K. Minkkinen et J. Laine, EFFECT OF FOREST DRAINAGE ON THE PEAT BULK-DENSITY OF PINE MIRES IN FINLAND, Canadian journal of forest research, 28(2), 1998, pp. 178-186
Drainage of peatlands for forestry causes the water level to draw down
, which results in subsidence of peat surface and increased peat bulk
density (D-b) Later on, an accelerated rate of organic matter decompos
ition and the pressure of the growing tree stand further compacts the
peat. We measured the peat D-b (0-80 cm) in 180 undrained and 209 drai
ned (ca. 60-year-old) peatland sites representing three nutrient level
s of pine fens and five macroclimatic regions from southern to norther
n Finland. D-b was affected by climatic conditions, nutrient status, a
nd the tree stand volume of the site. D-b was significantly higher in
drained than in undrained sites in all regions and site types: the mea
n (+/-SD) D-b in the whole material was 82 +/- 23 kg.m(-3) for the und
rained sites and 133 +/- 22 kg.m(-3) for the drained sites. The increa
se in D-b was significant in all regions down to a depth of 60 cm and
in southern Finland, even deeper than 80 cm. When the increase in carb
on concentration was taken into consideration, the average postdrainag
e increase in the Db Of the 0-80 cm layer equalled the amount of carbo
n in the 54-cm layer in average undrained peat. As the reported subsid
ences of pear surface in forest drainage areas in Finland are usually
below this limit, the carbon storage of peat is likely to increase aft
er drainage.