A comparison of seasonal patterns of photosynthate production and use in branches of red spruce saplings at two elevations

1991 ◽  
Vol 21 (4) ◽  
pp. 455-461 ◽  
Author(s):  
Christian P. Andersen ◽  
Samuel B. McLaughlin ◽  
W. Kelly Roy
Keyword(s):  
Carbon Assimilation ◽  
Growing Season ◽  
Red Spruce ◽  
Seasonal Patterns ◽  
Sink Strength ◽  
Great Smoky Mountains ◽  
Sink Activity ◽  
Lower Elevation ◽  
Branch Biomass ◽  
High Elevations

Seasonal patterns of carbon transport from 14C-labeled foliage were examined in red spruce (Picearubens Sarg.) branches at 1935 and 1720 m elevations in the Great Smoky Mountains National Park to characterize possible physiological mechanisms underlying the observed reductions in growth at high elevations. Current and 1-year-old foliage was labeled on 5- to 7-year-old branches of sapling-sized trees in June, August, and October. Retention of 14C was measured after 24 h, and allocation to other branch segments was characterized after 7 days. Total 14C-labeled carbon assimilation was greater in current than in 1-year-old foliage throughout the growing season. This suggests that photosynthetic capacity is high in developing foliage prior to needle maturity and remains high during the first growing season. In August, 14C retention in labeled foliage was less at the higher than at the lower elevation site, possibly reflecting increased respiratory losses that had been previously reported at the higher site. Retention of 14C in current-year shoots as a percent of 14C remaining after 7 days, a measure of sink strength, was high at both sites in June and remained high throughout the season in current-year shoots at the higher elevation site. The relatively high sink activity coupled with the large apportionment of biomass to current-year shoots (19.9 and 26.7% of total branch biomass at the lower and higher elevation sites, respectively) may make red spruce particularly susceptible to stresses such as winter injury that affect young foliage. In addition, the relatively greater sink activity of current-year shoots at the higher elevation site in August and October suggests that the contribution of current-year foliage to overall tree growth may be less at the higher than at the lower elevation site.

Red spruce seedling gas exchange in response to elevated CO2, water stress, and soil fertility treatments

1994 ◽  
Vol 24 (5) ◽  
pp. 954-959 ◽  
Author(s):  
L.J. Samuelson ◽  
J.R. Seiler
Keyword(s):  
Water Stress ◽  
Gas Exchange ◽  
Soil Fertility ◽  
Net Photosynthesis ◽  
Growing Season ◽  
Red Spruce ◽  
Fertility Treatment ◽  
Sink Strength ◽  
Growth Enhancement ◽  
Growing Seasons

The interactive influences of ambient (374 μL•L−1) or elevated (713 μL•L−1) CO2, low or high soil fertility, well-watered or water-stressed treatment, and rooting volume on gas exchange and growth were examined in red spruce (Picearubens Sarg.) grown from seed through two growing seasons. Leaf gas exchange throughout two growing seasons and growth after two growing seasons in response to elevated CO2 were independent of soil fertility and water-stress treatments, and rooting volume. During the first growing season, no reduction in leaf photosynthesis of seedlings grown in elevated CO2 compared with seedlings grown in ambient CO2 was observed when measured at the same CO2 concentration. During the second growing season, net photosynthesis was up to 21% lower for elevated CO2-grown seedlings than for ambient CO2-grown seedlings when measured at 358 μL•L−1. Thus, photosynthetic acclimation to growth in elevated CO2 occurred gradually and was not a function of root-sink strength or soil-fertility treatment. However, net photosynthesis of seedlings grown and measured at an elevated CO2 concentration was still over 2 times greater than the photosynthesis of seedlings grown and measured at an ambient CO2 concentration. Growth enhancement by CO2 was maintained, since seedlings grown in elevated CO2 were 40% larger in both size and weight after two growing seasons.

scholarly journals Ozone deposition into a boreal forest over a decade of observations: evaluating deposition partitioning and driving variables

