Ninth International Conference on Permafrost ... - IARC Research

Ni n t h In t e r n at i o n a l Co n f e r e n c e o n Pe r m a f r o s tFigure 2. Map of the intensive study area showing land cover and sampling sites. Land cover is simplified with Bare ground, lichen tundraand dry/moist shrub tundra combined into one class.Table 1. Summary of samples and land cover type coverageLand cover type Samples n/ %OrganiclayerTransectcoverageLandscapecoverageDry lichen tundra 3 / 9 % 3 cm 4 % 2 %Dry shrub tundra 4 / 12 % 5 cm 5 % 9 %Moist shrub tundra 12 / 35 % 6 cm 34 % 35 %Wet shrub tundra 4 / 12 % 19 cm 12 % 14 %Fen peatland 7 / 21 % 32 cm 21 % 21 %Bog peatland 4 / 12 % 65 cm 21 % 16 %ResultsA summary land cover type representation in samples,transects, and the intensive study area is presented in Table1. The land cover type Bare ground is only represented at thelandscape level (2% of the intensive study area), and is notincluded. As no lake sediments have been sampled, water isalso excluded.The percentage representation for the three differentupscaling techniques is quite similar. Dry lichen and shrubtundra is somewhat over represented in the number ofsamples collected, while Bog peatlands are under-sampled.The mean depth of the top organic layers of tundra habitatsseem to gradually increase along a moisture gradient. Averagepeat thickness in raised permafrost bogs is considerablyhigher than in fen peatlands. Radiocarbon dating shows thatbogs are generally older than fens; the oldest basal peat froma bog is 5220 ± 50 C 14 y BP while the corresponding age forfens is 1405 ± 30 C 14 y BP.Preliminary analyses indicate that most of the C is foundin fen and bog peatlands. Calculated from arithmetic means,about three-quarters of the C is stored in peat or peaty tundratop organics. The wet shrub tundra stores significantly moreC than do moist or dry shrub tundra classes, showing thatit is important to make a distinction between shrub tundraclasses for the landscape upscaling. Bog peatlands stand outwith regard to storage of frozen C.More than a third of all stored C is perennially frozenbeneath the active layer boundary, mainly in histic Cryosols.The soils in the study area are heavily cryoturbated and atenth of all C is found in cryoturbated soil layers.An additional objective of this study is to compare averagesoil carbon storage derived from these intensive landscapeanalyses with previously published local/regional estimatesas well as more general databases such as those providedby The Soil Organic Carbon of Canada Map (Tarnocai &Lacelle 1996).AcknowledgmentsFieldwork and analyses was supported through a grant ofthe Swedish Research Council. We wish to thank Ms. HelenDahlke for her assistance during fieldwork.ReferencesTarnocai, C. & Lacelle, B. 1996. Soil Organic Carbon ofCanada Map. Ottawa, Ontario: Eastern Cereal andOilseed Research Centre, Agriculture and Agri-FoodCanada, Research Branch.108