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Eurasian Meadow Steppe at elevation 2,180 m near Kemin, Kyrgyz Republic (Kyrgyzstan) dominated by Brachypodium pinnatum, Festuca valesiaca, Helictotrichon tianschanicum, Hypericum scabrum, and Stipa capillata. Mean annual temperature is 32.5° F. This cold temperate biotic community is a prime example of a "continental climate" and is a Palearctic analog to the Nearctic's Plains Grassland. The mean annual rainfall is 375 mm (15 in) with most falling during the growing season. July 2000, John B. Taft.
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We consider the plant and animal assemblages within the various grasslands depicted
to not only be varied and large, but to contribute to a better understanding of each grassland’s history and evolution. This presentation therefore incorporates the biotic community concepts originally proposed by H. S. Swarth, Forrest Shreve, and V. E. Shelford; ap...
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Context 1
... such as velvet lupine (Lupinus leucophyllus), Nuttall gilia (Gilia nuttallii), Rydberg's penstemon (Penstemon rydbergii), and slender mountain sandwort (Arenaria capillaris ssp. americana) may also be present ( Figure 20). Because of soil loss and increased evapotranspiration rates, many of these changes from bunchgrasses to weed fields are deemed irreversible (Franklin and Dyrness 1973). ...
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... and other herbaceous plants vary according to loca- tion, grazing pressure and ecological condition. A list of the most commonly encountered forbs would include yarrow (Achillea millefolium), pale agoseris (Agoseris glauca), sandworts (Arenaria spp.), paintbrushes (Castilleja parviflora, et al.), lance- leaf springbeauty (Claytonia lanceolata), larkspurs (Delphinium spp.), buckwheats (Eriogonum flavum, E. heracleoides, E. nudum), hawkweeds (Hieracium spp.), scarlet gilia (Ipomopsis aggregata), Gray's licorice-root (Ligusticum grayi), lupines (Lupinus brew- eri, L. latifolius), Jacob's-ladders (Polemonium spp.), Penstemon spp., Cascade aster (Eucephalus ledophyllus), fleabanes (Erigeron Figure 20. Cascade-Sierran Subalpine Grassland meadow at an altitude of 2,150 m (7,050 ft) near Serene Lake in the Sierra Nevada, Nevada County, California. ...
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... herbaceous biotic community found in the bore- al climatic zone -Guatemalan Subalpine Grassland- occurs in small patches from 0.5 to 2 m (1.6 -6.6 ft) tall above 3,050 m (10,000 ft) on the high volcanoes border- ing Mexico andGuatemala (Miranda 1952, Wagner 1964). One of the best developed of these resides above a 4,000 m North American Grasslands Desert Plants 29(2) 2014 Figure 22. "Meadow" community atop Cerro Potosí, Nuevo León, Mexico, at ca. 3,700 m (12,410 ft) populated by short-statured forbs such as Arenaria spp., Bidens muelleri, Castilleja bella, Lupinus cacuminis, Potentilla leonina, and Senecio scalaris (Beaman and Andersen 1966). ...
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... Taft. Figure 32. Plains Grassland short grass community, on Thunder Basin National Grassland in northeastern Wyoming having characteristics of both Plains Grassland and Great Basin Shrub-Grassland, ca. ...
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... 2003, D.E.B. other sites east of and in the Rocky Mountains. Plains Grassland also meets or merges along a broad front with Great Basin Conifer Woodland and Great Basin Shrub- Grassland from eastern Wyoming southward to Texas, New Mexico and north-central Arizona, the two grasslands being separated by the latter's presence of sagebrush and other short-statured shrubs along with a general dominance of Pascopyrum and other C3 grasses ( Figure 32). Other west- ern contacts involve isolated forests of ponderosa pine and other montane trees. ...
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... "island" forests stand in marked contrast to "savannas," which are grasslands thinly populated by trees, and "parklands", in which the grassland is surrounded by trees. Mottes in contact areas between Plains Grassland and Northeastern Deciduous Forest are often composed of any of several hickories (Carya spp.), black walnut (Juglans Figure 42. -Plains Grassland near Walsenburg, Huerfano County, Colorado, 1,850 m (6,070 ft), distinguished by its characteristic short grass species blue grama (Bouteloua gracilis) and buffalograss (Buchloe dactyloides). ...
