. Colberg","doi":"10.2458/AZU_JRM_V56I6_MERRILL","DOIUrl":"https://doi.org/10.2458/AZU_JRM_V56I6_MERRILL","url":null,"abstract":"Wet meadows are some of the most productive communities in the northern Rocky Mountains, USA but are also among the most sensitive to grazing by native ungulates and domestic livestock. These meadows typically are inundated with floodwater in spring and early summer but are relatively dry in summer. To determine the interactive effects of clipping and flooding on plant recovery after clipping, we subjected plants of tufted hairgrass (Deschampsia caespitosa (L.) Beauv) to 6-week and 10-week waterlogging treatments in combination with 1 and 2 clipping events, with and without dung amendment in a greenhouse experiment. The experiment was designed to mimic early and late growing-season patterns of herbivory by native and domestic herbivores on a dominant species of wet meadows of this region. Waterlogged plants produced a higher percentage of roots at the surface, elongated stems to the first axial leaf, increased the proportion of tillers that flowered, but increased aboveground yield and tiller height only with the addition of dung. Root biomass declined with waterlogging when dung was not added, and a second defoliation exacerbated the negative effects of waterlogging on roots. Defoliation with short-duration waterlogging increased shoot nitrogen (N) concentration and N yield/root biomass, while continuous waterlogging reduced shoot N concentration of aboveground biomass. Dung amendment did not reverse this effect. Although extended flooding in combination with moderate rates of defoliation did not reduce aboveground biomass of Deschampsia caespitosa, it aggravated total root loss, caused shifts to a shallower root distribution, and altered N concentration of aboveground biomass for herbivores. DOI:10.2458/azu_jrm_v56i6_merrill","PeriodicalId":16918,"journal":{"name":"Journal of Range Management","volume":"44 1","pages":"634-639"},"PeriodicalIF":0.0,"publicationDate":"2003-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89152482","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
D. L. Scarnecchia, R. Barnes, C. J. Nelson, M. Collins, K. Moore
{"title":"Forages. An Introduction to Grassland Agriculture. Vol. 1","authors":"D. L. Scarnecchia, R. Barnes, C. J. Nelson, M. Collins, K. Moore","doi":"10.2307/4003946","DOIUrl":"https://doi.org/10.2307/4003946","url":null,"abstract":"","PeriodicalId":16918,"journal":{"name":"Journal of Range Management","volume":"23 1","pages":"673"},"PeriodicalIF":0.0,"publicationDate":"2003-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73152052","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2003-11-01DOI: 10.2458/AZU_JRM_V56I6_JOHNSON
Douglas A. Johnson, K. H. Asay, K. Jensen
Selection for carbon isotope discrimination (delta) has potential for improving water-use efficiency in cool-season grasses. An understanding of how delta is affected by differential water application and its association with dry mater yield may be helpful in identifying the best cool-season grass species for breeding and improvement, and may assist in designing selection and breeding procedures for improving cool-season grasses. We designed a study to evaluate the response of delta and dry matter yield to a gradient of water application in 14 cool-season, perennial grasses. The grasses were established in a rainout shelter facility equipped with a line-source irrigation system to study the: i) trends in dry matter yield across 6 water levels (WL-1 through 6, ranging from 981 to 64 mm water applied) and delta across 3 water levels (WL-1, 3, and 5), ii) grass x water level interactions for these traits, and iii) relationship between dry matter yield and delta in these grasses across a 2-year period. When averaged across years, the grasses differed significantly for delta at the highest (WL-1) and lowest (WL-5) water levels, but not at WL-3. Reductions in delta were strongly linear from WL-1 to WL-5, and although some inconsistencies were evident, the trend was similar for all grasses. Grasses differed significantly for dry matter yield at each of the water levels. Although the change in dry matter yield was mostly linear across water levels, the trend was not consistent among the grasses. In general, delta was not closely associated with dry matter yield; however, some exceptions with high dry matter yield and high delta were evident. This lack of close association between dry matter yield and delta in these 14 grasses suggests that breeding efforts to improve these grasses should involve simultaneous selection for dry matter yield and delta. DOI:10.2458/azu_jrm_v56i6_johnson
