scholarly journals Macromolecular rate theory (MMRT) provides a thermodynamics rationale to underpin the convergent temperature response in plant leaf respiration

2017 ◽  
Vol 24 (4) ◽  
pp. 1538-1547 ◽  
Author(s):  
Liyin L. Liang ◽  
Vickery L. Arcus ◽  
Mary A. Heskel ◽  
Odhran S. O'Sullivan ◽  
Lasantha K. Weerasinghe ◽  
...  
Keyword(s):  
Temperature Response ◽  
Rate Theory ◽  
Leaf Respiration ◽  
Plant Leaf

scholarly journals Short-Term Temperature Response of Leaf Respiration in Different Subtropical Urban Tree Species

2021 ◽  
Vol 11 ◽  
Author(s):  
Man Xu ◽  
Lìyǐn L. Liáng ◽  
Miko U. F. Kirschbaum ◽  
Shuyi Fang ◽  
Yina Yu
Keyword(s):  
Thermodynamic Properties ◽  
Plant Species ◽  
Tree Species ◽  
Low Temperatures ◽  
Temperature Response ◽  
Rate Theory ◽  
Short Term ◽  
Leaf Respiration ◽  
Urban Tree ◽  
Plant Respiration

Plant leaf respiration is one of the critical components of the carbon cycle in terrestrial ecosystems. To predict changes of carbon emissions from leaves to the atmosphere under a warming climate, it is, therefore, important to understand the thermodynamics of the temperature response of leaf respiration. In this study, we measured the short-term temperature response of leaf respiration from five different urban tree species in a subtropical region of southern China. We applied two models, including an empirical model (the Kavanau model) and a mechanistic model (Macromolecular Rate Theory, MMRT), to investigate the thermodynamic properties in different plant species. Both models are equivalent in fitting measurements of the temperature response of leaf respiration with no significant difference (p = 0.67) in model efficiency, while MMRT provides an easy way to determine the thermodynamic properties, i.e., enthalpy, entropy, and Gibbs free energy of activation, for plant respiration. We found a conserved temperature response in the five studied plant species, showing no difference in thermodynamic properties and the relative temperature sensitivity for different species at low temperatures (<42°C). However, divergent temperature response among species happened at high temperatures over 42°C, showing more than two-fold differences in relative respiration rate compared to that below 42°C, although the causes of the divergent temperature response remain unclear. Notably, the convergent temperature response at low temperatures could provide useful information for land surface models to improve predictions of climate change effects on plant respiration.

scholarly journals Relative Abundance of Ammonia Oxidizing Archaea and Bacteria Influences Soil Nitrification Responses to Temperature

2019 ◽  
Vol 7 (11) ◽  
pp. 526 ◽  
Author(s):  
Hussnain Mukhtar ◽  
Yu-Pin Lin ◽  
Chiao-Ming Lin ◽  
Yann-Rong Lin
Keyword(s):  
Temperature Gradient ◽  
Relative Abundance ◽  
Temperature Response ◽  
Rate Theory ◽  
Fixed Temperature ◽  
Soil Nitrification ◽  
Ammonia Oxidizing Archaea ◽  
Different Temperatures ◽  
Order Of Magnitude ◽  
The Impact

Ammonia oxidizing archaea (AOA) and bacteria (AOB) are thought to contribute differently to soil nitrification, yet the extent to which their relative abundances influence the temperature response of nitrification is poorly understood. Here, we investigated the impact of different AOA to AOB ratios on soil nitrification potential (NP) across a temperature gradient from 4 °C to 40 °C in twenty different organic and inorganic fertilized soils. The temperature responses of different relative abundance of ammonia oxidizers for nitrification were modeled using square rate theory (SQRT) and macromolecular rate theory (MMRT) models. We found that the proportional nitrification rates at different temperatures varied among AOA to AOB ratios. Predicted by both models, an optimum temperature (Topt) for nitrification in AOA dominated soils was significantly higher than for soils where AOA and AOB abundances are within the same order of magnitude. Moreover, the change in heat capacity ( Δ C P ‡ ) associated with the temperature dependence of nitrification was positively correlated with Topt and significantly varied among the AOA to AOB ratios. The temperature ranges for NP decreased with increasing AOA abundance for both organic and inorganic fertilized soils. These results challenge the widely accepted approach of comparing NP rates in different soils at a fixed temperature. We conclude that a shift in AOA to AOB ratio in soils exhibits distinguished temperature-dependent characteristics that have an important impact on nitrification responses across the temperature gradient. The proposed approach benefits the accurate discernment of the true contribution of fertilized soils to nitrification for improvement of nitrogen management.

