Pub Date : 2003-07-01DOI: 10.2458/AZU_JRM_V56I4_CHRISTENSEN
L. Christensen, M. Coughenour, J. Ellis, Zuozhong Chen
The sustainability and resilience of an Asian typical steppe grazing ecosystem was assessed by determining thresholds and stable states with an ecosystem simulation model. This analysis used the Savanna model to simulate spatial climate, vegetation, and livestock grazing dynamics, at 14 different stocking rates (5.5-59.8 AUY km-2). Grazing effects on vegetation were assessed, including effects on primary production, vegetation composition, and root biomass. Simulations were run for 100 years: 50 years to examine sustainability and 50 years to examine resilience of the system. Results showed that a grazing intensity (1-g/u; g = biomass in grazed area, u = biomass in ungrazed area) of 0.49 was sustainable for this particular system. This region was resilient to grazing up to the intensity of 0.49, where the system remained dominated by herbaceous production. Grazing intensities higher than 0.49, in combination with low precipitation events, resulted in decreased herbaceous net primary production and root biomass, and increased shrub net primary production and root biomass. Herbaceous vegetation was unable to gain a competitive advantage over shrubs in areas where grazing intensities were above 0.49; consequently, the system shifted to a stable shrub-dominated state that could not return its original composition even without further grazing. DOI:10.2458/azu_jrm_v56i4_christensen
{"title":"Sustainability of Inner Mongolian grasslands: application of the Savanna model","authors":"L. Christensen, M. Coughenour, J. Ellis, Zuozhong Chen","doi":"10.2458/AZU_JRM_V56I4_CHRISTENSEN","DOIUrl":"https://doi.org/10.2458/AZU_JRM_V56I4_CHRISTENSEN","url":null,"abstract":"The sustainability and resilience of an Asian typical steppe grazing ecosystem was assessed by determining thresholds and stable states with an ecosystem simulation model. This analysis used the Savanna model to simulate spatial climate, vegetation, and livestock grazing dynamics, at 14 different stocking rates (5.5-59.8 AUY km-2). Grazing effects on vegetation were assessed, including effects on primary production, vegetation composition, and root biomass. Simulations were run for 100 years: 50 years to examine sustainability and 50 years to examine resilience of the system. Results showed that a grazing intensity (1-g/u; g = biomass in grazed area, u = biomass in ungrazed area) of 0.49 was sustainable for this particular system. This region was resilient to grazing up to the intensity of 0.49, where the system remained dominated by herbaceous production. Grazing intensities higher than 0.49, in combination with low precipitation events, resulted in decreased herbaceous net primary production and root biomass, and increased shrub net primary production and root biomass. Herbaceous vegetation was unable to gain a competitive advantage over shrubs in areas where grazing intensities were above 0.49; consequently, the system shifted to a stable shrub-dominated state that could not return its original composition even without further grazing. DOI:10.2458/azu_jrm_v56i4_christensen","PeriodicalId":16918,"journal":{"name":"Journal of Range Management","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79187559","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}
In many riparian corridors of the semi-arid west, stream incision has resulted in lowered water tables, basin big sagebrush (Artemisia tridentata var. tridentata Nutt.) encroachment and the loss of the dominant herbaceous vegetation. To determine the potential for restoring basin big sagebrush-dominated riparian corridors to greater herbaceous cover, a fall prescribed burn on sites with relatively shallow (-153 to -267 cm) and deep (-268 to > or = -300 cm) water tables was conducted. We evaluated the separate and interacting effects of water table depth and burning on total soil C and N, soil nutrient availability, and soil enzyme activities by microsite (sagebrush subcanopy, sagebrush interspace), and soil depth (ash/liter, 0-2, 2-5, and 10-20 cm). Three years after the prescribed burn, tissue nutrient content in silvery lupine (Lupinus argenteus Pursh) and Douglas sedge (Carex douglasii Boott), by microsite, growing in burned and unburned areas of 1 shallow water table site was measured. Influence of fire on soil attributes was largely limited to the top 5 cm. As a consequence of prescribed