scholarly journals Root vascular traits differ systematically between African savanna tree and grass species, with implications for water use

2021 ◽  
Vol 108 (1) ◽  
pp. 83-90
Author(s):  
Isabel K. Wargowsky ◽  
Julienne E. NeSmith ◽  
Ricardo M. Holdo
Keyword(s):  
Water Use ◽  
Grass Species ◽  
African Savanna

scholarly journals Inter-Annual Climate Differences Supersede Grazing Effects on the Anatomy and Physiology of a Dominant Grass Species.

2021 ◽  
Author(s):  
Seton Bachle ◽  
Jesse B Nippert
Keyword(s):  
Water Use ◽  
Great Plains ◽  
Carbon Assimilation ◽  
Grass Species ◽  
Anatomy And Physiology ◽  
Continental Scale ◽  
Drought Conditions ◽  
Leaf Level ◽  
Forage Value ◽  
Dominant Grass

Abstract Grassland ecosystems are historically shaped by climate, fire, and grazing as essential ecological drivers. These grassland drivers influence morphology and productivity via physiological processes, resulting in unique water and carbon use strategies among species and populations. Leaf-level physiological responses in plants are framed by the underlying microanatomy, previously shown to reflect patterns of carbon assimilation and water-use in leaf tissues. However, the magnitude to which microanatomy and physiology are impacted by grassland drivers, remains unstudied. To address this knowledge gap, we sampled from three locations along a latitudinal gradient in the mesic grassland region of the central Great Plains, USA during the 2018 and 2019 growing seasons. We measured annual biomass and forage quality at the plot level, while collecting physiological and microanatomical traits at the leaf-level in cattle grazed and ungrazed locations at each site. Leaf-level measurements were focused on the dominant grass species Andropogon gerardii (big bluestem) because of its high abundance, continental-scale distribution, and forage value. The two sampling seasons received markedly different levels of precipitation: drought conditions in 2018 and excessive early season precipitation in 2019. Ambient drought conditions negatively impacted A. gerardii physiology and drastically reduced productivity regardless of grazing. Leaf-level microanatomical traits, particularly those associated with water-use, varied within and across locations and between years. Our results highlight how trait plasticity can serve as an important tool for predicting future grassland responses to climate change and variable disturbances. Specifically, climate played a stronger role than grazing in shaping above-ground processes in microanatomy and physiology.

scholarly journals Naïve plant communities and individuals may initially suffer in the face of reintroduced megafauna: An experimental exploration of rewilding from an African savanna rangeland

PLoS ONE ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. e0248855
Author(s):  
Truman P. Young ◽  
Duncan M. Kimuyu ◽  
Wilfred O. Odadi ◽  
Harry B. M. Wells ◽  
Amelia A. Wolf
Keyword(s):  
Plant Communities ◽  
Human Impacts ◽  
Experimental Manipulation ◽  
Grass Species ◽  
Native Plant ◽  
African Savanna ◽  
Large Herbivores ◽  
Native Communities ◽  
Exclosure Experiment ◽  
Rich Diversity

Excluding large native mammals is an inverse test of rewilding. A 25-year exclosure experiment in an African savanna rangeland offers insight into the potentials and pitfalls of the rewilding endeavor as they relate to the native plant community. A broad theme that has emerged from this research is that entire plant communities, as well as individual plants, adjust to the absence of herbivores in ways that can ill-prepare them for the return of these herbivores. Three lines of evidence suggest that these “naïve” individuals, populations, and communities are likely to initially suffer from herbivore rewilding. First, plots protected from wild herbivores for the past 25 years have developed rich diversity of woody plants that are absent from unfenced plots, and presumably would disappear upon rewilding. Second, individuals of the dominant tree in this system, Acacia drepanolobium, greatly reduce their defences in the absence of browsers, and the sudden arrival of these herbivores (in this case, through a temporary fence break), resulted in far greater elephant damage than for their conspecifics in adjacent plots that had been continually exposed to herbivory. Third, the removal of herbivores favoured the most palatable grass species, and a large number of rarer species, which presumably would be at risk from herbivore re-introduction. In summary, the native communities that we observe in defaunated landscapes may be very different from their pre-defaunation states, and we are likely to see some large changes to these plant communities upon rewilding with large herbivores, including potential reductions in plant diversity. Lastly, our experimental manipulation of cattle represents an additional test of the role of livestock in rewilding. Cattle are in many ways ecologically dissimilar to wildlife (in particular their greater densities), but in other ways they may serve as ecological surrogates for wildlife, which could buffer ecosystems from some of the ecological costs of rewilding. More fundamentally, African savannah ecosystems represent a challenge to traditional Western definitions of “wilderness” as ecosystems free of human impacts. We support the suggestion that as we “rewild” our biodiversity landscapes, we redefine “wildness” in the 21st Century to be inclusive of (low impact, and sometimes traditional) human practices that are compatible with the sustainability of native (and re-introduced) biodiversity.

