Search Results

You are looking at 1 - 2 of 2 items for

  • Author: Dalibor Janous x
Clear All Modify Search
Open access

Klára Taufarová, Kateřina Havránková, Alice Dvorská, Marian Pavelka, Marek Urbaniak and Dalibor Janouš

Abstract

Net ecosystem production reflects the potential of the ecosystem to sequestrate atmospheric CO2. Daily net ecosystem production of a mountain Norway spruce forest of the temperate zone (Czech Republic) was determined using the eddy covariance method. Growing season days when the ecosystem was a CO2 source were examined with respect to current weather conditions. During the 2005, 2006, and 2007 growing seasons, there were 44, 65, and 39 days, respectively, when the forest was a net CO2 source. The current weather conditions associated with CO2 release during the growing seasons were: cool and overcast conditions at the beginning or end of the growing seasons characterized by a 3-year mean net ecosystem production of -7.2 kg C ha-1 day-1; overcast or/and rainy days (-23.1 kg C ha-1 day-1); partly cloudy and hot days (-11.8 kg C ha-1 day-1); and overcast and hot days (-13.5 kg C ha-1 day-1). CO2 release was the highest during the overcast or/and rainy conditions (84%, average from all years), which had the greatest impact during the major production periods. As forests are important CO2 sinks and more frequent weather extremes are expected due to climate change, it is important to predict future forest carbon balances to study the influence of heightened variability in climatic variables.

Open access

Marian Pavelka, Manuel Acosta, Ralf Kiese, Núria Altimir, Christian Brümmer, Patrick Crill, Eva Darenova, Roland Fuß, Bert Gielen, Alexander Graf, Leif Klemedtsson, Annalea Lohila, Bernhard Longdoz, Anders Lindroth, Mats Nilsson, Sara Maraňón Jiménez, Lutz Merbold, Leonardo Montagnani, Matthias Peichl, Mari Pihlatie, Jukka Pumpanen, Penelope Serrano Ortiz, Hanna Silvennoinen, Ute Skiba, Patrik Vestin, Per Weslien, Dalibor Janous and Werner Kutsch

Abstract

Chamber measurements of trace gas fluxes between the land surface and the atmosphere have been conducted for almost a century. Different chamber techniques, including static and dynamic, have been used with varying degrees of success in estimating greenhouse gases (CO2, CH4, N2O) fluxes. However, all of these have certain disadvantages which have either prevented them from providing an adequate estimate of greenhouse gas exchange or restricted them to be used under limited conditions. Generally, chamber methods are relatively low in cost and simple to operate. In combination with the appropriate sample allocations, chamber methods are adaptable for a wide variety of studies from local to global spatial scales, and they are particularly well suited for in situ and laboratory-based studies. Consequently, chamber measurements will play an important role in the portfolio of the Pan-European long-term research infrastructure Integrated Carbon Observation System. The respective working group of the Integrated Carbon Observation System Ecosystem Monitoring Station Assembly has decided to ascertain standards and quality checks for automated and manual chamber systems instead of defining one or several standard systems provided by commercial manufacturers in order to define minimum requirements for chamber measurements. The defined requirements and recommendations related to chamber measurements are described here.