排序方式: 共有54条查询结果,搜索用时 15 毫秒
1.
Trees tolerate an extreme heatwave via sustained transpirational cooling and increased leaf thermal tolerance
下载免费PDF全文
![点击此处可从《Global Change Biology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
John E. Drake Mark G. Tjoelker Angelica Vårhammar Belinda E. Medlyn Peter B. Reich Andrea Leigh Sebastian Pfautsch Chris J. Blackman Rosana López Michael J. Aspinwall Kristine Y. Crous Remko A. Duursma Dushan Kumarathunge Martin G. De Kauwe Mingkai Jiang Adrienne B. Nicotra David T. Tissue Brendan Choat Owen K. Atkin Craig V. M. Barton 《Global Change Biology》2018,24(6):2390-2402
Heatwaves are likely to increase in frequency and intensity with climate change, which may impair tree function and forest C uptake. However, we have little information regarding the impact of extreme heatwaves on the physiological performance of large trees in the field. Here, we grew Eucalyptus parramattensis trees for 1 year with experimental warming (+3°C) in a field setting, until they were greater than 6 m tall. We withheld irrigation for 1 month to dry the surface soils and then implemented an extreme heatwave treatment of 4 consecutive days with air temperatures exceeding 43°C, while monitoring whole‐canopy exchange of CO2 and H2O, leaf temperatures, leaf thermal tolerance, and leaf and branch hydraulic status. The heatwave reduced midday canopy photosynthesis to near zero but transpiration persisted, maintaining canopy cooling. A standard photosynthetic model was unable to capture the observed decoupling between photosynthesis and transpiration at high temperatures, suggesting that climate models may underestimate a moderating feedback of vegetation on heatwave intensity. The heatwave also triggered a rapid increase in leaf thermal tolerance, such that leaf temperatures observed during the heatwave were maintained within the thermal limits of leaf function. All responses were equivalent for trees with a prior history of ambient and warmed (+3°C) temperatures, indicating that climate warming conferred no added tolerance of heatwaves expected in the future. This coordinated physiological response utilizing latent cooling and adjustment of thermal thresholds has implications for tree tolerance of future climate extremes as well as model predictions of future heatwave intensity at landscape and global scales. 相似文献
2.
Catherine Morfopoulos Iain C. Prentice Trevor F. Keenan Pierre Friedlingstein Belinda E. Medlyn Josep Pe?uelas Malcolm Possell 《Annals of botany》2013,112(7):1223-1238
Background and Aims
Isoprene is the most important volatile organic compound emitted by land plants in terms of abundance and environmental effects. Controls on isoprene emission rates include light, temperature, water supply and CO2 concentration. A need to quantify these controls has long been recognized. There are already models that give realistic results, but they are complex, highly empirical and require separate responses to different drivers. This study sets out to find a simpler, unifying principle.Methods
A simple model is presented based on the idea of balancing demands for reducing power (derived from photosynthetic electron transport) in primary metabolism versus the secondary pathway that leads to the synthesis of isoprene. This model''s ability to account for key features in a variety of experimental data sets is assessed.Key results
The model simultaneously predicts the fundamental responses observed in short-term experiments, namely: (1) the decoupling between carbon assimilation and isoprene emission; (2) a continued increase in isoprene emission with photosynthetically active radiation (PAR) at high PAR, after carbon assimilation has saturated; (3) a maximum of isoprene emission at low internal CO2 concentration (ci) and an asymptotic decline thereafter with increasing ci; (4) maintenance of high isoprene emissions when carbon assimilation is restricted by drought; and (5) a temperature optimum higher than that of photosynthesis, but lower than that of isoprene synthase activity.Conclusions
A simple model was used to test the hypothesis that reducing power available to the synthesis pathway for isoprene varies according to the extent to which the needs of carbon assimilation are satisfied. Despite its simplicity the model explains much in terms of the observed response of isoprene to external drivers as well as the observed decoupling between carbon assimilation and isoprene emission. The concept has the potential to improve global-scale modelling of vegetation isoprene emission. 相似文献3.
4.
5.
