• Laboratory germination responses of 3 love-grasses to temperature in relation to seedbed temperature

      Roundy, B. A.; Young, J. A.; Sumrall, L. B.; Livingston, M. (Society for Range Management, 1992-05-01)
      Laboratory tests are often conducted to determine seed germination responses to temperatures for seedbed ecology interpretations and revegetation seeding rate calculations. To determine the utility of laboratory germination tests for indicating seedbank germinability of lovegrasses we measured seedbed temperatures and soil water on 2 semidesert grassland sites in the Southwest. We also tested germination of Lehmann lovegrass (Eragrostis lehmanniana Nees), 'Cochise' lovegrass (E. lehmanniana Nees X E. trichophora Coss & Dur.), and plains lovegrass (E. intermedia Hitch.) seed collections associated with natural or artificial revegetation studies on these 2 sites in relation to an array of constant and alternating temperatures. Germination responses to different temperatures varied with the year and source of collection and seed age and differed compared to those reported in the literature. Lehmann and Cochise lovegrass had high germination at temperature alternations similar to wet seedbed temperature extremes in December (0,2/15 degrees C) and these species and plains lovegrass were germinable at moderate temperature alternations representative of wet seedbeds in April (10/30 degrees C). Ability to germinate in laboratory tests at these temperatures is not necessarily indicative of germinability in the field for Lehmann lovegrass, which has been observed to germinate in April, not December, in wet seedbeds. All species had maximum or near maximum germination at a temperature alternation of 20/40 degrees C, which is similar to wet seedbed temperature extremes during the summer rainy period when these species usually emerge. Because of the variability in germinability of different seed collections of lovegrass over time, specific collections should be tested at specific ages relevant to seedbed ecology and revegetation studies or projects. Laboratory germination tests which mimic actual wet seedbed temperature curves might be more predictive of seedbed germinability than the usual tests which expose the seeds to abrupt temperature alternations.
    • Lack of Native Vegetation Recovery Following Biological Control of Leafy Spurge

      Butler, Jack L.; Wacker, Stefanie D. (Society for Range Management, 2010-09-01)
      Leafy spurge (Euphorbia esula L.) is an aggressive exotic species that has been successfully suppressed in a variety of situations using classical biological control (flea beetles; Aphthona spp.). This 9-yr study investigated patterns of vegetation responses following significant reductions in leafy spurge cover and density by flea beetles in southeastern Montana. We hypothesized that the vegetation following leafy spurge suppression would be dominated by species and plant functional groups able to persist through heavy infestations. Flea beetles were first released in 1998, and by 2006 leafy spurge foliar cover was reduced 80% to 90% compared to 1998 values on both release and nonrelease plots. Although total cover of the resident vegetation, excluding leafy spurge, increased 72% to 88%, relative cover of the functional groups (native forbs, native sedges, native grasses, and non- native species) was similar among years and between release and nonrelease plots. Mean diversity and mean species richness values did not differ among years or between release and nonrelease plots (P < 0.05), but mean diversity on both release and nonrelease plots was significantly less than noninfested plots, although richness was similar (P<0.05). Indicator species analysis revealed that non-native Poa spp. replaced leafy spurge as the dominant species on release and nonrelease plots. Conversely, noninfested plots contained a variety of native species with high indicator values. Although total abundance of the resident vegetation in 2006 was significantly greater than 1998, plant species composition and relative cover showed little change for the duration of the study. Failure of the native vegetation to recover to a community that approached nearby noninfested conditions may be attributed to a variety of interacting scenarios, some of which may be ameliorated by treating infestations as soon as possible to avoid long-term residual effects. 
    • Lana Vetch for Medusahead Control

      Mac Laughlan, R. S.; Miller, H. W.; Hoglund, O. K. (Society for Range Management, 1970-09-01)
      Medusahead is invading California and western Oregon rangeland at an alarming rate. Overseeding with Lana vetch, a self-perpetuating annual legume, appears to be one of the most practical controls. Because Lana vetch can be successfully established without seedbed preparation it offers a practical method of controlling medusahead on rough terrain. Increased production and improved quality of forage from infested annual grass range are the result.
    • Land management history of Canadian grasslands and the impact on soil carbon storage