{"title":"Carbon isotope discrimination and yield in 14 cool-season grasses","authors":"Douglas A. Johnson, K. H. Asay, K. Jensen","doi":"10.2458/AZU_JRM_V56I6_JOHNSON","DOIUrl":"https://doi.org/10.2458/AZU_JRM_V56I6_JOHNSON","url":null,"abstract":"Selection for carbon isotope discrimination (delta) has potential for improving water-use efficiency in cool-season grasses. An understanding of how delta is affected by differential water application and its association with dry mater yield may be helpful in identifying the best cool-season grass species for breeding and improvement, and may assist in designing selection and breeding procedures for improving cool-season grasses. We designed a study to evaluate the response of delta and dry matter yield to a gradient of water application in 14 cool-season, perennial grasses. The grasses were established in a rainout shelter facility equipped with a line-source irrigation system to study the: i) trends in dry matter yield across 6 water levels (WL-1 through 6, ranging from 981 to 64 mm water applied) and delta across 3 water levels (WL-1, 3, and 5), ii) grass x water level interactions for these traits, and iii) relationship between dry matter yield and delta in these grasses across a 2-year period. When averaged across years, the grasses differed significantly for delta at the highest (WL-1) and lowest (WL-5) water levels, but not at WL-3. Reductions in delta were strongly linear from WL-1 to WL-5, and although some inconsistencies were evident, the trend was similar for all grasses. Grasses differed significantly for dry matter yield at each of the water levels. Although the change in dry matter yield was mostly linear across water levels, the trend was not consistent among the grasses. In general, delta was not closely associated with dry matter yield; however, some exceptions with high dry matter yield and high delta were evident. This lack of close association between dry matter yield and delta in these 14 grasses suggests that breeding efforts to improve these grasses should involve simultaneous selection for dry matter yield and delta. DOI:10.2458/azu_jrm_v56i6_johnson","PeriodicalId":16918,"journal":{"name":"Journal of Range Management","volume":"575 1","pages":"654-659"},"PeriodicalIF":0.0,"publicationDate":"2003-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77788554","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2003-11-01DOI: 10.2458/AZU_JRM_V56I6_NEIL
K. Neil, R. Tiller, S. Faeth
Water availability in the germination stage of plants is crucial for seed germination and as a resource for developing seedlings. The effect of osmotic potential on percent germination and time to germination for big sacaton (Sporobolus wrightii Munro) and Arizona fescue (Festuca arizonica Vasey) was investigated. We predicted that seeds native to semi-arid environments would germinate at osmotic potentials less negative than about -1.5 MPa, the permanent wilting point (PWP) of many agronomic grasses. In addition, the systemic, asexual endophyte Neotyphodium is transmitted through the seed in Arizona fescue and is thought to increase germination of its host. Therefore, we also tested for an effect of the endophyte on germination and time to germination of Arizona fescue under varying osmotic potentials. To test for minimum osmotic potential supporting germination, big sacaton and Arizona fescue seeds were placed on acetate membranes in contact with PEG solutions of varying osmotic potentials for 2 weeks. Both grasses germinated at 50% of maximum germination (at soil saturation) at and below the standard PWP (-1.5 Mpa). Big sacaton and Arizona fescue germinated at 64% and 60% at -1.5 MPa, respectively, and Arizona fescue germinated at 35% at -1.8 MPa (70% was the maximum at saturation). The presence of the Neotyphodium endophyte did not affect percent or time to germination of Arizona fescue at any of the osmotic potentials tested. DOI:10.2458/azu_jrm_v56i6_neil
