caa a22 4500 467886164 CHVBK 20180406152735.0 cr unu---uuuuu 170328e20060301xx s 000 0 eng 10.1007/s10021-005-0146-y doi (NATIONALLICENCE)springer-10.1007/s10021-005-0146-y Identifying Differences in Carbon Exchange among Arctic Ecosystem Types [Elektronische Daten] [M. Williams, L. Street, M. van Wijk, G. Shaver] Our objective was to determine how varied is the response of C cycling to temperature and irradiance in tundra vegetation. We used a large chamber to measure C exchange at 23 locations within a small arctic catchment in Alaska during summer 2003 and 2004. At each location, we determined light response curves of C exchange using shade cloths, twice during a growing season. We used data to fit a simple photosynthesis-irradiance, respiration-temperature model, with four parameters. We used a maximum likelihood technique to determine the acceptable parameter space for each light curve, given measurement uncertainty. We then explored which sites and time periods had parameter sets in common—an indication of functional similarity. We found that seven distinct parameter sets were required to explain observed C flux responses to temperature and light variation at all sites and time periods. The variation in estimated maximum photosynthetic rate (Pmax) was strongly correlated with measurements of site leaf area index (LAI). The behavior of tussock tundra sites, the dominant vegetation of arctic tundra, could largely be described with a single parameter set, with a Pmax of 9.7μmol m−2 s−1. Tussock tundra sites had, correspondingly, similar LAI (mean = 0.66). Non-tussock sites (for example, sedge and shrub tundras) had larger spatial and temporal variations in both C dynamic parameters (Pmax varying from 9.7-25.7μmol m−2 s−1) and LAI (0.6-2.0). There were no clear relationships between dominant non-tussock vegetation types and a particular parameter set. Our results suggest that C dynamics of the acidic tussock tundra slopes and hilltops in northern Alaska are relatively simply described during the peak growing season. However, the foot-slopes and water tracks have more variable patterns of LAI and C exchange, not simply related to the dominant vegetation type. Springer Science+Business Media, Inc., 2006 carbon flux nationallicence leaf area index nationallicence tundra nationallicence landscape heterogeneity nationallicence net ecosystem exchange nationallicence photosynthesis nationallicence respiration nationallicence maximum likelihood analysis nationallicence Williams M. School of GeoSciences, University of Edinburgh, crew Building, EH9 3JN, Edinburgh, UK aut Street L. School of GeoSciences, University of Edinburgh, crew Building, EH9 3JN, Edinburgh, UK aut van Wijk M. Plant Production Systems, Wageningen University, Plant Sciences, Haarweg 333, 6709, Wageningen, RZ, The Netherlands aut Shaver G. The Ecosystems Center, Marine Biological Laboratory, 02543, Woods Hole, Massachusetts, USA aut Ecosystems Springer-Verlag; www.springer-ny.com 9/2(2006-03-01), 288-304 1432-9840 9:2<288 2006 9 10021 https://doi.org/10.1007/s10021-005-0146-y text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10021-005-0146-y text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Williams M. School of GeoSciences, University of Edinburgh, crew Building, EH9 3JN, Edinburgh, UK aut NATIONALLICENCE 700 1- Street L. School of GeoSciences, University of Edinburgh, crew Building, EH9 3JN, Edinburgh, UK aut NATIONALLICENCE 700 1- van Wijk M. Plant Production Systems, Wageningen University, Plant Sciences, Haarweg 333, 6709, Wageningen, RZ, The Netherlands aut NATIONALLICENCE 700 1- Shaver G. The Ecosystems Center, Marine Biological Laboratory, 02543, Woods Hole, Massachusetts, USA aut NATIONALLICENCE 773 0- Ecosystems Springer-Verlag; www.springer-ny.com 9/2(2006-03-01), 288-304 1432-9840 9:2<288 2006 9 10021 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer