Abstract. The purpose of this study was to relate regional variation in litter mass-loss rates (first year) in pine forests to climate across a large, continental-scale area. The variation in mass-loss rate was analyzed using 39 experimental sites spanning climatic regions from the subarctic to subtropical and Mediterranean: the latitudinal gradient ranged from 31 N to 70 N and may represent the the largest geographical area that has ever been sampled and observed for the purpose of studying biogeochemical processes. Because of unified site design and uniform laboratory procedures, data from all sites were directly comparable and permitted a determination of the relative influence of climate versus substrate quality viewed from the perspective of broad regional scales.Simple correlation applied to the entire data set indicated that annual actual evapotranspiration (AET) should be the leading climatic constraint on mass-loss rates (R2d = 128 0.496). The combination of AET, average July temp. and average annual temp. could explain about 70% of the sites' variability on litter mass-loss. In an analysis of 23 Scots pine sites north of the Alps and Carpatians AET alone could account for about 65% of the variation and the addition of a substrate-quality variable was sufficiently significant to be used in a model.The influence of litter quality was introduced into a model, using data from 11 sites at which litter of different quality had been incubated. These sites are found in Germany, the Netherlands, Sweden and Finland. At any one site most (> 90%/6) of the variation in mass-loss rates could be explained by one of the litter-quality variables giving concentration of nitrogen, phosphorus or water solubles. However, even when these models included nitrogen or phosphorus even small changes in potential evapotranspiration resulted in large changes in early-phase decay rates.Further regional subdivision of the data set, resulted in a range of strength in the relationship between loss rate and climatic variables, from very weak in Central Europe to strong for the Scandinavian and Atlantic coast sites (Rdj = 0.912; AET versus litter mass loss). Much of the variation in observed loss rates could be related to continental versus marine/Atlantic influences. Inland locations had mass-loss rates lower than should be expected on the basis of for example AET alone. Attempts to include seasonality variables were not successful. It is clear that either unknown errors and biases, or, unknown variables are causing these regional differences in response to climatic variables. Nevertheless these results show the powerful influence of climate as a control of the broad-scale geography of mass-loss rates and substrate quality at the stand level.Some of these relationships between mass-loss rate and climatic variables are among the highest ever reported, probably because of the care taken to select uniform sites and experimental methods. This suggest that superior, base line maps of predicted mass-loss rates could be produced using climatic...

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Effect of wood ash fertilization on soil chemical properties and stand nutrient status and growth of some coniferous stands in Finland .The effects of wood ash or wood ash plus nitrogen (N) fertilization on soil chemical properties, needle nutrient concentrations and tree growth were studied in five coniferous stands, aged 31 Á/75 yrs, after 5 and 10 yrs. In each experiment 3 t ha (1 of loose wood ash was applied to three replicated plots (30 )/30 m). In three of the experiments 120 Á/150 kg N ha (1 was applied together with the same wood ash (WAN). These three experiments also included a stand-specific fertilization (SSF) treatment, which consisted of 120, 150 or 180 kg N ha (1 . Five years after wood ash or WAN application the pH increase in the humus layer was 1 Á/1.7 pH-units and in the 0 Á/5 cm mineral soil layer 0.3 Á/0.4 pH-units. The increase was approximately the same 10 yrs after application, and was also associated with an increase in pH in the 5 Á/10 cm mineral soil layer. Wood ash or WAN significantly increased both the total and extractable calcium and magnesium concentrations in the humus layer on all the sites. Wood ash or WAN had an increasing effect on the boron concentrations, but a decreasing effect on the manganese concentrations in the needles. Wood ash had no significant effect on the volume growth. The trees on the WAN plots grew as well as or slightly better than those on the SSF plots.

The effects of wood ash fertilization on soil chemical properties were studied in three young Scots pine (Pinus sylvestris L.) plantations and a Norway spruce (Picea abies (L.) Karst.) plantation with different site fertility in southern Finland. The dose of 3 t ha -1 of loose wood ash was applied to 4 replicate plots (25 × 25 m) at each experiment. Humus layer and mineral soil samples were taken before the treatment and 7 and 16 years after wood ash application. Results showed that neutralization as well as fertilization effects of wood ash on forest soil were of long duration. An ash-induced pH increase of 0.6-1.0 pH units and exchangeable acidity (EA) decrease of 58-83% were detected in the humus layer 16 years after wood ash application. The decrease in acidity was most pronounced on the Calluna site with initially the lowest pH and highest EA. In the mineral soil the increase in pH was observed later than in the humus layer. After 16 years, the mineral soil pH was increased (0.2-0.3 pH units) on the Vaccinium and Myrtillus sites. A corresponding and in most cases a signifi cant increase in the extractable Ca and Mg concentrations was detected in both the humus layer and in the mineral soil. Wood ash signifi cantly increased the effective cation exchange capacity (CEC e ) and base saturation (BS) but decreased the concentration of exchangeable Al in both soil layers on all the sites. No response of N availability to wood ash application could be found.

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Disturbance may lead to fundamental changes in the structure and function of microbial communities (Balser Forest harvesting and site preparation alter many features of the et al., 2001; Schimel and Gulledge, 1998). Forest harvestsoil environment affecting biological activity and litter decomposition. ing and site preparation practices often disrupt organic One aspect of biological activity, "lignocellulase" enzyme activity, and mineral surface horizons, remove wood and slash, has been found to be a good predictor of litter mass loss. We deterincrease soil water content, temperature, and light intenmined the effects of postharvest treatments (SLASH, BROADCAST BURN, and CHIP AND PILE treatments with the intact FOREST sity at the soil surface, cause a loss of nutrients through treatment as a control) on lignocellulose degrading and nutrient releasvolatilization, leaching, and surface erosion, and alter ing enzyme activities (␤-glucosidase, cellobiohydrolase, ␤-xylosidase, microbial community composition and decomposition N-acetyl-glucosaminidase, phenol oxidase, and phosphatase) in de