Ari Ferm

Methane oxidation in soil profiles of Dutch and Finnish coniferous forests with different soil texture and atmospheric nitrogen deposition

Abstract We studied methane oxidation capacity in soil profiles of Dutch and Finnish coniferous forests. The Finnish sites ( n = 9) had nitrogen depositions from 3 to 36 kg N ha −1 a −1 . The deposition of N on the Dutch sites ( n = 13) was higher ranging from 50 to 92 kg N ha −1 a −1 . The Dutch sites had also limed counterparts. Methane oxidation rates were determined by incubating soil samples in the laboratory at + 15°C with 10 μl CH 4 l −1 (10 ppmv CH 4 ). In general, CH 4 oxidation rates were highest in the uppermost mineral layers. The average CH 4 oxidation rate in the Finnish mineral soils was three times higher than that in the Dutch soils. The litter layers did not oxidize CH 4 . In the Netherlands all organic horizons had a negligible capacity to oxidize CH 4 . However, some Finnish organic horizons showed high CH 4 oxidation capacity. In the Netherlands, in contrast to Finland, there were some soil profiles lacking CH 4 oxidation. Higher contents of nitrate and ammonium, as well as greater production of nitrous oxide (N 2 O) and lower production of carbon dioxide in the Dutch than in the Finnish forest soils reflected the high N deposition rate in the Netherlands. Not only the N deposition, but also the highly sorted soil texture (fine sand) with low amounts of both coarse and fine particles is an important reason for the low CH 4 oxidation in the Dutch soils. The proportions of fine and coarse particles, both well represented in moraine soils typical in northern Europe, correlated positively with the CH 4 oxidation. Fine particles provide a good surface for microbial growth. Coarse particles, on the other hand, enhance diffusion of CH 4 and oxygen into the soil. Methane oxidation in the Dutch mineral soils was slightly enhanced by liming.

C and N storage in living trees within Finland since 1950s

Living biomass contains 45 to 60% carbon and 0.05 to 3% nitrogen, in dry weight. Like throughout Europe, the amount of living biomass in Finnish forests has increased on average over the last decades, largely because of changes in forest management. The storage of organic C and N in biomass has also increased.Changes in biomass vary between regions. Data were analysed on changes in the last 30–40 years in C and N storage in living trees in Finland, subdivided into 20 regions. Tree biomass increased in 17 regions, and decreased in 3 regions. The storage rate varied between -170 and +480 kg C ha-1 a-1, and between −0.5 and +1.2 kg N ha-1 a-1.Nitrogen accumulation in trees was less than 15% of atmospheric N deposition in all regions. Although the eventual increase of the nitrogen concentration in tree tissues was omitted, it is not possible that living biomass has been the major sink for atmospheric N deposition to forests. A hypothesis is presented that the main sink is litter layer and organic soil. Carbon can also be accumulating in soils essentially faster than hitherto estimated in analyses of carbon budgets of European forests.

Initiation, structure and sprouting of dormant basal buds in Betula pubescens

Summary The morphological basis for sprouting in Betula pubescens E hrh ., is studied with special reference to the initiation, structure and number of buds at the base of the tree and their development into sprouts. The material consists of seedlings of varying ages and stumps of mature trees. The dormant basal buds begin life as axillary buds at the seedling stage, positioned in accordance with the leaf arrangement. These primary basal buds are initiated in the axils of retarded leaves, and it is perhaps partly for this reason that they remain in a protracted state of dormancy. This dormancy is no more than a superficial feature, however, as, unlike the axillary buds higher up the stem, they are engaged in constant growth. They also differ structurally from ordinary axillary buds, possessing a growth point and a few scales after the first growing season, but no foliage leaf primordia, and gaining more scales as they age, normally one whorl per year. Similarly the vascular connection of a dormant basal bud grows year by year in accordance with the radial growth of the tree, thus ensuring that the bud does not become buried within the wood. The basal buds normally increase in number as the seedling grows, the primary buds branching to form clusters of secondary buds located in the axils of their scales. This branching requires a some degree of bursting of the buds. The resulting clusters are also found to vary in structure. Felling causes the majority of the dormant basal buds to burst, but only a certain number develop into sprouts. These sprouts differ morphologically from seedlings, especially in their pattern of ramification.

Effects of wood bark ash on the growth and nutrition of a Scots pine afforestation in central Finland

Results are presented from a fertilization experiment with wood bark ash (0, 1, 2, 5, 10, 20 Mg ha-1) applied to prevent and cure visible nutrient disorders of young Scots pine established on a peatland field. 13 years after fertilization, dieback of trees and other symptoms of nutrient disorders were substantially reduced or even eliminated, especially where higher doses had been applied. The volume of the growing stock was more than 70 m3 ha-1 for the highest dose while control plots produced less than 15 m3 ha-1. Vegetation characteristics changed following ash treatments with high ash doses favouring grasses and low ash doses promoting mosses. Some major changes in soil and foliar nutrient concentrations were evident due to ash fertilization. K and B, however, were clearly the most limiting nutrients that could be cycled where high doses of ash were used. This was particularly the case with a dose of 20 Mg ha-1. Decomposition of the topsoil was at its highest on plots with ash doses of 5 and 10 Mg ha-1 ash and at its lowest when the dose was 2 Mg ha-1. This was partly due to differences in the C/N ratio of the soil. All decomposition parameters indicated a high degree of humification in the topsoil. High N content (of organic material), low C/N in the soil and optimum levels of foliar N concentrations suggested sufficient N mineralization for tree growth to have occurred in the soil.

