scholarly journals A Shift From Competition To Facilitation With Abiotic Stress is Limited For Two Codominant Grass Species

2021 ◽  
Author(s):  
Jesse E. Gray ◽  
Melinda D. Smith
Keyword(s):  
Abiotic Stress ◽  
Great Plains ◽  
Tallgrass Prairie ◽  
Stress Gradient ◽  
Niche Overlap ◽  
Growing Season ◽  
Grass Species ◽  
Drought Event ◽  
Asymmetric Competition ◽  
Positive Interaction

Abstract It remains unclear how competitive exclusion is avoided between two ecologically, economically, and culturally important codominant grass species in the tallgrass prairie of the Great Plains, Andropogon gerardii and Sorghastrum nutans. These functionally similar C4 grasses appear to coexist despite considerable niche overlap, and asymmetric competition and drought tolerance in favor of A. gerardii. According to the stress gradient hypothesis, it may be that the sum of interactions between these species, which is typically negative (competitive) due to similar resource requirements, shifts to positive (facilitative) as abiotic stress increases. For instance, if the canopy cover of the stronger competitor reduces losses of subcanopy humidity or shallow soil moisture, recruitment of S. nutans tillers may be extended further into the drought event than would occur in the absence of A. gerardii. As later months of the growing season are drier on average where these species are codominant, such a mechanism may enable S. nutans to recover from early season asymmetric competition and stabilize their codominance. We tested this hypothesis in a greenhouse experiment in which we manipulated community composition and water availability in the latter half of the growing season. We found no evidence that a shift from a negative to positive interaction occurs, with each species performing similarly in mixed communities and monocultures. The similarities of the two species in their functional traits and responses to water limitations may limit such a shift in interaction net effects and suggests that other mechanisms are determining coexistence of these co-occuring C4 grasses.

scholarly journals Timing of drought in the growing season and strong legacy effects determine the annual productivity of temperate grasses in a changing climate

2020 ◽  
Author(s):  
Claudia Hahn ◽  
Sara Ernst-Hasler ◽  
Andreas Lüscher ◽  
Ansgar Kahmen
Keyword(s):  
Growth Rates ◽  
Net Primary Production ◽  
Growing Season ◽  
Extreme Weather Events ◽  
Grass Species ◽  
Drought Event ◽  
Legacy Effects ◽  
Weather Events ◽  
Annual Biomass ◽  
Effects Of Drought

Abstract. The frequency of extreme weather events, such as droughts, is assumed to increase leading to alterations of ecosystem productivity and thus the terrestrial carbon cycle. Although grasslands typically show reduced productivity in response to drought, their effects have been shown to vary quite dramatically. Here we tested in a two-year field experiment, if the resistance and the resilience of grasses towards drought varies throughout a growing season and if the timing of drought, thus, influences drought-induced reductions in annual net primary production (NPP) of grasses. For the experiment we grew six temperate and perennial C3 grass species in a field as monocultures. The grasses were cut six times during the growing season and subject to 10-week drought treatments that occurred either in the spring, the summer or the fall. Across all species, drought-induced losses of productivity were smaller (−20 % to −51 %) than in summer and fall (−77 % to −87 %). This suggests a higher resistance to drought in spring when the productivity of the grasses is the highest and plants are in their reproductive stage. After the release of drought, we found no prolonged suppression of growth. In contrast, post-drought growth rates of formerly drought-stressed swards outperformed the growth rates of the control swards. In 2014, the overcompensation after drought release was similar in all seasons, but differed in 2015. The strong overcompensation of growth after drought release resulted in relatively small overall drought-induced losses of annual ANPP that ranged between −4 % to −14 % and were not affected by the timing of the drought event. Our results show that (i) the resistance of growth rates in grasses to drought varies across the season and is positively correlated with growth rates in the control, (ii) that positive legacy effects of drought indicate a high resilience of temperate grasses to drought, and (iii) that the high resilience can compensate immediate drought effects on total annual biomass production to a large extent.

scholarly journals Timing of drought in the growing season and strong legacy effects determine the annual productivity of temperate grasses in a changing climate

2021 ◽  
Vol 18 (2) ◽  
pp. 585-604
Author(s):  
Claudia Hahn ◽  
Andreas Lüscher ◽  
Sara Ernst-Hasler ◽  
Matthias Suter ◽  
Ansgar Kahmen
Keyword(s):  
Growth Rates ◽  
Net Primary Production ◽  
Growing Season ◽  
Extreme Weather Events ◽  
Grass Species ◽  
Drought Event ◽  
Legacy Effects ◽  
High Recovery ◽  
Recovery Potential ◽  
Effects Of Drought

