摘要:

Diameter and height distributions forPinus radiataD. Don trees grown from seed lots representing a range of genetic improvement were compared at midrotation (age 14 or 15) in seven large-plot trials at six sites. In one of the trials, comparisons were made at year 5 and annually from age 8 to 16. These are the first data from plantation conifers comparing tree size distributions of commercially planted seed lots. Differences among seed lots for quadratic mean diameter and mean height were statistically significant and generally reflected the expected level of genetic improvement. Standard deviation, skewness, and kurtosis were not significantly different among seed lots. However, diameter distributions of higher rated seed lots sometimes appeared very slightly more skewed to the right and flatter than the lower rated seed lots, a similar tendency observed as stands age. Models used to predict diameter distribution from stand parameters are not likely to require modification for genetically improved seed lots.

ISSN:0045-5067    

DOI:10.1139/x97-203

出版商:NRC Research Press    

年代:1998

数据来源: NRC

摘要:

The objective of this study was to develop and subsequently apply an individual-tree analytical approach for assessing resource competition processes within monospecific, even-aged, and spatially heterogeneous black spruce (Picea mariana(Mill.) BSP) stands. The approach consisted of five basic steps: (1) ranking competitors with respect to subject tree size using a relative scale, (2) stratifying competitors into competition strata based on their relative size differential with respect to a subject tree, (3) quantifying the intensity of competition within each stratum using spatially explicit local competition indices and subsequently formulating directional-specific cumulative indices, (4) regressing relative measures of stem growth against each directional-specific index, and (5) graphically and statistically assessing differences in resultant standardized regression coefficients as competition accumulated upward from below and downward from above. This analytical framework was used with stem growth data derived from 401 subject trees situated within 18 monospecific, even-aged, density-stressed, and spatially heterogeneous black spruce stands. The results indicated directional-specific asymmetrical relationships between subject trees and their neighbours in which increasing competition from above resulted in declines in stem production. Consequently, these results were in accord with those expected when competition is dominated by a resource preemption process.

ISSN:0045-5067    

DOI:10.1139/x97-192

出版商:NRC Research Press    

年代:1998

数据来源: NRC

摘要:

Status number is a measure of effective population size that is based on current relatedness only. Formulae are developed for group coancestry (=average coancestry) and status number for seed orchard crops. The formulae consider (1) differences in reproductive success among orchard genotypes, (2) relatedness between pairs of orchard genotypes, (3) inbreeding of orchard genotypes, (4) influence of pollen contamination (considering its relatedness both to itself and to the genotypes in the orchard), and (5) gender differences and sexual asymmetries of orchard genotypes. Properties of status number and other measures of effective number are discussed. They may refer to rate or state, to the reference population or the development of an idealized population, and to different moments in the sexual cycle.

ISSN:0045-5067    

DOI:10.1139/x97-217

出版商:NRC Research Press    

年代:1998

数据来源: NRC

摘要:

An evaluation of how coarse woody debris (CWD) changes in quantity and quality during stand development was conducted using a 426-year chronosequence of 71 stands in sub-boreal forests in British Columbia. Additional characteristics of CWD were determined in 14 of the stands. Most stands are fire initiated and input from the predisturbance stand is critical in controlling the amounts and characteristics of CWD within young stands. Log volume declines from over 100 m3/ha in young stands (0-50 years) to just over 60 m3/ha in stands from 51 to 200 years old, and then increases to greater than 140 m3/ha in the oldest (>= 400-year-old) stands. Mean snag basal area is highest (31.6 m2/ha) in young, postfire stands, decreases to a very low value (2.0 m2/ha) in stands 51-100 years old, and then reaches a second maximum (12.1 m2/ha) in stands that are 201-250 years old; it declines slightly in very old stands. The high snag basal area in stands 201-250 years old coincides with the successional transition from lodgepole pine (Pinus contortaDougl. ex Loud. var.latifoliaEngelm.) to stands dominated by subalpine fir (Abies lasiocarpa(Hook.) Nutt.) and interior spruce (hybrids ofPicea glauca(Moench) Voss andPicea engelmanniiParry). Stand age, characteristics of the predisturbance forest, and the disturbance history of stands subsequent to stand initiation all appear to be very important in determining variation in both the quality and quantity of CWD in these sub-boreal forests.

