Report of a Twelve-year study of Litter Fall and Productivity in a Stand of Mature Scots pine

Abstract

Litter collections were made in a Scots pine ( Pinus sylvestris L. ) plantation between its first major thinning at 40 years (effectively 35 years because of early stagnation) and its second thinning at 52 years. The response to thinning was immediate with no lag phase. Needle production peaked in the third growing season and remained more or less constant thereafter. Needle biomass peaked in the eighth year (10. 3 tonnes per hectare) after a year in which the retention of third year needles had been greater than usual. Cone production reached its first maximum in the fourth year, its second in the sixth year, but, thereafter, changed to a three-year cycle: it is suggested that the dip in overall productivity in the sixth and ninth years led to fewer flower bud initials being laid down in those years. Priority in resource allocation seems to have gone to cone production, once set in train, and then to needle production which stayed up in 1977 (the sixth year) but fell in 1980. Production of litter items was 20 per cent greater than litter fall over the first four years (range −minus; 0. 3% to +plus; 28. 3%) and 0. 4 per cent greater over the last eight years (range − 14. 5% to +plus; 12. 2%). The differences were due in the main to the two-year delay between production and fall of needles and the one-year delay for cones. However, the differences were not predictable because of greater third-year needle retention in certain years and the variable proportion of cones dismantled by squirrels and falling as fragments in the year of their production.