{"title":"Big sacaton and endophyte-infected Arizona fescue germination under water stress.","authors":"K. Neil, R. Tiller, S. Faeth","doi":"10.2458/AZU_JRM_V56I6_NEIL","DOIUrl":"https://doi.org/10.2458/AZU_JRM_V56I6_NEIL","url":null,"abstract":"Water availability in the germination stage of plants is crucial for seed germination and as a resource for developing seedlings. The effect of osmotic potential on percent germination and time to germination for big sacaton (Sporobolus wrightii Munro) and Arizona fescue (Festuca arizonica Vasey) was investigated. We predicted that seeds native to semi-arid environments would germinate at osmotic potentials less negative than about -1.5 MPa, the permanent wilting point (PWP) of many agronomic grasses. In addition, the systemic, asexual endophyte Neotyphodium is transmitted through the seed in Arizona fescue and is thought to increase germination of its host. Therefore, we also tested for an effect of the endophyte on germination and time to germination of Arizona fescue under varying osmotic potentials. To test for minimum osmotic potential supporting germination, big sacaton and Arizona fescue seeds were placed on acetate membranes in contact with PEG solutions of varying osmotic potentials for 2 weeks. Both grasses germinated at 50% of maximum germination (at soil saturation) at and below the standard PWP (-1.5 Mpa). Big sacaton and Arizona fescue germinated at 64% and 60% at -1.5 MPa, respectively, and Arizona fescue germinated at 35% at -1.8 MPa (70% was the maximum at saturation). The presence of the Neotyphodium endophyte did not affect percent or time to germination of Arizona fescue at any of the osmotic potentials tested. DOI:10.2458/azu_jrm_v56i6_neil","PeriodicalId":16918,"journal":{"name":"Journal of Range Management","volume":"43 1","pages":"616-622"},"PeriodicalIF":0.0,"publicationDate":"2003-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78545461","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2003-11-01DOI: 10.2458/AZU_JRM_V56I6_YOUNG
James A. Young, C. Clements, R. Wilson
Repeatedly during the late 19th and early 20 th century, exotic weeds were introduced to the sagebrush (Artemisia)/bunchgrass rangelands of the Great Basin. Once established these weeds became invasive, spreading without the conscious efforts of humans. Brassica elongata ssp. integrifolia (Boiss.) Breistr. offers evidence this process of introduction still continues. Brassica elongata ssp. integrifolia is native to southeastern Europe and Asia. It was first collected in North America near Portland, Ore. in 1911. This initial infestation apparently did not persist. The next collection was near Eureka, Nev. in 1968. Currently, Brassica elongata ssp. integrifolia has spread about 200 km east and west along U S Highway 50 and 100 km north and south of the highway along secondary roads. As a first step in understanding the seed and seedbed ecology of this new invasive weed we investigated the germination of seeds at a wide range of constant and alternating temperatures. This plant produces abundant seeds that germinate over a wide range of constant and alternating temperatures. Maximum germination ranged from 84 to 94% depending on the year of seed production. Germination was extremely limited at very cold seedbed temperatures and low at the cold category of seedbed temperatures. Germination at these temperature is a competitive advantage for other exotic species on Great Basin rangelands. DOI:10.2458/azu_jrm_v56i6_young
{"title":"Brassica elongata ssp. integrifolia seed germination.","authors":"James A. Young, C. Clements, R. Wilson","doi":"10.2458/AZU_JRM_V56I6_YOUNG","DOIUrl":"https://doi.org/10.2458/AZU_JRM_V56I6_YOUNG","url":null,"abstract":"Repeatedly during the late 19th and early 20 th century, exotic weeds were introduced to the sagebrush (Artemisia)/bunchgrass rangelands of the Great Basin. Once established these weeds became invasive, spreading without the conscious efforts of humans. Brassica elongata ssp. integrifolia (Boiss.) Breistr. offers evidence this process of introduction still continues. Brassica elongata ssp. integrifolia is native to southeastern Europe and Asia. It was first collected in North America near Portland, Ore. in 1911. This initial infestation apparently did not persist. The next collection was near Eureka, Nev. in 1968. Currently, Brassica elongata ssp. integrifolia has spread about 200 km east and west along U S Highway 50 and 100 km north and south of the highway along secondary roads. As a first step in understanding the seed and seedbed ecology of this new invasive weed we investigated the germination of seeds at a wide range of constant and alternating temperatures. This plant produces abundant seeds that germinate over a wide range of constant and alternating temperatures. Maximum germination ranged from 84 to 94% depending on the year of seed production. Germination was extremely limited at very cold seedbed temperatures and low at the cold category of seedbed temperatures. Germination at these temperature is a competitive advantage for other exotic species on Great Basin rangelands. DOI:10.2458/azu_jrm_v56i6_young","PeriodicalId":16918,"journal":{"name":"Journal of Range Management","volume":"173 1","pages":"623-626"},"PeriodicalIF":0.0,"publicationDate":"2003-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76765512","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2003-11-01DOI: 10.2458/AZU_JRM_V56I6_HEATON