scholarly journals 199 A PERFORMANCE. EVALUATION ON TWELVE SPECIES OF ORNAMENTAL GRASSES UNDER WATER STRESS IN GREENHOUSE AND FIELD CONDITIONS

HortScience ◽  
1994 ◽  
Vol 29 (5) ◽  
pp. 457f-457 ◽  
Author(s):  
June Wolfe ◽  
J.M. Zajicek ◽  
M.A. Hussey
Keyword(s):  
Drought Stress ◽  
Introduced Species ◽  
Water Use ◽  
Field Experiments ◽  
Imperata Cylindrica ◽  
Grass Species ◽  
Aesthetic Value ◽  
Public Survey ◽  
Overall Performance ◽  
The Aesthetic

Six native Texas and six introduced ornamental grass species were chosen for an evaluation of water use performance and aesthetic value under drought stress to identify material most appropriate for water conserving landscapes. Greenhouse and field experiments determined the overall performance of the grasses under drought conditions. A public survey evaluated the aesthetic value of investigated species. Greenhouse work determined that examination of total chlorophyll content was not a useful parameter for predicting drought stress. Water use and visual aesthetic decline rates were determined for all species in the greenhouse. On average, native and introduced species performed equally well. Imperata cylindrica exhibited the lowest rates of water use (by 92%) and visual decline (by 51%) in the greenhouse and was the most conservative water user in the field with lowest stomatal conductance (by 76%). The survey found that grasses were acceptable as ornamentals in the landscape and natives and introduced species equal in preference.

Contrasting hydraulic regulation in closely related forage grasses: implications for plant water use

2011 ◽  
Vol 38 (7) ◽  
pp. 594 ◽  
Author(s):  
Meisha-Marika Holloway-Phillips ◽  
Timothy J. Brodribb
Keyword(s):  
Water Transport ◽  
Water Use ◽  
Water Conservation ◽  
Plant Traits ◽  
Leaf Damage ◽  
Plant Performance ◽  
Grass Species ◽  
Forage Grasses ◽  
Drought Treatment ◽  
Stomatal Sensitivity

Plant traits that improve crop water use efficiency are highly sought after but difficult to isolate. Here, we examine the integrated function of xylem and stomata in closely related forage grasses to determine whether quantitative differences in water transport properties could be used to predict plant performance under limited water conditions. Cultivars of two forage grass species with different drought tolerance ratings, Lolium multiflorum Lam. and Festuca arundinacea Schreb., were assessed for maximum hydraulic conductivity (Kmax), vulnerability of xylem to hydraulic dysfunction (P50) and stomatal sensitivity to leaf water potential. Species-specific differences were observed in several of these traits, and their effect on whole-plant performance was examined under well-watered and restricted watering conditions. It was shown that although P50 was comparable between species, for F. arundinacea cultivars, there was greater hydraulic risk associated with reduced stomatal sensitivity to leaf hydration. In contrast, L. multiflorum cultivars expressed a higher capacity for water transport, but more conservative stomatal regulation. Despite different susceptibilities to leaf damage observed during acute drought, under the sustained moderate drought treatment, the two strategies were balanced in terms of water conservation and hydraulic utilisation, resulting in similar dry matter production. Characterisation of water use patterns according to the key hydraulic parameters is discussed in terms of implications to yield across different environmental scenarios as well as the applicability of water transport related traits to breeding programs.

scholarly journals Plant Morphoecological Traits, Grass-Weed Interactions and Water Use Efficiencies of Grasses Used for Restoration of African Rangelands