burning, deep water table sites lost relatively more N and C from litter horizons and released more aqueous-soluble Ca+2 from 0-2 cm mineral horizons than did corresponding horizons from shallow water table sites. Overall, compared to unburned controls, burning: (1) increased aqueous-extractable SO4(-2), K+, and KCl-extractable NH4+, (2) decreased activities of the enzymes asparaginase, urease and acid-phosphatase, and (3) decreased KCl-extractable NO3- and aqueous-soluble ortho-P. Out of 16 measured soil attributes reported, 7 were influenced by a microsite main effect and/or interaction. New tissue of silvery lupine on burned plots had greater N, greater Zn and Fe (only on subcanopy microsites) and less Ca than plants on control plots; new tissue of Douglas sedge had greater S and less Na, P, and Zn. The results indicate that burning alone is an appropriate restoration treatment for shallow water table sites because of minimal C and N loss and increased available nutrients for regrowth of understory herbaceous species. Deep water table sites require a burning prescription that minimizes fire severity because of higher potential C and N loss, and reseeding due to a lack of perennial understory herbaceous species and more xeric conditions. DOI:10.2458/azu_jrm_v56i4_blank
{"title":"Restoring riparian corridors with fire: effects on soil and vegetation","authors":"R. Blank, J. Chambers, D. C. Zamudio","doi":"10.2307/4004044","DOIUrl":"https://doi.org/10.2307/4004044","url":null,"abstract":"In many riparian corridors of the semi-arid west, stream incision has resulted in lowered water tables, basin big sagebrush (Artemisia tridentata var. tridentata Nutt.) encroachment and the loss of the dominant herbaceous vegetation. To determine the potential for restoring basin big sagebrush-dominated riparian corridors to greater herbaceous cover, a fall prescribed burn on sites with relatively shallow (-153 to -267 cm) and deep (-268 to > or = -300 cm) water tables was conducted. We evaluated the separate and interacting effects of water table depth and burning on total soil C and N, soil nutrient availability, and soil enzyme activities by microsite (sagebrush subcanopy, sagebrush interspace), and soil depth (ash/liter, 0-2, 2-5, and 10-20 cm). Three years after the prescribed burn, tissue nutrient content in silvery lupine (Lupinus argenteus Pursh) and Douglas sedge (Carex douglasii Boott), by microsite, growing in burned and unburned areas of 1 shallow water table site was measured. Influence of fire on soil attributes was largely limited to the top 5 cm. As a consequence of prescribed burning, deep water table sites lost relatively more N and C from litter horizons and released more aqueous-soluble Ca+2 from 0-2 cm mineral horizons than did corresponding horizons from shallow water table sites. Overall, compared to unburned controls, burning: (1) increased aqueous-extractable SO4(-2), K+, and KCl-extractable NH4+, (2) decreased activities of the enzymes asparaginase, urease and acid-phosphatase, and (3) decreased KCl-extractable NO3- and aqueous-soluble ortho-P. Out of 16 measured soil attributes reported, 7 were influenced by a microsite main effect and/or interaction. New tissue of silvery lupine on burned plots had greater N, greater Zn and Fe (only on subcanopy microsites) and less Ca than plants on control plots; new tissue of Douglas sedge had greater S and less Na, P, and Zn. The results indicate that burning alone is an appropriate restoration treatment for shallow water table sites because of minimal C and N loss and increased available nutrients for regrowth of understory herbaceous species. Deep water table sites require a burning prescription that minimizes fire severity because of higher potential C and N loss, and reseeding due to a lack of perennial understory herbaceous species and more xeric conditions. DOI:10.2458/azu_jrm_v56i4_blank","PeriodicalId":16918,"journal":{"name":"Journal of Range Management","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86632329","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}