Abstract. The frequency of extreme weather events, such as droughts, is assumed to increase and lead to alterations in ecosystem productivity and thus the terrestrial carbon cycle. Although grasslands typically show reduced productivity in response to drought, the effects of drought on grassland productivity have been shown to vary strongly. Here we tested, in a 2-year field experiment, if the resistance and the recovery of grasses to drought varies throughout a growing season and if the timing of the drought influences drought-induced reductions in annual aboveground net primary production (ANPP) of grasses. For the experiment we grew six temperate and perennial C3 grass species and cultivars in a field as pure stands. The grasses were cut six times during the growing season and subject to 10 week drought treatments that occurred either in the spring, the summer or the fall. Averaged across all grasses, drought-induced losses in productivity in spring were smaller (−20 % to −51 %) than in summer and fall (−77 % to −87 %). This suggests a higher resistance to drought in spring when plants are in their reproductive stage and their productivity is the highest. After the release from drought, we found no prolonged suppression in growth. In contrast, post-drought growth rates of formerly drought-stressed swards outperformed the growth rates of the control swards. The strong overcompensation in growth after the drought release resulted in relatively small overall drought-induced losses in annual ANPP that ranged from −4 % to −14 % and were not affected by the timing of the drought event. In summary, our results show that (i) the resistance in growth rates of grasses to drought varies across the season and is increased during the reproductive phenological stage when growth rates are highest; (ii) that the positive legacy effects of drought indicate a high recovery potential of temperate grasses to drought; and (iii) that the high recovery can compensate for immediate drought effects on total annual biomass production to a significant extent.

scholarly journals Microanatomical traits track climate gradients for a dominant C4 grass species across the Great Plains, USA

2020 ◽  
Author(s):  
Seton Bachle ◽  
Jesse B Nippert
Keyword(s):  
Water Use ◽  
Great Plains ◽  
Growing Season ◽  
Small Sample ◽  
Andropogon Gerardii ◽  
Temperate Climate ◽  
Grass Species ◽  
Climate Gradients ◽  
C4 Grass ◽  
Leaf Level

Abstract Background and Aims Andropogon gerardii is a highly productive C4 grass species with a large geographic range throughout the North American Great Plains, a biome characterized by a variable temperate climate. Plant traits are often invoked to explain growth rates and competitive abilities within broad climate gradients. For example, plant competition models typically predict that species with large geographic ranges benefit from variation in traits underlying high growth potential. Here, we examined the relationship between climate variability and leaf-level traits in A. gerardii, emphasizing how leaf-level microanatomical traits serve as a mechanism that may underlie variation in commonly measured traits, such as specific leaf area (SLA). Methods Andropogon gerardii leaves were collected in August 2017 from Cedar Creek Ecosystem Science Reserve (MN), Konza Prairie Biological Station (KS), Platte River Prairie (NE) and Rocky Mountain Research Station (SD). Leaves from ten individuals from each site were trimmed, stained and prepared for fluorescent confocal microscopy to analyse internal leaf anatomy. Leaf microanatomical data were compared with historical and growing season climate data extracted from PRISM spatial climate models. Key Results Microanatomical traits displayed large variation within and across sites. According to AICc (Akaike’s information criterion adjusted for small sample sizes) selection scores, the interaction of mean precipitation and temperature for the 2017 growing season was the best predictor of variability for the anatomical and morphological traits measured here. Mesophyll area and bundle sheath thickness were directly correlated with mean temperature (annual and growing season). Tissues related to water-use strategies, such as bulliform cell and xylem area, were significantly correlated with one another. Conclusions The results indicate that (1) microanatomical trait variation exists within this broadly distributed grass species, (2) microanatomical trait variability appears likely to impact leaf-level carbon and water use strategies, and (3) microanatomical trait values vary across climate gradients, and may underlie variation in traits measured at larger ecological scales.