2012 ◽  
Vol 12 (24) ◽  
pp. 12165-12182 ◽  
Author(s):  
Ü. Rannik ◽  
N. Altimir ◽  
I. Mammarella ◽  
J. Bäck ◽  
J. Rinne ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Water Vapour ◽  
Environmental Variables ◽  
Total Ozone ◽  
Explanatory Power ◽  
Growing Season ◽  
Sink Strength ◽  
Ozone Deposition ◽  
Air Space ◽  
Flux Measurements

Abstract. This study scrutinizes a decade-long series of ozone deposition measurements in a boreal forest in search for the signature and relevance of the different deposition processes. The canopy-level ozone flux measurements were analysed for deposition characteristics and partitioning into stomatal and non-stomatal fractions, with the main focus on growing season day-time data. Ten years of measurements enabled the analysis of ozone deposition variation at different time-scales, including daily to inter-annual variation as well as the dependence on environmental variables and concentration of biogenic volatile organic compounds (BVOC-s). Stomatal deposition was estimated by using multi-layer canopy dispersion and optimal stomatal control modelling from simultaneous carbon dioxide and water vapour flux measurements, non-stomatal was inferred as residual. Also, utilising the big-leaf assumption stomatal conductance was inferred from water vapour fluxes for dry canopy conditions. The total ozone deposition was highest during the peak growing season (4 mm s−1) and lowest during winter dormancy (1 mm s−1). During the course of the growing season the fraction of the non-stomatal deposition of ozone was determined to vary from 26 to 44% during day time, increasing from the start of the season until the end of the growing season. By using multi-variate analysis it was determined that day-time total ozone deposition was mainly driven by photosynthetic capacity of the canopy, vapour pressure deficit (VPD), photosynthetically active radiation and monoterpene concentration. The multi-variate linear model explained the high portion of ozone deposition variance on daily average level (R2 = 0.79). The explanatory power of the multi-variate model for ozone non-stomatal deposition was much lower (R2 = 0.38). The set of common environmental variables and terpene concentrations used in multivariate analysis were able to predict the observed average seasonal variation in total and non-stomatal deposition but failed to explain the inter-annual differences, suggesting that some still unknown mechanisms might be involved in determining the inter-annual variability. Model calculation was performed to evaluate the potential sink strength of the chemical reactions of ozone with sesquiterpenes in the canopy air space, which revealed that sesquiterpenes in typical amounts at the site were unlikely to cause significant ozone loss in canopy air space. The results clearly showed the importance of several non-stomatal removal mechanisms. Unknown chemical compounds or processes correlating with monoterpene concentrations, including potentially reactions at the surfaces, contribute to non-stomatal sink term.

scholarly journals From sink to source: long-term (2002-2019) trends and anomalies in net ecosystem exchange of CO2 from a Scottish temperate peatland.

2020 ◽  
Author(s):  
Karen Hei-Laan Yeung ◽  
Carole Helfter ◽  
Neil Mullinger ◽  
Mhairi Coyle ◽  
Eiko Nemitz
Keyword(s):  
Water Table ◽  
Ecosystem Respiration ◽  
Net Ecosystem Exchange ◽  
Growing Season ◽  
Water Table Depth ◽  
Sink Strength ◽  
Summer Drought ◽  
C Cycle ◽  
Dry Spell

