摘要:

In separate experiments, tolerance of root competition and of flooding were assessed for seedlings of Chinese tallow tree (Sapiumsebiferum(L.) Roxb.), an invasive species in some North American floodplains. In the root competition experiment, pots containing seedlings of Chinese tallow tree and a native North American floodplain species (green ash,FraxinuspennsylvanicaMarsh.) were buried in the soil of a closed-canopied floodplain forest in South Carolina. Approximately half of the pots were invaded by roots of surrounding vegetation. In both species, total seedling mass in invaded pots was 70% of that in uninvaded pots. In the flood tolerance experiment, potted seedlings of tallow tree and a highly flood-tolerant species (water tupelo,NyssaaquaticaL.) were subjected to flooded and well-drained treatments in two light regimes: 20 and 100% of full sunlight. Mortality of flooded tallow trees was lower than of flooded tupelos (0 vs. 7.5%). Growth reductions under flooding were similar for both species in 20% light, but greater for tallow tree than for tupelo in 100% light. Flooded tallow trees produced hypertrophied lenticels and adventitious roots. Sensitivity to root competition and high flood tolerance may explain why seedlings of Chinese tallow tree are concentrated in low wet areas of floodplain forests.

ISSN:0045-5067    

DOI:10.1139/x90-074

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

A study was undertaken to investigate the effects of nitrogen and boron, applied singly and in combination, on the growth of young, thinned lodgepole pine in the interior of British Columbia. Results indicate that subacute boron deficiencies without visible growth disturbance symptoms, may reduce the nitrogen fertilization response potential of lodgepole pine. Combined nitrogen and boron application significantly improved the 3-year mean height and volume increment over that obtained with nitrogen alone. Relatively small boron additions (i.e., 1.5 and 3.0 kg boron•ha−1) to the soil surface elevated foliar boron concentrations and maintained them throughout the 3-year study period. No toxic effects of boron application on foliage were observed. Both 1st-year fascicle weight response and 2nd-year branch elongation proved to be reliable indicators of subsequent stem volume response. The slightly larger stem growth response obtained with a complete fertilizer treatment, when combined with needle weight and foliar analysis data, indicates that nitrogen and nitrogen plus boron treatments may have induced a marginal sulphur deficiency. Because boron deficiency symptoms can develop rapidly following an interruption in boron uptake, and because top dieback can have such an adverse effect on stem quality and value, it is recommended that boron be added to nitrogenous fertilizer when undertaking aerial fertilization projects in lodgepole pine forests where average foliar boron concentrations are below 15 ppm.

ISSN:0045-5067    

DOI:10.1139/x90-075

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

Nuclear magnetic resonance (NMR) imaging is a valuable diagnostic tool that detects the presence of hydrogen protons or water in material studied. Recently the technique was successfully used to observe the occurrence of defects within logs. The present study examined the feasibility of using NMR imaging for analyzing moisture distributions within white oak (QuercusalbaL.) lumber. At selected days during drying, three thicknesses of lumber were imaged to detect free water, using a clinical 0.5-T whole body NMR scanner. NMR was shown to provide a noninvasive image of the internal structure of lumber. Images revealed that growth ring orientation and rays may play an important role in the drying process. Moisture distributions (shell and core) were qualitatively observed. For a quantitative interpretation, images were measured with an optical densitometer. The average moisture content of the board was correlated successfully to the weighted average optical density for the shell and core regions combined.

ISSN:0045-5067    

DOI:10.1139/x90-076

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

Seedlings of Scots pine (PinussylvestrisL.) were artificially frost hardened under controlled conditions. To follow the development of hardiness, the frost killing temperature was determined. Four levels of hardiness were defined during the course of frost hardening. After adaptation of the seedlings to dark conditions at room temperature, fluorescence induction and far red induced luminescence decay kinetics were recorded for seedlings of the four defined levels of hardiness. The induction curve of fluorescence and the decay curve of luminescence were digitized for 110 time intervals, and the values were used in a multivariate partial least squares analysis to evaluate the potential of luminescence and fluorescence as predictive probes for cold hardiness. The results showed that both fluorescence induction and luminescence decay kinetics contain information allowing the prediction of frost hardiness of artificially cold-hardened seedlings of Scots pine.

