Effects of radiation from 14CO2 absorbed by Pinus strobus L. seedlings during photosynthesis on their subsequent growth and metabolism

1968 ◽  
Vol 46 (8) ◽  
pp. 919-923 ◽  
Author(s):  
D. J. Ursino ◽  
V. Slankis ◽  
G. Krotkov

Several times during the year, white pine seedlings were placed in a closed system and each plant was permitted to photo-assimilate 400–500 μCi of 14CO2. At various periods of time after photo-assimilation, the fresh weight, apparent photosynthesis, dark respiration, and distribution of absorbed 14C throughout the seedlings were determined. The location and magnitude of depressed growth caused by the radiation from the incorporated 14C varied with the time of year when photo-assimilation occurred.When 14CO2 photo-assimilation occurred in May and June, suppression of growth was the greatest in the new shoots, whereas when photo-assimilation occurred in the fall, the suppression of growth was more pronounced in the roots. Seedlings which photo-assimilated 14CO2 in the fall appeared normal during winter but their buds failed to develop into new shoots the following spring.It is also suggested that a decrease in the rate of apparent photosynthesis may be used as an indicator of radiation damage brought about by the incorporated 14CO2.

2004 ◽  
Vol 21 (2) ◽  
pp. 61-68 ◽  
Author(s):  
Jerome A. Krueger ◽  
Klaus J. Puettmann

Abstract White pine seedlings were underplanted under a range of overstory densities in a hardwood stand in northern Minnesota. Vegetation surrounding seedlings was left untreated (control), weeded annually, or completely removed through monthly weeding. After 4 years, the benefit of weeding woody competition for diameter growth of seedlings was limited to areas with relatively open overstory conditions. Seedling height growth was reduced in areas with higher overstory density, but improved through weeding treatments that removed woody vegetation. The removal of herbaceous vegetation did not improve growth of seedlings in any conditions. Open growing conditions created by overstory removal and weed control resulted in higher incidences of seedling injuries, e.g., through infection by white pine blister rust. Conditions for pine bark adelgids also were enhanced in areas with low overstory densities and weeding treatments. The incidence for white pine weevil seems to follow a similar pattern, although the number of trees infected was minimal. Results show that improving growing conditions through management of the overstory and understory vegetation improves seedling growth rates, but must be balanced with potentially higher incidences of seedling injuries under more open conditions.


1982 ◽  
Vol 60 (10) ◽  
pp. 2046-2053 ◽  
Author(s):  
David E. Hibbs

Eastern white pine (Pinus strobus) in central New England is found in pure stands and as a component of mixed hardwood -pine stands. In older mixed forests, this pine is emergent over the surrounding hardwood canopy. Owing to the only moderate shade tolerance and initial slow growth rate of pine, there has been frequent speculation about how pine could survive and grow in hardwood forests. Results presented here indicate that successful white pine regeneration is achieved (i) by group reproduction in dense hardwood stands (25 m2∙h−1) where the group acts as a buffer around a central and eventually surviving pine; (ii) by single pine seedlings if hardwood competition is not too severe (18 m2∙h−1); (iii) occasionally by advanced regeneration from a previous stand; and, (iv) in mature forests, by regeneration in larger canopy gaps.


1987 ◽  
Vol 65 (5) ◽  
pp. 977-987 ◽  
Author(s):  
Peter B. Reich ◽  
Anna W. Schoettle ◽  
Hans F. Stroo ◽  
John Troiano ◽  
Robert G. Amundson

Four replicated factorial experiments were conducted to assess the response of potted white pine (Pinus strobus L.) seedlings to combined acid rain, ozone, and soil treatments. The objectives of the study were to quantify plant response to each pollutant alone and to determine whether the pollutants and edaphic factors interact in affecting physiological processes in white pine. In these studies, seedlings were grown in five forest soils and exposed for 4 months to realistic levels of acid rain and ozone. Acid rain treatments consisted of exposure to simulated rain of pH 5.6, 4.0, 3.5, or 3.0, while ozone treatments consisted of exposure to 0.02, 0.06, 0.10, or 0.14 ppm ozone. Minimal interaction between acid rain and ozone was observed with regard to photosynthesis or growth. Acid rain and soil type had a strong interaction in determining plant response. In general, acid rain caused increased growth and net photosynthesis as a result of nitrogen fertilization from the simulated rain. However, the extent of this response was inversely correlated with the availability of nitrogen in each soil. Ozone treatments caused decreased net photosynthesis in pine seedlings.


2008 ◽  
Vol 38 (2) ◽  
pp. 181-189 ◽  
Author(s):  
Eric K. Zenner

Following release, mature trees can acclimatively shift aboveground growth allocation from height to diameter at breast height (DBH) growth to adjust their stem form (reducing height/diameter ratio (HDR)) to better withstand increased wind stress. The purpose of this study was to determine if, over a 6-year period, 7- to 12-year-old eastern white pines ( Pinus strobus L.) also responded to different levels of partial release with (i) stem-form adjustments (reduced HDR) through growth-allocation shifts from height to DBH growth and (ii) lower HDR values (shorter heights) than for unreleased trees of the same DBH (“acclimative stem-form development hypothesis”). Over the 6-year postrelease period, juvenile white pine seedlings exhibited unsynchronized height and DBH growth response patterns that depended on their prerelease height growth. Height growth of faster growing white pines was temporarily reduced. Concurrently, DBH growth was enhanced with increasing release intensity. HDR reductions followed a fairly narrow and predictable trajectory, but HDR values of released trees were not lower than those of unreleased trees of the same DBH after 6 years. Juvenile white pine seedlings appear to maintain a balance among aboveground tree parts to enhance future tree stability, which may be an adaptive trait for moderately shade-tolerant species.


1978 ◽  
Vol 54 (2) ◽  
pp. 84-87 ◽  
Author(s):  
R. E. Mullin

A study was established to assess the effects of root exposure at time of planting on the performance of 3 + 0 white pine (Pinus strobus L.) seedlings. Stock was lifted weekly from April 22nd (1971) for 10 weeks, with and without root dipping in water, and exposed from 0-3 hours before planting. Survival, terminal growth (current leaders) and total heights were examined after five years.Exposure resulted in damage; affecting survival, current growth and total height at five years. However, survival was unaffected by exposures of up to two hours on days with relative humidity above 80%. Dipping in water was found to be ineffective.Extending the planting season with 'hot' planting (same day) resulted in reduction of terminal growth and total height. Survival was also reduced for dates following flushing.


1995 ◽  
Vol 12 (3) ◽  
pp. 115-120 ◽  
Author(s):  
David B. Kittredge ◽  
P. Mark S. Ashton

Abstract Browsing preferences by white-tailed deer were evaluated for 6 tree species in northeastern Connecticut. Deer density averaged 23/mile². Deer exhibited no species-specific preferences for seedlings greater than 19 in. For seedlings less than 19 in., hemlock and black birch were preferred. Red maple, sugar maple, and white pine seedlings were avoided. Red oak seedlings were neither preferred nor avoided. A much higher proportion of seedlings greater than 19.7 in. in height was browsed, regardless of species. Browsing preferences for species in the smaller seedling class, combined with a lack of preference for species in the larger class may result in future stands with less diverse tree species composition. Deer densities in excess of 23/mile² may be incompatible with regeneration of diverse forests in southern New England. North. J. Appl. For. 12(3):115-120.


New Forests ◽  
2013 ◽  
Vol 45 (1) ◽  
pp. 131-147 ◽  
Author(s):  
Yadav Uprety ◽  
Hugo Asselin ◽  
Yves Bergeron ◽  
Marc J. Mazerolle

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