'Romerillo' (Baccharis coridifolia DC), 'duraznillo negro' (Cestrum parqui L'Herit.), and 'sunchillo' (Wedelia glauca (Ort.) Hoff.) are highly toxic species producing important economic losses of livestock in Argentina. This study assessed the accuracy and precision in the estimation of the percentage and the mass of these species in the ingesta and feces of sheep experimentally poisoned. This study also evaluated whether the quantified percentage and the calculated mass of each toxic species in the rumen+reticulum, the easiest region to sample, are good estimates of their relative consumption. Results indicate that if species fragment density is quantified, and the percentages of non recognized fragments of the toxic species in their in vitro digestion residues are accounted for (attributing some proportion of the unidentified fragment pool to the target species), estimations are accurate, but their precision differ among species. For a 3 sheep sample, the average mass estimated by microhistological analysis represented 92.3 +/- 5.8 (romerillo), 96.5 +/- 17.3 (duraznillo negro), and 92.0 +/- 12.5% (sunchillo) (P 0.05) from those in the rumen+reticulum. For the evaluated species, the microhistological analysis of the rumen+reticulum not only confirmed the ingestion of the toxic species, but also adequately estimated the percentage in which they were ingested. DOI:10.2458/azu_jrm_v56i4_cid
{"title":"Acute toxic plant estimation in grazing sheep ingesta and feces","authors":"M. S. Cid, T. López, C. Yagueddú, M. Brizuela","doi":"10.2307/4004038","DOIUrl":"https://doi.org/10.2307/4004038","url":null,"abstract":"'Romerillo' (Baccharis coridifolia DC), 'duraznillo negro' (Cestrum parqui L'Herit.), and 'sunchillo' (Wedelia glauca (Ort.) Hoff.) are highly toxic species producing important economic losses of livestock in Argentina. This study assessed the accuracy and precision in the estimation of the percentage and the mass of these species in the ingesta and feces of sheep experimentally poisoned. This study also evaluated whether the quantified percentage and the calculated mass of each toxic species in the rumen+reticulum, the easiest region to sample, are good estimates of their relative consumption. Results indicate that if species fragment density is quantified, and the percentages of non recognized fragments of the toxic species in their in vitro digestion residues are accounted for (attributing some proportion of the unidentified fragment pool to the target species), estimations are accurate, but their precision differ among species. For a 3 sheep sample, the average mass estimated by microhistological analysis represented 92.3 +/- 5.8 (romerillo), 96.5 +/- 17.3 (duraznillo negro), and 92.0 +/- 12.5% (sunchillo) (P 0.05) from those in the rumen+reticulum. For the evaluated species, the microhistological analysis of the rumen+reticulum not only confirmed the ingestion of the toxic species, but also adequately estimated the percentage in which they were ingested. DOI:10.2458/azu_jrm_v56i4_cid","PeriodicalId":16918,"journal":{"name":"Journal of Range Management","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78149776","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 : 2003-05-01DOI: 10.2458/AZU_JRM_V56I3_SPAETH
K. Spaeth, F. Pierson, M. Weltz, W. H. Blackburn
The Universal Soil Loss Equation (USLE) and the Revised Universal Soil Loss Equation (RUSLE 1.06) were evaluated with rainfall simulation data from a diverse set of rangeland vegetation types (8 states, 22 sites, 132 plots). Dry, wet, and very-wet rainfall simulation treatments were applied to the study plots within a 2-day period. The rainfall simulation rate was 65mm/hr for the dry and wet simulation treatments and alternated between 65-130 mm/hr for the very-wet treatment. Average soil loss for all plots for the representative simulation runs were: 0.011 kg/m2, 0.007 kg/m2, and 0.035 kg/m2 for the dry, wet, and very-wet simulation treatments, respectively. The Nash-Sutcliffe Model efficiencies (R2eff) of the USLE for the dry, wet, very-wet simulation treatments and sum of all soil loss measured in the three composite simulation treatments (pooled data) were negative. This indicates that the observed mean measured soil loss from the field rainfall simulations is better than predicted USLE soil loss. The USLE tended to consistently overpredict soil loss for all 3 rainfall simulation treatments. As the USLE predicted values increased in magnitude, the error variance between predicted and observed soil loss increased. Nash-Sutcliffe model efficiency for the RUSLE was also negative, except for the dry run simulation treatment [R2eff = 0.16 using RUSLE cover management (C) subfactor parameters from the RUSLE manual (C(table)), NRCS soil erodibility factor (K); and R2eff = 0.17 with C(table) and K estimated from the soil-erodibility nomograph]. In comparison to the USLE, there was less error between observed and RUSLE predicted soil loss. The RUSLE error variances showed a consistent trend of underpredicted soil loss among the 3 rainfall simulation treatments. When actual field measured root biomass, plant production and soil random roughness values were used in calculating the RUSLE C subfactors: the R2eff values for the dry, wet, very-wet rainfall simulation treatments and the pooled data were all negative. DOI:10.2458/azu_jrm_v56i3_spaeth
