The Ingrowth Bag Method in Measuring Root Production on Peatland Sites
Root production was measured with the ingrowth bag method on two pristine and three drained mire sites of different fertility in southern Finland during 1993-1995. The sites were selected among those where root production had also been measured with other methods. Root biomass on the drained sites started to increase clearly only during the second growing season, whereas on the pristine sites the ingrowth of roots began during the first summer after the installation of the bags in spring. This suggested a slower ingrowth rate of Scots pine (Pinus sylvestris L.) and dwarf shrub roots than of herbs and Cyperaceous species, which were more dominant on the pristine sites. The ingrowth bag method gave results comparable to the sequential coring method for the fine-root production (diameter < 2 mm) on the drained sites within 2-3 yrs after installation of the bags, whereas on the pristine site the estimate for total root production (diameter ≤ 10 mm) was significantly lower than that obtained with the 14C turnover method.