1. Feb. 8th, 2011 B4730/5730 Plant Physiological Ecology
Respiration II

2. Acclimation of Respiration
Respiration rates
Increase during acclimation to cold
Decrease during acclimation to heat
Biochemical regulation counteracts the tendencies of the physiological rates
Depend on tissue/organ status
Quantitative description of respiration
Arrhenius, activation energy
Q10 R=Roexp[(lnQ10/10)·T]
Q10 varies from 1.0 to 3
reference respiration and Q10 still not fully predictable

3. Pinus radiata Ryan et al. Tree Phys. 1996
Eucalyptus regnans Ryan et al Eco Mono 2004

4. Pinus radiata; Kruse et al New Phyt 2008

5. Chamaecyparis obtusa,
Hagihara and Hozumi 1991
Rook 1969

6. California grass and shrubs; Carbone et al JGR Bio 2008

7. Picea mariana fen
(2006 warmer and drier); Cai et al PCE 2010

8. Respiration components
60% of maintenance R is from protein synthesis/repair, membrane repair, and ion gradients
Growth respiration includes carbon cost of synthesizing tissue from sugars and minerals
Theoretical analysis of biochemical pathways
Elemental analysis
Heat of Combustion
~25% of carbon allocation?
N uptake costs (transport) are usually much higher than phosphorous and other nutrients
Few estimates of total carbon costs, 10-60% (Ryan 1991)
Uses reductant (e.g. NADH reductase) from mitochondria

9. Lavingne et al
New Phyt 2004

10. Lavingne et al New Phyt 2004

11. Intro to Stable Isotopes Origin of Atoms and Elements
Composition of an atom (“nuclide”) is described by the number of protons and neutrons in the nucleus:
A = Z + N
where A is mass number, Z is number of protons, N is number of neutrons
Only 264 of 1700 known nuclides are stable
Most of these have even Z and even N; even Z and odd N are less common; odd Z and odd N are rare

12. Origin of Atoms and Elements (5)
Most relevant for ecological applications:
Element
Isotope
Abundance (%)
Hydrogen 1H
99.985 2H
0.015
Carbon
12C
98.89
13C
1.11
14C
<10-10
Nitrogen
14N
99.63
15N
0.37
Oxygen
16O
99.759
17O
0.037
18O
0.204

13. Terms and Definitions I
Stable isotopes are rare in abundance but can be measured very accurately by isotope ratio mass spectrometers (IRMS) (or lasers now), in which the ratio of heavy to light isotopes in a samples is compared with the ratio in a standard
Use delta notation to express these values conveniently:
d13C = ([(13C/12C)sample/(13C/12C)standard] - 1) 1000
Delta values are expressed in parts per thousand, or “per mil” (‰)
International standards are used so all delta values are intercomparable

14. Terms and Definitions (and a little jargon)
Standards: PDB limestone for C, Standard Mean Ocean Water (SMOW) for H and O, atmospheric N2 for N
If a sample has more of the heavy isotope than the standard (or than another substance) it is “enriched” or “heavier” and if it has less it is “depleted” or “lighter”
Examples:
d13C of PDB = 0‰
d13C of atmospheric CO2 = -8‰
d13C of C3 plants is around -25‰
IF Pee Dee Belemnite (PDB) has 13C/12C = , what is the 13C/12C ratio of CO2 in air?