{"title":"Evaluation of USLE and RUSLE estimated soil loss on rangeland.","authors":"K. Spaeth, F. Pierson, M. Weltz, W. H. Blackburn","doi":"10.2458/AZU_JRM_V56I3_SPAETH","DOIUrl":"https://doi.org/10.2458/AZU_JRM_V56I3_SPAETH","url":null,"abstract":"The Universal Soil Loss Equation (USLE) and the Revised Universal Soil Loss Equation (RUSLE 1.06) were evaluated with rainfall simulation data from a diverse set of rangeland vegetation types (8 states, 22 sites, 132 plots). Dry, wet, and very-wet rainfall simulation treatments were applied to the study plots within a 2-day period. The rainfall simulation rate was 65mm/hr for the dry and wet simulation treatments and alternated between 65-130 mm/hr for the very-wet treatment. Average soil loss for all plots for the representative simulation runs were: 0.011 kg/m2, 0.007 kg/m2, and 0.035 kg/m2 for the dry, wet, and very-wet simulation treatments, respectively. The Nash-Sutcliffe Model efficiencies (R2eff) of the USLE for the dry, wet, very-wet simulation treatments and sum of all soil loss measured in the three composite simulation treatments (pooled data) were negative. This indicates that the observed mean measured soil loss from the field rainfall simulations is better than predicted USLE soil loss. The USLE tended to consistently overpredict soil loss for all 3 rainfall simulation treatments. As the USLE predicted values increased in magnitude, the error variance between predicted and observed soil loss increased. Nash-Sutcliffe model efficiency for the RUSLE was also negative, except for the dry run simulation treatment [R2eff = 0.16 using RUSLE cover management (C) subfactor parameters from the RUSLE manual (C(table)), NRCS soil erodibility factor (K); and R2eff = 0.17 with C(table) and K estimated from the soil-erodibility nomograph]. In comparison to the USLE, there was less error between observed and RUSLE predicted soil loss. The RUSLE error variances showed a consistent trend of underpredicted soil loss among the 3 rainfall simulation treatments. When actual field measured root biomass, plant production and soil random roughness values were used in calculating the RUSLE C subfactors: the R2eff values for the dry, wet, very-wet rainfall simulation treatments and the pooled data were all negative. DOI:10.2458/azu_jrm_v56i3_spaeth","PeriodicalId":16918,"journal":{"name":"Journal of Range Management","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86787948","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 : 2003-05-01DOI: 10.2458/AZU_JRM_V56I3_AGUILERA
M. Aguilera, D. Steinaker, M. Demaría
Vegetation influences runoff and soil losses in semiarid environments. In shrublands of Central Argentina, grazing has resulted in a reduction of plant cover, an increase in the proportion of bare soil, and eroded soils. Patterns of runoff and soil losses affected by seeding cultivated grasses were evaluated. We investigated the effects of roller-seeding of Cenchrus ciliaris L and the influence of microsite cover-type on the dynamics of water erosion. Evaluated cover-types were: bare soil, shortgrass cover, and tallgrass cover. Evaluations were performed 2 growing seasons after roller-seeding. The experimental design was a split-plot, replicated 3 times using a portable rainfall simulator. After simulation runs of 45 min at an average rate of 110 mm hour-1, runoff of tallgrass cover was the least, whereas bare soil and shortgrass cover had similar values (ca. 60%). However, both types of grass cover reduced soil splash compared to the bare soil cover-type. An exponential function between runoff and soil loss suggested that increasing runoff beyond 60% produced an abrupt rising of sediment loss. Roller-seeding did not influence runoff or sediment loss at the microsite-scale. Nevertheless, roller-seeding reduced the proportion of area covered by microsites prone to erosion (bare soil and shortgrass cover-types) at the whole plot level. We propose that any management tool that promotes the replacement of bare soil and shortgrasses by tallgrasses should reduce runoff and increase forage productivity via amelioration of hydrologic conditions of the rangeland site. Conversely, overgrazing will result in more bare soil, increasing runoff, and further intensifying the loss of sediments by detachment. DOI:10.2458/azu_jrm_v56i3_aguilera
