scholarly journals Predicting plant vulnerability to drought in biodiverse regions using functional traits

2015 ◽  
Vol 112 (18) ◽  
pp. 5744-5749 ◽  
Author(s):  
Robert Paul Skelton ◽  
Adam G. West ◽  
Todd E. Dawson
Keyword(s):  
Stomatal Closure ◽  
Safety Margin ◽  
Carbon Assimilation ◽  
High Water ◽  
Cape Floristic Region ◽  
Carbon Limitation ◽  
Response Curves ◽  
Stomatal Regulation ◽  
Coexisting Species ◽  
Use Behavior

Attempts to understand mechanisms underlying plant mortality during drought have led to the emergence of a hydraulic framework describing distinct hydraulic strategies among coexisting species. This framework distinguishes species that rapidly decrease stomatal conductance (gs), thereby maintaining high water potential (Px; isohydric), from those species that maintain relatively high gs at low Px, thereby maintaining carbon assimilation, albeit at the cost of loss of hydraulic conductivity (anisohydric). This framework is yet to be tested in biodiverse communities, potentially due to a lack of standardized reference values upon which hydraulic strategies can be defined. We developed a system of quantifying hydraulic strategy using indices from vulnerability curves and stomatal dehydration response curves and tested it in a speciose community from South Africa’s Cape Floristic Region. Degree of stomatal regulation over cavitation was defined as the margin between Px at stomatal closure (Pg12) and Px at 50% loss of conductivity. To assess relationships between hydraulic strategy and mortality mechanisms, we developed proxies for carbon limitation and hydraulic failure using time since Pg12 and loss of conductivity at minimum seasonal Px, respectively. Our approach captured continuous variation along an isohydry/anisohydry axis and showed that this variation was linearly related to xylem safety margin. Degree of isohydry/anisohydry was associated with contrasting predictions for mortality during drought. Merging stomatal regulation strategies that represent an index of water use behavior with xylem vulnerability facilitates a more comprehensive framework with which to characterize plant response to drought, thus opening up an avenue for predicting the response of diverse communities to future droughts.

scholarly journals Xylem embolism in leaves does not occur with open stomata: evidence from direct observations using the optical visualization technique

2019 ◽  
Vol 71 (3) ◽  
pp. 1151-1159 ◽  
Author(s):  
Danielle Creek ◽  
Laurent J Lamarque ◽  
José M Torres-Ruiz ◽  
Camille Parise ◽  
Regis Burlett ◽  
...  
Keyword(s):  
Water Stress ◽  
Stomatal Closure ◽  
Safety Margin ◽  
Carbon Assimilation ◽  
Xylem Embolism ◽  
Growth And Survival ◽  
Direct Observations ◽  
Optical Visualization ◽  
Embolism Resistance ◽  
The One

Abstract Drought represents a major abiotic constraint to plant growth and survival. On the one hand, plants keep stomata open for efficient carbon assimilation while, on the other hand, they close them to prevent permanent hydraulic impairment from xylem embolism. The order of occurrence of these two processes (stomatal closure and the onset of leaf embolism) during plant dehydration has remained controversial, largely due to methodological limitations. However, the newly developed optical visualization method now allows concurrent monitoring of stomatal behaviour and leaf embolism formation in intact plants. We used this new approach directly by dehydrating intact saplings of three contrasting tree species and indirectly by conducting a literature survey across a greater range of plant taxa. Our results indicate that increasing water stress generates the onset of leaf embolism consistently after stomatal closure, and that the lag time between these processes (i.e. the safety margin) rises with increasing embolism resistance. This suggests that during water stress, embolism-mediated declines in leaf hydraulic conductivity are unlikely to act as a signal for stomatal down-regulation. Instead, these species converge towards a strategy of closing stomata early to prevent water loss and delay catastrophic xylem dysfunction.

scholarly journals Continental vs. Global Niche-Based Modelling of Freshwater Species’ Distributions: How Big Are the Differences in the Estimated Climate Change Effects?

Water ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 816
Author(s):  
Danijela Markovic ◽  
Jörg Freyhof ◽  
Oskar Kärcher
Keyword(s):  
Climate Change ◽  
Thermal Properties ◽  
Safety Margin ◽  
Thermal Response ◽  
Future Climate Change ◽  
Freshwater Species ◽  
Response Curves ◽  
Preferred Temperature ◽  
Continental Scale ◽  
Management Actions

