摘要:

A comparison was made for chemical composition and mass‐loss rates between needle litters from Scots pine and lodgepole pine during a four‐year period. Initial chemical composition differed. Thus lodgepole pine needle litter had higher concentrations of sulfuric‐acid lignin, phosphorus, magnesium and manganese, whereas Scots pine needles were richer in soluble substances. No difference between species was noted in concentrations of nitrogen, calcium and potassium. In the early stages of decomposition (<1 yr and <30% mass loss) Scots pine needles decomposed faster than those of lodgepole pine (p<0.001); whereas in the later stages (>300 days) there was no difference in the decomposition rate. Combining both species, mass‐loss rates were positively correlated to concentrations of water solubles and nitrogen, and negatively correlated to those of lignin. Mass‐loss rate was correlated to phosphorus concentrations only within species. For lodgepole pine needles the early phase of decomposition appeared to be considerably shorter than for those of Scots pine. In later stages mass‐loss rates were negatively correlated to concentrations of lignin for both individual and combined litter types. However, at the same concentration of lignin, mass loss and lignin loss were faster in lodgepole pine needles than in those of Scots pine.

ISSN:0282-7581    

DOI:10.1080/02827588709382441

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Over a period of five months, the forest floor of a coniferous stand was irrigated 20 times with a total of 100 mm of artificial rain in addition to the normal precipitation (302 mm). The experiment was made with a fully randomized two‐factorial design. The two treatment factors were acid (a mixture of 2/3 sulphuric and 1/3 nitric acid) and heavy metals (cadmium and copper). Both factors were tested at three levels, whereby altogether nine combinations of acid and metal load could be studied. The highest load corresponded to 100 times the actual wet deposition of acid and heavy metals. The forest floor respiration was measured on intact cores (radius and depth = 3 cm) respectively one day after and 7 months after the final irrigation which took place in October. There was no statistically significant effect on respiration of any of the treatments examined. The pH of the forest floor was slightly lowered by the most acid treatment. This effect was statistically significant four days after the final treatment, but not after 7 months, although the tendency still remained.

ISSN:0282-7581    

DOI:10.1080/02827588709382442

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Piles of logging residues (slash‐piles) are a consequence of modem logging techniques. The piles cover 10 to 15% of a clear‐felled area. The effect of slash‐piles on nitrogen leaching was estimated by collecting precipitation1and percolating water below slash‐piles and below the O, E and B horizons of an Orthic Podzol during two growing seasons. Open funnels were used for precipitation, PVC troughs for water leaving the pile and filled‐in zero tension lysimeters for percolating soil water. Exchangeable ammonium and nitrate of humus samples were analysed. The increased nitrogen leaching from the soil below slash‐piles was probably caused by an increased mineralization of the humus layer and a reduced nitrogen uptake by roots.

ISSN:0282-7581    

DOI:10.1080/02827588709382443

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Four late frost reistant trees in a young plantation ofPicea abieswere selected and compared with 15 non‐resistant ones after they had been propagated as cuttings. Two cutting trials were established, one in a nursery and one at the original selection site. Flushing, growth rate and total growth were assessed during four years. Frost resistant clones were found to be delayed in their flushing and growth development in early summer as compared to non‐resistant clones but the differences were not statistically significant. Large block variance and errors reduced the power of the statistical tests. Clone, site and year were found to be significant sources of variation in ANOVA, but neither interaction between clone and site nor clone and year were statistically significant. It is concluded that differences in growth rhythm parameters cannot be established between resistant and non‐resistant clones in this experiment, but the results are encouraging for the deployment of clones in forest plantations, provided the clones are tested and their performance remain stable over several propagation cycles.

ISSN:0282-7581    

DOI:10.1080/02827588709382444

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Flooding of soil for 55 days altered the rate of growth and stem anatomy of 9‐month‐oldCryptomeria japonicaseedlings. Although flooding did not affect height growth it reduced the rate of dry weight increment of seedlings while increasing stem diameter. The reduction in dry weight increment of seedlings resulted largely from decay of roots and, to a lesser extent, from inhibition of growth of roots and needles. The increased diameter growth of flooded seedlings resulted largely from an increase in bark thickness associated with increased phloem production and greater amount of intercellular space. Flooding reduced xylem increment in submerged stems but increased it above the water level because of larger tracheids rather than more tracheids per radial file. Flooding also increased lumen diameters of tracheids, decreased tracheid wall thickness (as a proportion of tracheid diameter), and stimulated formation of axial parenchyma cells in the xylem.Cryptomeria japonicaseedlings adapted to flooding by forming adventitious roots, primarily on the original root system and submerged portion of the stem. Such new roots originated in the xylem ray parenchyma. Flooding stimulated ACC synthesis in roots and ethylene production in stems. The role of ethylene in alteration of stem anatomy is discussed.