在半干旱环境中，植被影响径流和土壤流失。在阿根廷中部的灌木丛中，放牧导致植物覆盖减少，裸露土壤比例增加和土壤侵蚀。评估了播播栽培牧草对径流和土壤流失的影响模式。研究了卷播对毛蕊草(Cenchrus ciliaris L .)土壤水分侵蚀动态的影响，以及不同覆盖类型对土壤水分侵蚀动态的影响。被评价的植被类型为:裸地、矮草覆盖和高草覆盖。轮播后2个生长季进行评价。实验设计为分离式图，使用便携式降雨模拟器重复3次。在以平均110 mm小时-1的速率模拟运行45分钟后，高草覆盖的径流量最少，而裸土和短草覆盖的径流量相似(约为60%)。然而，与裸露的土壤覆盖相比，两种类型的草覆盖都减少了土壤飞溅。径流量与土壤流失量之间的指数函数表明，径流量超过60%时，泥沙流失量急剧上升。在微站点尺度上，滚轮播种对径流和泥沙损失没有影响。然而，在整个地块水平上，滚播减少了易受侵蚀的微型场地(裸土和短草覆盖类型)覆盖的面积比例。我们建议任何促进高草取代裸地和矮草的管理工具都应该通过改善牧场的水文条件来减少径流和提高饲料生产力。相反，过度放牧将导致更多的裸露土壤，增加径流，并进一步加剧分离导致的沉积物损失。DOI: 10.2458 / azu_jrm_v56i3_aguilera
{"title":"Runoff and soil loss in undisturbed and roller-seeded shrublands of semiarid Argentina.","authors":"M. Aguilera, D. Steinaker, M. Demaría","doi":"10.2458/AZU_JRM_V56I3_AGUILERA","DOIUrl":"https://doi.org/10.2458/AZU_JRM_V56I3_AGUILERA","url":null,"abstract":"Vegetation influences runoff and soil losses in semiarid environments. In shrublands of Central Argentina, grazing has resulted in a reduction of plant cover, an increase in the proportion of bare soil, and eroded soils. Patterns of runoff and soil losses affected by seeding cultivated grasses were evaluated. We investigated the effects of roller-seeding of Cenchrus ciliaris L and the influence of microsite cover-type on the dynamics of water erosion. Evaluated cover-types were: bare soil, shortgrass cover, and tallgrass cover. Evaluations were performed 2 growing seasons after roller-seeding. The experimental design was a split-plot, replicated 3 times using a portable rainfall simulator. After simulation runs of 45 min at an average rate of 110 mm hour-1, runoff of tallgrass cover was the least, whereas bare soil and shortgrass cover had similar values (ca. 60%). However, both types of grass cover reduced soil splash compared to the bare soil cover-type. An exponential function between runoff and soil loss suggested that increasing runoff beyond 60% produced an abrupt rising of sediment loss. Roller-seeding did not influence runoff or sediment loss at the microsite-scale. Nevertheless, roller-seeding reduced the proportion of area covered by microsites prone to erosion (bare soil and shortgrass cover-types) at the whole plot level. We propose that any management tool that promotes the replacement of bare soil and shortgrasses by tallgrasses should reduce runoff and increase forage productivity via amelioration of hydrologic conditions of the rangeland site. Conversely, overgrazing will result in more bare soil, increasing runoff, and further intensifying the loss of sediments by detachment. DOI:10.2458/azu_jrm_v56i3_aguilera","PeriodicalId":16918,"journal":{"name":"Journal of Range Management","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90394618","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 : 2003-05-01DOI: 10.2458/AZU_JRM_V56I3_GOSLEE
S. Goslee, K. Beck, D. Peters
Russian knapweed (Acroptilon repens (L.) DC.) was introduced to the western United States during the early 1900s. This invasive perennial was a contaminant of alfalfa seed, and was distributed widely across Colorado. Thus, current distributions reflect the climate and soils tolerances of Russian knapweed, and management history, rather than dispersal processes. We surveyed extension and weed agents across Colorado, and were able to locate 528 current or recently eliminated Russian knapweed stands. These patches were superimposed on climate and soils maps to identify 1 km grid cells that were known to contain Russian knapweed. The status of Russian knapweed within a cell was used as the dependent variable in a logistic regression model to define the environmental envelope for this species. At the scale of our analysis, Russian knapweed was most prevalent on fine-textured soils (clay and clay loam), and in warmer, drier regions of Colorado (precipitation 18-73 cm/yr, mean annual temperature 1-12C). June precipitation was the most important single factor, although nearly all environmental, annual, and monthly climatic factors were significantly related to Russian knapweed occurrence. The multivariate logistic regression model we developed was used to predict the probability of occurrence of Russian knapweed for the entire state of Colorado. Our predictions matched the areas of highest abundance of Russian knapweed from a new field survey, and also indicated areas of high risk that were not identified by the field survey. DOI:10.2458/azu_jrm_v56i3_goslee
