ISSN:0282-7581    

DOI:10.1080/02827589908540792

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Growth and the distribution of biomass among above- and below-ground components were measured in 12-year-old Scots pine (Pinus sylvestrisL.) from 19 populations grown in a provenance experiment in central Poland (52° N). The populations originated from the northern (>55°N in Russia, Sweden and Latvia), central (54–47° N in Poland, Germany, Belgium, France, Slovakia, Hungary), and southern (<45° N in Bosnia, Montenegro and Turkey) European range of Scots pine. Height, diameter and biomass were all significantly related to latitude of origin. For populations of northern, central and southern origin, above-ground biomass averaged 3.1, 4.7 and 3.3 kg tree−1and 25, 43 and 12 Mg ha−1. Total root biomass accounted for 22, 19 and 28% of total stand biomass for northern, central and southern populations, respectively. These differences were primarily the result of proportionally higher fine root biomass in the slower-growing northern and southern than central populations. Since the allometric regression equations based on diameter for total aboveground and coarse root biomass did not differ among populations or regions, biomass of Scots pine, excluding fine roots, may be accurately estimated from forest inventory data.

ISSN:0282-7581    

DOI:10.1080/02827589908540804

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

ISSN:0282-7581    

DOI:10.1080/02827589908540805

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Stands included in seven thinning trials with Norway spruce (Piceu ahies (L.) Karst.) originally planted on highly productive sites in southern Sweden were investigated for the influence of different thinning regimes on basic density and ring width. Light thinnings from below did not have any direct effect on these properties. However, heavy thinnings that removed a total of 40% of the basal area considerably enhanced diameter development without a loss in volume production or a reduction in the uniformity of the wood. Thinning from above resulted in higher basic density and lower ring width compared with thinning from below. This was found to be an effect of selection because basic density increased with decreasing tree diameter. Diameter class had no effect on response to thinning as indicated by the fact that the smaller trees also responded strongly when thinned from above. Since no difference in basic density level between thinning regimes was found, it was concluded that differences in basic density were due to differences in annual ring width.

ISSN:0282-7581    

DOI:10.1080/02827589908540806

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Seven thinning trials in stands of Norway spruce (Picea abies(L.) Karst.) planted on highly productive sites in southern Sweden were investigated. Cross-sectional weighted basic density was not affected by a thinning regime characterized by several thinnings from below compared with naturally thinned stands. Heavy thinnings decreased basic density. However, the decrease was moderate compared with those reported in earlier investigations, probably owing to the lower stand density prior to first thinning which affected competition between trees and crown differentiation. Thinning from above resulted in a higher basic density, mainly because trees with decreased growth ring development up until the time of the first thinning were favored. Dry matter production was not decreased any more than volume production by any of the treatments except for the very heavy thinning from below. Generally, thinning decreased the juvenile wood content of the stand. As a consequence of selection, thinning from above will decrease the juvenile wood content more compared with thinning from below, provided that trees reach the same diameter in the final stand. Branch diameter in the lower part of the stem was found to be higher in the naturally thinned stands than in the thinned ones. This appeared to be due exclusively to selection since the live crown probably had already started receding upwards prior to the first thinning. Differences in stem taper between thinning regimes could be attributed to changes in growth allocation and effects of selection between trees.

