Climatic warming and the future of bison as grazers

Climatic warming is likely to exacerbate nutritional stress and reduce weight gain in large mammalian herbivores by reducing plant nutritional quality. Yet accurate predictions of the effects of climatic warming on herbivores are limited by a poor understanding of how herbivore diet varies along climate gradients. We utilized DNA metabarcoding to reconstruct seasonal variation in the diet of North American bison (Bison bison) in two grasslands that differ in mean annual temperature by 6&thinsp;&deg;C. Here, we show that associated with greater nutritional stress in warmer climates, bison consistently consumed fewer graminoids and more shrubs and forbs, i.e. eudicots. Bison in the warmer grassland consumed a lower proportion of C3 grass, but not a greater proportion of C4 grass. Instead, bison diet in the warmer grassland had a greater proportion of N2-fixing eudicots, regularly comprising &gt;60% of their protein intake in spring and fall. Although bison have been considered strict grazers, as climatic warming reduces grass protein concentrations, bison may have to attempt to compensate by grazing less and browsing more. Promotion of high-protein, palatable eudicots or increasing the protein concentrations of grasses will be critical to minimizing warming-imposed nutritional stress for bison and perhaps other large mammalian herbivores. </div

VASCULAR PLANTS OF KONZA PRAIRIE BIOLOGICAL STATION: AN ANNOTATED CHECKLIST OF SPECIES IN A KANSAS TALLGRASS PRAIRIE

Volume: 20Start Page: 269End Page: 29

A Critical Examination of Timing of Burning in the Kansas Flint Hills

Frequent burning is a crucial ecological and economic component of the Kansas Flint Hills. Although burning is important for the preservation of tallgrass prairie and improving livestock production, it has become a controversial societal issue because of its potential impact on air quality standards. Over the past 80 years, recommendations on burning in Kansas have ranged from total fire exclusion to burning only in late April; and for the past 40 years, the concept that burning should only occur in late spring has become ingrained in the cultural practices of rangeland management. Yet the scientific basis for these recommendations has received little rigorous scrutiny. Herein, we critically review the research on dormant-season burning in the Flint Hills that formed the foundation for modern burn practices in Kansas. Close examination of the historical data does not support the tenet that burning must be limited to a narrow window in late spring. Many conclusions of the research that led to recommending burning only in late spring were ambiguous, not subjected to statistical analysis, or were influenced by an antiburn bias. Current research suggests that timing of a burn is not as critical as ranchers have been led to believe and burning does not have to be restricted to a narrow window in late April. There is an absence of scientific evidence that burning earlier in the spring adversely affects forage production, plant species composition, soil moisture, or cattle weight gain. Although there is a need for research on the consequences of burning grazed pastures at different times of the year, expanding the window for burning earlier in the dormant season should help alleviate air quality issues downwind of the burned areas and potentially be beneficial to ranchers. © 2016 Society for Range Management. Published by Elsevier Inc. All rights reserved.The Rangeland Ecology & Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information

Long-Term Response Patterns of Tallgrass Prairie to Frequent Summer Burning

Knowledge of how tallgrass prairie vegetation responds to fire in the late growing season is relatively sparse and is based upon studies that are either spatially or temporally limited. To gain a more robust perspective of vegetation response to summer burning and to determine if repeated summer fire can drive vegetational changes in native tallgrass prairie, we evaluated species cover and richness over a 14-yr period on different topographic positions from ungrazed watersheds that were burned biennially in the growing season. We found that annual forbs were the primary beneficiaries of summer burning, but their fluctuations varied inconsistently among years. Concomitantly, species richness and diversity increased significantly with summer burning but remained stable through time with annual spring burning. After 14 yr, species richness was 28% higher in prairie that was burned in the summer than in prairie burned in the spring. Canopy cover of big bluestem (Andropogon gerardii Vitman) and Indiangrass (Sorghastrum nutans [L.] Nash) increased significantly over time with both summer and spring burning, whereas heath aster (Symphyotrichum ericoides [L.] Nesom), aromatic aster (Symphyotrichum oblongifolium [Nutt.] Nesom), and sedges (Carex spp.) increased in response to only summer burning. Kentucky bluegrass (Poa pratensis L.) cover declined in both spring-burned and summer-burned watersheds. Repeated burning in either spring or summer did not reduce the cover or frequency of any woody species. Most perennial species were neutral in their reaction to summer fire, but a few species responded with large and inconsistent temporal fluctuations that overwhelmed any clear patterns of change. Although summer burning did not preferentially encourage spring-flowering forbs or suppress dominance of the warm-season grasses, it is a potentially useful tool to increase community heterogeneity in ungrazed prairie. The Rangeland Ecology & Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202