<p>Peatlands North of 45˚ represent one of the largest terrestrial carbon (C) stores. They play an important role in the global C-cycle, and their ability to sequester carbon is controlled by multiple, often competing, factors including precipitation, temperature and phenology. Land-atmosphere exchange of carbon dioxide (CO<sub>2</sub>) is dynamic, and exhibits marked seasonal and inter-annual variations which can effect the overall carbon sink strength in both the short- and long-term.</p><p>Due to increased incidences of climate anomalies in recent years, long-term datasets are essential to disambiguate natural variability in Net Ecosystem Exchange (NEE) from shorter-term fluctuations. This is particularly important at high latitudes (>45˚N) where the majority of global peatlands are found. With increasing pressure from stressors such as climate and land-use change, it has been predicted that with a ca. 3<sup>o</sup>C global temperature rise by 2100, UK peatlands could become a net source of C.</p><p>NEE of CO<sub>2</sub> has been measured using the eddy-covariance (EC) method at Auchencorth Moss (55°47’32 N, 3°14’35 W, 267 m a.s.l.), a temperate, lowland, ombrotrophic peatland in central Scotland, continuously since 2002. Alongside EC data, we present a range of meteorological parameters measured at site including soil temperature, total solar and photosynthetically active radiation (PAR), rainfall, and, since April 2007, half-hourly water table depth readings. The length of record and range of measurements make this dataset an important resource as one of the longest term records of CO<sub>2</sub> fluxes from a temperate peatland.</p><p>Although seasonal cycles of gross primary productivity (GPP) were highly variable between years, the site was a consistent CO<sub>2</sub> sink for the period 2002-2012. However, net annual losses of CO<sub>2</sub> have been recorded on several occasions since 2013. Whilst NEE tends to be positively correlated with the length of growing season, anomalies in winter weather also explain some of the variability in CO<sub>2</sub> sink strength the following summer.</p><p>Additionally, water table depth (WTD) plays a crucial role, affecting both GPP and ecosystem respiration (R<sub>eco</sub>). Relatively dry summers in recent years have contributed to shifting the balance between R<sub>eco</sub> and GPP: prolonged periods of low WTD were typically accompanied by an increase in R<sub>eco</sub>, and a decrease in GPP, hence weakening the overall CO<sub>2</sub> sink strength. Extreme events such as drought periods and cold winter temperatures can have significant and complex effects on NEE, particularly when such meteorological anomalies co-occur. For example, a positive annual NEE occurred in 2003 when Europe experienced heatwave and summer drought. More recently, an unusually long spell of snow lasting until the end of March delayed the onset of the 2018 growing season by up to 1.5 months compared to previous years. This was followed by a prolonged dry spell in summer 2018, which weakened GPP, increased R<sub>eco</sub> and led to a net annual loss of 47.4 ton CO<sub>2</sub>-C km<sup>-2</sup>. It is clear that the role of Northern peatlands within the carbon cycle is being modified, driven by changes in climate at both local and global scales.</p>

scholarly journals Preliminary Study on Effect of Early Defoliation on Dry Matter Accumulation and Storage of Reserves on ‘Abbé Fétel’ Pear Trees

HortScience ◽  
2019 ◽  
Vol 54 (12) ◽  
pp. 2169-2177 ◽  
Author(s):  
Karen Mesa ◽  
Sara Serra ◽  
Andrea Masia ◽  
Federico Gagliardi ◽  
Daniele Bucci ◽  
...  
Keyword(s):  
Dry Matter ◽  
Management Practices ◽  
Soluble Sugar ◽  
Soluble Sugars ◽  
Growing Season ◽  
Soluble Carbohydrates ◽  
Soluble Carbohydrate ◽  
Sink Strength ◽  
Dry Matter Accumulation ◽  
Pear Trees

Annual accumulation of starch is affected by carbon reserves stored in the organs during the growing season and is controlled mainly by sink strength gradients within the tree. However, unfavorable environmental conditions (e.g., hail events) or application of management practices (e.g., defoliation to enhance overcolor in bicolor apple) could influence the allocation of storage carbohydrates. This preliminary research was conducted to determine the effects of early defoliation on the dry matter, starch, and soluble carbohydrate dynamics in woody organs, roots, and mixed buds classified by age and two levels of crop-load for one growing season in ‘Abbé Fétel’ pear trees (Oct. 2012 to mid-Jan. 2013 in the northern hemisphere). Regardless of the organs evaluated (woody organs, roots, and mixed buds), an increase of soluble carbohydrate concentration was observed in these organs in the period between after harvest (October) and January (dormancy period). Among all organs, woody short-old spurs showed the highest increase (+93.5%) in soluble sugars. With respect to starch, woody organs showed a clear trend of decreasing in concentration between October and January. In this case, short-old spurs showed the smallest decline in starch concentrations, only 6.5%, whereas in other tree organs starch decreased by 34.5%. After harvest (October), leaves showed substantially higher starch and soluble sugar concentrations in trees with lower crop-loads. These results confirm that in the period between October and January, dynamic interconversions between starch and soluble carbohydrates occur at varying magnitudes among organs in pear trees.