ISSN:0045-5067    

DOI:10.1139/x90-077

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

Six-month-old black spruce (Piceamariana(Mill.) B.S.P.) container seedlings were placed in either a cool (18 ± 4: 6 ± 4 °C, light:dark) or a warm (26 ± 3: 18 ± 2 °C, light:dark) hardening regime for 12 weeks after bud initiation to assess the effects of temperature on needle maturation and transpiration. Stomatal transpiration was greater in warm-hardened seedlings than in cool-hardened seedlings. Cuticular transpiration was found to be greater in cool-hardened excised shoots than in warm-hardened shoots. Needle cuticle thickness increased in seedlings exposed to both warm and cool temperatures, however, cuticular growth after bud initiation was greater in the warm-hardening regime.

ISSN:0045-5067    

DOI:10.1139/x90-078

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

This study presents results from a stand structure analysis of an energy forest plantation ofSalixviminalisL., clone 77-683. The stand, which was expected to contain only one clone, was shown to be composed of at least one male and one female clone. The male clone was susceptible toMelampsoraepiteaThüm. and displayed a larger proportion of frost damage after infection and lower mean size and weight than the uninfected clone. Regression analysis showed that the infected and uninfected shoots differed significantly in their size-weight relationships. Relative differences in size and damage between infected and uninfected stools were larger within the stand than along the border rows. The results illustrate how genetic differences in response to a pathogen can result in unevenly structured stands.

ISSN:0045-5067    

DOI:10.1139/x90-079

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

Overland flow and soil movement were measured on small plots of three forest types in the Kumaun Himalaya. Average seasonal (June through September) overland flow (measured over 2 years) was 0.49% of the seasonal rainfall (1967 mm) and was always less than 1% of each rain event (there was less than 0.1% difference among forest types). Seasonal soil movement ranged from 2.3 to 3.2 g•m−2among forest types and averaged 2.6 g•m−2. Both overland flow and soil movement were significantly different between months, being positively correlated with amount of rainfall. Sediment concentration of runoff water did not vary among months by more than 0.1 g•L−1. The study indicates that steep, forested slopes are not an important sediment source in Kumaun Himalaya.

ISSN:0045-5067    

DOI:10.1139/x90-080

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

To guide in deciding whether artificial inoculation of container-grown woody seedlings used for reclamation purposes in Alberta might be beneficial, a survey was made of seven nurseries to determine the symbiotic status of plants ready for outplanting. Eight species of woody shrubs were rarely vesicular-arbuscular mycorrhizal if less than 1 year old and were erratically mycorrhizal after 1 to 2 years nursery residence time. Actinorhizal shrubs (ElaeagnuscommutataBernh. ex Rydb. andShepherdiaspp.) did not become nodulated in the 1st year, and planting stock generally lacked N2-fixing ability. The mycorrhizal status of pines (PinusbanksianaLamb, andPinuscontortaDougl.) and white spruce (Piceaglauca(Moench) Voss) seedlings ranged from mycorrhizal-free to complete mycorrhization. A majority of the mycorrhizae were formed byThelephoraterrestrisEhrh.:Fr., E-strain (Complexipes), andMyceliumradicisatrovirensMelin.Amphinemabyssoides(Fr.) J. Erikss. formed a large proportion of the mycorrhizae on white spruce, which were held in nurseries for over 1 year. A stipitate polypore,Coltriciasp., is reported as a mycorrhizal associate of nursery stock for the first time.

ISSN:0045-5067    

DOI:10.1139/x90-081

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

not available

ISSN:0045-5067    

DOI:10.1139/x90-082

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

not available

ISSN:0045-5067    

DOI:10.1139/x90-083

出版商:NRC Research Press    

年代:1990

数据来源: NRC