      Wang, X.; Vandenbygaart, A. J.; McConkey, B. C. (Society for Range Management, 2014-07)
      Grasslands represent a large potential reservoir in storing carbon (C) in plant biomass and soil organic matter via C sequestration, but the potential greatly depends on how grasslands are managed, especially for livestock and wild animal grazing. Positive and negative grazing effects on soil organic carbon have been reported by various studies globally, but it is not known if Canadian grasslands function as a source or a sink for atmospheric C under current management practices. This article examines the effect of grassland management on carbon storage by compiling historical range management facts and measurements from multiple experiments. Results indicate that grazing on grasslands has contributed to a net C sink in the top 15-cm depth under current utilization regimes with a removal rate of CO2 at 0.19 ± 0.02 Mg · C · ha-1 · yr-1 from the atmosphere during recent decades, and net C sequestration was estimated at 5.64 ± 0.97 Mg · C · ha-1 on average. Naturalization of 2.3 M ha of previously cultivated grasslands in the 1930s has also led to C sequestration in the Canadian prairies but has likely abated as the pool has saturated. Efforts made by researchers, policymakers, and the public has successfully led to the restoration of the Canadian prairies to a healthier state and to achieve considerable C sequestration in soils since their severe deterioration in the 1930s. In-depth analysis of management, legislation, and agricultural programs is urgently needed to place the focus on maintaining range health and achieving more C storage in soils, particularly when facing the reduced potential for further C sequestration. © 2014 The Society for Range Management.
    • Land Management Policy and Development of Ecological Concepts

      Jameson, D. A. (Society for Range Management, 1970-09-01)
      As ecological concepts become incorporated into the training and background information of professional land managers, they also become incorporated into land management policies. Recent developments in ecology, such as nutrient cycling studies and computer simulation of complex processes, have a favorable climate for acceptance. Possible applications should be carefully studied by land managers.
    • Land use change effects on breeding bird community composition

      Boren, J. C.; Engle, D. M.; Palmer, M. W.; Masters, R. E.; Criner, T. (Society for Range Management, 1999-09-01)
      We identified land uses, vegetation cover types, and landscape patterns associated with avian community diversity in 2 rural landscapes in a hardwood forest-tallgrass prairie ecotone that differ with regard to human population density. We obtained long-term (24 years) changes in avian community composition through records from the North American Breeding Bird Survey. We obtained historical and present land use, vegetation cover types, and landscape structure of both landscapes from high-resolution aerial photography. Avian community composition in the low density rural population landscape was primarily related to the amount of land in deciduous forest and land treated with fire or herbicides. In contrast, avian community composition in the high density rural population landscape was primarily related to the amount of land in deciduous forest, native grassland, and roads. Changes in vegetation cover type were related to changes in the avian community composition by increasing prairie habitat associated species in the low density rural population and generalist habitat associated species in the high density rural population landscapes. Loss of neotropical migrants and increased number of generalist species in the high density rural population landscape was related to decreased native vegetation, road development, and increased landscape fragmentation. Biologists and conservationists in this region should focus attention on preserving biological diversity of rural ecosystems by maintaining native plant communities.
    • Land Use Influences Carbon Fluxes in Northern Kazakhstan

      Perez-Quezada, Jorge F.; Saliendra, Nicanor Z.; Akshalov, Kanat; Johnson, Douglas A.; Laca, Emilio (Society for Range Management, 2010-01-01)
      A mobile, closed-chamber system (CC) was used to measure carbon and water fluxes on four land-use types common in the Kazakh steppe ecoregion. Land uses represented crop (wheat or barley, WB), abandoned land (AL), crested wheatgrass (CW), and virgin land (VL). Measurements were conducted during the growing season of 2002 in northern Kazakhstan at three locations (blocks) 15-20 km apart. The CC allowed the measurement of the carbon flux components of net ecosystem exchange (NEE), ecosystem respiration (RE) and soil respiration (RS), together with evapotranspiration (ET). Nonlinear regression analyses were used to model gross primary production (GPP) and ET as a function of photosynthetically active radiation (Q); RE and RS were modeled based on air (Tair) and soil (Ts) temperature, respectively. GPP, RE, RS, and ET were estimated for the entire year with the use of continuous 20-min means of Q, Tair, and Ts. Annual NEE indicated that AL gained 536 g CO2 m-2, WB lost – 191 g CO2 m-2, CW was near equilibrium (–14g CO2 m-2), and VL exhibited considerable carbon accumulation (153g CO2 m-2). The lower GPP values of the land-use types dominated by native species (CW and VL) compared to WB and AL were compensated by positive NEE values that were maintained during a longer growing season. As expected, VL and CW allocated a larger proportion of their carbon assimilates belowground. Non-growing-season RE accounted for about 19% of annual RE in all land-use types. The results of this landscape-level study suggest that carbon lost by cultivation of VLs is partially being restored when fields are left uncultivated, and that VLs are net sinks of carbon. Estimations of carbon balances have important management implications, such as estimation of ecosystem productivity and carbon credit certification. 
    • Land Use, Ethics, and Property Rights—a Western View from the East

