Climate Change Reverses the Competitive Balance of Ash and Beech Seedlings under Simulated Forest Conditions

Abstract

This study identifies the important role of climate change and photosynthetic photon flux density (PPFD) in the regenerative competence of ash and beech seedlings in 12 inter- and intra-specific competition designs in simulated mixed ash-beech forest gaps under conditions of non-limiting soil volume, water and nutrient supply. The growth conditions simulated natural forest conditions as closely as possible. Simulations were performed by growing interacting seedling canopies for one season in temperature-regulated closed-top chambers (CTCs). Eight CTCs were used in a factorial design with replicate treatments of [CO₂] × temperature × PPFD × competition design. [CO₂] tracked ambient levels or was 360 µmol mol^-1 higher. Temperature tracked ambient levels or was 2.8 °C higher. PPFD on two plant tables inside each CTC was 16 % and 5 % of open-field levels, respectively, representative of typical light flux levels in a natural forest gap. In several of the competition designs, climate change made the ash seedlings grow taller than the beech seedlings and, at the same time, attain a larger leaf area and a larger total biomass. Advantages of this type for ash were found particularly at lower PPFD. There was a positive synergistic interaction of elevated temperature × [CO₂] for both species, but more so for ash. There are many uncertainties when a study of chambered seedlings is to be projected to real changes in natural forests. Nevertheless, this study supports a possible future shift towards ash in north European, unmanaged, mixed ash-beech forests in response to the predicted climate change.

Key words

Ash - beech - climate change - competition - forest gap - temperature-regulated closed-top chambers (CTCs) - unmanaged forests.

