To predict how forests will respond to rising temperatures and atmospheric CO₂concentrations, we need to understand how trees respond to both of these environmental factors. In this review, we ...discuss the importance of scaling, moving from leaf‐level responses to those of the canopy, and from short‐term to long‐term responses of vegetation to climate change. While our knowledge of leaf‐level, instantaneous responses of photosynthesis, respiration, stomatal conductance, transpiration and water‐use efficiency to elevated CO₂and temperature is quite good, our ability to scale these responses up to larger spatial and temporal scales is less developed. We highlight which physiological processes are least understood at various levels of study, and discuss how ignoring differences in the spatial or temporal scale of a physiological process impedes our ability to predict how forest carbon and water fluxes forests will be altered in the future. We also synthesize data from the literature to show that light respiration follows a generalized temperature response across studies, and that the light compensation point of photosynthesis is reduced by elevated growth CO₂. Lastly, we emphasize the need to move beyond single factorial experiments whenever possible, and to combine both CO₂and temperature treatments in studies of tree performance.
Increasing temperatures and atmospheric CO2 concentrations will affect tree carbon fluxes, generating potential feedbacks between forests and the global climate system. We studied how elevated ...temperatures and CO2 impacted leaf carbon dynamics in Norway spruce (Picea abies), a dominant northern forest species, to improve predictions of future photosynthetic and respiratory fluxes from high‐latitude conifers. Seedlings were grown under ambient (AC, c. 435 μmol mol−1) or elevated (EC, 750 μmol mol−1) CO2 concentrations at ambient, +4 °C, or +8 °C growing temperatures. Photosynthetic rates (Asat) were high in +4 °C/EC seedlings and lowest in +8 °C spruce, implying that moderate, but not extreme, climate change may stimulate carbon uptake. Asat, dark respiration (Rdark), and light respiration (Rlight) rates acclimated to temperature, but not CO2: the thermal optimum of Asat increased, and Rdark and Rlight were suppressed under warming. In all treatments, the Q10 of Rlight (the relative increase in respiration for a 10 °C increase in leaf temperature) was 35% higher than the Q10 of Rdark, so the ratio of Rlight to Rdark increased with rising leaf temperature. However, across all treatments and a range of 10–40 °C leaf temperatures, a consistent relationship between Rlight and Rdark was found, which could be used to model Rlight in future climates. Acclimation reduced daily modeled respiratory losses from warm‐grown seedlings by 22–56%. When Rlight was modeled as a constant fraction of Rdark, modeled daily respiratory losses were 11–65% greater than when using measured values of Rlight. Our findings highlight the impact of acclimation to future climates on predictions of carbon uptake and losses in northern trees, in particular the need to model daytime respiratory losses from direct measurements of Rlight or appropriate relationships with Rdark.
Abstract
Increasing temperatures and atmospheric
CO
2
concentrations will affect tree carbon fluxes, generating potential feedbacks between forests and the global climate system. We studied how ...elevated temperatures and
CO
2
impacted leaf carbon dynamics in Norway spruce (
Picea abies
), a dominant northern forest species, to improve predictions of future photosynthetic and respiratory fluxes from high‐latitude conifers. Seedlings were grown under ambient (
AC
,
c
. 435
μ
mol mol
−1
) or elevated (
EC
, 750
μ
mol mol
−1
)
CO
2
concentrations at ambient, +4 °C, or +8 °C growing temperatures. Photosynthetic rates (A
sat
) were high in +4 °C/
EC
seedlings and lowest in +8 °C spruce, implying that moderate, but not extreme, climate change may stimulate carbon uptake. A
sat
, dark respiration (R
dark
), and light respiration (R
light
) rates acclimated to temperature, but not
CO
2
: the thermal optimum of A
sat
increased, and R
dark
and R
light
were suppressed under warming. In all treatments, the Q
10
of R
light
(the relative increase in respiration for a 10 °C increase in leaf temperature) was 35% higher than the Q
10
of R
dark
, so the ratio of R
light
to R
dark
increased with rising leaf temperature. However, across all treatments and a range of 10–40 °C leaf temperatures, a consistent relationship between R
light
and R
dark
was found, which could be used to model R
light
in future climates. Acclimation reduced daily modeled respiratory losses from warm‐grown seedlings by 22–56%. When R
light
was modeled as a constant fraction of R
dark
, modeled daily respiratory losses were 11–65% greater than when using measured values of R
light
. Our findings highlight the impact of acclimation to future climates on predictions of carbon uptake and losses in northern trees, in particular the need to model daytime respiratory losses from direct measurements of R
light
or appropriate relationships with R
dark
.
