Litter fall in some European coniferous forests as dependent on climate: a synthesis

Litter fall data was available for 64 sites in Europe, most of them in Fennoscandia. Included were 48 sites with pine (Pinus spp.), mainly Scots pine (Pinus sylvestris L.), and 16 sites with spruce (Picea spp.), mainly Norway spruce (Picea abies (L.) Karst.). Regressions were calculated for needle and total litter fall against a set of climatic parameters, and the best simple relationships were obtained with annual actual evapotranspiration (AET) and other parameters including temperature, whereas for example, precipitation gave lower r values. For needle litter fall and AET using all data, the R2adj value was 0.635 (n = 64), and for needle litter for pine and spruce separately, the R2adj were 0.576 (n = 48) and 0.775 (n = 16), respectively. AET plus stand age gave highly significant relationships for both coniferous genera combined (R2adj = 0.683), and for pine and spruce separately the corresponding values were 0.655 and 0.843, respectively. Using all available data we found highly significant relationships between needle litter fall and total litter fall. For Fennoscandia, litter fall for Scots pine and Norway spruce were compared. AET versus needle litter fall gave highly significant relationships for Scots pine (R2adj = 0.448, n = 34) and for Norway spruce (R2adj = 0.678, n = 13); the relationships were significantly different from each other.