Effects of seedbed substrate on moisture conditions and germination of Scots pine (Pinus sylvestris) seeds in a mixed conifer stand

The objective of this investigation was to compare moisture conditions and Scots pine (Pinus sylvestris L.) seed germination percentages in four types of seedbed substrates (i.e., feather mosses. mineral soil, humus, and ground organic material). Two experiments were conducted, with and without irrigation, in the summer of 1996 in a stand in northern Sweden. The moisture conditions were determined by periodically weighing seed samples. When plots were not irrigated, no seeds germinated, probably because conditions were too dry in the seedbeds, as indicated by the low seed moisture content (under 15%). However, during rainy days, seed moisture contents were relatively high (20-45%). On the irrigated plots the seeds germinated on all seedbed substrates, with the best germination occurring in humus (about 40%). Seed moisture contents were high and relatively consistent in all irrigated seedbed substrates (35-55%). In irrigated plots temperature rather than moisture, was a limiting factor, and germination was highest in the warmest seedbed types which are generally regarded as poor germination substrates. We suggest that seedbeds in areas scheduled for harvesting he prepared in the stand before clear-cutting, and that the preparation should enhance not only the substrates's water-holding capacity, but its thermal conductivity as well.