{"title":"Distribution of Russian knapweed in Colorado: Climate and environmental factors","authors":"S. Goslee, K. Beck, D. Peters","doi":"10.2458/AZU_JRM_V56I3_GOSLEE","DOIUrl":"https://doi.org/10.2458/AZU_JRM_V56I3_GOSLEE","url":null,"abstract":"Russian knapweed (Acroptilon repens (L.) DC.) was introduced to the western United States during the early 1900s. This invasive perennial was a contaminant of alfalfa seed, and was distributed widely across Colorado. Thus, current distributions reflect the climate and soils tolerances of Russian knapweed, and management history, rather than dispersal processes. We surveyed extension and weed agents across Colorado, and were able to locate 528 current or recently eliminated Russian knapweed stands. These patches were superimposed on climate and soils maps to identify 1 km grid cells that were known to contain Russian knapweed. The status of Russian knapweed within a cell was used as the dependent variable in a logistic regression model to define the environmental envelope for this species. At the scale of our analysis, Russian knapweed was most prevalent on fine-textured soils (clay and clay loam), and in warmer, drier regions of Colorado (precipitation 18-73 cm/yr, mean annual temperature 1-12C). June precipitation was the most important single factor, although nearly all environmental, annual, and monthly climatic factors were significantly related to Russian knapweed occurrence. The multivariate logistic regression model we developed was used to predict the probability of occurrence of Russian knapweed for the entire state of Colorado. Our predictions matched the areas of highest abundance of Russian knapweed from a new field survey, and also indicated areas of high risk that were not identified by the field survey. DOI:10.2458/azu_jrm_v56i3_goslee","PeriodicalId":16918,"journal":{"name":"Journal of Range Management","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89413728","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}
Consumption of mesquite (Prosopis glandulosa Torr. var glandulosa) fruit by ruminants is an important component of seed dispersal. Two experiments were conducted to estimate the role of livestock and wildlife in the dispersion of mesquite fruit. In Experiment 1, 3 trials were conducted to determine preference for mesquite fruit by different species of livestock, intake relative to fruit maturity, and seed survival of digestion. Cattle, sheep, and goats were offered immature (IM), mature off the tree (MT), or mature off the ground (MG) fruit to quantify intake and seed survival of digestion. Germination of seeds surviving digestion was also assessed. Experiment 2 assessed rate of pod disappearance from pastures with and without livestock grazing and attempted to quantify seed loss to wildlife. In Experiment 1, livestock consumed more (P 0.05) to seeds that experienced natural weathering for 6 months. In Experiment 2, the presence or absence of livestock did not affect the disappearance of seeds; seeds disappeared from the ground within 3 weeks in 1999 and 5 weeks in 2000 presumably by wildlife. Deer, raccoons, skunks, bobcats, turkeys, and other birds visited plots with fresh mesquite fruit. Collectively, these results suggest that cattle readily consume and disperse viable mesquite seeds; sheep and goat consumption of mesquite fruit may reduce the number of viable seeds; and mesquite fruit may only remain on the ground for a short period of time even without livestock grazing because of consumption by wildlife. DOI:10.2458/azu_jrm_v56i3_kneuper