Emergence Pattern of Five Weeds in the Central Great Plains

1996 ◽  
Vol 10 (4) ◽  
pp. 744-749 ◽  
Author(s):  
R. L. Anderson ◽  
D. C. Nielsen
Keyword(s):  
Great Plains ◽  
Seedling Emergence ◽  
Growing Season ◽  
Crop Canopy ◽  
Emergence Pattern ◽  
Proso Millet ◽  
Annual Crops ◽  
No Till ◽  
Green Foxtail ◽  
Wheat Stubble

Seedling emergence was characterized for five weeds that infest summer annual crops in the central Great Plains as affected by crop canopy or tillage. The study was established in winter wheat stubble between 1987 and 1990, with seedling emergence recorded weekly between April 1 and November 1. Kochia emerged primarily from early April to late June, whereas green foxtail, wild-proso millet, and redroot pigweed began emerging in late May and continued until August. Volunteer wheat emerged throughout the growing season. Tillage did not affect the emergence pattern of any species, but the numbers of kochia, volunteer wheat, and green foxtail seedlings were increased in no-till. Conversely, wild-proso millet emergence was greater with tillage. Only volunteer wheat's emergence was affected by crop canopy, as fall emergence of volunteer wheat was more than three times greater in corn than in proso millet.

scholarly journals Facilitation Effects of Haloxylon salicornicum Shrubs on Associated Understory Annuals, and a Modified “Stress-Gradient” Hypothesis for Droughty Times

Plants ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 1726
Author(s):  
Nasr H. Gomaa ◽  
Ahmad K. Hegazy ◽  
Arafat Abdel Hamed Abdel Latef
Keyword(s):  
Species Richness ◽  
Water Availability ◽  
Stress Gradient ◽  
Growing Season ◽  
Annual Species ◽  
Negative Effects ◽  
Growing Seasons ◽  
Dry Seasons ◽  
The Impact ◽  
Haloxylon Salicornicum

Perennial shrub-annual plant interactions play key roles in desert regions influencing the structure and dynamics of plant communities there. In the present study, carried out in northwestern Saudi Arabia, we examined the effect of Haloxylon salicornicum shrubs on their associated understory annual species across four consecutive growing seasons, along with a record of the seasonal rainfall patterns. We measured density and species richness of all the annual species in permanent quadrats located beneath individual shrubs, as well as in the spaces between shrubs. During wet growing season H. salicornicum shrubs significantly enhanced the density and species richness of sub-canopy species, whereas in the relatively dry seasons they exerted negative effects on the associated species. In all growing seasons, the presence of shrubs was associated with enhanced soil properties, including increased organic carbon content, silt + clay, and levels of nutrients (N, P and K). Shrubs improved soil moisture content beneath their canopies in the wet growing season, while in the dry seasons they had negative effects on water availability. Differences in effects of H. salicornicum on understory plants between growing seasons seem due to the temporal changes in the impact of shrubs on water availability. Our results suggest the facilitative effects of shrubs on sub-canopy annuals in arid ecosystems may switch to negative effects with increasing drought stress. We discuss the study in light of recent refinements of the well-known “stress-gradient hypothesis”.

Seasonal and temperature effects on mycorrhizal activity and dependence of cool- and warm-season tallgrass prairie grasses

1992 ◽  
Vol 70 (8) ◽  
pp. 1596-1602 ◽  
Author(s):  
S. P. Bentivenga ◽  
B. A. D. Hetrick
Keyword(s):  
Tallgrass Prairie ◽  
Mycorrhizal Fungi ◽  
Warm Season ◽  
Growing Season ◽  
Cool Temperature ◽  
Cool Season ◽  
Fungal Activity ◽  
Prairie Grasses ◽  
Vesicular Arbuscular ◽  
Warm Season Grasses

Previous research on North American tallgrass prairie grasses has shown that warm-season grasses rely heavily on vesicular–arbuscular mycorrhizal symbiosis, while cool-season grasses are less dependent on the symbiosis (i.e., receive less benefit). This led to the hypothesis that cool-season grasses are less dependent on the symbiosis, because the growth of these plants occurs when mycorrhizal fungi are inactive. Field studies were performed to assess the effect of phenology of cool- and warm-season grasses on mycorrhizal fungal activity and fungal species composition. Mycorrhizal fungal activity in field samples was assessed using the vital stain nitro blue tetrazolium in addition to traditional staining techniques. Mycorrhizal activity was greater in cool-season grasses than in warm-season grasses early (April and May) and late (December) in the growing season, while mycorrhizal activity in roots of the warm-season grasses was greater (compared with cool-season grasses) in midseason (July and August). Active mycorrhizal colonization was relatively high in both groups of grasses late in the growing season, suggesting that mycorrhizal fungi may proliferate internally or may be parasitic at this time. Total Glomales sporulation was generally greater in the rhizosphere of cool-season grasses in June and in the rhizosphere of the warm-season grasses in October. A growth chamber experiment was conducted to examine the effect of temperature on mycorrhizal dependence of cool- and warm-season grasses. For both groups of grasses, mycorrhizal dependence was greatest at the temperature that favored growth of the host. The results suggest that mycorrhizal fungi are active in roots when cool-season grasses are growing and that cool-season grasses may receive benefit from the symbiosis under relatively cool temperature regimes. Key words: cool-season grasses, tallgrass prairie, vesicular–arbuscular mycorrhizae, warm-season grasses.

