NOTEAging discrepancies of white spruce affect the interpretation of static age structure in boreal mixedwoods

2002 ◽  
Vol 32 (8) ◽  
pp. 1496-1501 ◽  
Author(s):  
Vernon S Peters ◽  
S Ellen Macdonald ◽  
Mark RT Dale
Keyword(s):  
Picea Glauca ◽  
Ground Level ◽  
Stand Age ◽  
First Year ◽  
Stand Development ◽  
Boreal Mixedwoods ◽  
Soil Level ◽  
Root Collar ◽  
Humus Soil ◽  
Over Time

Post-fire regeneration of Picea glauca (Moench) Voss on boreal mixedwood sites appears to be highly variable over time. Our objectives were to determine whether ground-level ring counts underestimate root collar age of understory P. glauca and whether aging errors increase with stand age. Trees were collected from one to nine stands in each of three fires occurring in mast years between 1961 and 1991. Trees were cut at ground level (humus soil level), and the belowground stumps were excavated, sectioned, and internally cross-dated with skeleton plots after identifying the root-collar location. Ground-level disks were visually cross-dated with a master chronology, which was constructed using the dendrochronology program COFECHA. Ground-level ring counts underestimated age by a mean of 2.4 years (range 0–6) and 6.4 years (range 0–13) in 20- and 38-year-old stands, respectively. Age underestimation was significantly greater at the root collar than ground level because of missing rings. Cross-dated age structures showed that apparent regeneration lags in 20- and 38-year-old stands were artifacts of ground-level ring counts and that the first year post-fire was the most important establishment year in all mast year burns. We conclude that aging errors have led to inaccurate depictions of regeneration patterns during early mixedwood stand development. Our results portray a different picture of P. glauca succession and have important implications for forest management.

INFLUENCE OF ROOT PRUNING ON HEIGHT INCREMENT AND ROOT DEVELOPMENT OF OUTPLANTED SPRUCE

1967 ◽  
Vol 45 (9) ◽  
pp. 1671-1682 ◽  
Author(s):  
R. F. Sutton
Keyword(s):  
New York ◽  
Picea Glauca ◽  
First Year ◽  
Root Pruning ◽  
Silt Loam ◽  
Height Increment ◽  
Loam Soil ◽  
Second Year ◽  
Root Collar ◽  
Block Experiment

Three-year-old seedlings of Picea glauca and P. abies were outplanted in a fertile silt loam soil at Ithaca, New York, in a split-plot randomized block experiment involving large- and small-size classes of stock and four root-pruning treatments: control; laterals pruned to 5 cm; all roots pruned at 10 cm measured from the root collar; and all laterals pruned flush with the tap or main root.Survival was good except in the last treatment. First- and second-year height increments within each species were unaffected by root-pruning treatments, even the most extreme. This suggests that either water stress is not aggravated by root pruning or that root pruning has compensating advantages. In the second year, height increment of P. glauca was significantly inferior to that of the first year. Height increment of P. abies was significantly greater in the second than in the first year.Root systems of 20 P. glauca were excavated in the second year. Percentage increases of total root length (of all roots 1 cm or more long) in root-pruned trees were twice those of control trees. Highest values (> 1000%) were for vigorous trees in the moderate root-pruning treatments.

Glyphosate Herbicide: An Assessment of Forestry Potential

1978 ◽  
Vol 54 (1) ◽  
pp. 24-28 ◽  
Author(s):  
Roy F. Sutton
Keyword(s):  
Populus Tremuloides ◽  
Picea Glauca ◽  
Woody Species ◽  
Ground Level ◽  
White Spruce ◽  
Woody Vegetation ◽  
First Year ◽  
Height Increment ◽  
White Birch ◽  
Second Year

Environmentally safe, yet potent in controlling herbs, grasses, and woody species, with possibilities for selective use, glyphosate (Roundup®) has great potential usefulness in forestry.In the small study reported here, twelve.01 ha plots were established in August, 1973 in dense 6-year-old shrub and hardwood post-fire regrowth near Chapleau, Ontario. In each plot, 16 rising 3 + 0 white spruce (Picea glauca [Moench] Voss) were planted centrally at.9 m ×.9 m spacing. Six treatments with two replications were applied at random the next day: 1, control; 2, all woody vegetation cut off at ground level; 3, all woody vegetation cut off in central planted area of plot; 4, sprayed with 60 mL glyphosate in 1.892 L of water; 5, sprayed with double strength glyphosate; 6, sprayed with sextuple strength glyphosate. Eight trees in each plot were shielded during the spraying. Browsing affected 16% of the spruce after 2 weeks, 96% by spring. Half of each plot was replanted with eight white spruce (four of them caged against browsing) in May, 1974.The objectives were to observe the effect of glyphosate on hardwood and shrub competition, to assay this effect by white spruce outplantings, and to evaluate the resistance to glyphosate of newly planted white spruce. Glyphosate was highly effective in killing trembling aspen (Populus tremuloides Michx.), white birch (Betula papyrifera Marsh.), and beaked hazel (Corylus cornuta Marsh.): pin cherry (Prunus pensylvanica L. f.) resprouted with moderate vigor. White spruce responded significantly (P.01) to first-year non-herbicide (i.e., immediate) weed control, but second-year height increment was significantly (P.001) less than that of the first year: second-year height increment in the glyphosate treatments was significantly (P.001) greater than in the non-herbicide treatments. Growth and survival were both affected by non-treatment disturbances, but shielding during spraying improved second-year survival significantly (P.001).

