STRUCTURAL CHANGES IN PRIMARY LENTICELS OF NORWAY SPRUCE OVER THE SEASONS

IAWA Journal ◽  
2003 ◽  
Vol 24 (2) ◽  
pp. 105-116 ◽  
Author(s):  
Sabine Rosner ◽  
Birgit Kartusch
Keyword(s):  
Norway Spruce ◽  
Structural Changes ◽  
Phase 1 ◽  
Late Summer ◽  
Early Summer ◽  
Climatic Conditions ◽  
Wall Thickening ◽  
Intercellular Spaces ◽  
Phase 3

Seasonal production of lenticel tissues was compared between Norway spruce trees (Picea abies (L.) Karst.) from a mountain site (1200 m), where they are autochthonous, and seven allochthonous lowland sites (250–600 m).The periodic changes of lenticel structure were grouped into four stages, based on the degree of their opening: phase 1 - winter dormancy; phase 2 - beginning of meristem activity in spring; phase 3 - production of non-suberised filling tissue in early summer, which causes the disruption of the closing layer formed in the previous growing season; and phase 4 - differentiation of a new closing layer in late summer. Structural changes in lenticels of P. abies may be interpreted as a long-term reaction to climatic conditions, balancing transpiration and respiration. During the most active period of wood production, lenticels were found in their most permeable phase, phase 3. The production of a new closing layer takes place when summer temperatures reach maximum values, and when demand for effective regulation of transpiration is high. During phase 4 transpiration is successfully controlled because differentiating cells of the new closing layer are already suberised, although not in their final rounded shape, and therefore have small intercellular spaces. High annual variability in stratification of lenticel tissues, such as the proportion between closing layer and filling tissue, wall thickening and size of intercellular spaces, also indicates possible long-term regulation mechanisms for transpiration.

scholarly journals Control of Black Oak and Tanoak in the Sierra Cascade Range

2004 ◽  
Vol 19 (4) ◽  
pp. 268-276 ◽  
Author(s):  
Joseph M. DiTomaso ◽  
Guy B. Kyser ◽  
Edward A. Fredrickson
Keyword(s):  
Late Summer ◽  
Early Summer ◽  
Cascade Range ◽  
Oak Trees ◽  
Lithocarpus Densiflorus ◽  
Stem Injection ◽  
Versatile Tool ◽  
Excellent Control ◽  
Black Oak

Abstract Broadcast, directed, and stem injection herbicide techniques were applied to 3- to 8-year-old black oak (Quercus kelloggii) and 3-year-old tanoak (Lithocarpus densiflorus) clumps (directed applications only). Broadcast applications of imazapyr at all rates to black oak and directed applications of imazapyr to tanoak performed better with the addition of an adjuvant compared to treatments without the adjuvant. However, even with an adjuvant, broadcast treatments of imazapyr at or below 560 g acid equivalent (ae/ha) only suppressed black oak growth and did not provide long-term control. Directed applications of imazapyr gave excellent control of both black oak (0.43–2.17% ae plus Sylgard) and tanoak (0.14–1.13% ae plus Hasten) clumps. Imazapyr was more effective than basal bark treatments with triclopyr (8.9% ae), and tank-mixing imazapyr with glyphosate did not improve the level of control. Stem injection treatment of black oak trees or clumps with imazapyr was very effective with nearly all rates and hack intervals, but late summer or fall applications gave greater suppression of basal re-sprouts compared to spring and early summer treatments. These results demonstrate that imazapyr is a very effective and versatile tool for the control of black oak and tanoak clumps and black oak trees. West. J. Appl. For. 19(4):268–276.

scholarly journals Seasonal measurements of total OH reactivity fluxes, total ozone loss rates and missing emissions from Norway spruce in 2011

2012 ◽  
Vol 9 (10) ◽  
pp. 13497-13536
Author(s):  
A.C. Nölscher ◽  
E. Bourtsoukidis ◽  
B. Bonn ◽  
J. Kesselmeier ◽  
J. Lelieveld ◽  
...  
Keyword(s):  
Heat Stress ◽  
Norway Spruce ◽  
Total Ozone ◽  
Late Summer ◽  
Early Summer ◽  
Unknown Primary ◽  
Oh Radicals ◽  
Strong Wind ◽  
Emission Rates ◽  
Loss Rates

