The concentration and efflux of tree stem CO₂ and the role of xylem sap flow

Abstract

The accurate assessment of actual tree stem respiration and its relation with temperature plays a considerable role in investigating the forest carbon cycle. An increasing number of research reports have indicated that tree stem respiration determined with the commonly-applied chamber gas exchange measuring system does not follow expectations regarding temperature relationships. This method is based on the nowadays widely-accepted theory that the respired CO₂ in a tree stem would all diffuse outward into the atmosphere. However, it neglects partial CO₂ that is dissolved in the xylem sap and is carried away by the transpirational stream. Scientists have started to realize that the respired CO₂ measured with the chamber gas exchange method is only a portion of the total stem respiration (CO₂ efflux), while the other portion, which is sometimes very substantial in quantity (thought to occupy maybe 15%-75% of the total stem respiration), is transported to the upper part of the stem and to the canopy by sap flow. This suggests that the CO₂ produced by respiration is re-allocated within the stem. Accordingly, the change in CO₂ efflux could be reflected in the rates of sap flow in addition to its dependence on temperature. Proper methods and instruments are required to quantify the internal and external CO₂ fluxes in the trunk and their interaction with related environmental factors.

Key words： sap flow rates; respired CO₂ in the stem; re-translocation of stem respiration

Acknowledgements

Authors are grateful to the National Natural Science Foundation of China (Grant No. 30770328) and the Natural Science Foundation of Guangdong Province (No. 07006917) for support.

References

1 Amthor J S (1989). Respiration and crop productivity. New York: Springer-Verlag

2 Barbour M M, Whitehead D (2003). A demonstration of the theoretical prediction that sap velocity is related to wood density in the conifer, Dacrydium cupressinum (rimu). New Phytologist, 158: 477-488

3 Bowman W P, Barbour M M, Turnbull M H, Tissue D T, Whitehead D, Griffin K (2005). Sap flow rates and sapwood density are critical factors in within- and between-tree variation in CO₂ efflux from stems of mature Dacrydium cupressinum trees. New Phytologist, 167: 815-828

4 Campbell G S, Norman J M (1998). An Introduction to Environmental Biophysics. New York: Springer-Verlag

5 Cavaleri M A, Oberbauer S T, Ryan M G (2006). Wood CO₂ efflux in a primary tropical rain forest. Global Change Biology, 12: 2442-2458

6 Chambers J Q, Tribuzy E S, Toledo L C, Crispim B F, Higuchi N, Santos J D, Araújo A C, Kruijt B, Nobre A D, Trumbore S E (2004). Respiration from a tropical forest ecosystem: partitioning of sources and low carbon use efficiency. Ecological Applications, 14: S72-88

7 Damesin C, Ceschia E, Le Goff N, Ottorini J M, Dufrêne E (2002). Stem and branch respiration of beech: from tree measurements to estimation at the stand level. New Phytologist, 153: 159-172

8 Eklund L (1990). Endogenous levels of oxygen, carbon dioxide and ethylene in stems of Norway spruce trees during one growing season. Trees, 4: 150-154

9 Gansert D, Burgdorf M (2005). Effects of xylem sap flow on carbon dioxide efflux from stems of birch (Betula pendula Roth). Flora, 200: 444-455

10 Gansert D (2004). A new type of cuvette for the measurement of daily variation of CO₂ efflux from stems and branches in controlled temperature conditions. Trees, 18: 221-229

11 Hari P, Nygren P, Korpilahti E (1991). Internal circulation of carbon dioxide within a tree. Canadian Journal of Forest Research, 21: 514-515

12 Janssens I A, Lankreijer H, Matteucci GKowalski A S, Buchmann N, Epron D, Pilegaard K, Kutsch W, Longdoz B, Grünwald T, Montagnani L, Dore S, Rebmann C, Moors E J, Grelle A, Rannik Ü, Morgenstern K, Oltchev S, Clement R, Guðmundsson J, Minerbi S, Berbigier P, Ibrom A, Moncrieff J, Aubinet M, Bernhofer C, Jensen N O, Vesala T, Granier A, Schulze E D, Lindroth A, Dolman A J, Jarvis P G, Ceulemans R, Valentini R (2001). Productivity overshadows temperature in determining soil and ecosystem respiration across European forests. Global Change Biology, 7: 269-278