      Burch, W. R. (Society for Range Management, 1975-01-01)
      Changes in the nature of property rights regulate the survival potential of social systems. In our era the traditional market system no longer manages the property realities where former scarcities become abundant and former abundance becomes scarce. The experience of land-use in the arid West and John Wesley Powell's vision of the future provide essential lessons for both the dry and humid zones of modern America.
    • Land Use, Soil Erosion, and Livestock Problems in Ceylon

      Gorrie, R. M. (Society for Range Management, 1952-07-01)
    • Land-Use Legacies and Vegetation Recovery 90 Years After Cultivation in Great Basin Sagebrush Ecosystems

      Morris, L. R.; Monaco, T. A.; Sheley, R. L. (Society for Range Management, 2011-09-01)
       Agricultural land use is known to alter ecological processes, and native plant communities can require decades to centuries to recover from the disturbance of cultivation. ‘‘Recovery’’ is typically measured by comparison to undisturbed adjacent sites as a control. Recovery following cultivation in sagebrush ecosystems of the Great Basin remains largely unexamined even though nearly a half million hectares of land were dry-farmed and abandoned in the early 1900s. We tested the hypothesis that the native vegetation has not recovered from this exotic disturbance by evaluating differences in canopy cover of shrubs, grasses, and forbs between paired sets of historically dry-farmed land and adjacent never-cultivated areas. Paired sites were located in three ecological sites in northwestern Utah. We found that vegetation recovery from cultivation is variable by growth form, species, and ecological site. Shrub recovery was different among sagebrush (Artemisia) species. Yellow rabbitbrush (Chrysothamnus viscidiflorus [Hook.] Nutt.) and black greasewood (Sarcobatus vermiculatus [Hook.] Torr.), which often increase following disturbance, maintained higher cover inside old fields. At one of the paired sets, shrub composition was altered from a mix of four species to dominance of mainly Wyoming big sagebrush (Artemisia tridentata Nutt. subsp. wyomingensis Beetle Young). Total forb cover was generally lower in cultivated areas and some species, such as spiny phlox (Phlox hoodii Richardson), had not recovered. The most common grass species encountered across all ecological sites, bottlebrush squirreltail (Elymus elymoides [Raf.] Swezey), had higher cover in cultivated areas. Surprisingly, exotic annual species, such as cheatgrass (Bromus tectorum L.), did not dominate these sites as they have for decades after cultivation in other areas of the Great Basin. This study demonstrates that the land-use legacy of dry farming on vegetation remains nearly a century after cultivation has ceased, and has direct implications for describing ecological site conditions. Resumen Es sabido que la actividad agr ́ıcola altera los procesos ecolo ́gicos y las comunidades de plantas nativas pueden requerir de ́cadas o siglos para recuperarse del disturbio provocado por el cultivo. La ‘‘Recuperacio ́n’’ es mide normalmente, comparando un sitio con disturbio con otro sin disturbio como control. La recuperacio ́n de los ecosistemas de artemisa del Great Basin, en los Estados Unidos de Norteame ́rica permanece sin investigar aun cuando cerca de medio millo ́n de hecta ́reas de tierra fueron abiertas al cultivo y despue ́s abandonadas a principios del 1900. Probamos la hipo ́tesis de que la vegetacio ́n nativa no se ha recuperado de ese disturbio, evaluando diferencias en la cubierta del dosel de arbustos, pastos y hierbas entre parcelas pares; una histo ́ricamente cultivada en condiciones de temporal y otra parcela adyacente nunca cultivada. Las parcelas apareadas fueron ubicadas en tres sitios ecolo ́gicos en la parte noroeste de Utah. Encontramos que la recuperacio ́n de la vegetacio ́n por efecto del cultivo es variable por formas de crecimiento, especies y sitio ecolo ́gico. La recuperacio ́n de los arbustos fue diferente entre las especies de artemisas. Las especies Chrysothamnus viscidiflorus (Hook.) Nutt. y Sarcobatus vermiculatus (Hook.) Torr. que normalmente incrementan despue ́s del disturbio mantuvieron alta cobertura en las tierras de cultivo abandonadas. En uno de los grupos de parcelas, la composicio ́n de arbustos fue dominada principalmente, por cuatro especies Artemisia tridentata Nutt. subsp. wyomingensis Beetle Young. La cubierta de hierbas fue generalmente baja en a ́reas cultivadas y algunas especies como Phlox hoodii Richardson no tuvieron recuperacio ́n. La especie de pasto comu ́nmente encontrada en todos los sitios ecolo ́gicos fue, Elymus elymoides (Raf.) Swezey que mostro alta cobertura en areas cultivadas. Sorpresivamente, especies exo ́ticas anuales como Bromus tectorum L no dominaron esos sitios como lo han hecho por de ́cadas en tierras abiertas al cultivo en otras partes de la Great Basin. Este estudio demuestra que la herencia dejada por la agricultura en condiciones de temporal se mantiene despue ́s de casi un siglo que la actividad agrı ́cola haya terminado y tiene implicaciones directas para describir la condicio ́n de sitio ecolo ́gico.
    • Landowner willingness to participate in a Texas brush reduction program