ISSN:0282-7581    

DOI:10.1080/02827588709382445

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

NPK fertilization on a dwarf shrub pine bog initially increased the amount and nutrient content of the tree litter. Eight years after fertilization, however, the amount of micronutrients decreased compared to the amount of N and P in the litter. Fertilization on a fertile mire also increased the nutrient content of the litter fall, especially in the mature pine and birch stands. The amount of nutrients in the litter fall of the birch stands was considerably greater than that in the pine stand of the same volume.

ISSN:0282-7581    

DOI:10.1080/02827588709382446

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Young trees (4–5 year old) ofBetula pubescensEhrh. growing in a stand in the middle of Sweden (lat. 60°15'N) were cut in early June to stump heights of 0 and 10 cm. The birch stumps were exposed to different relative light intensities (100, 50, 25 and 10%) for 100 days until mid September. Five stumps per treatment were used in a randomized complete block with seven blocks on mesic dwarf‐shrub type with low herbs and three blocks on moist dwarf‐shrub type. The number of sprouting stumps was correlated with relative light intensity and forest type. 2.5 % of the stumps of mesic and 14 % of moist forest type did not produce suckers. On mesic forest type, 7% of the stumps exposed to 10% light did not sprout compared with 1.4, 3.0 and 0% at 25, 50 and 100% light, respectively. At stump height 0 cm fewer sprouting stumps were produced than at 10 cm. The mean height of suckers was significantly lower at 10% light intensity than at other levels. The number of suckers per sprouting stump was not related to light intensity but to forest type. More suckers were produced on mesic than on moist forest type. The dry weight of suckers was significantly lower at 10 and 25% relative light intensity than at 50 and 100%. On moist forest type, the dry weight of suckers was lower than on mesic forest type.

ISSN:0282-7581    

DOI:10.1080/02827588709382447

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Results from surveys of the Swedish experiment in 1976, 1981, 1983 and 1985 are presented. The experiment was thinned when the average dominant heights were 10.3, 13.7 and 16.2 m, respectively. The increment of stem volume for the periods 1977–81 and 1982–85 is given in Tables 1 and 2, respectively. In comparison with unthinned control subplots, the volume increment for the periods 1977–81 and 1982–85 was reduced by the following relative figures:-treatment 2 with strip road width 3.5 m, 9 and 17% respectively-treatment 3 with strip road width 3.5 m, 16 and 14% respectively-treatment 4 with strip road width 5.0 m, 7 and 20% respectively

ISSN:0282-7581    

DOI:10.1080/02827588709382448

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The aim of this study is to quantify the variations of energy forestry production at different locations in south Sweden that can be expected because of variations in climate only. The growth of first‐year shoots of willow(Salix viminalis)is simulated by means of a model based on photosynthesis. The production is examined over a 15‐year period and at 13 different locations. The mean yearly stem production ranged between 10.0 tonnes of dry matter per hectare and year at Helsingborg and 6.5 tonnes per hectare and year at Hagshult. The yearly variation was within ±25 % for sites located in the inland areas while those at the coast generally showed variations within ±15%. On a regional basis, Skåne had the highest mean production with 9.4 tonnes per hectare and year while the production of the Mälardalen region was about 13% lower. The difference in production between Mälardalen and Östergötland was about 2%. A sensitivity analysis showed that the growth response of clones to temperature might be an important selection criterion when aiming at increasing the production.

ISSN:0282-7581    

DOI:10.1080/02827588709382449

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Two years of heavy defoliation ofPinus sylvestrisbyNeodiprion sertifercaused a volume loss of 33%during a 9‐year period after the defoliation of 90–120 years old pine forests. This loss corresponds to 3 normal annual increments. The increment losses in height, diameter and basal area are calculated both for the old stands and a young one (40 years of age). The economic consequences of the growth loss are also calculated and discussed.

ISSN:0282-7581    

DOI:10.1080/02827588709382450

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor