摘要:

Estimates of individual-tree narrow-sense heritability and additive genetic coefficient of variation of seven traits of forest trees were compiled from 67 published papers. Distributions of the values for each trait were characterized and compared by calculating medians and running Kolmogorov–Smirnov and Wilcoxon signed-rank tests. Generalizations are possible about at least some of the traits examined. Heritability of wood specific gravity was almost always above 0.3 (median 0.48). Heritabilities for other traits tended to be low: medians ranged from 0.185 to 0.26, and individual values generally ranged from 0.1 to 0.4. Evidence that heritabilities of form traits tend to be higher than those of growth traits was weak. The analysis of additive genetic coefficients of variation suggested that specific gravity tends to have lower values than other traits (median 5.1%), while height and diameter (medians 8.5 and 8.6%, respectively) had lower values than straightness (median 11.65%). Individual-tree volume showed the highest levels of additive genetic coefficient of variation (median 20.3%). The levels of additive genetic variation and heritabilities suggest that reasonable levels of genetic gain can be achieved by screening relatively low numbers of trees.

ISSN:0045-5067    

DOI:10.1139/x94-050

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

Uses of recently available calorimetry technology are explored for measurement of metabolic activity–temperature relations in coast redwoods (Sequoiasempervirens(D. Don) Endl.). These redwoods were collected from different parts of the native range and grown in a common-garden plantation. Analysis of metabolic activity from 10 to 55 °C was used to examine site adaptedness of respiratory metabolism in 16 representative clones of coast redwood. Apparent activation energies changed markedly over the range 12–52 °C, but the patterns of change were similar for clones from five geographical regions and thus appear to be general for the species. However, high-temperature stability, the temperature of peak activity, and the peak metabolic heat rate differed substantially among samples from the five regions. Additional variability in high temperature stability and the temperature of peak activity was measured between trees from the same stands within regions. We suggest that the observed regional and clonal variations in high-temperature stability, the temperature of peak activity, and the peak metabolic heat rate are biologically meaningful. These may be used both to understand the adaptive architecture of coast redwood and to select clones likely to be adapted to particular sites or defined ranges of sites.

ISSN:0045-5067    

DOI:10.1139/x94-051

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

One of the most common ways to account for investment risk is to add a risk premium to the risk-free discount rate when computing present values of expected revenues which are uncertain. Using certainty-equivalent analysis, we show that the correct risk premium for short-term investments can easily be in the commonly used 7-percentage-point range. But for such risk premiums to be appropriate for long-term forestry investments, the necessary certainty-equivalent conditions often seem to be unreasonably restrictive. Results suggest that the appropriate risk premium may decline with lengthening payoff period for many forest investments. Limited empirical data provide tentative support, but more research is needed to resolve the issue. We review policy implications and suggest areas for further research.

ISSN:0045-5067    

DOI:10.1139/x94-052

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

The distribution of within-stand basal area growth following silvicultural treatments was investigated using a relative size–relative growth (RSG) function. The effects of thinning on the distribution of tree basal area, including changes in location or scale, can be incorporated into the estimation of the RSG function parameters. Additional stand growth due to fertilization can also be allocated to individual trees using the same RSG function, since the contribution of a tree's response to total stand treatment response depends on its relative size in the stand. Statistical tests and validation of the RSG function indicated that thinning and fertilization do not alter the characteristic relationships between tree size, stand density, stand structure, and the relative distribution of growth across size classes within a stand. Therefore, silvicultural treatment growth responses predicted at a whole-stand level of resolution can be disaggregated to a list of individual trees using the RSG function developed from untreated plots.

ISSN:0045-5067    

DOI:10.1139/x94-053

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

A parameter recovery procedure for the Weibull distribution function was modified to incorporate monocultures and mixtures of eastern cottonwood (PopulusdeltoidesBartr.) clones planted in Mississippi and Kentucky. Components of the system included functions to predict stand-level basal area and four percentiles (0th, 25th, 50th, and 95th) of the cumulative diameter distribution. Basal area was predicted as a function of surviving number of trees, dominant height, age, planting location, and the proportion of each clone planted. Clonal proportions, which accounted for 3.6% of the variation in observed basal area, were more important than differences in planting locations, which accounted for 3.0% of the variation. Interactions between clones in mixtures were not significant (p = 0.5676), but some cases of both over- and under-compensation appeared to be developing. Percentiles of the cumulative diameter distribution were predicted as functions of quadratic mean diameter, and therefore included indirect effects of both genetic and planting site differences. Only the minimum diameter (D0) was directly affected by proportions of clones planted. Most of the monocultures and mixtures of clones had smaller minimum diameters than expected for a given value of quadratic mean diameter. The predicted quadratic mean diameter and percentiles were used to recover parameters of the Weibull distribution such that the predicted diameter distribution has the same quadratic mean diameter as obtained from the stand basal area model. The predicted distributions indicated that a common stand-level model was not sufficient for accounting for variations in diameter distributions of eastern cottonwood clones. As a result of the differences in diameter distributions, monocultures and mixtures of the Texas clones appeared to have less volume and greater stand variance than the Mississippi clones.

ISSN:0045-5067    

DOI:10.1139/x94-054

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

This study reports on the relationship of glutathione to the recovery and death of red-osier dogwood,CornussericeaL., plants from "near-lethal" (NL) heat stress. Shoots of dormant red-osier dogwood plants were exposed to 51 °C for 1 h during early February, and then incubated in the dark at either 0 or 23 °C post-stress environment (PSE). In a previous study, NL heat stress treated plants incubated at 23 and 0 °C PSE recovered and died, respectively. Reduced and oxidized forms of glutathione (GSH and GSSG, respectively) were measured with HPLC at 365 nm absorbance after 0 h, 24 h, 2 weeks, and 4 weeks PSE, respectively. Incubation of the NL heat stress treatments for 24 h at 23 ± 3 °C prior to post-treatments resulted in a significant decrease of GSSG and slight decrease of GSH. In contrast, the sudden exposure of NL stressed plants to 0 °C for 24 h resulted in a significant reduction of both GSH and GSSG levels after 2 and 4 weeks incubation. At 23 °C PSE, GSH and GSSG levels of NL heat stressed plants increased, while at 0 °C PSE the levels of both decreased.

ISSN:0045-5067    

DOI:10.1139/x94-055

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

Precursors to small subunits (SSU) of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco, EC 4.1.1.39) and apoproteins of light-harvesting chlorophylla/bbinding protein (LHCPII) in photosystem II were synthesized in vitro by expressing pine (Pinus thunbergiiParl.) cDNA clones encoding these proteins. The precursors to pine SSU and LHCPII were post-translationally transported into spinach chloroplasts, processed into mature size, and localized in only stroma and thylakoid membranes, respectively. The pine SSU was tightly integrated into spinach Rubisco; however, the pine LHCPII was not found in the light-harvesting chlorophyll–protein complex. These results suggest that a common biogenesis pathway of nuclear-encoded chloroplast proteins is present both in gymnosperms and in angiosperms.

ISSN:0045-5067    

DOI:10.1139/x94-056

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

Chloroplast DNABamHI restriction fragments were studied inPinuselliottiiEngelm. var.elliottii(11 trees),P.elliottiivar.densa(2 trees), the three taxonomic varieties ofPinuscaribaeaMorelet (39 trees), andPinusoocarpaSchiede (9 trees). Polymorphism was detected within bothP.elliottiivarieties, but not withinP.oocarpa. Each of theP.caribaeavarieties was monomorphic, but the Cuban variety,P.caribaeavar.caribaea, differed clearly from the Bahamian (P.caribaeavar.bahamensis) and Honduran (P.caribaeavar.hondurensis) varieties. Varietycaribaeashared the most frequent chloroplast genotype ofP.elliottiivar.elliottii, while varietiesbahamensisandhondurensisshared the second most frequent genotype ofP.elliottiivar.elliottii. TheP.oocarpachloroplast genotype was not found in other taxa of the present study, but was found previously inPinusechinataMill, andPinuspalustrisMill. The results of this study, taken together with other chloroplast data from subsectionAustrales, suggest a close relationship betweenP.caribaeaandP.elliottii. This confirms previous morphological and biochemical evidence, but several discrepancies were apparent and are discussed.

ISSN:0045-5067    

DOI:10.1139/x94-057

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

Tabulated Student'st-values and climatic insensitivity among inner tree-ring widths can bias estimates of statistical significance for cross correlations relating "floating" and master tree-ring series. These biases can be removed by (i) directly computing significance levels for cross-correlation coefficients at dating positions and (ii) deleting insensitive inner rings from a dated floating sample before final correlation analysis. The number of early rings to delete can be determined from plots of cross-correlation coefficients linking a dated floating series of artificially decreasing length with a master series. These modifications improve the precision of Yamaguchi and Allen's approach (D.K. Yamaguchi and G.L. Allen. 1992. Can. J. For. Res. 22: 1215–1221) for estimating significance.

ISSN:0045-5067    

DOI:10.1139/x94-058

出版商:NRC Research Press    

年代:1994

数据来源: NRC