Vegetation dynamics from annually burning tallgrass prairie in different seasons

Traditional perception of how tallgrass prairie responds to fire at times other than late spring is either anecdotal or extrapolated from studies that lack spatial or temporal variability. Therefore, we evaluated patterns of change in vegetation cover, species richness, diversity, and aboveground biomass production on 2 different topographic positions from ungrazed watersheds that were burned annually for 8 years in either autumn (November), winter (February), or spring (April). Topoedaphic factors influenced the response patterns of some species to seasonal fire, although differences were primarily in the rate of change. Annual burning in autumn and winter produced similar trends through time for most species. Big bluestem (Andropogon gerardii Vitman) cover increased with all burn regimes, whereas indiangrass [Sorghastrum nutans (L.) Nash] increased only with spring burning. Repeated autumn and winter burning eventually increased perennial forb cover, with the largest increases occurring in heath aster [Symphyotrichum ericoides (L.) Nesom], aromatic aster [S. oblognifolium (Nutt.) Nesom], tall goldenrod (Solidago canadensis L.), and legumes. Species richness increased (P < 0.001) through time with spring and winter burning, but was similar among all burn treatments after 8 years of annual fire. Average grass and forb biomass did not differ among burn seasons on either topographic position, although interannual biomass production fluctuated inconsistently with time of burn. Our findings contrast with many of the conventional views of how tallgrass prairie vegetation responds to seasonal fire and challenges traditional recommendations that burning should only occur in late spring.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202

Changes from 1994–2013 of (a) NMDS axis 2 scores for all upland and lowland plots, and cover values of (b) <i>Koeleria macrantha</i>, (c) <i>Carex</i> spp., and (d) <i>Sorghastrum nutans</i>.

<p>Cover values were averaged for uplands and lowlands for a given burn treatment for all examples, except for <i>Koeleria</i>, which is shown for just uplands, since it was rarely found in lowlands.</p

Critical climate periods for uplands (top black bar in pair) and lowlands (lower black bar in pair) for autumn-, winter-, and spring-burned plots.

<p>Gray bars represent standard errors on start and end dates for the 20 critical climate periods that explain the most variation in grass productivity.</p

Changes in flowering culm production for (a,b) <i>Andropogon gerardii</i>, (c,d) <i>Schizachyrium scoparium</i>, and (e,f) <i>Sorghastrum nutans</i> from 1994–2013 for uplands (a,c,e) and lowlands (b,d,f) in autumn-, winter-, and spring-burned watersheds.

<p>Changes in flowering culm production for (a,b) <i>Andropogon gerardii</i>, (c,d) <i>Schizachyrium scoparium</i>, and (e,f) <i>Sorghastrum nutans</i> from 1994–2013 for uplands (a,c,e) and lowlands (b,d,f) in autumn-, winter-, and spring-burned watersheds.</p

Changes in upland and lowland grass (a,b) and forb (c,d) productivity over time for autumn-, winter-, and spring-burned watersheds on upland (a,c) and lowland (b,d) positions.

<p>Inset in each graph represents the 20 year mean with means that were significantly different (<i>P</i><0.05) denoted with different letters.</p

Relationships among NMDS axes of upland (closed circles) and lowland (open circles) grasslands burned in autumn (red), winter (blue), or spring (green). Stress value = 0.07 for k = 3.

<p>Relationships among NMDS axes of upland (closed circles) and lowland (open circles) grasslands burned in autumn (red), winter (blue), or spring (green). Stress value = 0.07 for k = 3.</p