ISSN:0282-7581    

DOI:10.1080/02827589908540807

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Long-term changes of the acid/base relations of organic soils after drainage, fertilization and/or liming at three experimental sites—two ombrogenous and one soligenous—in south central Norway are discussed. These sites were drained, fertilized and/or limed in 1953–1956 and sampled in 1991–1992. Drainage at the ombrogelious sites caused: insignificant shifts of pH, higher bulk densities to 40 cm depth, higher ash percentage, higher contents of N and P to 20 cm depth and reduced concentrations of total Ca, K, Mg, Na, A1 and Fe in soil layers deeper than 20 cm. The soligenous site was not effectively drained; despite this, pH dropped about 0.5 unit in the surface and subsurface soil layers of the control plots, while small changes were measured for most other soil variables. The suggested reason for the pH drop is limited sulphide oxidation in the upper 20 cm drained layer. Base saturation at actual soil pH, when all treatments were included, was estimated with good precision by four regressors: pH, extractable Al, extractable Fe and extractable Ca (R2=0.90–0.95). Similar models explained 97–99”” of the variation in base saturation at soil pH=7.0. The lime effects at the properly drained oligotrophic sites were proportional to applied doses; for pH to 40 cm, base saturation to 60 cm, and Ca concentration to 60 cm depth. At the less well-drained soligenous site, effects were limited to the upper 30 cm layer. Both drainage and liming caused higher cation exchange capacities and proper drainage seems to be a prerequisite for the liming effect. Estimated recovery of calcium to 60 cm depth was 64–79% at the ombrogenous sites and 42–46% at the soligenous site.

ISSN:0282-7581    

DOI:10.1080/02827589908540808

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Mobility, exchangeability and accumulation of macro elements and heavy metals after liming and fertilization of organic soils were studied on three sites, two oligotrophic and one mesotrophic. These were drained, fertilized and/or limed in 1953–1956 and sampled in 1991–1992. Fertilization and liming caused marginal changes in bulk density, N stores and C/N ratios, while percentage ash content increased significantly to 40 cm depth at the two oligotrophic sites and to 10 cm at the mesotrophic site. Applied P was relatively immobile and liming caused more P to accumulate in the surface layer, whereas applied K and Mg were mobile with elevated concentrations being measured to 60 cm depth at the oligotrophic sites. Even if liming reduced the relative exchangeable pools of Fe and A1 these elements moved to this depth after combined fertilization and liming, but mobility was less after liming alone. Relative exchangeable pools of K, Ca and Mg were high, of Fe and A1 intermediate to low and of S and P low. The relative exchangeable P pools were site and treatment specific. The “old P pool” of organic soils seemed quite stable and strongly fixed, while the “new P pool” from fertilizer P probably had higher exchange ratio. Increased stores of Cr, Ni, Sr and Ti resulted from impurities in both fertilizer and lime, Cu from the compound fertilizer, and V and Y probably from the P fertilizer. Stores of Pb were not significantly changed by the treatments; those of Zn was unchanged after liming or even reduced after combined fertilization and liming. The Cu and Pb concentrations were sometimes above the suggested critical levels of toxicity

ISSN:0282-7581    

DOI:10.1080/02827589908540809

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Hydrological properties, in particular water-retention characteristics (WRC) and hydraulic conductivity (K), were studied in eight different growth media based on low-humified sphagnum peat with coarse (perlite) and fine (sand) constituents. The temporal change of matric potential(ψ)in the media, which were connected to two contrasting mineral soils (fine and coarse sandy soil) with higherψ, was studied in the laboratory in order to emulate the hydraulic situation in field conditions after outplanting of container seedlings. It was shown that the hydrological properties of peat medium and its hydraulic interaction with sandy soil can be altered markedly by the additives used. Adding a coarse constituent (perlite) to peat increased air-filled porosity (AFP) and saturated K of the medium, but decreased water retention (WR) (especially in wet conditions) and unsaturated K. Addition of a fine constituent (sand) decreased AFP and saturated K, but increased WR and K in dryish conditions. In general, the effect of additives on these hydrological properties increased with increasing proportion of additive in the medium. By using ternary mixtures (peat+perlite+sand), extreme values of these properties were avoided. When in contact with sandy soils, fine-textured sand constituent added to peat was found to cause the greatest movement of water into the growth medium. The results suggest that, after outplanting, additives in peat growth medium could be important for the movement of water from the surrounding soil and for the availability of water to seedling roots.

ISSN:0282-7581    

DOI:10.1080/02827589908540810

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

ISSN:0282-7581    

DOI:10.1080/02827589908540811

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor