Effects of Seedbed Substrate on Moisture Conditions and Germination of Pinus sylvestris Seeds in a Clearcut
The objective of the investigation was to describe moisture conditions and germination of Scots pine (Pinus sylvestris L.) seeds in different seedbed substrates (feather mosses, mineral soil, humus and ground organic material) with and without irrigation during 2 weeks, in a clearcut in northern Sweden. Without irrigation no seeds germinated, which could be explained as an effect of the low moisture conditions of the seedbed substrates. This was shown in the seeds' low moisture content, with highest values in mineral soil, 10–20%, and for the other seedbed substrates 5–15%. The moisture conditions were highest during the night and lowest in the afternoon. With irrigation, moisture conditions improved (seed moisture content 20–50%) and diurnal changes were moderated. Seeds germinated in all substrates with most seedlings in mineral soil (60% of sown germinable seeds). The moisture conditions of the seedbed substrates proved to be in poor agreement with the seeds' requirement for germination, especially during warm weather with no precipitation.