Seedling emergence of Pinus sylvestris in characterized seedbed substratesunder different moisture conditions

Establishment of Scots pine (Pinus sylvestris L.) stands from seed is often unsuccessful because of unsuitable environmental conditions, such as limit ed soil moisture or air humidity. Improved seedling emergence could be achi eved by soil preparation if site-specific optimal seedbeds were specified. Therefore the effects of seedbed substrates (13 characterized mixtures of s and, silt, and organic matter) on seedling emergence were determined after 14-day emergence tests in small laboratory chambers with four moisture cond itions (2 levels of relative air humidity (RH), 95 and 65%, in combination with 2 levels of substrate water tension, 3 and 10 kPa). Seeds were placed in (partially buried) and on noncompacted and compacted substrates. At 95% RH, seedling emergence was 80 to 95% (seed lot maximum 94%) regardless of t he substrate, with the exception of seeds placed in silt substrates (30-70% ). At 65% RH, seedling emergence was 90% on silt, but considerably lower on organic matter and sand substrates, where organic admixture improved emerg ence for sand, but had a neutral or negative effect for silt. At 65% RH, pa rtial seed burial, i.e., with good seed-substrate contact, improved emergen ce for organic matter and sand substrates, but impaired emergence for pure silt in noncompacted substrates at 3 kPa soil water tension. The effect of compaction on emergence was small for most substrates and had an effect onl y at 65% RH and 10 kPa tension. Seedling emergence and soil hydraulic condu ctivity at 3 kPa water tension and 95% RH were negatively correlated for pa rtially buried seeds, but regardless of seed position, they were positively correlated at 10 kPa tension and 65% RH. These results can be used as guid ing principles for the creation of seedbed substrates and seeding technique s.