Developmental and seasonal patterns of mesophyll ultrastructure in Abies balsamea

1975 ◽  
Vol 53 (3) ◽  
pp. 295-304 ◽  
Author(s):  
Jean Fincher Chabot ◽  
Brian F. Chabot
Keyword(s):  
Cell Structure ◽  
Abies Balsamea ◽  
Growing Season ◽  
Synthetic Activity ◽  
Seasonal Patterns ◽  
Winter Dormancy ◽  
Chloroplast Structure ◽  
Starch Grains ◽  
Mesophyll Ultrastructure ◽  
Accumulation Of Lipids

Changes in mesophyll ultrastructure with development and season are described for Abies balsamea. Cells mature sequentially during expansion of the needles. Most cells appear to be fully mature and actively photosynthesizing at the time of budbreak. Tannins appear early and accumulate throughout the growing season. Winter dormancy is marked by an accumulation of lipids throughout the cell, an aggregation of organelles around the nucleus, some loss of chloroplast structure, and a failure of chloroplasts to form starch grains. Reorganization of cell structure and resumption of synthetic activity in the spring occurs about 2 months before budbreak.

Prevalence of individual-tree growth decline in red spruce populations of the southern Appalachian Mountains

1992 ◽  
Vol 22 (6) ◽  
pp. 905-914 ◽  
Author(s):  
David C. LeBlanc ◽  
N.S. Nicholas ◽  
S.M. Zedaker
Keyword(s):  
Tree Growth ◽  
Stand Density ◽  
Red Spruce ◽  
Slope Aspect ◽  
Individual Tree ◽  
Great Smoky Mountains ◽  
Individual Tree Growth ◽  
Growth Decline ◽  
Recreation Area ◽  
A Site

The prevalence of individual-tree growth decline was determined for red spruce (Picearubens Sarg.) populations at three locations in the southern Appalachians: Mount Rogers National Recreation Area, the Black Mountains, and Great Smoky Mountain National Park. An index of annual stemwood volume increment (AVI) was computed from dendrochronological data and a site-specific DBH–height regression equation. Individual-tree AVI time series were analyzed to identify changes in 20-year periodic mean AVI and AVI trend. The proportion of red spruce that exhibited decreasing mean AVI or negative AVI trend was determined for the most recent 20-year period, and this was compared with the estimated historical prevalence of these indications of growth decline. Also, the prevalence of growth decline was compared among subpopulations that differed with regard to various tree, stand, and site characteristics. Of 263 red spruce sampled, 25% exhibited a decrease in mean AVI during the period 1967–1986, 8% exhibited a negative AVI trend without a reduction in mean AVI, and 17% exhibited a reduction in the slope of the AVI curve. The proportion of trees that exhibited decreasing or slowed growth after 1967 was substantially greater among trees growing at 1980 m than in populations at lower elevations; no relationship was found between elevation and growth decline below 1980 m. No difference was found in prevalence of growth decline between subpopulations that differed with regard to age, DBH, competitive status, stand density, slope aspect, or site exposure. The prevalence of individual-tree growth decline for the most recent 20-year period did not exceed estimated levels for historical periods of decline in the Great Smoky Mountains population.

scholarly journals Ozone deposition into a boreal forest over a decade of observations: evaluating deposition partitioning and driving variables

2012 ◽  
Vol 12 (5) ◽  
pp. 12715-12758
Author(s):  
Ü. Rannik ◽  
N. Altimir ◽  
I. Mammarella ◽  
J. Bäck ◽  
J. Rinne ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Water Vapour ◽  
Chemical Reactions ◽  
Total Ozone ◽  
Explanatory Power ◽  
Growing Season ◽  
Sink Strength ◽  
Ozone Deposition ◽  
Air Space ◽  
Flux Measurements