Increasing temperatures and atmospheric CO sub(2) concentrations will affect tree carbon fluxes, generating potential feedbacks between forests and the global climate system. We studied how elevated ...temperatures and CO sub(2) impacted leaf carbon dynamics in Norway spruce (Picea abies), a dominant northern forest species, to improve predictions of future photosynthetic and respiratory fluxes from high-latitude conifers. Seedlings were grown under ambient (AC, c. 435 mu mol mol super(-1)) or elevated (EC, 750 mu mol mol super(-1)) CO sub(2) concentrations at ambient, +4 degree C, or +8 degree C growing temperatures. Photosynthetic rates (A sub(sat)) were high in +4 degree C/EC seedlings and lowest in +8 degree C spruce, implying that moderate, but not extreme, climate change may stimulate carbon uptake. A sub(sat), dark respiration (R sub(dark)), and light respiration (R sub(light)) rates acclimated to temperature, but not CO sub(2): the thermal optimum of A sub(sat) increased, and R sub(dark) and R sub(light) were suppressed under warming. In all treatments, the Q sub(10) of R sub(light) (the relative increase in respiration for a 10 degree C increase in leaf temperature) was 35% higher than the Q sub(10) of R sub(dark), so the ratio of R sub(light) to R sub(dark) increased with rising leaf temperature. However, across all treatments and a range of 10-40 degree C leaf temperatures, a consistent relationship between R sub(light) and R sub(dark) was found, which could be used to model R sub(light) in future climates. Acclimation reduced daily modeled respiratory losses from warm-grown seedlings by 22-56%. When R sub(light) was modeled as a constant fraction of R sub(dark), modeled daily respiratory losses were 11-65% greater than when using measured values of R sub(light). Our findings highlight the impact of acclimation to future climates on predictions of carbon uptake and losses in northern trees, in particular the need to model daytime respiratory losses from direct measurements of R sub(light) or appropriate relationships with R sub(dark).
Abstract
To predict how forests will respond to rising temperatures and atmospheric
CO
2
concentrations, we need to understand how trees respond to both of these environmental factors. In this ...review, we discuss the importance of scaling, moving from leaf‐level responses to those of the canopy, and from short‐term to long‐term responses of vegetation to climate change. While our knowledge of leaf‐level, instantaneous responses of photosynthesis, respiration, stomatal conductance, transpiration and water‐use efficiency to elevated
CO
2
and temperature is quite good, our ability to scale these responses up to larger spatial and temporal scales is less developed. We highlight which physiological processes are least understood at various levels of study, and discuss how ignoring differences in the spatial or temporal scale of a physiological process impedes our ability to predict how forest carbon and water fluxes forests will be altered in the future. We also synthesize data from the literature to show that light respiration follows a generalized temperature response across studies, and that the light compensation point of photosynthesis is reduced by elevated growth
CO
2
. Lastly, we emphasize the need to move beyond single factorial experiments whenever possible, and to combine both
CO
2
and temperature treatments in studies of tree performance.
Rising atmospheric
CO2
and associated increases in temperature both affect tree physiology, and our ability to predict forest responses to climate change depends on understanding these responses. In this review, we summarize how elevated
CO
2 and high growth temperatures alter leaf physiological processes, concentrating on
CO
2 and water fluxes (photosynthesis, respiration in the darkness and in the light, stomatal conductance and transpiration). We focus on the gap between our knowledge of direct
CO
2 and temperature effects on leaf performance at short timescales (minutes to hours) and the scarcity of data on how these processes respond to climate change at larger spatial and temporal scales. We also highlight potential issues that may impede the ability to extrapolate results from short‐term or leaf‐level studies to longer‐term or forest‐level predictions, and provide new analyses of data from the literature to investigate patterns in photosynthetic and respiratory traits to
CO
2 and temperature. Lastly, we emphasize the need to study elevated
CO
2 and temperature together whenever possible, and to aim for long term studies of larger scope, to provide more realistic data on how forest systems will be affected by climate change.
