Expanding the Outlook to Effects on Ecosystems
Mixed results are shown for the leaf area index of small, dense stands of young deciduous trees in soil-litter-plant enclosures (model ecosystems) at elevated [CO2]. More living biomass is accumulated each year over up to 6 years of growth at almost doubled ambient [CO2]. Examples of daily courses of CO2 gas exchange rates of these stands and canopy gross photosynthesis are calculated by means of the net CO2 gas exchange and dark respiration rates of the whole soil-litter-plant systems under unchanged ambient and elevated [CO2]. System total respiration is shown in response to changes in soil temperature, and selected daily courses illustrate the comparison of total system CO2 gross uptake with the total system and leaf dark respiration. All measured daily courses of system CO2 net assimilation are combined into monthly averages for one experimental year. This shows that the effect of elevated [CO2] on the overall CO2 gas exchange balance of the small tree groups is significantly positive early in the growth season. Water use efficiency is calculated for the whole system using special mathematical formulas (see Chap. 2). A clear reduction in water use at elevated [CO2] occurs at the stand level.
Production of litter is enhanced, and wider C/N ratios indicate reduced litter quality. Effects of more leaf litter recycled to the soil, of lower nutrient concentrations in soil organic material, of more root exudates, and of increased root mass turnover on soil bacteria are discussed. Despite some negative effects, it seems likely that fungi mass and activity will increase more than bacterial mass in forest soils should tropospheric [CO2] increase further. Effects on a few soil animals are also documented and summarized. As with bacteria and fungi, they also respond to reduced litter quality at elevated [CO2]. Wider C/N ratios also determine herbivory above- and belowground. Effects are discussed on the basis of examples in terms of animal abundance, consumption, developmental time, and relative growth rates. In addition, plausible effects of increased temperature on consumption rates are considered with respect to altered food quality.
KeywordsLeaf area index Net primary production Phytomass accumulation CO2 gas exchange of soil-litter-plant systems Evapotranspiration Soil warming Litter quality Decomposition Soil bacteria Soil fungi Earthworms Herbivory Consumption rate Soil invertebrate community
- Allen AS, Andrews JA, Finzi AC, Matamala R, Richter DD, Schlesinger WH (2000) Effects of free-air CO2 enrichment (FACE) on belowground processes in a Pinus taeda forest. Ecol Appl 10:437–448Google Scholar
- Dieleman WIJ, Vicca S, Dijkstra FA, Hagedorn F, Hovenden MJ, Larsen K, Morgan JA, Volder A, Beier C, Dukes JS, King J, Leuzinger S, Linder S, Luo Y, Oren R, De Angelis P, Tingey D, Hoosbeek MR, Janssens IA (2012) Simple additive effects are rare: a quantitative review of plant biomass and soil process responses to combines manipulations of CO2 and temperature. Glob Chang Biol 18:2681–2693PubMedCrossRefGoogle Scholar
- Forstreuter M (2001) Auswirkungen globaler Klimaänderungen auf das Wachstum und den Gaswechsel (CO2/H2O) von Rotbuchenbeständen (Fagus sylvatica L.). Habilitationsschrift (in German with English abstract), TU-Berlin, Gerrmany, pp 115–120, 180–183Google Scholar
- Kratz W, Reining E, Reining F, Overdieck D (1996) Qualität und Zersetzung der Streu von Acer pseudoplatanus L. nach Wachstum bei erhöhter CO2-Konzentration Verhandlungen der Gesellschaft für Ökologie 26:115–119 (in German, with English abstract)Google Scholar
- Norby RJ, DeLucia EH, Gielen B, Calfapietra C, Giardini CP, King JS, Ledford J, McCarthy HR, Moore DJP, Ceulemans R, DeAngelis P, Finzi AC, Karnosky DF, Kubiske ME, Lukac M, Pregnitzer KS, Scarascia-Mugnozza GE, Schlesinger WH, Oren R (2005) Forest response to elevated CO2 is conserved across a broad range of productivity. Proc Natl Acad Sci U S A 102:18052–18056PubMedPubMedCentralCrossRefGoogle Scholar
- Ryalls JM.W., Riegler M, Moore BD, Lopaticki G, Johnson SN (2013) Effects of elevated temperature and CO2 on aboveground-belowground systems: a case study with plants, their mutualistic bacteria and root/shoot herbivores. Frontiers in Plant Science 5, Article 445: 1–7Google Scholar
- Strain BR, Bazzaz FA (1983) Terrestrial plant communities. In: Lemon ER (ed) CO2 and plants. The response of plants to rising levels of atmospheric carbon dioxide. Westview, Boulder, pp 177–222Google Scholar
- Strassemeyer J (2002) Gaswechsel (CO2/H2O) von Eichenbeständen (Quercus robur L.) unter erhöhter atmosphärischer CO2-Konzentration. Dissertation, TU-Berlin, Germany, pp 98–99, 120–123 (in German, with English abstract)Google Scholar
- von Liebig J (1840) Die organische Chemie in ihrer Anwendung auf Agricultur und Physiologie. Friedrich Vieweg und Sohn, Braunschweig (in German)Google Scholar
- Weigt RB, Raidl S, Verma R, Rodenkirchen H, Göttlein A, Agerer R (2011) Effects of twice-ambient carbon dioxide and nitrogen amendment on biomass, nutrient contents and carbon costs of Norway spruce seedlings as influenced by mycorrhization with Piloderma croceum and Tomentellopsis submollis. Mycorrhiza 21:375–391PubMedCrossRefGoogle Scholar
- Wittig VE, Bernacchi CJ, Zhu X-G, Calfapietra C, Ceulemans R, De Angelis P, Gielen B, Miglietta F, Morgan PB, Long SP (2005) Gross primary production is stimulated for three Populus species grown under free-air CO2 enrichment from planting through canopy closure. Glob Chang Biol 11:644–656CrossRefGoogle Scholar