      Kreuter, Urs P.; Tays, Mark R.; Conner, J. Richard (Society for Range Management, 2004-05-01)
      Because most of Texas consists of privately owned land and the amount of brush cover on rangelands may affect off-site water yields, there has been increasing interest in publicly funded brush clearing programs aimed at increasing water yield. The Pedernales River was selected as 1 of 8 watersheds to determine the feasibility of implementing such a program. A survey questionnaire was mailed to 720 landowners in Blanco and Gillespie County (containing most of the Pedernales watershed) in June 2000 to identify factors that influence their interest in participating in a brush reduction program. The sample consisted of equal numbers of landowners with 4-20, 21-202, and > 202 ha of land. Fifty eight percent of the survey participants responded, 82% of whom answered questions about their willingness to enroll at least part of their land in a brush reduction program. Property size and income from wildlife were found to be significant positive determinants and level of satisfaction with brush a significant negative determinant of respondents' willingness to enroll. To optimize public investments, it may be preferable to maximize the area enrolled in a brush removal program by targeting larger landowners who appear to be willing to enroll larger portions of their land without requiring compensation that exceeds their net cost of enrollment. Because land in the Edwards Plateau is being subdivided and purchased by people who do not depend on land-based income and who may be more tolerant of brush, public funds required to encourage landowner participation may increase over time.
    • Landsat Computer-aided Analysis Techniques for Range Vegetation Mapping

      McGraw, J. F.; Tueller, P. T. (Society for Range Management, 1983-09-01)
      Landsat computer-aided analysis techniques were used to map the sagebrush-grass vegetation of northern Nevada. A final Landsat digital classification resulted in 14 spectral classes representing 8 range plant communities. Classification accuracy for all sample plots was 86.4%, with individual class accuracies ranging from 77.8 to 95.4%. Classification methods included supervised, unsupervised, and guided clustering techniques using a maximum likelihood classifier.
    • Landscape Factors Influencing the Abundance and Dominance of the Invasive Plant Potentilla recta

      Endress, Bryan A.; Naylor, Bridgett J.; Parks, Catherine; Radosevich, Steven R. (Society for Range Management, 2007-05-01)
      Little is known about the relative importance of environmental, biotic, historical, and spatial factors that influence invasive plant abundance, dominance, and distribution across landscapes. We identified factors that influence the abundance and dominance of Potentilla recta L. (sulfur cinquefoil) in bunchgrass grasslands of northeastern Oregon to better understand the conditions under which it becomes a major component of plant communities. We estimated P. recta stem density and dominance from field measurements across the landscape and used classification and regression tree analyses to assess the importance of environmental, biotic, spatial, and historical factors in explaining P. recta presence, stem density, and dominance. Plots were sampled within a systematic grid with 250-m spacing within our 6.5-km2 study landscape. At each sample point we recorded P. recta presence, stem density, and dominance as well as 11 biological, environmental, spatial, and historical variables. P. recta was widely distributed, with stem densities in occupied plots averaging 5.8 stems N m-2 and dominance values ranging from 1% to 52%. Percent cover of bare ground was the most important variable to predict the presence of P. recta, though the model fit was poor, likely because the entire study area is suitable for P. recta establishment. A strong relationship between P. recta dominance and habitat type (r2 = 67.5%) was found, with dominance greatest in old fields on relatively flat slopes (mean dominance of 34.1%). Dominance estimates were < 1% in plots located in forest, shrub, and grassland habitats. Factors that make old fields susceptible to dominance remain unknown, though microsite conditions that increase P. recta seedling survival rates and limited native propagule availability due to previous cultivation may be involved. Since old fields are found throughout the region, are highly susceptible to P. recta invasion, and represent a source of seeds, containment and restoration activities should focus on these areas. 
    • Landscape heterogeneity and long-term animal production in Tierra del Fuego