Abstract. Numerous reactive volatile organic compounds (VOCs) are emitted into the atmosphere by vegetation. Most biogenic VOCs are highly reactive towards the atmosphere's most important oxidant, the hydroxyl (OH) radical. One way to investigate the chemical interplay between biosphere and atmosphere is through the measurement of total OH reactivity, the total loss rate of OH radicals. This study presents the first determination of total OH reactivity emission rates (measurements via the Comparative Reactivity Method) based on a branch cuvette enclosure system mounted on a Norway spruce (Picea abies) throughout spring, summer and autumn 2011. In parallel separate VOC emission rates were monitored by a Proton Transfer Reaction-Mass Spectrometer (PTR-MS), and total ozone (O3) loss rates were obtained inside the cuvette. Total OH reactivity emission rates were in general temperature and light dependent, showing strong diel cycles with highest values during daytime. Monoterpene emissions contributed most, accounting for 56–69% of the measured total OH reactivity flux in spring and early summer. However, during late summer and autumn the monoterpene contribution decreased to 11–16%. At this time, a large missing fraction of the total OH reactivity emission rate (70–84%) was found when compared to the VOC budget measured by PTR-MS. Total OH reactivity and missing total OH reactivity emission rates reached maximum values in late summer corresponding to the period of highest temperature. Total O3 loss rates within the closed cuvette showed similar diel profiles and comparable seasonality to the total OH reactivity fluxes. Total OH reactivity fluxes were also compared to emissions from needle storage pools predicted by a temperature-only dependent algorithm. Deviations of total OH reactivity fluxes from the temperature-only dependent emission algorithm were observed for occasions of mechanical and heat stress. While for mechanical stress, induced by strong wind, measured VOCs could explain total OH reactivity emissions, during heat stress they could not. The temperature driven algorithm matched the diel course much better in spring than in summer, indicating a different production and emission scheme for summer and early autumn. During these times, unmeasured and possibly unknown primary biogenic emissions contributed significantly to the observed total OH reactivity flux.

scholarly journals Seasonal measurements of total OH reactivity emission rates from Norway spruce in 2011

2013 ◽  
Vol 10 (6) ◽  
pp. 4241-4257 ◽  
Author(s):  
A.C. Nölscher ◽  
E. Bourtsoukidis ◽  
B. Bonn ◽  
J. Kesselmeier ◽  
J. Lelieveld ◽  
...  
Keyword(s):  
Heat Stress ◽  
Norway Spruce ◽  
Late Summer ◽  
Early Summer ◽  
Unknown Primary ◽  
Oh Radicals ◽  
Diel Variation ◽  
Strong Wind ◽  
Emission Rates ◽  
Loss Rates

Abstract. Numerous reactive volatile organic compounds (VOCs) are emitted into the atmosphere by vegetation. Most biogenic VOCs are highly reactive towards the atmosphere's most important oxidant, the hydroxyl (OH) radical. One way to investigate the chemical interplay between biosphere and atmosphere is through the measurement of total OH reactivity, the total loss rate of OH radicals. This study presents the first determination of total OH reactivity emission rates (measurements via the comparative reactivity method) based on a branch cuvette enclosure system mounted on a Norway spruce (Picea abies) throughout spring, summer and autumn 2011. In parallel VOC emission rates were monitored by a second proton-transfer-reaction mass spectrometer (PTR-MS), and total ozone (O3) loss rates were obtained inside the cuvette. Total OH reactivity emission rates were in general temperature and light dependent, showing strong diel cycles with highest values during daytime. Monoterpene emissions contributed most, accounting for 56–69% of the measured total OH reactivity flux in spring and early summer. However, during late summer and autumn the monoterpene contribution decreased to 11–16%. At this time, a large missing fraction of the total OH reactivity emission rate (70–84%) was found when compared to the VOC budget measured by PTR-MS. Total OH reactivity and missing total OH reactivity emission rates reached maximum values in late summer corresponding to the period of highest temperature. Total O3 loss rates within the closed cuvette showed similar diel profiles and comparable seasonality to the total OH reactivity fluxes. Total OH reactivity fluxes were also compared to emissions from needle storage pools predicted by a temperature-only-dependent algorithm. Deviations of total OH reactivity fluxes from the temperature-only-dependent emission algorithm were observed for occasions of mechanical and heat stress. While for mechanical stress, induced by strong wind, measured VOCs could explain total OH reactivity emissions, during heat stress they could not. The temperature-driven algorithm matched the diel variation of total OH reactivity emission rates much better in spring than in summer, indicating a different production and emission scheme for summer and early autumn. During these times, unmeasured and possibly unknown primary biogenic emissions contributed significantly to the observed total OH reactivity flux.

scholarly journals Active Learning Strategies and Competency-Based Design in Research Education: a Longitudinal Review

