Sampling at Zackenberg 2010

Objectives

• Collection of 75 microarthropod samples with soil corer from 5 grazed (E), 5 ungrazed plots (SC) and 5 control (C) plots (5 samples per plot).
  
• Install 150 litterbags, 10 in each plot, to determine decomposition of cellulose filter paper after minimum one year of field incubation.
  
• Collecting ≈20 30x20 cm blocks of soil/foerne to a depth of approx. 10 cm for bulk microarthropod extraction.
  
• Collection of soil samples for physico-chemical soil characterisation.
  

Sampling location

 The location of the plots are not yet settled.

Selection and positioning of sampling plots

There may be a humid gradient that must be covered by the blocks so each block are homogeneous with respect to plant community and humidity.

Microarthropod samples

20 big 20x30 cm blocks, approx. 2 from each plot, for bulk extraction are carefully cut and dug out of the turf and kept in plastic boxes during shipping until bulk extraction in Silkeborg.

Compression is avoided at all stages of handling soil samples for microarthropods. The samples are kept at 5 ^oC until processing.

5 samples (6 cm diameter, depth 5.5 cm) are collected randomly from each plot using a split corer soil sampler. The sampling procedure in section 2.3.1 of Aastrup et al. (2009) is followed.
 

Litterbags

VWR filter paper are used as a surrogate for indigenous litter and filled into litterbags. 150 litterbags each containing 2 g filter paper, corresponding to 4 round pieces 9 cm Ø, are buried horizontally 3-5 cm into the soil. The litterbags are left open in one end for ease of emptying and further processing. Sticks with colored (yellow) tape are used to locate the litterbags after  retrieval. The procedure in section 2.3.2 of Aastrup et al. (2009) is followed.

The 10 litterbags are placed randomly within each plot according to the random allocation scheme.

To check the state of decomposition in addition 20 extra bags are placed in control plots to monitor the current level of decomposition. Only two replicate plot may be chosen for the monitoring purpose in the wettest and the driest plots. Decomposition should be terminated when the remaining dry-weight is between 30-75%.

Collection of soil samples for physico-chemical soil characterisation

Sample treatment at Zackenberg

After 1 year litterbags are retrieved and brought to the Zackenberg laboratory, and then cleaned for roots, organic matter, soil particles etc. dried at 60 degrees and weighed. If the remaining dried filter paper is still contaminated by soil particles, they will have to be burned and loss on ignition (LOI) is used to determine the breakdown rate.

See detailed filter paper decomposition procedure.

Sample treatment at DMU/Silkeborg

• Extraction of microarthropods from standard 5.5 cm depth x 6 cm diameter soil cores, 75 pcs.
  
• Bulk extraction of large 20x30 cm soil/foerne blocks of microarthropods for natural isotope analysis, ca. 24 pcs.
  
• Stable isotope analyses according to Analysis of trophic structure.
  
• Determination of
• • actual water content by drying a subsample of minimum 3 samples at 105 ^oC from each block
    
  • nutrients (minimum NPK)
  • soil texture incl. pH and organic matter of representative soil samples from upper 20 cm of the soil profile (concerning samples see above).
    The soil analyses will be done at OKLab Viborg Denmark.
    
• A number of representative pieces of the filter paper batch are heated at 50 ^oC to determine water content and dry-weight and ignited in a muffle oven to determine organic matter and ash content.
  
  

  VWR cat. no. 516-0814; Qualitative filterpaper, 413; medium filtrationrate; particle retention 5-13 ym; size: 90 mm

List of materials shipped to Zackenberg May 2010

• Soil corer
  
• 75 cylinders for soil cores and 150 red lids
• ≈20 boxes for large 20x30 samples (complete protection from pressure)
  
• Filterpaper and meshbags for 150 litterbags
  

References

Aastrup, P., Nymand, J., Raundrup, K. R., Lauridsen, T. L., Krogh, P. H., Schmidt, N. M., Illeris, L., Ro-Poulsen, H., NuukBasic. Conceptual design and sampling procedures of the biological programme of NuukBasic. NERI Technical Report no. 745. National Environmental Research Institute, Aarhus University, 2009, pp. 70.

Contacts

Niels Martin Schmidt

Afd. for Arktisk Miljø, DMU/AU: Phone +45 4630 1931; Cell: +45 4191 5664

Paul Henning Krogh

Department of Terrestrial Ecology
University of Aarhus
P.O. Box 314, Vejlsoevej 25
DK-8600 Silkeborg, Denmark
Office  +45 89 20 15 88 
Switchboard  +45 89 20 14 00 
Mobile  +45 27 57 10 34 
Fax +45 89 20 14 13
Private  +45 32 11 71 06 
E-mail krogh.ph@gmail.com