References

• 1 Aaslyng J. M., Rosenqvist E.. A sensor for microclimatic measurement of PAR in a plant canopy.  Agricultural and Forest Meteorology. (1999);  96 189-197
• 2 Bruhn D., Leverenz J. W., Saxe H.. Effects of tree size and temperature on relative growth rate and its components of Fagus sylvatica seedlings exposed to two partial pressures of atmospheric [CO₂].  New Phytologist. (2000);  146 415-425
• 3 Bruhn D., Mikkelsen T., Pilagaard K., Gavito M. E., Saxe H.. Climate change in a plant ecophysiological perspective. Jørgensen, A. M. K., Fenger, J., and Halsnæs, K., eds. Climate Change Research - Danish Contributions Chapter 11. Danish Climate Centre, DMI, Ministry of Transport. Copenhagen; Gads Forlag (2001): 407
• 4 Caspersen J. P., Kobe R. K.. Interspecific variation in sapling mortality in relation to growth and soil moisture.  Oikos. (2001);  92 160-168
• 5 Catovsky S., Bazzaz F. A.. Plant competition in an elevated CO₂ world. Mooney, H. A. and Canadell, J. G., eds. Encyclopedia of Global Environmental Change. Chichester; John Wiley and Sons, Ltd. (2002): 471-481
• 6 Cavender-Bares J., Potts M., Zacharias E., Bazzaz F. A.. Consequences of CO₂ and light interactions for leaf phenology, growth, and senescence in Quercus rubra. .  Global Change Biology. (2000);  6 877-887
• 7 Finzi A. C., Canham C. D.. Sapling growth in response to light and nitrogen availability in a southern New England forest.  Forest Ecology and Management. (2000);  131 153-165
• 8 Gill R.. The impact of deer on woodland biodiversity. Information note. Forestry Commission. http://www.forestry.gov.uk/website/PDF.nsf/pdf/fcin36.pdf/$FILE/fcin36.pdf . (2000)
• 9 Gunter L. L., Tuskan G. A., Gunderson C. A., Norby R. J.. Genetic variation and spatial structure in sugar maple (Acer saccharum Marsh.) and implications for predicted global-scale environmental change.  Global Change Biology. (2000);  6 335-344
• 10 Hättenschwiler S.. Tree seedling growth in natural deep shade: functional traits related to interspecific variation in response to elevated CO₂.  Oecologia. (2001);  129 31-42
• 11 Idso K. E., Idso S. B.. Plant responses to atmospheric CO₂ enrichment in the face of environmental constraints: a review of the past ten years' research.  Agricultural and Forest Meteorology. (1994);  69 153-204
• 12 Idso S. B., Idso K. E., Garcia R. L., Kimball B. A., Hoober J. K.. Effects of atmospheric CO₂ enrichment and foliar methanol application on net photosynthesis of sour orange tree (Citrus aurantium; Rutaceae) leaves.  American Journal of Botany. (1995);  82 26-30
• 13 Iverson L. R., Prasad A. M.. Potential changes in tree species richness and forest community types following climate change.  Ecosystems. (2001);  4 200-215
• 14 IPCC .Intergovernmental Panel on Climate Change 2001. Synthesis Report. Summary for Policymakers, and Report. (2001) http://www.grida.no/climate/ipcc_tar/vol4/english/009.htm, and http://www.grida.no/climate/ipcc/emission/
• 15 Johnson K.. The effects of deer browsing and salvage operations in ice storm disturbed forests of northern New York state. The Roosevelt Wildlife Station. Educational homepage: http://www.esf.edu/resorg/rooseveltwildlife/Research/Dbrow/Dbrow.htm . (2005)
• 16 Kaae B., Madsen L.. Opinions and preferences of Danish nature [in Danish]. By-og Landsplanserien 21. Hørsholm: Skov and Landskab, pp. 128. http://www.fsl.dk/pubsalg/Elektr-pub/BogL-nr-21.pdf . (2003)
• 17 Karnosky D. F.. Impacts of elevated atmospheric CO₂ on forest trees and forest ecosystems: knowledge gaps.  Environment International. (2002);  29 161-169
• 18 Kellomäki S., Wang K.-Y.. Growth and resource use of birch seedlings under elevated carbon dioxide and temperature.  Annals of Botany. (2001);  87 669-682
• 19 King J. S., Thomas R. B., Strain B. R.. Growth and carbon allocation in root systems of Pinus taeda and Pinus ponderosa seedlings as affected by varying CO₂, temperature and nitrogen.  Tree Physiology. (1996);  16 635-642
• 20 Kozlowski T. T., Pallardy S. G.. Growth Control in Woody Plants. Section on Temperature, pp. 236 - 270. London; Academic Press (1997): 641
• 21 Kuokkanen K., Julkunen-Tiitto R., Kainänen M., Niemelä P., Tahvanainen J.. The effect of elevated CO₂ and temperature on the secondary chemistry of Betula pendula. .  Trees. (2001);  15 378-384
• 22 Larsen B., Saxe H.. Danish forestry and Climate Change. Jørgensen, A. M. K., Fenger, J., and Halsnæs, K., eds. Climate Change Research - Danish Contributions, Chapter 13. Danish Climate Centre, DMI, Ministry of Transport. Copenhagen; Gads Forlag (2001): 407
• 23 Leakey A. D. B., Press M. C., Scholes J. D., Watling J. R.. Relative enhancement of photosynthesis and growth at elevated CO₂ is greater under sunflecks than uniform irradiance in a tropical rain forest tree seedling.  Plant, Cell and Environment. (2002);  25 1701-1714
• 24 Leverenz J. W., Bruhn D., Saxe H.. Responses of two provenences of Fagus sylvatica L. seedlings to a combination of four temperature and two CO₂ regimes during their first growing season: Gas exchange of leaves and roots.  New Phytologist. (1999 a);  144 437-454
• 25 Leverenz J. W., Paludan-Müller G., Saxe H.. Response to three seasons of elevated ozone in the progeny of healthy and unhealthy Norway spruce trees from a plantation with the “top dying” syndrome.  New Phytologist. (1999 b);  142 259-270
• 26 Liozon R., Badeck F.-W., Genty B., Meyer S., Saugier B.. Leaf photosynthetic characteristics of beech (Fagus sylvatica) saplings during three years of exposure to elevated CO₂ concentration.  Tree Physiology. (2000);  20 239-247
• 27 Medlyn B. E., Badeck F.-W., Pury D. G. G., de Barton C. V. M., Broadmeadow M., Ceulemans R., Angelis P., de Forstreuter M., Jach M. E., Kellomäki S., Laitat E., Marek M., Philippot S., Rey A., Strassemeyer J., Laitinen K., Liozon R., Portier B., Roberntz P., Wang K., Jarvis P. G.. Effects of elevated [CO₂] on photosynthesis in European forest species: a meta-analysis of model parameters.  Plant, Cell and Environment. (1999);  22 1475-1495
• 28 Mickler R. A., Fox S.. The productivity and sustainability of southern forest ecosystems in a changing environment. Ecological Studies 128. New York; Springer-Verlag Inc. (1998): 892
• 29 Mohren G. M. J., Kramer K., Sabaté S.. Impacts of global change on tree physiology and forest ecosystems. Proceedings of the International Conference on Impacts of Global Change on Tree Physiology and Forest Ecosystems, 26 - 29. November 1996, Wageningen, The Netherlands. London; Kluwer Academic Publishers (1997): 372
• 30 Nagy M., Ogawa K., Hagihara A.. Interactive effects of CO₂ enrichment and temperature on the photosynthesis of field-grown hinoki cypress (Chamaecyparis obtusa) branches.  Trees. (2000);  14 282-288
• 31 Norby R., Luo Y.. Evaluating ecosystem responses to rising atmospheric CO₂ and global warming in a multi-factor world.  New Phytologist. (2004);  162 281-293
• 32 Polle A., McKee I., Blaschke L.. Altered physiological and growth responses to elevated [CO₂] in offspring from holm oak (Quercus ilex L.) Mother trees with lifetime exposure to naturally elevated [CO₂].  Plant, Cell and Environment. (2001);  24 1075-1083
• 33 Rust S., Savill P. S.. The root systems of Fraxinus excelsior and Fagus sylvatica and their competitive relationships.  Forestry. (2000);  73 499-508
• 34 Sack L., Grubb P. J.. Why do species of woody seedlings change rank in relative growth rate between low and high irradiance?.  Functional Ecology. (2001);  15 145-154
• 35 Saxe H., Ellsworth D., Heath J.. Tree and forest functioning in an enriched CO₂ atmosphere. Tansley Review No. 98.  New Phytologist. (1998);  139 395-436
• 36 Saxe H., Cannell M. G. R., Johnsen Ø., Ryan M. G., Vourlitis G.. Tree and forest functioning in response to global warming. Tansley Review no. 123.  New Phytologist. (2001);  123 369-400
• 37 Stitt M., Krapp A.. The interaction between elevated carbon dioxide and nitrogen nutrition: the physiological and molecular background.  Plant, Cell and Environment. (1999);  22 583-621
• 38 Taylor G., Ceulemans R., Ferris R., Gardner S. D. L., Shao B. Y.. Increased leaf area expansion of hybrid poplar in elevated CO₂. From controlled environments to open-top chambers and to FACE.  Environmental Pollution. (2001);  115 463-472
• 39 Teskey R. O.. Combined effects of elevated CO₂ and air temperature on carbon assimilation of Pinus taeda trees.  Plant, Cell and Environment. (1997);  20 373-380
• 40 Tjoelker M. G., Oleksyn J., Reich P. B.. Temperature and ontogeny mediated growth response to elevated CO₂ in seedlings of five boreal tree species.  New Phytologist. (1998);  140 197-210
• 41 Tognetti R., Minotta G., Pinzauti S., Michelozzi M., Borghetti M.. Acclimation to changing light conditions of long-term shade-grown beech (Fagus sylvatica L.) seedlings of different geographical origins.  Trees. (1998);  12 326-333
• 42 Usami T., Lee J., Oikawa T.. Interactive effects of increased temperature and CO₂ on the growth of Quercus myrsinaefolia saplings.  Plant, Cell and Environment. (2001);  24 1007-1019

Editor: H. Rennenberg