{"title":"Consumption and dispersion of mesquite seeds by ruminants.","authors":"Charles L. Kneuper, C. Scott, W. E. Pinchak","doi":"10.2307/4003815","DOIUrl":"https://doi.org/10.2307/4003815","url":null,"abstract":"Consumption of mesquite (Prosopis glandulosa Torr. var glandulosa) fruit by ruminants is an important component of seed dispersal. Two experiments were conducted to estimate the role of livestock and wildlife in the dispersion of mesquite fruit. In Experiment 1, 3 trials were conducted to determine preference for mesquite fruit by different species of livestock, intake relative to fruit maturity, and seed survival of digestion. Cattle, sheep, and goats were offered immature (IM), mature off the tree (MT), or mature off the ground (MG) fruit to quantify intake and seed survival of digestion. Germination of seeds surviving digestion was also assessed. Experiment 2 assessed rate of pod disappearance from pastures with and without livestock grazing and attempted to quantify seed loss to wildlife. In Experiment 1, livestock consumed more (P 0.05) to seeds that experienced natural weathering for 6 months. In Experiment 2, the presence or absence of livestock did not affect the disappearance of seeds; seeds disappeared from the ground within 3 weeks in 1999 and 5 weeks in 2000 presumably by wildlife. Deer, raccoons, skunks, bobcats, turkeys, and other birds visited plots with fresh mesquite fruit. Collectively, these results suggest that cattle readily consume and disperse viable mesquite seeds; sheep and goat consumption of mesquite fruit may reduce the number of viable seeds; and mesquite fruit may only remain on the ground for a short period of time even without livestock grazing because of consumption by wildlife. DOI:10.2458/azu_jrm_v56i3_kneuper","PeriodicalId":16918,"journal":{"name":"Journal of Range Management","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85796375","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}
J. Korfmacher, J. Chambers, R. Tausch, B. Roundy, S. Meyer, S. Kitchen
An experimental design required burn treatments for 10-m2 circular plots. We constructed a fire enclosure for the plots using sheetmetal, electrical conduit, and other commonly available materials. We field tested the enclosure in sagebrush-grass ecosystems in central Nevada and central Utah, and evaluated peak fire temperatures using small metal tags striped with temperature sensitive paint. We obtained average peak surface temperatures of 310, 307, and 381 C in bare ground, under grass, and under shrub microsites, respectively, for the Nevada sites and 253, 299, and 337 C for the same microsites, respectively, in Utah. Subsurface (2-cm depth) temperatures rarely exceeded 79 C, the lowest temperature detectable by our method. The enclosure contained the fire and did not permit escape of any embers or firebrands. The fire enclosure, burn technique and temperature monitoring method used are inexpensive, easily deployed, and desirable for experiments where larger-scale burns are impractical. DOI:10.2458/azu_jrm_v56i3_korfmacher
{"title":"Technical Note: A technique for conducting small-plot burn treatments","authors":"J. Korfmacher, J. Chambers, R. Tausch, B. Roundy, S. Meyer, S. Kitchen","doi":"10.2307/4003814","DOIUrl":"https://doi.org/10.2307/4003814","url":null,"abstract":"An experimental design required burn treatments for 10-m2 circular plots. We constructed a fire enclosure for the plots using sheetmetal, electrical conduit, and other commonly available materials. We field tested the enclosure in sagebrush-grass ecosystems in central Nevada and central Utah, and evaluated peak fire temperatures using small metal tags striped with temperature sensitive paint. We obtained average peak surface temperatures of 310, 307, and 381 C in bare ground, under grass, and under shrub microsites, respectively, for the Nevada sites and 253, 299, and 337 C for the same microsites, respectively, in Utah. Subsurface (2-cm depth) temperatures rarely exceeded 79 C, the lowest temperature detectable by our method. The enclosure contained the fire and did not permit escape of any embers or firebrands. The fire enclosure, burn technique and temperature monitoring method used are inexpensive, easily deployed, and desirable for experiments where larger-scale burns are impractical. DOI:10.2458/azu_jrm_v56i3_korfmacher","PeriodicalId":16918,"journal":{"name":"Journal of Range Management","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76425111","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}
T. Monaco, Douglas A. Johnson, J. Norton, T. A. Jones, K. Connors, J. Norton, Margaret B. Redinbaugh