Thermal response curves that depict the probability of occurrence along a thermal gradient are used to derive various species’ thermal properties and abilities to cope with warming. However, different thermal responses can be expected for different portions of a species range. We focus on differences in thermal response curves (TRCs) and thermal niche requirements for four freshwater fishes (Coregonus sardinella, Pungitius pungitius, Rutilus rutilus, Salvelinus alpinus) native to Europe at (1) the global and (2) European continental scale. European ranges captured only a portion of the global thermal range with major differences in the minimum (Tmin), maximum (Tmax) and average temperature (Tav) of the respective distributions. Further investigations of the model-derived preferred temperature (Tpref), warming tolerance (WT = Tmax − Tpref), safety margin (SM = Tpref − Tav) and the future climatic impact showed substantially differing results. All considered thermal properties either were under- or overestimated at the European level. Our results highlight that, although continental analyses have an impressive spatial extent, they might deliver misleading estimates of species thermal niches and future climate change impacts, if they do not cover the full species ranges. Studies and management actions should therefore favor whole global range distribution data for analyzing species responses to environmental gradients.

Practical Constitutive Model in the Application of Arch Dam Shape Design Calculation

2011 ◽  
Vol 105-107 ◽  
pp. 857-861
Author(s):  
Hong Wang ◽  
Chong Jin ◽  
Xiao Zhou Xia ◽  
Hong Yuan
Keyword(s):  
Constitutive Model ◽  
Mechanical Performance ◽  
Water Pressure ◽  
Safety Margin ◽  
Least Square Method ◽  
High Water ◽  
Arch Dam ◽  
Least Square ◽  
Design Calculation ◽  
High Arch Dam

A fitting curve of stress-strain relation given is applied in numerical analyzing based on Legendre orthogonal polynomial and least square method. The nonlinear constitutive model is employed to examine the shape of an arch dam. For the asymmetries and high water pressure, the safety of High Arch Dam is one of key issues in the design and construction of High Arch Dam. The simulation results show that the basic mechanical performance index is symmetrical distribution. The dam mainly bears pressure and no obvious tensile stress exists in the dam when water level is normal. Material yields in dam heel when 1.4 times overloading is considered. It can be concluded that the dam is reliable and the safety margin is satisfactory.

Homeostatic response of Aptian gymnosperms to changes in atmospheric CO2 concentrations

Geology ◽  
2021 ◽  
Author(s):  
Germán Mora ◽  
Ana M. Carmo ◽  
William Elliott
Keyword(s):  
Stomatal Closure ◽  
Carbon Assimilation ◽  
Atmospheric Co2 ◽  
The Past ◽  
A Value ◽  
Co2 Concentrations ◽  
Bulk Organic Matter ◽  
The Subject ◽  
Atmospheric Co2 Concentrations ◽  
Homeostatic Response

The sensitivity of plant carbon isotope fractionation (13Δleaf) to changes in atmospheric CO2 concentrations (Ca) is the subject of heavy debate, with some studies finding no sensitivity, while others show a strong dependency. We tested the hypothesis of photosynthetic homeostasis by using δ13C of n-alkanes, cuticles, and bulk organic matter of gymnosperm-rich rocks (Arundel Clay) from two sites deposited during the Aptian, a time that experienced significant Ca variations. Our results show no effect of Ca on 13Δleaf, and a relatively constant Ci/Ca (0.64 ± 0.04, 1σ; i—intercellular space), a value that is similar to that of modern gymnosperms. These results suggest that Aptian gymnosperms used homeostatic adjustments with rising Ca, probably involving increased carbon assimilation and/or stomatal closure, a response also found in modern gymnosperms. The similarity between Aptian and modern gymnosperms suggests that the processes responsible for regulating CO2 and water vapor exchange during photosynthesis have remained unaltered in gymnosperms for the past 128 m.y.

scholarly journals Evolution of chloroplast retrograde signaling facilitates green plant adaptation to land

2019 ◽  
Vol 116 (11) ◽  
pp. 5015-5020 ◽  
Author(s):  
Chenchen Zhao ◽  
Yuanyuan Wang ◽  
Kai Xun Chan ◽  
D. Blaine Marchant ◽  
Peter J. Franks ◽  
...  
Keyword(s):  
Drought Stress ◽  
Physcomitrella Patens ◽  
Stomatal Closure ◽  
Guard Cells ◽  
Green Plant ◽  
Land Plants ◽  
Retrograde Signaling ◽  
Plant Adaptation ◽  
Origin And Evolution ◽  
Stomatal Regulation

Chloroplast retrograde signaling networks are vital for chloroplast biogenesis, operation, and signaling, including excess light and drought stress signaling. To date, retrograde signaling has been considered in the context of land plant adaptation, but not regarding the origin and evolution of signaling cascades linking chloroplast function to stomatal regulation. We show that key elements of the chloroplast retrograde signaling process, the nucleotide phosphatase (SAL1) and 3′-phosphoadenosine-5′-phosphate (PAP) metabolism, evolved in streptophyte algae—the algal ancestors of land plants. We discover an early evolution of SAL1-PAP chloroplast retrograde signaling in stomatal regulation based on conserved gene and protein structure, function, and enzyme activity and transit peptides of SAL1s in species including flowering plants, the fern Ceratopteris richardii, and the moss Physcomitrella patens. Moreover, we demonstrate that PAP regulates stomatal closure via secondary messengers and ion transport in guard cells of these diverse lineages. The origin of stomata facilitated gas exchange in the earliest land plants. Our findings suggest that the conquest of land by plants was enabled by rapid response to drought stress through the deployment of an ancestral SAL1-PAP signaling pathway, intersecting with the core abscisic acid signaling in stomatal guard cells.