13 Kakubari Y (1988). Diurnal and seasonal fluctuations in the bark respiration of standing Fagus sylvatica trees at Solling, West Germany. Journal of Japanese Forest Society, 70: 64-70

14 Larcher W (2001). Ökophysiologie der Pflanzen. Stugttgart: Verlag Eugen Ulmer, 150-157

15 Lavigne M B, Franklin S E, Hunt E R Jr (1996). Estimating stem maintenance respiration rates for dissimilar balsam fir stands. Tree Physiology, 16: 687-695

16 Lavigne M B (1987). Differences in stem respiration responses to temperature between balsam fir trees in thinned and unthinned stands. Tree Physiology, 3: 225-233

17 Levy P E, Jarvis P G (1998). Stem CO₂ fluxes in two Sahelian shrub species (Guiera senegalensis and Combretum micranthum). Functional Ecology, 1998, 12: 107-116

18 Levy P E, Meir P, Allen S J, Jarvis P G (1999). The effect of aqueous transport of CO₂ in xylem sap on gas exchange in woody plants. Tree Physiology, 19: 53-58

19 Maier C A, Clinton B D (2006). Relationship between stem CO₂ efflux, stem sap velocity and xylem CO₂ concentration in young loblolly pine trees. Plant, Cell and Environment, 29: 1471-1483

20 Maier C A, Zarnoch S J, Dougherty P M (1998). Effects of temperature and tissue nitrogen on dormant seasonal stem and branch maintenance respiration in a young loblolly pine (Pinus taeda) plantation. Tree Physiology, 1998, 18: 11-20

21 Martin T A, Teskey R O, Dougherty P M (1994). Movement of respiratory CO₂ in stems of loblolly pine (Pinus taeda L.) seedlings. Tree Physiology, 14: 481-495

22 McGuire M A, Teskey R O, Cerasoli S (2007). CO₂ fluxes and respiration of branch segments of sycamore (Platanus occidentalis L.) examined at different sap velocities, branch diameters, and temperatures. Journal of Experimental Botany, 58: 2159-2168

23 McGuire M A, Teskey R O (2004). Estimating stem respiration in trees by a mass balance approach that accounts for internal and external fluxes of CO₂. Tree Physiology, 24: 571-578

24 Meir P, Grace J (2002). Scaling relationships for woody tissue respiration in two tropical rain forests. Plant, Cell and Environment, 25: 963-973

25 Pfanz H, Aschan G (2001). The existence of bark and stem photosynthesis in woody plants and its significance for the overall carbon gain. An eco-physiological and ecological approach. Progress in Botany, 62: 477-510

26 Pruyn M L, Gartner B L, Harmon M E (2002). Within stem variation of respiration in Douglas fir trees. New Phytologist, 154: 359-372

27 Pruyn M L, Harmon M E, Gartner B L (2003). Stem respiratory potential in six softwood and four hardwood tree species in the central cascades of Oregon. Oecologia, 137: 10-21

28 Ryan M G, Gower S T, Hubbard R M, Waring R H, Gholz H L, Cropper W P, Running S W (1995). Woody tissue maintenance respiration of four conifers in contrasting climates. Oecologia, 101: 133-140

29 Ryan M G, Hubbard R M, Clark D A, Sanford R L (1994). Woody-tissue respiration for Simarouba amara and Minquartia guianensis, two tropical wet forest trees with different growth habits. Oecologia, 100: 213-220

30 Saveyn A, Steppe K, Lemeur R. Report on non-temperature related variations in CO₂ efflux rates from young tree stems in the dormant season (2008). Trees, 22(2): 165-174

31 Stringer J W, Kimmerer T W (1993). Refixation of xylem sap CO₂ in Populus deltoides. Physiol Plant, 89: 243-251

32 Teskey R O, McGuire M A (2005). CO₂ transported in xylem sap affects CO₂ efflux from Liquidambar styraciflua and Platanus occidentalis stems, and contributes to observed wound respiration phenomena. Trees, 19: 357-362