      Cingolani, A. M.; Anchorena, J.; Collantes, M. B. (Society for Range Management, 1998-01-01)
      Grasslands of northern Tierra del Fuego sustain 1 sheep/ha and are very extensively managed, with flocks roaming freely in large paddocks (2,000-4,000 ha). This system requires knowledge of landscape-level constraints and influences upon production for decision making. On a typical sheep ranch we checked upland floristic gradients against 30-years records of animal production. Community types and landscape units were surveyed and mapped. Using gradient analysis techniques we obtained animal production differences at the landscape scale that were strongly related to a vegetation gradient associated with soil fertility. Extensive and strongly variable lithological mantles allowed expression of the fertility gradient at that scale. Landscapes with fertile soils and neutrophilous community types were best for sheep breeding. These landscapes produced a mean of 37% more lambs ha-1 yr-1 than lands with soils of intermediate fertility and slightly acidophilous community types, and 116% more lambs ha-1 yr-1 than lands with highly infertile soils and highly acidophilous vegetation. Contrarily, the soil moisture gradient, being mainly expressed at the topographic scale, was not related with sheep production records. A forage gradient which was identified behind the fertility gradient supported our findings. Poa spp., the main item in sheep diets, and other important forage species attained the highest covers in neutrophilous community types. With the range in proportion of lowlands present in this ranch (12 to 30%), no relationship was found between the percentage of hygrophitic vegetation in the landscape and animal production.
    • Landscape structure and change in a hardwood forest-tall-grass prairie ecotone

      Boren, J. C.; Engle, D. M.; Gregory, M. S.; Masters, R. E.; Bidwell, T. G.; Mast, V. A. (Society for Range Management, 1997-05-01)
      Temporal changes in land use, vegetation cover types, and landscape structure were examined in a hardwood forest-tallgrass prairie ecotone in northern Oklahoma using a Geographic Information System. Our objective was to examine relationships between human activity, changes in land use and vegetation cover type, and landscape structure in rural landscapes between 1966 and 1990. Cover types in most of the high density rural population landscape in this study require more intensive inputs and management, which resulted in a landscape with lower diversity, higher homogeneity, and greater patch fragmentation compared to the low density rural population landscape. Both native grasslands and forests were less fragmented in the low density rural population landscape whereas forests were increasingly fragmented in the high density rural population landscape. Native grasslands were less fragmented than forests for all years in both the low density rural population and high density rural population landscapes. Our study suggests conservationists should focus their concerns on fragmentation and losses in biological diversity that accompany increased human activity in densely populated rural landscapes that surround urban centers. Extensively managed landscapes dominated by native vegetation that are under less pressure from expanding human influence are in less peril.
    • Landscape use by cattle affected by pasture developments and season

      Zuo, Haitao; Miller-Goodman, Mary S. (Society for Range Management, 2004-09-01)
      Allowing cattle (Bos taurus L.) unrestricted access to streams can contribute to degradation of riparian and aquatic habitats. The objectives of this study were (1) to quantify the amount of time cattle spend using streams and associated riparian habitats when off-stream water and shade sources are offered and (2) to relate these patterns of habitat use to diurnal and seasonal changes in environmental conditions characteristic of the lower southeast. Diurnal (dawn-to-dusk) patterns of cattle location and behaviors were monitored between March 2000 and October 2001 in north-central Alabama at farms with pastures in which wooded streams were present. No significant decrease was detected in the length of diurnal periods cattle spent in riparian habitats after water and shade developments were in place. Grazing (7.8 hours) dominated daytime behaviors of cattle during the cool season when preference was for grassland habitat (7.6 hours). During the warm season, time spent lying increased to 4.7 hours versus 2.7 hours during the cool season; cattle consistently sought either riparian or other wooded habitat at midday and afternoon in comparison to morning and evening periods. Overall, grazing behaviors occurred predominantly (80%) in grassland habitat and lying behaviors occurred mainly (60%) in wooded habitat. Results suggested that comfort (relief from heat stress) appeared to be a major criterion in habitat use decisions by cattle during the warm season for the relatively small spatial scales (3.3 and 6.9 ha) studied. Therefore, dependence only on water and shade developments for alterations in livestock distribution may not be the most effective strategy for reduced degradation of many riparian habitats found in this region.
    • Landscape-level dynamics of grassland-forest transitions in British Columbia

