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Matyssek R.,TU Munich | Wieser G.,Federal Office and Research Center for Forests | Fleischmann F.,TU Munich | Grunhage L.,Justus Liebig University
Developments in Environmental Science | Year: 2013

Empirical evidence underlines enhanced ground-level O3 regimes as components of global change, although interaction responses of forest trees and ecosystems have only recently been addressed by research. One case study is the tree-level Kranzberg Forest Experiment, having been resumed for envisioning "next-generation" ecosystem-level O3 research. Quantifying enhanced O3 impact is highlighted as part of a multi-factorial, abiotic-biotic interaction network of experiments and monitoring sites, which challenge the required quantitative predictability of the plasticity, and hence, extent and risk in system response, given the significance of forests as global determinants of carbon storage and sequestration. Here, we outline such integrated research concepts, cross-linking experimentation, monitoring and modelling to scale up O3 responses from internal tree processes towards zonobiomic spatio-temporal scales. The availability of conceptual and methodological means as pre-requisites is emphasized. The relevance of respective research for providing spin-offs within socio-economic contexts related to biogenic energy production and CO2 emission trading is examined. © 2013 Elsevier Ltd. Source

Wieser G.,Federal Office and Research Center for Forests | Oberhuber W.,University of Innsbruck | Walder L.,University of Innsbruck | Spieler D.,University of Innsbruck | Gruber A.,University of Innsbruck
Annals of Forest Science | Year: 2010

Temperature is suggested to determine the upper limit of tree life. Therefore, future climate warming may be of importance for tree distribution within the European Alps, where low temperatures limit carbon metabolism. We focused on the effects of air and soil temperature on net photosynthesis (P n) of Pinus cembra an evergreen climax species of the timberline ecotone of the Central Austrian Alps. Light response and temperature response curves were estimated along an altitudinal gradient ranging from the forest limit up to the krummholz limit in both summer and fall. In general, P n was significantly lower in fall as compared to summer. Nevertheless, independent from season mean Pn values tended to increase with elevation and were positively correlated with root zone temperatures. The specific leaf area by contrast declined with increasing elevation. Furthermore, the temperature optimum of net photosynthesis declined with increasing elevation and was positively correlated with the mean maximum air temperature of the 10 days prior the date of measurement. Thus, our findings appear to reflect a long-term adaptation of the photosynthetic apparatus of Pinus cembra to the general temperature conditions with respect to elevation combined with a short term acclimation to the prevailing temperature regime. © INRA, EDP Sciences, 2010. Source

Uddling J.,Gothenburg University | Matyssek R.,TU Munich | Pettersson J.B.C.,Gothenburg University | Wieser G.,Federal Office and Research Center for Forests
Environmental Pollution | Year: 2012

Pre-requisite for reliable O 3 risk assessment for plants is determination of stomatal O 3 uptake. One unaddressed uncertainty in this context relates to transpiration-induced molecular collisions impeding stomatal O 3 influx. This study quantifies, through physical modelling, the error made when estimating stomatal O 3 flux without accounting for molecular collisions arising from transpiratory mass flow of gas out of the leaf. The analysis demonstrates that the error increases with increasing leaf-to-air water vapour mole fraction difference (Δw), being zero in water vapour saturated air and 4.2% overestimation at Δw of 0.05. Overestimation is approximately twice as large in empirical studies quantifying stomatal O 3 flux from measured leaf or canopy water flux, if neglecting both water vapour-dry air collisions (causing overestimation of leaf conductance) and collisions involving O 3. Correction for transpiration-induced molecular collisions is thus relevant for both empirical research and for large-scale modelling of stomatal O 3 flux across strong spatial Δw gradients. © 2012 Elsevier Ltd. All rights reserved. Source

Inclan R.,CIEMAT | Uribe C.,CIEMAT | Sanchez L.,Polytechnic University of Mozambique | Sanchez D.M.,CIEMAT | And 5 more authors.
Biogeochemistry | Year: 2012

We investigated N 2O and CH 4 fluxes from soils of Quercus ilex,Quercus pyrenaica and Pinus sylvestris stands located in the surrounding area of Madrid (Spain). The fluxes were measured for 18 months from both mature stands and post fire stands using the static chamber technique. Simultaneously with gas fluxes, soil temperature, soil water content, soil C and soil N were measured in the stands. Nitrous oxide fluxes ranged from -11. 43 to 8. 34 μg N 2O-N m -2 h -1 in Q. ilex, -7. 74 to 13. 52 μg N 2O-N m -2 h -1 in Q. pyrenaica and -28. 17 to 21. 89 μg N 2O-N m -2 h -1 in P. sylvestris. Fluxes of CH 4 ranged from -8. 12 to 4. 11 μg CH 4-C m -2 h -1 in Q. ilex, -7. 74 to 3. 0 μg CH 4-C m -2 h -1 in Q. pyrenaica and -24. 46 to 6. 07 μg CH 4-C m -2 h -1 in P. sylvestris. Seasonal differences were detected; N 2O fluxes being higher in wet months whereas N 2O fluxes declined in dry months. Net consumption of N 2O was related to low N availability, high soil C contents, high soil temperatures and low moisture content. Fire decreased N 2O fluxes in spring. N 2O emissions were closely correlated with previous day's rainfall and soil moisture. Our ecosystems generally were a sink for methane in the dry season and a source of CH 4 during wet months. The available water in the soil influenced the observed seasonal trend. The burned sites showed higher CH 4 oxidation rates in Q. ilex, and lower rates in P. sylvestris. Overall, the data suggest that fire alters both N 2O and CH 4 fluxes. However, the magnitude of such variation depends on the site, soil characteristics and seasonal climatic conditions. © 2010 Springer Science+Business Media B.V. Source

Matyssek R.,TU Munich | Wieser G.,Federal Office and Research Center for Forests | Calfapietra C.,National Research Council Italy | De Vries W.,Wageningen University | And 9 more authors.
Environmental Pollution | Year: 2012

Forests in Europe face significant changes in climate, which in interaction with air quality changes, may significantly affect forest productivity, stand composition and carbon sequestration in both vegetation and soils. Identified knowledge gaps and research needs include: (i) interaction between changes in air quality (trace gas concentrations), climate and other site factors on forest ecosystem response, (ii) significance of biotic processes in system response, (iii) tools for mechanistic and diagnostic understanding and upscaling, and (iv) the need for unifying modelling and empirical research for synthesis. This position paper highlights the above focuses, including the global dimension of air pollution as part of climate change and the need for knowledge transfer to enable reliable risk assessment. A new type of research site in forest ecosystems ("supersites") will be conducive to addressing these gaps by enabling integration of experimentation and modelling within the soil-plant-atmosphere interface, as well as further model development. © 2011 Elsevier Ltd. All rights reserved. Source

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