scholarly journals Higher Renovation Pruning Height Improves Early Yields of ‘Woodard’ Rabbiteye Blueberry

2021 ◽  
pp. 1-4
Author(s):  
Eric T. Stafne ◽  
Barbara J. Smith
Keyword(s):  
Harvest Index ◽  
Growth Parameters ◽  
Foliar Spray ◽  
Phosphorous Acid ◽  
Ground Level ◽  
First Year ◽  
Economic Returns ◽  
Above Ground Level ◽  
Over Time

Rabbiteye blueberry (Vaccinium virgatum) bushes are relatively easy to grow and commonplace across Mississippi; however, if not properly maintained, the bushes will decline over time. Eighteen, aged, low-productivity ‘Woodard’ rabbiteye blueberry bushes were pruned at two different heights (ground level and a 50-cm above ground level) after harvest in July 2017, and phosphorous acid was applied as a drench and foliar spray in the first year, but this was discontinued as the applications had no effect on the bushes. For two seasons, fruit yields were collected and weighed, bushes were measured for growth parameters, and canes were weighed. Bushes pruned at the 50-cm above ground level had much higher yields in both 2019 (3.47 vs. 0.63 kg) and 2020 (3.91 vs. 1.23 kg), thus providing a substantial yield benefit. The 50-cm above ground level pruning treatment bushes produced more canes by the end of the study, therefore accounting for more fruiting area, as seen in the harvest index. In short, pruning old, nonproductive bushes at a 50-cm above ground level can provide growers with greater potential for early economic returns than pruning at ground level, for ‘Woodard’ rabbiteye blueberry.

Correlating entrance data and first year academic performance of students enrolled in the Integrated Master in Mechanical Engineering at the University of Porto

2021 ◽  
pp. 030641902110156
Author(s):  
TMGP Duarte ◽  
AM Lopes ◽  
LFM da Silva
Keyword(s):  
Academic Performance ◽  
Secondary School ◽  
Undergraduate Students ◽  
Mechanical Engineering ◽  
Institutional Factors ◽  
First Year ◽  
Female Type ◽  
The University ◽  
First Year University ◽  
Over Time

Understanding how the academic performance of first year undergraduate students is influenced by home, personal and institutional factors is fundamental to delineate policies able to mitigate failure. This paper investigates possible correlations between the academic performance of students at the end of high school with their achievements at the end of first year university. Data for students in the Integrated Master in Mechanical Engineering (MIEM) program within the Faculty of Engineering at the University of Porto are analysed for the period 2016/2017 to 2019/2020. The students’ performance is measured by two metrics and the students are structured as a whole and by groups, according to their gender (Male/Female), type of secondary school (Public/Private), living place (Away/Home) and the rank of MIEM in their application list of options (Option 1/Option 2–6). The information is organized statistically and possible correlations between the data are investigated. The analysis reveals limited correlation between the two metrics, meaning that all students may exhibit good or poor results at the end of first year in MIEM, independent of their status at entrance. An unanticipated pattern is exhibited for the group Option 2–6, since it shows that, despite entering into MIEM without top application marks, the students in this group can perform as well as the others. This behavior is consistent over time.

Root rot damage in naturally regenerated stands of spruce and balsam fir in Ontario

1989 ◽  
Vol 19 (3) ◽  
pp. 295-308 ◽  
Author(s):  
R. D. Whitney
Keyword(s):  
Root Rot ◽  
Black Spruce ◽  
Basal Area ◽  
Ground Level ◽  
White Spruce ◽  
Balsam Fir ◽  
Tree Age ◽  
Stand Age ◽  
Root Decay ◽  
Forest Region