C. B. Heaton, X. Wu, R. Ansley
Several studies have examined the impact of woody plant (i.e., brush) management efforts on mesquite (Prosopis glandulosa Torr.) cover and associated ecological impacts, but little research has been done on spatial attributes of vegetation following mesquite management treatments. This study examined the effects of above-ground mortality (triclopyr or 2,4,5-T) and whole-plant mortality (clopyralid or triclopyr+clopyralid) mesquite herbicide treatments on the canopy cover and spatial pattern of vegetation in a mesquite savanna and the associated ecological and management implications. A GIS and landscape analysis based on classified color-infrared aerial photos were used to quantify the spatial patterns of woody and non-woody vegetation. The results indicate long-term (> 20 year) persistence of disturbance effects on the amount and spatial pattern of woody vegetation. Significant differences in spatial pattern were found between the herbicide treatments and the non-treated plots, as well as between the above-ground mortality (AGM) and whole-plant mortality (WPM) herbicide treatments. The differential changes in the amount and spatial distribution of woody cover under different treatments resulted in substantially different spatial distributions of non-woody vegetation with respect to distance to nearest woody vegetation. These spatial variations may influence production and zonation of herbaceous vegetation due to modified shading and root competition from mesquite. Our results support observations of differential rates of mesquite seedling recruitment and establishment between treatment types. We conclude that consideration of spatial pattern should be an important component of future brush management plans. DOI:10.2458/azu_jrm_v56i6_heaton
{"title":"Herbicide effects on vegetation spatial patterns in a mesquite savanna.","authors":"C. B. Heaton, X. Wu, R. Ansley","doi":"10.2458/AZU_JRM_V56I6_HEATON","DOIUrl":"https://doi.org/10.2458/AZU_JRM_V56I6_HEATON","url":null,"abstract":"Several studies have examined the impact of woody plant (i.e., brush) management efforts on mesquite (Prosopis glandulosa Torr.) cover and associated ecological impacts, but little research has been done on spatial attributes of vegetation following mesquite management treatments. This study examined the effects of above-ground mortality (triclopyr or 2,4,5-T) and whole-plant mortality (clopyralid or triclopyr+clopyralid) mesquite herbicide treatments on the canopy cover and spatial pattern of vegetation in a mesquite savanna and the associated ecological and management implications. A GIS and landscape analysis based on classified color-infrared aerial photos were used to quantify the spatial patterns of woody and non-woody vegetation. The results indicate long-term (> 20 year) persistence of disturbance effects on the amount and spatial pattern of woody vegetation. Significant differences in spatial pattern were found between the herbicide treatments and the non-treated plots, as well as between the above-ground mortality (AGM) and whole-plant mortality (WPM) herbicide treatments. The differential changes in the amount and spatial distribution of woody cover under different treatments resulted in substantially different spatial distributions of non-woody vegetation with respect to distance to nearest woody vegetation. These spatial variations may influence production and zonation of herbaceous vegetation due to modified shading and root competition from mesquite. Our results support observations of differential rates of mesquite seedling recruitment and establishment between treatment types. We conclude that consideration of spatial pattern should be an important component of future brush management plans. DOI:10.2458/azu_jrm_v56i6_heaton","PeriodicalId":16918,"journal":{"name":"Journal of Range Management","volume":"4 1","pages":"627-633"},"PeriodicalIF":0.0,"publicationDate":"2003-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91135894","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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