The transcription of the cbb operon in Nitrosomonas europaea

Microbiology ◽  
2004 ◽  
Vol 150 (6) ◽  
pp. 1869-1879 ◽  
Author(s):  
Xueming Wei ◽  
Luis A. Sayavedra-Soto ◽  
Daniel J. Arp
Keyword(s):  
Carbon Source ◽  
Regulatory Protein ◽  
Carbon Assimilation ◽  
Nitrosomonas Europaea ◽  
Gene Organization ◽  
Carbon Limitation ◽  
Type I ◽  
Ribulose Bisphosphate Carboxylase ◽  
External Energy ◽  
Bisphosphate Carboxylase

Nitrosomonas europaea is an aerobic ammonia-oxidizing bacterium that participates in the C and N cycles. N. europaea utilizes CO2 as its predominant carbon source, and is an obligate chemolithotroph, deriving all the reductant required for energy and biosynthesis from the oxidation of ammonia (NH3) to nitrite (). This bacterium fixes carbon via the Calvin–Benson–Bassham (CBB) cycle via a type I ribulose bisphosphate carboxylase/oxygenase (RubisCO). The RubisCO operon is composed of five genes, cbbLSQON. This gene organization is similar to that of the operon for ‘green-like’ type I RubisCOs in other organisms. The cbbR gene encoding the putative regulatory protein for RubisCO transcription was identified upstream of cbbL. This study showed that transcription of cbb genes was upregulated when the carbon source was limited, while amo, hao and other energy-harvesting-related genes were downregulated. N. europaea responds to carbon limitation by prioritizing resources towards key components for carbon assimilation. Unlike the situation for amo genes, NH3 was not required for the transcription of the cbb genes. All five cbb genes were only transcribed when an external energy source was provided. In actively growing cells, mRNAs from the five genes in the RubisCO operon were present at different levels, probably due to premature termination of transcription, rapid mRNA processing and mRNA degradation.

Exposure of mature Norway spruce to ozone in twig-chambers: effects on gas exchange

1994 ◽  
Vol 102 ◽  
pp. 119-125
Author(s):  
Gerhard Wieser ◽  
Wilhelm M. Havranek
Keyword(s):  
Gas Exchange ◽  
Picea Abies ◽  
Norway Spruce ◽  
Treatment Effects ◽  
Stomatal Closure ◽  
Ambient Conditions ◽  
Response Curves ◽  
Adult Trees

SynopsisLittle is known about ozone (O3) effects on adult trees in the field, where ecophysiological parameters control pollutant uptake. It was the goal of this study to examine how ambient and above ambient O3 concentrations affect gas exchange of mature Norway spruce (Picea abies (L.) Karst.). Therefore, twigs were enclosed in chambers and exposed to different O3 concentrations for one and two seasons over three years. During winter periods twigs were maintained under ambient conditions. Data from the shade crown of spruce trees at 1000 m a.s.l. are presented. After one and two fumigation periods no clear treatment effects on gas exchange were observed in twigs fumigated with O3 concentrations ranging from zero up to ambient (A) + 60 ppb. However, O3 at 90 ppb reduced photosynthesis and conductance. CO2 response curves indicated that in A + 90 twigs the efficiency of CO2 uptake was diminished. Observed losses in Pn of A + 90 twigs were greater than reductions in conductance indicating that stomatal closure alone did not limit CO2 uptake. We conclude that ambient and slightly above ambient O3 concentrations do not alter gas exchange of mature Norway spruce. Therefore, suppositions on O3 damage on mature spruce trees should be critically questioned.