SIBYLLE STEINBEISS HOLGER BEßLER CHRISTOF ENGELS VICKY M. TEMPERTON NINA BUCHMANN CHRISTIANE ROSCHER YVONNE KREUTZIGER JUSSI BAADE MAIKE HABEKOST GERD GLEIXNER 《Global Change Biology》2008,14(12):2937-2949
Increasing atmospheric CO2 concentration and related climate change have stimulated much interest in the potential of soils to sequester carbon. In ‘The Jena Experiment’, a managed grassland experiment on a former agricultural field, we investigated the link between plant diversity and soil carbon storage. The biodiversity gradient ranged from one to 60 species belonging to four functional groups. Stratified soil samples were taken to 30 cm depth from 86 plots in 2002, 2004 and 2006, and organic carbon contents were determined. Soil organic carbon stocks in 0–30 cm decreased from 7.3 kg C m?2 in 2002 to 6.9 kg C m?2 in 2004, but had recovered to 7.8 kg C m?2 by 2006. During the first 2 years, carbon storage was limited to the top 5 cm of soil while below 10 cm depth, carbon was lost probably as short‐term effect of the land use change. After 4 years, carbon stocks significantly increased within the top 20 cm. More importantly, carbon storage significantly increased with sown species richness (log‐transformed) in all depth segments and even carbon losses were significantly smaller with higher species richness. Although increasing species diversity increased root biomass production, statistical analyses revealed that species diversity per se was more important than biomass production for changes in soil carbon. Below 20 cm depth, the presence of one functional group, tall herbs, significantly reduced carbon losses in the beginning of the experiment. Our analysis indicates that plant species richness and certain plant functional traits accelerate the build‐up of new carbon pools within 4 years. Additionally, higher plant diversity mitigated soil carbon losses in deeper horizons. This suggests that higher biodiversity might lead to higher soil carbon sequestration in the long‐term and therefore the conservation of biodiversity might play a role in greenhouse gas mitigation. 相似文献
6.
Kristine Y. Crous Audrey G. Quentin Yan‐Shih Lin Belinda E. Medlyn David G. Williams Craig V. M. Barton David S. Ellsworth 《Global Change Biology》2013,19(12):3790-3807
Eucalyptus species are grown widely outside of their native ranges in plantations on all vegetated continents of the world. We predicted that such a plantation species would show high potential for acclimation of photosynthetic traits across a wide range of growth conditions, including elevated [CO2] and climate warming. To test this prediction, we planted temperate Eucalyptus globulus Labill. seedlings in climate‐controlled chambers in the field located >700 km closer to the equator than the nearest natural occurrence of this species. Trees were grown in a complete factorial combination of elevated CO2 concentration (eC; ambient [CO2] +240 ppm) and air warming treatments (eT; ambient +3 °C) for 15 months until they reached ca. 10 m height. There was little acclimation of photosynthetic capacity to eC and hence the CO2‐induced photosynthetic enhancement was large (ca. 50%) in this treatment during summer. The warming treatment significantly increased rates of both carboxylation capacity (Vcmax) and electron transport (Jmax) (measured at a common temperature of 25 °C) during winter, but decreased them significantly by 20–30% in summer. The photosynthetic CO2 compensation point in the absence of dark respiration (Γ*) was relatively less sensitive to temperature in this temperate eucalypt species than for warm‐season tobacco. The temperature optima for photosynthesis and Jmax significantly changed by about 6 °C between winter and summer, but without further adjustment from early to late summer. These results suggest that there is an upper limit for the photosynthetic capacity of E. globulus ssp. globulus outside its native range to acclimate to growth temperatures above 25 °C. Limitations to temperature acclimation of photosynthesis in summer may be one factor that defines climate zones where E. globulus plantation productivity can be sustained under anticipated global environmental change. 相似文献
7.