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... across central Texas, and on the east through eastern Oklahoma, northwestern Missouri, northern Illinois, and western Minnesota (Madson and Oberle 1993;Brown and Makings 2014;Fig. 2). ...
... 2). A west-to-east gradient of increasing precipitation and north-to-south gradient of increasing temperature, along with underlying geology, determine the grassland structure and composition across the biome, with shortgrass prairie in the west, mixedgrass prairie in central regions, and tallgrass prairie in the east (Madson and Oberle 1993;Brown and Makings 2014; Fig. 1). Because grasslands occur in landscapes with limited precipitation, wetlands play an important role within these landscapes. ...
... across central Texas, and on the east through eastern Oklahoma, northwestern Missouri, northern Illinois, and western Minnesota (Madson and Oberle 1993;Brown and Makings 2014;Fig. 2). ...
... 2). A west-to-east gradient of increasing precipitation and north-to-south gradient of increasing temperature, along with underlying geology, determine the grassland structure and composition across the biome, with shortgrass prairie in the west, mixedgrass prairie in central regions, and tallgrass prairie in the east (Madson and Oberle 1993;Brown and Makings 2014; Fig. 1). Because grasslands occur in landscapes with limited precipitation, wetlands play an important role within these landscapes. ...
... Sonoran desertscrub is dominated by small leguminous trees such as velvet mesquite (Prosopis velutina) and paloverde (Parkinsonia sp.), shrubs such as creosote (Larrea tridentata) and bursage (Ambrosia sp.), and various cacti, grasses, and forbs (Turner and Brown 1982). Semi-desert grassland is dominated by open woodlands of velvet mesquite and various grasses and subshrubs such as burroweed (Isocoma tenuisecta) and snakeweed (Gutierrezia sarothrae; Brown and Makings 2014). ...
Accurate abundance estimates of plant populations are fundamental to numerous ecological questions and for conservation. Estimating population parameters for rare or cryptic plant species, however, can be challenging and thus developing and testing new methods is useful. We assessed the efficacy of distance sampling for estimating abundance and habitat associations of the endangered Pima pineapple cactus (Coryphantha scheeri var. robustispina), a rare plant in the Sonoran Desert of southwestern North America that has traditionally been surveyed with census-based methods. Distance sampling (DS) involves measuring distances between focal objects and samples of lines or points, and modeling detection functions that adjust estimates for variation in detection probability (P). Although often used in animal systems, DS remains largely untested for plants. We encountered 105 live individuals along 36.9 km of transects in 11 study plots placed across much of the geographic range of the species, and estimated an average density of 1.47 individuals/ha (CV = 0.139). Compared to values from intensive censuses, density estimates from DS were underestimated by only 2.3% on average and highly correlated on the untransformed (r = 0.84) and logarithmic (r = 0.93) scales. Estimates of P averaged 0.49 and declined as soils became increasingly dominated by larger soil substrates, and somewhat with increasing vegetation volume and decreasing cactus height. Local densities increased with increasing slope and soil substrate size and decreased with increasing vegetation volume (p ≤ 0.024). Combined with careful survey design, DS offers an efficient method for estimating population parameters for uncommon and cryptic plants.
... The static environmental conditions (topography and fuels) associated with these entrapments are widespread in the western US, but the dynamic conditions are rare. The precip and maxNDVI values linked to these entrapments suggest that these locations most likely represent vegetation conditions typical of grasslands [68], shrub lands, or dry conifer forest types [69]. Several well-known entrapments had conditions that were typical of the cluster including, Oakland Hills (1991) [70], Esperanza (2006) [71], and Twisp River (2015) [72]. ...
Previous attempts to identify the environmental factors associated with firefighter entrapments in the United States have suggested that there are several common denominators. Despite the widespread acceptance of the assumed commonalities, few studies have quantified how often entrapments actually meet these criteria. An analysis of the environmental conditions at the times and locations of 166 firefighter entrapments involving 1202 people and 117 fatalities that occurred between 1981 and 2017 in the conterminous United States revealed some surprising results. Contrary to general assumptions, we found that at broad spatial scales firefighter entrapments happen under a wide range of environmental conditions, including during low fire danger and on flat terrain. A cluster-based analysis of the data suggested that entrapments group into four unique archetypes that typify the common environmental conditions: (1) low fire danger, (2) high fire danger and steep slopes, (3) high fire danger and low canopy cover, and (4) high fire danger and high canopy cover. There are at least three important implications from the results of this study; one, fire environment conditions do not need to be extreme or unusual for an entrapment to occur, two, the region and site specific context is important, and, three, non-environmental factors such as human behavior remain a critical but difficult to assess factor in wildland firefighter entrapment potential.