scholarly journals Managing Tallgrass Prairies for Productivity and Ecological Function: A Long-Term Grazing Experiment in the Southern Great Plains, USA

Agronomy ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 699 ◽  
Author(s):  
Steiner ◽  
Starks ◽  
Neel ◽  
Northup ◽  
Turner ◽  
...  
Keyword(s):  
Great Plains ◽  
Tallgrass Prairie ◽  
Production Efficiency ◽  
Nutritive Value ◽  
Plant Biomass ◽  
Continuous System ◽  
Livestock Grazing ◽  
Long Term Study ◽  
Wide Range

The Great Plains of the USA is one of largest expanses of prairie ecosystems in the world. Prairies have been extensively converted to other land uses. The remaining prairie ecosystems are important for livestock grazing and provide benefits including habitat for avian, terrestrial, and aquatic species, carbon regulation, and hydrologic function. While producers, land management agencies, and some researchers have promoted livestock management using rotational stocking for increased production efficiency and enhanced ecosystem function, scientific literature has not provided a consensus on whether rotational stocking results in increased plant biomass or animal productivity. To address this research need, we established long-term grazing research using an adaptive management framework to encompass a wide range of production and ecological interactions on native grassland pastures. This paper describes objectives, design, and implementation of the long-term study to evaluate productivity and ecological effects of beef cow–calf management and production under continuous system (CS) or rotational system (RS) on native tallgrass prairie. Findings from 2009 to 2015 indicate that plant biomass and animal productivity were similar in the two grazing management systems. There were some indicators that forage nutritive value of standing biomass and soil nutrient content were enhanced in the RS system compared with the CS, yet individual calf body weight (BW) at weaning was greater in the CS. This prepares us to engage with producers to help determine the focus for the next phase of the research.

Fermentation kinetic, chemical composition, organic matter degradation and metabolisable energy of three non-cultivated pastures located in the central plateau of Mexico

2009 ◽  
Vol 2009 ◽  
pp. 92-92
Author(s):  
A A Rayas-Amor ◽  
P Dorward ◽  
T Rehman ◽  
F L Mould ◽  
O A Castelan-Ortega
Keyword(s):  
Economic Benefit ◽  
Nutritive Value ◽  
Growing Season ◽  
Production Costs ◽  
Grass Species ◽  
Organic Matter Degradation ◽  
Central Plateau ◽  
Maize Stover ◽  
Resource Poor ◽  
Metabolisable Energy

Approximately 80% of all production costs are related to the purchase of forages and other feeds in dairy enterprises in Mexico. Resource poor, smallholder (campesino) systems are heavily reliant on the use of maize stover, noncultivated/cultivated grass species and weeds to feed their dairy cattle, thus a nutritional understanding of local forage resources would be of considerable economic benefit. The objective of this study was to determine the nutritive value of non-cultivated pastures (NcP) across the growing season.

DROUGHT SURVIVAL OF SELECTED FORAGE GRASSES COMMONLY SEEDED IN THE NORTHERN GREAT PLAINS

1982 ◽  
Vol 62 (4) ◽  
pp. 949-955 ◽  
Author(s):  
PAT O. CURRIE ◽  
RICHARD S. WHITE
Keyword(s):  
Great Plains ◽  
Leaf Growth ◽  
Basal Area ◽  
Grass Species ◽  
Northern Great Plains ◽  
Severe Drought ◽  
Forage Grasses ◽  
Drought Tolerant ◽  
Drought Survival ◽  
Moisture Conditions

Prolonged drought between 1979 and 1981 killed or severely reduced stands of a number of grass species presumably adapted and frequently recommended for seeding rangelands in the Northern Great Plains. The drought damage took place on recently planted as well as established 2 years or older seedings. Cultivars of the intermediate-pubescent wheatgrass complex were killed or most severely damaged. Damage was also severe on seeded stands of the native green needlegrass, western and thickspike wheatgrasses and big bluegrass. Crested wheatgrass was only moderately drought tolerant, but two cultivars of Russian wild ryegrass established well even with adverse moisture conditions in the seeding year. Altai wild ryegrass seedlings established well but did not survive the drought. An established stand of Vinall Russian wild ryegrass increased in basal area and produced leaf growth and seedstalks during the most severe drought periods. These periodic droughts are sporadic in occurrence but need to be considered in reference to species recommendations for range seedings in the Northern Great Plains.

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