Plants interact with many different bacteria at various stages of their life. A mutualistic relationship between a plant and an endophytic bacterium occurs when a plant provides a safe habitat and a ...secure food supply to the microbe and it, in return, benefits the plants’ capacity to function in its environment. In this study, corn sap was screened for the diversity and functionality of culturable bacterial endophytes, and a total of 437 bacterial endophytes were isolated, identified, and characterized for their possible role as biofertilizers and biocontrol agents. The growth promoting traits that were characterized included siderophore production, phosphate and zinc solubilization, nitrogen fixation, indole acetic acid production, and antifungal activity against several plant pathogens. Most isolates (71.8%) were found to fix nitrogen and solubilize phosphate (66.8%), close to half (42.5%) could solubilize zinc, and 28.3% of the corn bacterial endophytes could sequester iron. Most isolates (77.3%) displayed antifungal activity, and 186 of the 437 isolates tested were found to promote plant growth in a gnotobiotic assay. These results suggest that growth promotion from these bacterial endophytes is the outcome of multiple biochemical and microbiological mechanisms.
Projected increase in growth temperatures and CO2 may affect carbon balance in Norway spruce (Picea abies), a dominant coniferous species of the boreal forest ecosystem. To examine the effects of ...elevated growth temperatures and CO2 on photosynthesis and respiration rates in this species, I exposed three-year-old seedlings to six treatments: ambient (400 ppm) and elevated (750 ppm) CO2 concentrations combined with three growth temperatures: ambient, ambient +4 oC, and ambient +8 oC. I found that while net growth was generally not affected by growth CO2 or temperature, leaf nitrogen concentrations were reduced, mortality rates were higher, and needles were shorter and thinner in +8 oC treatments, compared to cooler treatments. I found that net CO2 assimilation rates and dark respiration acclimated to temperature but not CO2, while patterns of acclimation of light respiration in the light varied between years. The highest net CO2 assimilation rates were found in trees grown at +4 oC combined with elevated CO2, which could indicate that a slight increase in growth temperature with elevated CO2 may benefit the carbon balance of Norway spruce. However, further warming had negative effects on carbon uptake, with trees from the +8 oC treatments showing the lowest CO2 assimilation and dark respiration rates. The Q10 of light respiration was 35% higher than the Q10 of dark respiration, so that the ratio of light respiration to dark respiration increased as leaf temperature increased. I conclude that light respiration is not a constant fraction of dark respiration, although both parameters are tightly correlated, and this relationship can be used to improve models of terrestrial vegetation.
We examined the association of mtDNA variation with Alzheimer disease (AD) risk in Caucasians (989 cases and 328 controls) testing the effect of individual haplogroups and single nucleotide ...polymorphisms (SNPs). Logistic regression analyses were used to assess risk of haplogroups and SNPs with AD in both main effects and interaction models. Males classified as haplogroup U showed an increase in risk (OR=2.30; 95% CI, 1.03–5.11;
P=0.04) of AD relative to the most common haplogroup H, while females demonstrated a significant decrease in risk with haplogroup U (OR=0.44; 95% CI, 0.24–0.80;
P=0.007). Our results were independent of APOE genotype, demonstrating that the effect of mt variation is not confounded by APOE4 carrier status. We suggest that variations within haplogroup U may be involved in AD expression in combination with environmental exposures or nuclear proteins other than APOE.
Event processing in sensor networks Braun, Alexander; Kroner, Paula; Leontyeva, Yulia ...
Proceedings of the 6th ACM International Conference on Distributed Event-Based Systems,
07/2012
Conference Proceeding
Powerful public transportation infrastructures are indispensable for today's rapidly growing metropolitan areas and service breakdowns potentially affect millions of passengers. Thus, fast mitigation ...of emergency situations is a high-priority issue in facilities such as airports or metro systems. We propose a decision support system for emergency management in metro systems and a prototypical implementation that employs rule-based processing of sensor events to detect exceptional situations such as fires. Its specialized 2D/3D user interface assists the operator in choosing adequate actions.
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