Drought Enhances Stomatal Closure in Response to Shading in Sorghum (Sorghum bicolor) and in Millet (Pennisetum americanum)

1995 ◽  
Vol 22 (1) ◽  
pp. 1 ◽  
Author(s):  
HG Jones ◽  
DO Hall ◽  
JE Corlett ◽  
A Massacci
Keyword(s):  
Sorghum Bicolor ◽  
Water Status ◽  
Stomatal Closure ◽  
Light Response ◽  
Pennisetum Americanum ◽  
Crop Water ◽  
Response Curves ◽  
Early Stages ◽  
Light Response Curves ◽  
Sorghum Bicolor L

When field-grown sorghum (Sorghum bicolor (L.) Moench) and millet (Pennisetum americanum (L.) Leeke) plants are subjected to drought, the speed of stomatal closure in response to darkness is enhanced in comparison with the speed observed in well-irrigated control plants. This shade-induced closure is most apparent at early stages of desiccation and is not rapidly reversible. These results need to be considered when developing protocols for the measurement of photosynthetic light response curves in the field. The sensitivity to crop water status of this stomatal closure response potentially provides a very valuable means for detection of the early stages of soil drying, and may also provide opportunities for screening different varieties for their adaptation to drought conditions.

scholarly journals Interspecific Variations in the Growth, Water Relations and Photosynthetic Responses of Switchgrass Genotypes to Salinity Targets Salt Exclusion for Maximising Bioenergy Production

Agriculture ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 205
Author(s):  
Ángel Cordero ◽  
Idoia Garmendia ◽  
Bruce A. Osborne
Keyword(s):  
Stomatal Closure ◽  
Carbon Assimilation ◽  
Bioenergy Crops ◽  
Salt Glands ◽  
High Productivity ◽  
Bioenergy Production ◽  
Salt Exclusion ◽  
The Alamo ◽  
Photosynthetic Responses ◽  
High Yields

The expansion in the cultivation of bioenergy crops to saline lands is of importance for ensuring food security as long as high productivity is maintained. The potential of switchgrass to grow under saline conditions was examined in three genotypes from a early seedling growth to full maturity at 50, 100, 200 and 300 mM of sodium chloride (NaCl). The carbon assimilation rates were generally lower and correlated to stomatal closure in plants exposed to salinity in all the tested genotypes. Based on the results of ion concentrations in different parts of the plant, switchgrass genotypes differed in their responses to NaCl. The Alamo genotype excluded salt from the roots, whereas Trailblazer and Kanlow accumulated it in the root, stem and leaf tissues. The increased leaf salt concentration was accompanied by a higher proline concentration in the 200 and 300 mM NaCl treatments toward the end of the experiment. Overall, Alamo showed the highest yields at all salinity levels, indicating that excluding salt from the roots may result in a better performance in terms of biomass production. The accumulation of salt observed in Kanlow and Trailblazer resulted in lower yields, even when other mechanisms, such as the production of salt glands, were observed, especially in Kanlow. These results suggest that the Alamo genotype has the ability to maintain high yields under saline conditions and that this characteristic could be further exploited for maximizing bioenergy production under saline conditions.

Explaining the exceptional 4270 m high elevation limit of an evergreen oak in the south-eastern Himalayas

2020 ◽  
Vol 40 (10) ◽  
pp. 1327-1342 ◽  
Author(s):  
Yang Yang ◽  
Hang Sun ◽  
Christian Körner
Keyword(s):  
Safety Margin ◽  
High Elevation ◽  
Carbon Limitation ◽  
Range Limit ◽  
The South ◽  
Freezing Resistance ◽  
Eastern Himalayas ◽  
Alpine Treeline ◽  
South Eastern ◽  
Stressful Environment

Abstract Unlike the well-understood alpine treeline, the upper range limits of tree taxa that do not reach the alpine treeline are largely unexplained. In this study, we explored the causes of the exceptionally high elevation (4270 m) occurrence of broad-leaved evergreen oaks (Quercus pannosa) in the south-eastern Himalayas. We assessed the course of freezing resistance of buds and leaves from winter to summer at the upper elevational limit of this oak species. Linked to leaf phenology, we analyzed freezing resistance and assessed minimum crown temperature for the past 65 years. We also examined potential carbon limitation at the range limit of this species. Last season buds and leaves operated at a safety margin of 5.5 and 11 K in mid-winter. Once fully dehardened early in July, last season foliage is damaged at −5.9 and new foliage at −4.6 °C. Bud break is timed for late June to early July when low temperature extremes historically were never below −3.0 °C. The monsoon regime ensures a long remaining season (149 days), thus compensating for the late onset of shoot growth. Compared with a site at 3450 m, specific leaf area is reduced, foliar non-structural carbohydrate concentrations are similar and the δ13C signal is higher, jointly suggesting that carbon limitation is unlikely at the range limit of this species. We also show that these oaks enter the growing season with fully intact (not embolized) xylem. We conclude that the interaction between phenology and freezing tolerance results in safe flushing, while still facilitating shoot maturation before winter. These factors jointly determine the upper range limit of this oak species. Our study illuminates an exceptional case of broad-leaved evergreen tree performance near the treeline, and by exploring a suite of traits, we can underpin the central role of flushing phenology in such a stressful environment.

Sign in / Sign up

Export Citation Format

Share Document