... Elevations range from sea level to about 3,190 m (Silva-Flores, Pérez-Verdín, & Wehenkel, 2014). From the tropics of southern Mexico to the Sonoran and Chihuahuan deserts, biomes shift from tropical evergreen, semideciduous and deciduous forests to thorn forest and xeric shrubland with Neotropical savanna and warm temperate grasslands interspaced with sky islands of coniferous forests and Madrean montane grassland (Brown & Makings, 2014). Within these biomes, plant communities are highly variable based on aspect and soil characteristics, with high diversity of xerophytic plants along limestone escarpments (Gehlbach, 1967;Sánchez-González & López-Mata, 2005). ...
Aim The Mexican long-tongued bat (Choeronycteris mexicana), Mexican long-nosed bat (Leptonycteris nivalis), and lesser long-nosed bat (Leptonycteris yerbabuenae) (Phyllostomidae: Glossophaginae) undertake long-distance migrations from south-central Mexico to the southwestern United States. It is proposed that these bats migrate along a nectar corridor of columnar cacti and Agave species, but this has not been tested with independent data and the spatiotemporal nature of this relationship is poorly understood. Our goal was to test this nectar corridor hypothesis and determine the relative importance of food plant and abiotic variables to the distribution and seasonal movements of these migratory nectarivores.
Location Mexico and the southwestern United States
Methods We generated species distribution models (SDMs) of documented food plants for these bats. We then created SDMs for each bat following a model selection approach, using food plant and abiotic predictor variables. We modeled migration pathways for C. mexicana and L. yerbabuenae using circuit theory and seasonal SDMs based on seasonally available food plants.
Main conclusions Food plants were more important than climatic and topographic variables in shaping the distribution of these bats. The most important predictors of distribution were Agave, columnar cacti, and species richness of food plants. Species richness of food plants was the most consistently important variable, but the components of this diversity varied by bat species: Choeronycteris mexicana was influenced by Agave and cacti; Leptonycteris nivalis was influenced solely by Agave; Leptonycteris yerbabuenae was influenced more generally by cacti, Agave, and C3 plants. Migration models for C. mexicana and L. yerbabuenae provided independent support for the nectar corridor hypothesis and indicate shifts in relative importance of specific food plants throughout the year. These results suggest that conservation of these bats should focus more broadly on management for species richness of food plants, especially in tropical dry forests.
... In North America, desert grasslands occur from the southwestern United States into northern Mexico at elevations of 1,100-1,800 m (McClaran and Van Devender 1995). In our study region of southeastern Arizona, these grasslands include what other sources name semidesert grassland interspersed in a mosaic with plains grassland (Brown and Makings 2014). The climate here is dry, hot, and sunny. ...
... The climate here is dry, hot, and sunny. Mean annual precipitation in desert grasslands ranges from 300 mm to 450 mm (Brown and Makings 2014); in southeastern Arizona,~60% of annual precipitation occurs between July and September, with significant spatial and temporal variation (McClaran and Van Devender 1995). The mean annual temperature is 13-168C. ...
Avian species endemic to desert grasslands of North America contend with significant ecological challenges, including monsoonal rains, droughts, and variable temperatures. These birds have evolved physiological and behavioral means of coping with such extremes, but ongoing changes to temperature and precipitation patterns are affecting their breeding phenology, reproductive success, and population growth rates. We examined how seasonal and daily weather conditions and habitat structure were associated with the nest survival of Arizona Grasshopper Sparrows (Ammodramus savannarum ammolegus) in the semidesert and plains grasslands of southeastern Arizona, USA. The mean ± SE daily survival rate (DSR) of nests was 0.960 ± 0.006, corresponding to overall nest success of 46%. The previous season's precipitation, large rain events, and nest concealment were the most important factors explaining DSR. Grasshopper Sparrow nest survival decreased with a wetter previous growing season and with large rain events on previous days. Nests that were more concealed had lower survival rates. There was some evidence that nest survival was lower later in the nesting season. In addition, when nest concealment was included in models, there were positive but weak associations between other vegetation variables and DSR-nests with higher visual obstruction at the nest and nest plot scales, and nests that were farther from shrubs >2 m tall, showed higher survival rates. Predation was the major cause of nest failure, suggesting complex interactions among predation, precipitation, and nest concealment. Further, our findings suggest tradeoffs in the potential effects of future climate change on A. s. ammolegus. The increased frequency of extreme storm events predicted for the region may result in reduced nest survival of A. s. ammolegus, but, conversely, lower seasonal precipitation prior to nesting may positively influence nest survival.