2021 ◽  
Vol 8 ◽  
Author(s):  
Kevin Z. Mganga ◽  
Eric Kaindi ◽  
Aphaxard J. N. Ndathi ◽  
Luwieke Bosma ◽  
Theophilus Kioko ◽  
...  
Keyword(s):  
Water Use ◽  
Aboveground Biomass ◽  
Vegetation Cover ◽  
Perennial Grasses ◽  
Grass Species ◽  
Production Plant ◽  
Cenchrus Ciliaris ◽  
Basal Cover ◽  
Plant Densities ◽  
Water Use Efficiencies

Degradation characterized by depleted vegetation cover is a serious environmental problem in African rangelands. It poses a serious threat to millions of pastoralists and agropastoralists who depend on livestock as a source of livelihood. Consequently, there has been a growing global interest to consolidate efforts to restore degraded ecosystems. For example, the UN decade of Ecosystem Restoration initiative aims at uniting the world behind a common goal of preventing, halting and reversing the degradation of ecosystems. Grass reseeding using native perennial species has been identified as one of the practical ecological strategies for restoring degraded African rangelands, enhancing vegetation cover and forage production. Knowledge of the multifaceted performance of African rangeland grasses in terms of morphoecological traits, interaction with weeds and water use efficiencies is however largely limited and often elusive. Perennial grasses indigenous to African rangelands Cenchrus ciliaris L. (African foxtail grass), Enteropogon macrostachyus (Hochst. Ex A. Rich.) Monro ex Benth. (Bush rye grass) and Eragrostis superba Peyr. (Maasai love grass), were established in an African semi-arid rangeland under natural conditions to fill this knowledge gap. Morphoecological plant traits: aboveground biomass (shoot, leaf and stem) production, plant densities, basal cover, tiller densities and plant height were measured 9 months after establishment. Interaction between the target grass species and weeds and water use efficiencies (WUE) were also determined. Enteropogon macrostachyus displayed significantly higher values for plant densities, tiller densities and basal cover, indices commonly used to estimate the potential of grasses for ecological restoration. Eragrostis superba produced the highest shoot biomass and water use efficiencies. This is attributed to its higher leafy biomass fraction. Higher aboveground biomass production of E. superba demonstrate its suitability for enhancing rangeland productivity. Cenchrus ciliaris suppressed the weeds. This is linked to its aggressive and allelopathic nature. In conclusion, the three perennial grasses displayed distinct morphoecological traits. In order to achieve successful seed-based restoration of degraded African rangelands using native perennial grasses, careful selection species to maximize on their unique traits is recommended. Ultimately, this selection process should match the desired restoration outcomes and subsequent use of the rangeland.

scholarly journals Irrigation Requirements and Drought Response of Two Ornamental Grass Species

HortScience ◽  
2006 ◽  
Vol 41 (4) ◽  
pp. 1009B-1009
Author(s):  
Erin Alvarez ◽  
Sloane M. Scheiber ◽  
David R. Sandrock
Keyword(s):  
Water Use ◽  
Native Species ◽  
Native Plants ◽  
Growth Index ◽  
Dry Weight ◽  
Grass Species ◽  
Miscanthus Sinensis ◽  
Drought Response ◽  
Significant Treatment ◽  
Irrigation Requirements

Water use is the most important environmental issue facing the horticulture industry. As a result, many water management districts are recommending native plants for their putative low-water requirements. Numerous textbooks and trade journals claim native plants use less water than non-natives; however, previous research found no difference in water use efficiency in the field between native and non-native species. Furthermore, recommendations of ornamental grasses for use as low-maintenance and low-water-requiring landscape plants have recently escalated. This study evaluated non-native Miscanthus sinensis `Adagio' and the native Eragrostis spectabilis for irrigation requirements and drought response in a landscape setting. To simulate maximum stress, both species were planted into field plots in an open-sided, clear polyethylene covered shelter. Each species was irrigated on alternating days at 0, 0.25, 0.5, or 0.75 L for a 90-day period. Growth index and height were recorded at biweekly intervals, and final shoot and root dry masses were taken at completion of the study. Significant treatment and species effects were found for height, growth index, shoot dry weight, and biomass. Plants receiving 0.75 L of irrigation had the greatest growth, and non-irrigated plants grew significantly less. Comparisons between species found growth was greatest among Eragrostis spectabilis plants for all parameters.

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