2019 ◽  
Vol 19 (4) ◽  
Author(s):  
Noela A. Haughton
Keyword(s):  
Learning Strategies ◽  
Phase 1 ◽  
Methods Course ◽  
Phase 3 ◽  
Research Education ◽  
Graduate Research ◽  
Active Learning Strategies ◽  
Competency Based ◽  
Multiple Levels

This paper describes the long-term re-development of an introductory graduate research methods course. The initial design is presented, followed by the two re-design phases. Phase 2 introduced additional inquiry-based strategies such as concept mapping and multiple levels of peer collaboration. Phase 3 incorporated competency-based techniques as well as additional technical, social, and instructional support. Assessment results, student feedback, moderate to strong relationships between scores on key assessments, and design principles support the assertion that the Phase 3 course is an improvement over the Phase 1 version. Limitations and further research are presented.

Safety of TG-C: 12 years of follow-up safety data from phase 1, phase 2, ongoing phase 3, and long term safety trials

2021 ◽  
Vol 29 ◽  
pp. S253-S254
Author(s):  
D. Hunter ◽  
A. Mobasheri ◽  
S. Mareya ◽  
M. Wang ◽  
H. Choi ◽  
...  
Keyword(s):  
Phase 1 ◽  
Safety Data ◽  
Phase 2 ◽  
Phase 3 ◽  
Ongoing Phase

scholarly journals Climate Effect on Ponderosa Pine Radial Growth Varies with Tree Density and Shrub Removal

Forests ◽  
2019 ◽  
Vol 10 (6) ◽  
pp. 477 ◽  
Author(s):  
Kaelyn Finley ◽  
Jianwei Zhang
Keyword(s):  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
Radial Growth ◽  
Explanatory Power ◽  
Early Summer ◽  
Climatic Conditions ◽  
Mountain Range ◽  
Climate Effect ◽  
Moisture Availability

With increasing temperatures and projected changes in moisture availability for the Mediterranean climate of northern California, empirical evidence of the long-term responses of forests to climate are important for managing these ecosystems. We can assess forest treatment strategies to improve climate resilience by examining past responses to climate for both managed and unmanaged plantations. Using an experimental, long-term density and shrub removal study of ponderosa pine (Pinus ponderosa Lawson & C. Lawson) on a poor-quality site with low water-holding capacity and high runoff of the North Coastal mountain range in California, we examined the relationships between radial growth and climate for these trees over a common interval of 1977–2011. Resistance indices, defined here as the ratio between current year radial growth and the performance of the four previous years, were correlated to climatic variables during the same years. We found that all treatments’ radial growth benefited from seasonal spring moisture availability during the current growing year. Conversely, high spring and early summer temperatures had detrimental effects on growth. High-density treatments with manzanita understories were sensitive to summer droughts while lower densities and treatments with full shrub removal were not. The explanatory power of the climate regression models was generally more consistent for the same shrub treatments across the four different densities. The resistance indices for the lower density and complete shrub removal treatment groups were less dependent on previous years’ climatic conditions. We conclude that, for ponderosa pine plantations with significant manzanita encroachment, understory removal and heavy thinning treatments increase subsequent growth for remaining trees and decrease sensitivity to climate.

scholarly journals Paleoenvironmental shifts spanning the last ~6000 years and recent anthropogenic controls inferred from a high-altitude temperate lake: Anchar Lake, NW Himalaya

The Holocene ◽  
2019 ◽  
Vol 30 (1) ◽  
pp. 23-36 ◽  
Author(s):  
Aasif Mohmad Lone ◽  
Hema Achyuthan ◽  
Rayees Ahmad Shah ◽  
Satish Jadgeo Sangode ◽  
Pankaj Kumar ◽  
...  
Keyword(s):  
High Altitude ◽  
Anthropogenic Activities ◽  
Phase 1 ◽  
Early Summer ◽  
Climatic Conditions ◽  
Lake Basin ◽  
Phase 2 ◽  
Nw Himalaya ◽  
Magnetic Parameters ◽  
Mineral Magnetic