Despite great gains in knowledge about the Late Archaic/Early Agricultural period in the Tucson Basin, understanding of the Middle Archaic period remains slim. This paper reports on volunteer investigations at three buried Archaic sites within the Santa Cruz River floodplain: the Joe Ben Site (AZ BB:13:11), AZ BB:13:70, and an unnumbered locus north of the latter. The AZ BB:13:70 artifact assemblage and the Joe Ben site records suggest small-scale, short-term, repeated use of this portion of the Santa Cruz floodplain and the Santa Rita bajada by foragers between 4200 and 5100 BP, continuing into the Late Archaic/Early Agricultural period. Though assumed to be absent within the southern Southwest during the Middle and Late Holocene, the skull of a juvenile bison at AZ BB:13:70 and post-cranial bison bones at the unnumbered locus indicate their sporadic presence within the Tucson Basin during this period and their occasional exploitation by Middle Archaic hunters.
Over the past 130 years in the North American tallgrass prairie, dramatic changes in
grassland extent, structure and function have resulted from cessation of fire, extirpation of native herbivores (grazers and browsers), and the fragmentation of the landscape. One consequence of these changes is woody encroachment, the increased cover and abundance of woody species in grasslands. Woody encroachment is a worldwide phenomenon, resulting from global drivers (increased CO2 concentrations [CO2], changes in climate) and local drivers (i.e. land-use history, habitat fragmentation, changes in herbivore diversity, and land management practices). In this dissertation, I investigated the role of fire and browsing (local drivers) on woody plant ecophysiology (Chapter 2 & 3). I then addressed how elevated [CO2], and drought (global drivers) impact the growth and physiology of woody plant seedlings (Chapter 4). Chapter 5 reports on breakpoint models to identify temporal and spatial thresholds in ecosystems to help improve adaptive management. In Chapter 2, I observed that fire and repeated browsing significantly decreased Cornus drummondii canopy cover, ramet density, and root nonstructural carbohydrates. These results suggest the significance of both fire and browsing on reducing C. drummondii dominance in the tallgrass prairie. In Chapter 3, I tested the limited leaf homeothermy hypothesis (LLHH) which posits that leaves can thermoregulate during periods of high temperatures to maximize carbon gain. I used C. drummondii shrub islands to test LLHH. Tleaf was lower during the hottest parts of the day, had minimal spatial variability within the shrub islands, and had little to no variation between browsed and unbrowsed shrub islands. This regulation of Tleaf by C. drummondii suggests support for the LLHH via high rates of transpiration and low water-use efficiency. In Chapter 4, I investigated how increased [CO2] and water stress impacted the growth and physiology of four woody encroaching species (C. drummondii, Rhus glabra, Gleditsia tricanthos, Juniperus osteosperma). I found that elevated [CO2] ameliorated the conditions of drought for all species through tight regulation of stomatal conductance. Starch concentrations within leaf and stem tissues had variable responses to treatments based on the species. However, I did not observe any increases in total biomass in response to increased [CO2]. These results demonstrate that these seedlings were
resilient to water stress in conjunction with elevated [CO2]. In Chapter 5, I developed a method to quantitatively estimate temporal and spatial thresholds using Bayesian breakpoint models. Both models estimated breakpoints and corresponding uncertainties. Breakpoints and the latent spatial interpolation of breakpoints were mapped. Mapping of spatial breakpoints will allow managers to track where thresholds were crossed to help allocate resources. Overall, the results from my dissertation highlight the key roles of local and global drivers on woody plant ecophysiology, and the mechanisms contributing to their ability to maximize carbon gain in fluctuating environmental conditions. My work also provided a framework for linking the knowledge of drivers and mechanisms to create quantitative models that can inform when and where thresholds occur for adaptive management of grassland ecosystems.