The mechanisms responsible for soil-N-mediated species replacement of native perennial grasses by the invasive annual grasses cheatgrass (Bromus tectorum L.) and medusahead (Taeniatherum caput-medusae [L.] Nevski) on rangelands are not completely understood. In addition, the contributions of distinct forms of inorganic N (i.e., NH 4 + and NO 3 -) to these shifts in species composition are currently unclear. Consequently, we conducted a greenhouse experiment to test 2 hypotheses: 1) that low N availability reduces growth (root and shoot) and N allocation of invasive annual seedlings more than native perennial species, and 2) that seedling growth and N allocation of invasive annual grasses is more responsive than native perennial grasses when supplied with NO 3 - relative to NH 4 +. We grew seedlings of 2 annual grasses and the native perennial grasses bluebunch wheatgrass (Pseudoroegneria spicata [Pursh] A. Love), and 4 populations of squirreltail (Elymus elymoides [Raf.] Swezey; E. multisetus [J.G. Smith] M.E. Jones) in separate pots and exposed them to treatments differing in N form and availability for 17 weeks. Unexpectedly, root and shoot growth of annual grasses were equal or greater than native perennial grasses under low N availability. Annual grasses took up more NO 3 - and allocated more growth and N to shoots than the perennial grasses (P < 0.05). Perennial grasses had significantly greater root:shoot dry mass ratios than the invasive annual grasses across treatments (P < 0.05). Invasive annual and native perennial grasses both had greater (P < 0.05) shoot and root mass and allocated more N to these structures when supplied with NO 3 - relative to NH 4 +. The ecological implications of these growth and N allocation patterns in response to N availability and form provide important clues regarding the specific traits responsible for differences in competitive ability between invasive annual and native perennial grasses on semiarid rangelands.
{"title":"Contrasting responses of Intermountain West grasses to soil nitrogen","authors":"T. Monaco, Douglas A. Johnson, J. Norton, T. A. Jones, K. Connors, J. Norton, Margaret B. Redinbaugh","doi":"10.2307/4003820","DOIUrl":"https://doi.org/10.2307/4003820","url":null,"abstract":"The mechanisms responsible for soil-N-mediated species replacement of native perennial grasses by the invasive annual grasses cheatgrass (Bromus tectorum L.) and medusahead (Taeniatherum caput-medusae [L.] Nevski) on rangelands are not completely understood. In addition, the contributions of distinct forms of inorganic N (i.e., NH 4 + and NO 3 -) to these shifts in species composition are currently unclear. Consequently, we conducted a greenhouse experiment to test 2 hypotheses: 1) that low N availability reduces growth (root and shoot) and N allocation of invasive annual seedlings more than native perennial species, and 2) that seedling growth and N allocation of invasive annual grasses is more responsive than native perennial grasses when supplied with NO 3 - relative to NH 4 +. We grew seedlings of 2 annual grasses and the native perennial grasses bluebunch wheatgrass (Pseudoroegneria spicata [Pursh] A. Love), and 4 populations of squirreltail (Elymus elymoides [Raf.] Swezey; E. multisetus [J.G. Smith] M.E. Jones) in separate pots and exposed them to treatments differing in N form and availability for 17 weeks. Unexpectedly, root and shoot growth of annual grasses were equal or greater than native perennial grasses under low N availability. Annual grasses took up more NO 3 - and allocated more growth and N to shoots than the perennial grasses (P < 0.05). Perennial grasses had significantly greater root:shoot dry mass ratios than the invasive annual grasses across treatments (P < 0.05). Invasive annual and native perennial grasses both had greater (P < 0.05) shoot and root mass and allocated more N to these structures when supplied with NO 3 - relative to NH 4 +. The ecological implications of these growth and N allocation patterns in response to N availability and form provide important clues regarding the specific traits responsible for differences in competitive ability between invasive annual and native perennial grasses on semiarid rangelands.","PeriodicalId":16918,"journal":{"name":"Journal of Range Management","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85356456","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}
Roje S. Gootee, R. L. Knight, Wendell C. Gilgert, E. Marston
{"title":"Ranching West of the 100th Meridian. Culture, Ecology and Economics","authors":"Roje S. Gootee, R. L. Knight, Wendell C. Gilgert, E. Marston","doi":"10.2307/4003826","DOIUrl":"https://doi.org/10.2307/4003826","url":null,"abstract":"","PeriodicalId":16918,"journal":{"name":"Journal of Range Management","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79354120","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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