33 Teskey R O, McGuire M A (2002). Carbon dioxide transport in xylem causes errors in estimation of rates of respiration in stems and branches of trees. Plant, Cell and Environment, 25, 1571-1577

34 Wang M, Liu Y Q, Hao Z Q, Wang Y S (2006). Respiration rate of broadleaved Korean pine forest ecosystem in Changbai Mountains. Chinese Journal of Applied Ecology, 17(10): 1789-1795 (in Chinese)

35 Wang W J, Wang H M, Zu Y G, Li X Y, Takayoshi K (2005). Characteristics of root, stem, and soil respiration Q₁₀ temperature coefficients in forest ecosystems. Acta Phytoecologica Sinica, 29(4): 680-691 (in Chinese)

36 Wang W J, Yang F J, Zu Y G, Wang H M, Kentaro T, Kaichiro S, Takayoshi K (2003). Stem Respiration of a Larch (Larix gmelini) Plantation in Northeast China. Acta Botanica Sinica, 45(12): 1387-1397

37 Wang W J (2004). Methods for the determination of CO₂ flux from non-photosynthetic organs of trees and their influences on the results. Acta Ecologica Sinica, 24(9): 2056-2067

38 Waring R H, Schlesinger W H (1985). Forest ecosystems: concepts and management. London: Academic Press

39 Xiao F M, Wang S L, Du T Z, Chen L C, Yu X J (2005). Respiration of Chinese fir in plantations in Huitong, Hu’nan Province. Acta Ecologica Sinica, 25(10): 2514-2519 (in Chinese)

40 Xu M, Debiase T A, Qi Y, Goldstein A, Liu Z (2001). Ecosystem respiration in a young ponderosa pine plantation in Sierra Nevada Mountains, California. Tree Physiology, 21: 309-318

41 Yan Y P, Sha L Q, Cao M (2008). Diurnal Variation of Stem Respiration of Three Tropical Tree Species in Xishuangbanna, Southwest China. Journal of Plant Ecology, 32(1): 23-30 (in Chinese)

42 Yoder B J, Ryan M G, Waring R H, Schoettle A W, Kaufmann M R (1994). Evidence of reduced photosynthetic rates in old trees. Forest Science, 40: 513-527

43 Zeng X P, Peng S L, Zhao P (2000). Measurement of respiration amount in artificial Acacia Mangium forest in a low subtropical hill forest region of Guangdong. Acta Phytoecologica Sinica, 24(2): 420-424 (in Chinese)

44 Zeng X P, Zhao P, Sun G C (2006). Effects of climate warming on terraneous plants. Chinese Journal of Applied Ecology, 17(12): 2445-2450 (in Chinese)

45 Zeng Z P (2007). Productivity, structure and function of 3 types of man-made forest communities in Heshan, South China. Guangzhou: PhD Dissertation of Graduate School of Chinese Academy of Sciences (in Chinese)

46 Zhao P, Lu P, Ma L, Sun G C, Rao X Q, Cai X A, Zeng X P (2005). Combining sap flow measurement-based canopy stomatal conductance and ¹³C discrimination to estimate forest carbon assimilation. Chinese Science Bulletin, 50(18): 2021-2027

47 Zhao P, Rao X Q, Ma L, Cai X A, Zeng X P (2006a). Sap flow-scaled stand transpiration and canopy stomatal conductance in an Acacia mangium forest. Acta Phytoecologica Sinica, 30(4): 655-665

48 Zhao P, Rao X Q, Ma L, Cai X A, Zeng X P (2006b). The variations of sap flux density and whole-tree transpiration across individuals of Acacia mangium. Acta Ecologica Sinica, 26(12): 4050-4058

49 Zhao X S, Guan D X, Wu J B, Zhang M, Jin C J, Han S J (2006c). The relationship between CO₂ flux and temperature of the mixed forest of broadleaved and Korean-Pine in Changbai Mountain. Acta Ecologica Sinica, 26(4): 1088-1095