In an 11-year study in northern Ontario, root rot damage was heaviest in balsam fir, intermediate in black spruce, and least in white spruce. As a result of root rot, 16, 11, and 6%, respectively, of dominant or codominant trees of the three species were killed or experienced premature windfall. Butt rot, which resulted from the upward extension of root rot into the boles of living trees, led to a scaled cull of 17, 12, and 10%, respectively, of gross merchantable volume of the remaining living trees in the three species. The total volume of wood lost to rot was, therefore, 33, 23, and 16%, respectively. Of 1108 living dominant and codominant balsam fir, 1243 black spruce, and 501 white spruce in 165 stands, 87, 68, and 63%, respectively, exhibited some degree of advanced root decay. Losses resulting from root rot increased with tree age. Significant amounts of root decay and stain (>30% of root volume) first occurred at 60 years of age in balsam fir and 80 years in black spruce and white spruce. For the three species together, the proportion of trees that were dead and windfallen as a result of root rot increased from an average of 3% at 41–50 years to 13% at 71–80 years and 26% at 101–110 years. The root rot index, based on the number of dead and windfallen trees and estimated loss of merchantable volume, also increased, from an average of 17 at 41–50 years to 40 at 71–80 years and 53 at 101–110 years. Death and windfall of balsam fir and black spruce were more common in northwestern Ontario than in northeastern Ontario. Damage to balsam fir was greater in the Great Lakes–St. Lawrence Forest region than in the Boreal Forest region. In all three tree species, the degree of root rot (decay and stain) was highly correlated with the number of dead and windfallen trees, stand age, and root decay at ground level (as a percentage of basal area) for a 10-tree sample.

Interaction of Cottonwood Clones with Site and Planting Year

1973 ◽  
Vol 3 (3) ◽  
pp. 329-332 ◽  
Author(s):  
C. A. Mohn ◽  
W. K. Randall
Keyword(s):  
First Year ◽  
Diameter Growth ◽  
Mississippi Valley ◽  
Lower Mississippi Valley ◽  
Large Clone ◽  
Over Time

Height and diameter growth to age three and the number of first year branches were analyzed for 25 cottonwood clones grown in six plantations in central Mississippi. Plantations were on two contrasting sites and planted in three consecutive years. Results showed small clone × planting year interactions and large clone × site interactions for all parameters. In the lower Mississippi Valley, therefore, emphasis should be placed on testing over a range of sites rather than replicating over time.

scholarly journals Changes in Soil Arthropod Abundance and Community Structure across a Poplar Plantation Chronosequence in Reclaimed Coastal Saline Soil

Forests ◽  
2018 ◽  
Vol 9 (10) ◽  
pp. 644 ◽  
Author(s):  
Yuanyuan Li ◽  
Han Chen ◽  
Qianyun Song ◽  
Jiahui Liao ◽  
Ziqian Xu ◽  
...  
Keyword(s):  
Community Dynamics ◽  
Stand Age ◽  
Stand Development ◽  
Soil Arthropods ◽  
Total Abundance ◽  
Soil Arthropod ◽  
Plantation Development ◽  
Poplar Plantations ◽  
Hill Numbers ◽  
One Year

Poplar plantations have the capacity to improve the properties of soils in muddy coastal areas; however, our understanding of the impacts of plantation development on soil arthropods remains limited. For this study, we determined the community dynamics of soil dwelling arthropods across poplar plantations of different ages (5-, 10-, and 21-years) over the course of one year in Eastern Coastal China. The total abundance of soil arthropods differed with stand development. Further, there were some interactions that involved the sampling date. On average, total abundance was highest in the 10-year-old stands and lowest in the 5-year-old stands. Total abundance exhibited strong age-dependent trends in June and September, but not in March or December. The abundance of Prostigmata and Oribatida increased in the 5- to 21-year-old stands, with the highest levels being in the 10-year-old stands. The abundance of Collembola increased with stand development; however, the stand age had no significant impact on the abundance of epedapic, hemiedaphic, and euedaphic Collembola. Order richness (Hill number q = 0) curve confidence intervals overlapped among three stand ages. Shannon and Simpson diversity (Hill numbers q = 1 and q = 2) differed between 10- and 21-year-old stand age. They showed almost similar trends, and the highest and lowest values were recorded in the 21- and 10-year-old stand ages, respectively. Permutational multivariate analysis of variance demonstrated that composition also varied significantly with the sampling date and stand age, and the 10-year-old stands that were sampled in June stood well-separated from the others. Indicator analysis revealed that Scolopendromorpha and Prostigmata were indicators in June for the 10-year-old stands, while Collembola were indicators for the 21-year-old stands sampled in September. Our results highlight that both stand development and climate seasonality can significantly impact soil arthropod community dynamics in the reclaimed coastal saline soils of managed poplar plantations.

A Longitudinal Investigation of Dropout from College in the United States

2002 ◽  
Vol 4 (2) ◽  
pp. 173-201 ◽  
Author(s):  
Terry T. Ishitani ◽  
Stephen L. DesJardins
Keyword(s):  
United States ◽  
College Students ◽  
Financial Aid ◽  
The United States ◽  
Dropout Rates ◽  
First Year ◽  
Student Financial Aid ◽  
Student Dropout ◽  
Longitudinal Investigation ◽  
Over Time

This study investigates the dropout behavior of college students in the United States. Previous attrition studies have typically focused on dropout at specific points in time, such as the first year of enrollment. In this study we examine the timing of dropout over a five-year period and find that factors that affect student dropout often have effects that change over time. For instance, the results demonstrate that students who receive financial aid generally have lower dropout rates than non-aided students. But of special interest is our findings that dropout rates vary depending on the amount and timing of student financial aid.

Sign in / Sign up

Export Citation Format

Share Document