scholarly journals High Leaf Respiration Rates May Limit the Success of White Spruce Saplings Growing in the Kampfzone at the Arctic Treeline

2021 ◽  
Vol 12 ◽  
Author(s):  
Kevin L. Griffin ◽  
Stephanie C. Schmiege ◽  
Sarah G. Bruner ◽  
Natalie T. Boelman ◽  
Lee A. Vierling ◽  
...  
Keyword(s):  
Picea Glauca ◽  
Temperature Response ◽  
White Spruce ◽  
The Arctic ◽  
Leaf Respiration ◽  
Respiration Rates ◽  
Canopy Position ◽  
Arctic Treeline ◽  
Biological Environment ◽  
The Relationship

Arctic Treeline is the transition from the boreal forest to the treeless tundra and may be determined by growing season temperatures. The physiological mechanisms involved in determining the relationship between the physical and biological environment and the location of treeline are not fully understood. In Northern Alaska, we studied the relationship between temperature and leaf respiration in 36 white spruce (Picea glauca) trees, sampling both the upper and lower canopy, to test two research hypotheses. The first hypothesis is that upper canopy leaves, which are more directly coupled to the atmosphere, will experience more challenging environmental conditions and thus have higher respiration rates to facilitate metabolic function. The second hypothesis is that saplings [stems that are 5–10cm DBH (diameter at breast height)] will have higher respiration rates than trees (stems ≥10cm DBH) since saplings represent the transition from seedlings growing in the more favorable aerodynamic boundary layer, to trees which are fully coupled to the atmosphere but of sufficient size to persist. Respiration did not change with canopy position, however respiration at 25°C was 42% higher in saplings compared to trees (3.43±0.19 vs. 2.41±0.14μmolm−2 s−1). Furthermore, there were significant differences in the temperature response of respiration, and seedlings reached their maximum respiration rates at 59°C, more than two degrees higher than trees. Our results demonstrate that the respiratory characteristics of white spruce saplings at treeline impose a significant carbon cost that may contribute to their lack of perseverance beyond treeline. In the absence of thermal acclimation, the rate of leaf respiration could increase by 57% by the end of the century, posing further challenges to the ecology of this massive ecotone.

The apparent temperature response of leaf respiration depends on the timescale of measurements: a study of two cold climate species

Plant Biology ◽  
2008 ◽  
Vol 10 (2) ◽  
pp. 185-193 ◽  
Author(s):  
D. Bruhn ◽  
M. Schortemeyer ◽  
E. J. Edwards ◽  
J. J. G. Egerton ◽  
C. H. Hocart ◽  
...  
Keyword(s):  
Temperature Response ◽  
Cold Climate ◽  
Apparent Temperature ◽  
Leaf Respiration

scholarly journals High Leaf Respiration Rates May Limit the Success of White Spruce Saplings growing in The Kampfzone at the Arctic Treeline

2021 ◽  
Author(s):  
Kevin L Griffin ◽  
Stephanie C Schmeige ◽  
Sarah G Bruner ◽  
Natalie T Boelman ◽  
Lee A Vierling ◽  
...  
Keyword(s):  
Picea Glauca ◽  
Alternative Hypothesis ◽  
Temperature Response ◽  
White Spruce ◽  
The Arctic ◽  
Leaf Respiration ◽  
Respiration Rates ◽  
Canopy Position ◽  
Arctic Treeline ◽  
The Relationship

Arctic Treeline is the transition from the boreal forest to the treeless tundra and may be determined by growing season temperatures. The physiological mechanisms involved in determining the relationship between the physical and biological environment and the location of treeline are not fully understood. In Northern Alaska we studied the relationship between temperature and leaf respiration in 36 white spruce (Picea glauca) trees, sampling both the upper and lower canopy, to test two research hypotheses (H0). The first H01 is that canopy position will not influence leaf respiration. The associated alternative hypothesis (HA) is that the upper canopy leaves which are more directly coupled to the atmosphere will experience more challenging environmental conditions and thus have higher respiration rates to facilitate metabolic function. The second H02 is that tree size will not influence leaf respiration. The associated HA is that saplings (stems that are 5-10 cm DBH (diameter at breast height)) will have higher respiration rates than trees (stems ≥ 10 cm DBH) since saplings represent the transition from seedlings growing in the more favorable aerodynamic boundary layer, to trees which are fully coupled to the atmosphere but of sufficient size to persist. Respiration did not change with canopy position, however respiration at 25°C was 42% higher in saplings compared to trees (3.43 ± 0.19 vs. 2.41 ± 0.14 μmol m-2s-1). Furthermore, there were significant differences in the temperature response of respiration, and seedlings reached their maximum respiration rates at 59°C, more than two degrees higher than trees. Our results demonstrate that the respiratory characteristics of white spruce saplings at treeline are extreme, imposing a significant carbon cost that may contribute to their lack of perseverance beyond treeline. In the absence of thermal acclimation, the rate of leaf respiration could increase by 57% by the end of the century, posing further challenges to the ecology of this massive ecotone.