Tree hydraulic traits are coordinated and strongly linked to climate‐of‐origin across a rainfall gradient
下载免费PDF全文
![点击此处可从《Plant, cell & environment》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Ximeng Li Chris J. Blackman Brendan Choat Remko A. Duursma Paul D. Rymer Belinda E. Medlyn David T. Tissue 《Plant, cell & environment》2018,41(3):646-660
Plant hydraulic traits capture the impacts of drought stress on plant function, yet vegetation models lack sufficient information regarding trait coordination and variation with climate‐of‐origin across species. Here, we investigated key hydraulic and carbon economy traits of 12 woody species in Australia from a broad climatic gradient, with the aim of identifying the coordination among these traits and the role of climate in shaping cross‐species trait variation. The influence of environmental variation was minimized by a common garden approach, allowing us to factor out the influence of environment on phenotypic variation across species. We found that hydraulic traits (leaf turgor loss point, stomatal sensitivity to drought [Pgs], xylem vulnerability to cavitation [Px], and branch capacitance [Cbranch]) were highly coordinated across species and strongly related to rainfall and aridity in the species native distributional range. In addition, trade‐offs between drought tolerance and plant growth rate were observed across species. Collectively, these results provide critical insight into the coordination among hydraulic traits in modulating drought adaptation and will significantly advance our ability to predict drought vulnerability in these dominant trees species. 相似文献
8.
Ophioglossum petiolatum . Unlike Angiopteris (Marattiales), which is monoplastidic, Ophioglossum undergoes polyplastidic meiosis like members of the fern-seed plant clade. The meiotic spindle is distinctly multipolar in
origin and is consolidated into a bipolar spindle that is variously twisted and curved to accommodate the large number of
chromosomes. Although a phragmoplast forms after first meiosis, no wall is deposited. Instead, an organelle band consisting
of intermingled plastids and mitochondria is formed in the equatorial region between the dyad domains. Following second meiosis,
a complex of phragmoplasts forms among sister and non-sister nuclei. Cell plates are deposited first between sister nuclei
and then in the region of the organelle band resulting in a tetrad of spores each with a equal allotment of organelles.
Received 30 January 2001/ Accepted in revised form 24 April 2001 相似文献
9.
A flux analysis of glucose metabolism in the filamentous fungus Rhizopus oryzae was achieved using a specific radioactivity curve-matching program, TFLUX. Glycolytic and tricarboxylic acid cycle intermediates labeled through the addition of extracellular [U-14C]glucose were isolated and purified for specific radioactivity determinations. This information, together with pool sizes and the rates of glucose utilization and end product production, provided input for flux maps of the metabolic network under two different experimental conditions. Based upon the flux analysis of this system, a mutant of R. oryzae with higher lactate and lower ethanol yields than the parent was sought for and found. 相似文献
10.
NM Kouyoumdzian NL Rukavina Mikusic G Cao MR Choi SL Della Penna BE Fernández 《Biotechnic & histochemistry》2016,91(8):510-521
We studied the effects of tempol, an oxygen radical scavenger, on hydrosaline balance in rats with acute sodium overload. Male rats with free access to water were injected with isotonic (control group) or hypertonic saline solution (0.80 mol/l NaCl) either alone (Na group) or with tempol (Na-T group). Hydrosaline balance was determined during a 90 min experimental period. Protein expressions of aquaporin 1 (AQP1), aquaporin 2 (AQP2), angiotensin II (Ang II) and endothelial nitric oxide synthase (eNOS) were measured in renal tissue. Water intake, creatinine clearance, diuresis and natriuresis increased in the Na group. Under conditions of sodium overload, tempol increased plasma sodium and protein levels and increased diuresis, natriuresis and sodium excretion. Tempol also decreased water intake without affecting creatinine clearance. AQP1 and eNOS were increased and Ang II decreased in the renal cortex of the Na group, whereas AQP2 was increased in the renal medulla. Nonglycosylated AQP1 and eNOS were increased further in the renal cortex of the Na-T group, whereas AQP2 was decreased in the renal medulla and was localized mainly in the cell membrane. Moreover, p47-phox immunostaining was increased in the hypothalamus of Na group, and this increase was prevented by tempol. Our findings suggest that tempol causes hypernatremia after acute sodium overload by inhibiting the thirst mechanism and facilitating diuresis, despite increasing renal eNOS expression and natriuresis. 相似文献