Integrating multiproxy results (geochemistry, mineral magnetism, grain size, and C/N ratio variability supported by 14C AMS dating), obtained from a 1.4-m sediment core retrieved from high-altitude Anchar Lake, Kashmir Valley, NW Himalaya, we present a 6000-years record of paleoenvironmental and paleolimnological shifts. Phase 1 (6000–4700 cal. yr BP) revealed a wetter climate with a significant terrestrial input corresponding to the gradual strengthening of the westerlies. Phase 2 (4700–3900 cal. yr BP) reflects an overall improved westerly precipitation and autochthonous sources of organic matter (OM). Magnetic parameters also indicate higher lake levels and reducing conditions during this phase. Phase 2 was followed by a gradual diminishing pattern of the westerlies as also represented by phase 3 (3900–2500 cal. yr BP) and phase 4 (2500–1600 cal. yr BP) indicating moderate precipitation conditions, catchment stability, and temperate and/or cold-dry climatic conditions. Phase 5 (1600–500 cal. yr BP) revealed the prevalence of moderately cold/dry and further subdued westerly precipitation. Phase 6 (500 cal. yr BP to present) is represented by reduced westerly precipitation, shrinking lake margins, and significant terrestrial/anthropogenic controls over the lake basin. Mineral magnetic parameters indicate reducing lake bottom water conditions and eutrophication during this phase due to anthropogenic activities. These paleoenvironmental shifts reveal near synchronous changes (within dating uncertainties) with other regional paleoclimate records close to the present Anchar Lake location and reflect the gradual late-Holocene diminishment of the amount of winter/early summer moisture provided by the mid-latitude westerlies.

Long-Term Memory of Pigeons for Stimulus-Outcome Associations Involving Multiple Stimuli, each Seen in a Single Brief Trial

1992 ◽  
Vol 45 (2b) ◽  
pp. 81-98 ◽  
Author(s):  
Euan M. Macphail ◽  
Steve Reilly ◽  
Mark Good
Keyword(s):  
Recognition Memory ◽  
Phase 1 ◽  
Cycle Phase ◽  
Long Term Memory ◽  
Phase 2 ◽  
Phase 3 ◽  
Term Memory ◽  
The One ◽  
High Level

Experiment 1 explored performance of pigeons in two versions of a shortterm recognition memory procedure. In one version responding to entirely novel slides was rewarded, and responding to familiar slides (slides seen once, for 10 sec) was not rewarded; in the other version, responding to familiar slides was rewarded. Performance was initially below chance in both versions of the procedure. This result indicated that in this procedure associations were formed between the slides and the outcome (reward or non-reward) that followed their presentation. The result also suggested that the true capacity of pigeon recognition memory cannot be assessed using these procedures, as performance is inevitably disrupted by the bird's associative memory. The tendency of pigeons to form one-trial associations was exploited in Experiment 2. Phase 1 consisted of 16 two-session cycles: in Session 1 of each cycle, birds were shown 20 novel slides and were rewarded for responding to 10 of those slides; in Session 2, the same slides were shown again, with the same reinforcement contingencies. The birds showed significant overnight retention of the one-trial associations formed in Session 1 of each cycle. Phase 2 showed significant retention over periods of more than 20 days of associations involving 320 slides seen twice only. Phase 3 re-exposed for nine daily sessions one of the sets of 20 slides used in Phases 1 and 2; a high level of discrimination emerged rapidly and 4 (of 8) birds showed, by the end of training, no overlap in response rates to positive and negative slides. Comparative implications of the results are discussed.

Phenology, Population Dynamics, and Flowering Dynamics of Case's Ladies'-tresses, Spiranthes casei var. casei (Orchidaceae), in Ottawa, Ontario

2009 ◽  
Vol 123 (1) ◽  
pp. 19 ◽  
Author(s):  
Joyce M. Reddoch ◽  
Allan H. Reddoch
Keyword(s):  
Population Dynamics ◽  
Life History ◽  
Seed Production ◽  
Late Summer ◽  
Early Summer ◽  
Population Trends ◽  
Life History Stages ◽  
Deer Herbivory ◽  
Cloudy Weather

We describe a seven-year study (2002–2008) of a population of Case’s Ladies’-tresses (Spiranthes casei var. casei) in the western Greenbelt in Ottawa, Ontario, that had been extant since at least 1972. We also record a temporary colonization in the eastern Greenbelt for 11 years (1998–2008). The seven life history stages identified were seed, juvenile, immature, flowering, vegetative, offshoot (ramet), and non-emergent. Mature plants present in the first two years of the study had mean half lives of 9.4 years. Flowering and seed production were limited by damp, cloudy weather when fall rosettes develop, by gastropod herbivory in early summer, by drought in mid-summer, and by deer herbivory in late summer. Given the resulting wide fluctuations in the fractions of plants flowering, as well as the lack of visibility of vegetative plants, this study demonstrates the limitations of annual censuses of flowering stems for determining the actual sizes of populations and for detecting long-term population trends.

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