Sprouting ability and significance for coppicing of dormant buds on Betula pubescens Ehrh. Stumps

The numbers of basal dormant buds and resulting sprouts and their distribution on the stumps of the trees were studied in specimens of Betula pubescens Ehrh. of vegetative and seedling origin of different ages and growing on peatland or mineral soil. The results suggest that the number of buds at the base of the tree varies markedly from one tree to another. The old and young trees had quite similar numbers of buds, but those on mineral soil had less than those growing on peatland. The highest numbers of basal buds were found on sprout‐origin trees. Although about 90% of the basal buds were found below ground level, 1/3 of the sprouts originated from above the ground. This discrepancy can be explained by the formation of bud clusters, since the majority of the sprouts were derived from buds which occurred singly or in very small clusters. The total number of basal buds explains only part of the observed variation in sprouting potential. More important is the formation of bud clusters during the maturation...

Birch production and utilization for energy

Abstract Natural birch stands represent a significant biomass resource since birches are one of the most common deciduous genera in cool temperate regions, even in places ranging up to the forest line. Many characteristics of birch make it highly suited for short rotation forestry. However, growing birch in very short rotations (less than 10 years) in northern climates is not worthwhile on the basis of biomass production and economics. Rotations of 15 to 20 years may give good results everywhere. The intensive culture of birch plantations has largely remained untested, but it is very likely that the yield levels can be increased significantly by using cloned material as well as improved silvicultural treatments, fertilization and pest control. Birch feedstock, compared to material of many other tree species, is of even quality. Moisture content is low and basic density high. Branches and bark are also suitable for energy use. Birch plays an important part in the energy budget of entire nations, particularly of Finland and Sweden

Effects of High Nitrogen Deposition on Forests: Case Studies Close to Fur Animal Farms

Amount and effects of nitrogen depositions near fur animal farms in the major mink and fox growing area of Finland were investigated in Scots pine (Pinus sylvestris) forests along gradients. Distance from the farm and presence of forest canopy had a strong effect on ammonium depositions measured as bulk deposition from May to October. The highest deposition values were recorded in the stand near a large mink farm, where 50 m from the farm the ammonium deposition was 33 kg N ha−1 yr−1 under the canopy and 7 kg N ha−1 yr−1 in the open field. The macroscopic symptoms of forest damages resembled growth disturbances of nutritional origin. The observed tree damage and growth disturbances were in correlation with the high foliar total N and ammonium N contents and high contents of soluble nitrogen in the humus. High amounts of ammonia led to a decrease in the K, Ca and particularly Mg and B contents in the needles and to an increase in total nitrogen, amides and amino acids. Excessive nitrogen was stored mainly in the form of arginine.

Coppicing as a means for increasing hardwood biomass production

Abstract This report summarizes work done under the International Energy Agency Activity entitled “Developing the coppicing potential of selected hardwoods”. Altogether, 26 papers and publications have been prepared under this project, discussing a large number of coppicing mechanisms and factors of many important short-rotation hardwood tree species, the main emphasis being on birch, poplar, alder and willow. Coppicing research is reviewed briefly on the basis of two inquiries. There were 20 research projects and a total of 39 researchers dealing with coppicing in the various participating countries. A survey of coppicing problems indicates a need for scientific projects in ecophysiology, anatomy and stand dynamics.

Effect of spacing and nitrogen fertilization on the establishment and biomass production of short rotation poplar in Finland

Abstract Short rotation trials cuttings poplar ( Populus x rasumowskyana ) in Southern Finland investigated establishment of poplar plantations and the effects of spacing and application of nitrogen fertilizer on biomass production over a period of 6 years. Thicker cuttings grew better whilst those of less than 1 cm diameter grew only moderately. Nitrogen fertilization improved height and diameter growth and above-ground dry mass yield. Woody biomass production was 4·2 dry tons/ha per year, at 300 kg/ha nitrogen. A spacing of 15 000 stems/ha gave the best yield after 4 years, but 5000 stems/ha was a more productive spacing in the next 2 years.

Origin, Structure and Shoot-Formation Ability of Buds in Cutting-Origin Stools of Salix ‘Aquatica’

Summary The cultivation of trees and their use as an energy source have been investigated intensively during the last twenty years. Fast growing willows are the species to which most attention has been paid in Northern Europe in the context of short-rotation coppicing stands. Basic research into sprouting in these species is still quite insufficient, however, especially regarding the bursting dynamics of the buds and the shooting intensity of willows. The present work describes the structure and numbers of buds in cutting origin stools of Salix ‘Aquatica’ coppiced twice and four times. It was normal that two accessory, collateral buds developed at the base of the primary axillary bud all these then being covered by two solid, overlapping scales. The primary bud usually burst first, and after that the accessory buds could burst at any time, but sometimes only after a few years. Most of the new shoots grew on the sideshoots above ground level, although the shooting intensity of the buds was greatest on the mainstem. The buds located at ground level also produced shoots very well, but these were small in number. Coppicing markedly accelerated the growth of the accessory buds into shoots, the number of sideshoots trebling in two weeks. Since the shooting intensity of the willows increased markedly even after the fourth annual coppicing, Salix ‘Aquatica’ may be said to withstand many repeated coppicings, and thus appears to be suitable for short-rotation cultivation in this respect, too.