Abstract. This study scrutinizes a decade-long series of ozone deposition measurements in a boreal forest in search for the signature and relevance of the different deposition processes. Canopy-level ozone flux measurements were analysed for deposition characteristics and partitioning into stomatal and non-stomatal fractions, focusing on growing season day-time data. Ten years of measurements enabled the analysis of ozone deposition variation at different time- scales, including daily to inter-annual variation as well as the dependence on environmental variables and concentration of biogenic volatile organic compounds (BVOC-s). Stomatal deposition was estimated by using multi-layer canopy dispersion and optimal stomatal control modelling from simultaneous carbon dioxide and water vapour flux measurements, non-stomatal was inferred as residual. Also, utilising big-leaf assumption stomatal conductance was inferred from water vapour fluxes for dry canopy conditions. The total ozone deposition was highest during the peak growing season (4 mm s−1) and lowest during winter dormancy (1 mm s−1). During the course of the growing season the fraction of the non-stomatal deposition of ozone was determined to vary from 26 to 44% during day time, increasing from the start of the season until the end of the growing season. By using multi-variate analysis it was determined that day-time total ozone deposition was mainly driven by photosynthetic capacity of the canopy, vapour pressure deficit (VPD), photosynthetically active radiation and monoterpene concentration. The multi-variate linear model explained high portion of ozone deposition variance on daily average level (R2 = 0.79). The explanatory power of the multi-variate model for ozone non-stomatal deposition was much lower (R2 = 0.38). Model calculation was performed to evaluate the potential sink strength of the chemical reactions of ozone with sesquiterpenes in the canopy air space, which revealed that sesquiterpenes in typical amounts at the site were unlikely to cause significant ozone loss in canopy air space. This was also confirmed by the statistical analysis that did not link measured sesquiterpene concentration with ozone deposition. It was concluded that chemical reactions with monoterpenes, or other removal mechanisms such as surface reactions, play a role as ozone non-stomatal sink inside canopy.

scholarly journals Translocation and Recovery Efforts for the Telkwa Caribou, Rangifer tarandus caribou, Herd in Westcentral British Columbia, 1997-2005

2007 ◽  
Vol 121 (2) ◽  
pp. 155 ◽  
Author(s):  
Astrid Vik Stronen ◽  
Paul Paquet ◽  
Stephen Herrero ◽  
Seán Sharpe ◽  
Nigel Waters
Keyword(s):  
British Columbia ◽  
Habitat Use ◽  
Rangifer Tarandus ◽  
Initial Study ◽  
High Elevation ◽  
Rangifer Tarandus Caribou ◽  
Habitat Features ◽  
Lower Elevation ◽  
Significant Difference ◽  
High Elevations

During 1997–1999, 32 Woodland Caribou (Rangifer tarandus caribou) were translocated from the Sustut Herd to the Telkwa Mountains in westcentral British Columbia to augment recovery of the Telkwa Caribou Herd. The animals were fitted with radiocollars and located during 1997–2000 to determine selection of habitat features and terrain variables. Six Caribou calves were also collared to determine causes and timing of calf mortality during summer 1999. Defining available habitat for newly translocated animals is often arbitrary and subjective, and we based the analyses on ranks for habitat use and availability as this is less sensitive to the inclusion or exclusion of a questionable resource. This method represents some loss of information but provides indications of the relative importance of various habitat types without classifying any as avoided. High elevation habitat (> 1700 masl) on moderate slopes (16 – 45°) received the highest ranks, as did “warm” (136 – 315°) aspects and forests > 250 years old. Three calves died shortly after birth. One calf appeared to have been killed by predation, likely by a Golden Eagle (Aquila chrysaetos), and one calf was abandoned by the cow. Cause of death for the third calf is unknown. To assess habitat use associated with calving we compared summer locations with data obtained throughout the rest of 1999 for eight cows with calves and eight without calves. We found significant difference in use of elevation during calving time, when cows with calves remained at high elevations and barren cows generally descended to lower elevation habitat. Surveys conducted in 2005, five years after the completion of the initial study, produced a count of approximately 90 Caribou. This suggests that in the short term, the translocation was successful in re-establishing a self-sustaining Caribou population in the Telkwa Mountains.

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