ISSN:0045-5067    

DOI:10.1139/x97-208

出版商:NRC Research Press    

年代:1998

数据来源: NRC

摘要:

This paper reports on the results of a simultaneous equations sawlog market model using monthly data for Finland in 1985-1997. Johansen's multivariate method is used to estimate cointegration vectors, which are then included in a dynamic error-correction model. Rank tests indicate two cointegrating vectors, which is theoretically consistent with the demand and supply equations. In the sawlog demand, the equilibrium is established for sawlog stumpage price and quantity and sawn wood price and capital stock, while the supply function in a perfect capital market entails sawlog price and quantity, real interest rate, and the effect of increasing timber stock as captured by a linear trend. Contrary to earlier findings, stumpage price seems to have a positive effect on sawlog supply, both in the short and long run, while only the long-run price effect is present in the sawlog demand. Disequilibrium in demand is corrected within one quarter, while the speed of adjustment is found to be slow in the sawlog supply.

ISSN:0045-5067    

DOI:10.1139/x98-010

出版商:NRC Research Press    

年代:1998

数据来源: NRC

摘要:

The impact of an acidifying fertilizer on litter decomposition, root mycorrhizae, and soil and tree chemistry was assessed in two hardwood forests in central Ontario, Canada. Soil beneath mature sugar maple (Acer saccharumMarsh.) trees was treated with (NH4)2SO4granules at application rates of 0, 250, 500, and 1000 kg/ha in May of each year between 1993 and 1994 at Dorset and between 1993 and 1995 at Loring. The fertilizer treatments did not cause visual symptoms of forest decline. At Dorset, SO4and cation concentrations in soil leachate increased, but no difference in soil pH between treatments was found. An increase in foliar N was recorded at Dorset in treated plots, although there were no other differences in foliar or tree ring chemistry between treatments. At Loring, a decrease in soil pH and an increase in SO4in soil leachate were found in treated plots. Mycorrhizal infection and litter decomposition were also reduced in plots treated with (NH4)2SO4. Fertilizer application at Loring led to increases in foliar concentrations of N, Mg, Mn, and Cd, along with increases in concentrations of trace metals (As, Co, Cr, Mn, Ni, and Zn) in tree rings formed during fertilizer application. Significant positive correlations (p< 0.05) were found between wood (rings formed between 1993 and 1995) and foliage (mean of 1993-1995 values) for Mg, Mn, and Al. Deliberate acidification of surface soil resulted in changes in wood and foliar chemistry, although it remains to be established whether acidification of surface soil is responsible for the reported decline in sugar maple.

ISSN:0045-5067    

DOI:10.1139/x97-215

出版商:NRC Research Press    

年代:1998

数据来源: NRC

摘要:

The volatile emissions of black spruce (Picea mariana(Mill.) BSP) seed cones still attached to a live 7 m tall tree (in situ) were compared with those of cones from the same tree that had been severed (ex situ). Volatiles were collected simultaneously with a manifold headspace sampling system, adsorbed on Porapak®Q, and the extracts analysed by capillary gas chromatography (GC) and GC - mass spectrometry. The relative abundance of the identified constituents, tricyclene, alpha- and beta-pinene, camphene, sabinene, beta-myrcene, DELTA-3-carene,p-cymene, beta-phellandrene, limonene, gamma-terpinene, alpha-terpinolene, camphor, borneol, and bornyl acetate differed quantitatively, almost qualitatively, between in situ and ex situ samples. For example, camphene and bornyl acetate represented ca. 7% and 12% of total emissions, respectively, of the volatiles from in situ cones and ca. 0.9% and <0.2%, respectively, of the volatiles from ex situ cones. beta-phellandrene and beta-pinene were consistently less abundant in extracts of in situ collections (ca. 4.5% and 22%, respectively) than in those of ex situ collections (ca. 6% and 32%, respectively). Also, the release rate of total monoterpenes from in situ seed cones was approximately twice as high as that from ex situ cones. These results indicate that ex situ sampling does not accurately depict the composition of volatile emissions by seed cones and suggest that tests for biological activity based on such compositions could lead to erroneous conclusions.

ISSN:0045-5067    

DOI:10.1139/x97-216

出版商:NRC Research Press    

年代:1998

数据来源: NRC

摘要:

This study describes the application of previously characterized chloroplast microsatellites as markers for paternity analysis in a conifer species. The investigations were performed on silver fir (Abies albaMill.) relic trees in an endangered population of the Ore Mountains (Germany). Two relatively isolated adult trees about 30 m apart, as well as 24 naturally regenerated young trees in their direct neighborhood, were analyzed at two chloroplast microsatellite loci. Results reveal the potential usefulness of the markers for paternity analysis.

ISSN:0045-5067    

DOI:10.1139/x97-213

出版商:NRC Research Press    

年代:1998

数据来源: NRC