scholarly journals Canopy position affects the temperature response of leaf respiration in Populus deltoides

2002 ◽  
Vol 154 (3) ◽  
pp. 609-619 ◽  
Author(s):  
Kevin L. Griffin ◽  
Matthew Turnbull ◽  
Ramesh Murthy
Keyword(s):  
Populus Deltoides ◽  
Temperature Response ◽  
Leaf Respiration ◽  
Canopy Position

scholarly journals Convergence in the temperature response of leaf respiration across biomes and plant functional types

2016 ◽  
Vol 113 (14) ◽  
pp. 3832-3837 ◽  
Author(s):  
Mary A. Heskel ◽  
Odhran S. O’Sullivan ◽  
Peter B. Reich ◽  
Mark G. Tjoelker ◽  
Lasantha K. Weerasinghe ◽  
...  
Keyword(s):  
Temperature Sensitivity ◽  
Land Surface ◽  
Response Curve ◽  
Fossil Fuels ◽  
Temperature Response ◽  
Plant Functional Types ◽  
Leaf Respiration ◽  
Functional Types ◽  
Carbon Release ◽  
Plant Respiration

Plant respiration constitutes a massive carbon flux to the atmosphere, and a major control on the evolution of the global carbon cycle. It therefore has the potential to modulate levels of climate change due to the human burning of fossil fuels. Neither current physiological nor terrestrial biosphere models adequately describe its short-term temperature response, and even minor differences in the shape of the response curve can significantly impact estimates of ecosystem carbon release and/or storage. Given this, it is critical to establish whether there are predictable patterns in the shape of the respiration–temperature response curve, and thus in the intrinsic temperature sensitivity of respiration across the globe. Analyzing measurements in a comprehensive database for 231 species spanning 7 biomes, we demonstrate that temperature-dependent increases in leaf respiration do not follow a commonly used exponential function. Instead, we find a decelerating function as leaves warm, reflecting a declining sensitivity to higher temperatures that is remarkably uniform across all biomes and plant functional types. Such convergence in the temperature sensitivity of leaf respiration suggests that there are universally applicable controls on the temperature response of plant energy metabolism, such that a single new function can predict the temperature dependence of leaf respiration for global vegetation. This simple function enables straightforward description of plant respiration in the land-surface components of coupled earth system models. Our cross-biome analyses shows significant implications for such fluxes in cold climates, generally projecting lower values compared with previous estimates.

On the interpretation of dislocation-loop growth during in-situ high-voltage Electron Microscopy

1990 ◽  
Vol 48 (4) ◽  
pp. 532-533
Author(s):  
E. Holzäpfel ◽  
F. Phillipp ◽  
M. Wilkens
Keyword(s):  
Point Defect ◽  
Rate Equations ◽  
Rate Theory ◽  
Dislocation Loops ◽  
High Voltage Electron Microscopy ◽  
Vacancy Migration ◽  
Voltage Electron ◽  
Reaction Rate Theory ◽  
Defect Reactions

During in-situ radiation damage experiments aiming on the investigation of vacancy-migration properties interstitial-type dislocation loops are used as probes monitoring the development of the point defect concentrations. The temperature dependence of the loop-growth rate v is analyzed in terms of reaction-rate theory yielding information on the vacancy migration enthalpy. The relation between v and the point-defect production rate P provides a critical test of such a treatment since it is sensitive to the defect reactions which are dominant. If mutual recombination of vacancies and interstitials is the dominant reaction, vαP0.5 holds. If, however, annihilation of the defects at unsaturable sinks determines the concentrations, a linear relationship vαP is expected.Detailed studies in pure bcc-metals yielded vαPx with 0.7≾×≾1.0 showing that besides recombination of vacancies and interstitials annihilation at sinks plays an important role in the concentration development which has properly to be incorporated into the rate equations.

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