      Bai, Yuguang; Broersma, Klaas; Thompson, Don; Ross, Timothy J. (Society for Range Management, 2004-01-01)
      Grasslands in the interior British Columbia of Canada are adjacent to forests and are susceptible to tree encroachment. Grazing, fire suppression, and climate variability are among factors affecting vegetation dynamics in the ecotone between grassland and forest, but topographic factors such as slope aspect, slope degree and elevation may interact with these factors and result in uneven changes in vegetation among landscape elements. Nine sites with a total of approximately 50,000 ha of grasslands and forests in the Cariboo/Chilcotin forest region of British Columbia were selected to study the effect of slope aspect, slope degree and elevation on vegetation distribution, dynamics and forest expansion from the 1960's to 1990's. Vegetation maps of the 1960's and 1990's were generated using aerial photos and overlaid with GIS layers including aspect, slope and elevation. The classification of open grassland, treed grassland, open forest and closed forest was based on the percent coverage of coniferous species, ranging from 0-5%, 5-15%, 15-35%, and ≥ 35%, respectively. A probability index (P-value) was developed to test the effect of aspect, slope, and elevation on vegetation distribution, dynamics, and forest expansion based on the distribution and changed areas. Results show that open grasslands occurred on southerly aspects and the shift to treed grassland occurred mostly on these aspects. The probability of vegetation shift from open to treed grasslands decreased with increasing slope degree, probably due to the less favorable moisture regime on steep slopes. Treed grassland also shifted to open forest on south facing slopes and more level sites. In contrast, closed forest most often occurred on northerly facing slopes and the shift from open to closed forests was most likely to occur there. The greatest changes in vegetation cover types occurred at mid-elevations between 700 and 1,000 m. Management plans aimed at the control of tree encroachment and forest ingrowth should take these topographic factors into consideration.
    • Large Alligator Junipers Benefit Early-Spring Forage

      Clary, W. P.; Morrison, D. C. (Society for Range Management, 1973-01-01)
      The production of early-spring grasses in central Arizona was four to five times higher under crowns of large alligator juniper than for similar sized areas away from the trees. Virtually all utilization of green forage by grazing animals at this time of the year occurred under the juniper crowns. These large alligator junipers should be protected during pinyon-juniper control operations.
    • Large Seeds Produce More, Better Alkali Sacaton Plants

      Knipe, O. D. (Society for Range Management, 1970-09-01)
      Larger seeds of alkali sacaton germinated better and faster than the smaller sizes. Seedlings from larger seeds emerged from deeper depths and had a higher growth rate.
    • Large ungulate habitat preference in Chobe National Park, Botswana

      Omphile, U. J.; Powell, J. (Society for Range Management, 2002-07-01)
      Both large ungulates and wildlife tourists tend to concentrate along the Chobe River in Chobe National Park, Botswana, during the dry season causing concern for wildlife habitat and the recreational experience for wildlife viewers. Therefore, ground reconnaissance inventory data of 5 most common large ungulates were collected during the early morning and late afternoon hours along tourist routes in 5 different habitat types every second month for a period of 24 months in Chobe National Park to determine their relative, seasonal habitat preference and availability for viewing by vehicular tourists. A total of 909 herds: greater kudu (Tragelaphus strepsiceros), 285; impala (Aepyceros melampus), 209; elephant (Loxodonta africana), 200; giraffe (Giraffa camelopardalis), 138; and buffalo (Syncerus caffra), 77 were observed during the 760 observation periods. The average frequency of observation of a herd of 1 or more of these 5 ungulates per habitat type was alkali flats, 3.42; floodplain grassland, 2.67; shrub savanna, 2.29; tree savanna, 1.04; and woodland, 0.30. This order of frequency of observation is highly correlated with nearness to the Chobe River, the major water source during the dry season. Elephant and giraffe were more wide-ranging than buffalo, impala, and kudu. During the dry season, all animals were seen more often on the floodplain grassland in the afternoon than in the morning. Giraffe were never seen in any habitat type in December, and impala were never seen in the woodland in any month. Our data confirm that tour operators interested primarily in providing their guests with a view of the greatest numbers of animals in a limited period of time are justified in congregating along the Chobe River during the dry season. However, as in most public wildlife reserves, Chobe National Park management is faced with the decision of how best to optimize the biological needs of Park animals and their habitat with the economic and recreational desires of Park users.