Blocking phloem transport triggers bimodal radial growth in Pinus sylvestris at a xeric site

A bimodal radial grow pattern, i.e. growth peaks in spring and autumn, was repeatedly found in trees in Mediterranean regions, where summer drought causes reduction or cessation of cambial activity. In a dry inner Alpine valley of the Eastern Alps (Tyrol, Austria, c. 750 m asl), which is characterized by drought periods at the start of the growing season in spring and more favorable conditions during summer, Pinus sylvestris shows an unimodal growth pattern with onset and cessation of cambial activity in early April and late June, respectively. Although xylem cell differentiation (cell wall thickening) may last until end of August, a resumption of cambial activity after intense summer rainfall was not observed in this region. In a field experiment we therefore tested the hypothesis that early cessation of cambial activity under drought is an adaptation to limited water availability during the growing season (April through June), leading to an early and irreversible switch of carbon (C) allocation to belowground. To accomplish this, the C status of c. 20 year old Pinus sylvestris saplings (mean stem height 1.5 m) was manipulated at a xeric site by physical blockage of phloem transport (girdling) in mid-July (doy 199), i.e. c. four weeks after cessation of cambial cell division. The influence of manipulated C availability on radial growth was continuously recorded by stem dendrometers, which were mounted 5 cm above girdling. In response to blockage of phloem flow, resumption of radial growth was detected above the girdling zone after about 2 weeks, i.e., bimodal growth could be triggered above girdling by increasing C availability. Although the experimentally induced second growth surge lasted for the same period as in spring (i.e., c. 2 months), the increment was more than twice as large. Below girdling radial growth was not affected (i.e., no reactivation of cambial activity occurred), but cell wall thickness of last latewood cells was significantly reduced indicating lack of C after girdling. Intense radial growth resumption in Pinus sylvestris saplings after girdling indicates that cessation of stem cambial activity can be reversed by manipulating the C status of the stem suggesting a high belowground C demand on the drought-prone, nutrient deficient site. This work highlights the need of in-depth experimental studies in order to understand the impact of endogenous and exogenous factors on cambial activity more clearly.The research was funded by the Austrian Science Fund (FWF; project number P25643-B16).

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Triggering Bimodal Radial Stem Growth in Pinus sylvestris at a Drought-Prone Site by Manipulating Stem Carbon Availability

Frontiers in Plant Science ◽

10.3389/fpls.2021.674438 ◽

2021 ◽

Vol 12 ◽

Author(s):

Walter Oberhuber ◽

Anton Landlinger-Weilbold ◽

Dennis Marko Schröter

Keyword(s):

Cell Differentiation ◽

Pinus Sylvestris ◽

Experimental Studies ◽

Strong Support ◽

Summer Rainfall ◽

Phloem Transport ◽

Cambial Activity ◽

Daily Maximum ◽

Summer Drought ◽

Alpine Valley

A bimodal radial growth (RG) pattern, i.e., growth peaks in spring and autumn, was repeatedly found in trees in the Mediterranean regions, where summer drought causes reduction or cessation of cambial activity. In a dry inner Alpine valley of the Eastern Alps (Tyrol, Austria, 750 m asl), Pinus sylvestris shows unimodal RG with onset and cessation of cambial activity in early April and late June, respectively. A resumption of cambial activity after intense summer rainfall was not observed in this region. In a field experiment, we tested the hypothesis that early cessation of cambial activity at this drought-prone site is an adaptation to limited water availability leading to an early and irreversible switch of carbon (C) allocation to belowground. To accomplish this, the C status of young P. sylvestris trees was manipulated by physical blockage of phloem transport (girdling) 6 weeks after cessation of cambial cell division. Influence of manipulated C availability on RG was recorded by stem dendrometers, which were mounted above the girdling zone. In response to blockage of phloem flow, resumption of cambial activity was detected above girdling after about 2 weeks. Although the experimentally induced second growth surge lasted for the same period as in spring (c. 2 months), the increment was more than twice as large due to doubling of daily maximum RG rate. After girdling, wood anatomical traits above girdling no longer showed any significant differences between earlywood and latewood tracheids indicating pronounced effects of C availability on cell differentiation. Below girdling, no reactivation of cambial activity occurred, but cell wall thickness of last formed latewood cell was reduced due to lack of C supply after girdling. Intense RG resumption after girdling indicates that cessation of cambial activity can be reversed by manipulating C status of the stem. Hence, our girdling study yielded strong support for the hypothesis that belowground organs exert high C sink strengths on the drought-prone study site. Furthermore, this work highlights the need of in-depth experimental studies in order to understand the interactions between endogenous and exogenous factors on cambial activity and xylem cell differentiation more clearly.

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Temporal dynamics of nonstructural carbohydrates and xylem growth in Pinus sylvestris exposed to drought

Canadian Journal of Forest Research ◽

10.1139/x11-084 ◽

2011 ◽

Vol 41 (8) ◽

pp. 1590-1597 ◽

Cited By ~ 39

Author(s):

Walter Oberhuber ◽

Irene Swidrak ◽

Daniela Pirkebner ◽

Andreas Gruber

Keyword(s):

Pinus Sylvestris ◽

Temporal Dynamics ◽

Growing Season ◽

Cambial Activity ◽

Wood Formation ◽

Nonstructural Carbohydrates ◽

Late Wood ◽

Structural Growth ◽

Xylem Growth ◽

Soil Dryness

Wood formation requires a continuous supply of carbohydrates for structural growth and metabolism. In the montane belt of the central Austrian Alps, we monitored the temporal dynamics of xylem growth and nonstructural carbohydrates (NSC) in stem sapwood of Scots pine ( Pinus sylvestris L.) during the growing season of 2009, which was characterized by exceptional soil dryness within the study area. Soil water content dropped below 10% at the time of maximum xylem growth at the end of May. Histological analyses have been used to describe cambial activity and xylem growth. Determination of NSC was performed using specific enzymatic assays revealing that total NSC ranged from 0.8% to 1.7% dry matter throughout the year. Significant variations (P < 0.05) of the size of the NSC pool were observed during the growing season. Starch showed persistent abundance throughout the year, reaching a maximum shortly before onset of late wood formation in mid-July. Seasonal dynamics of NSC and xylem growth suggest that (i) high sink activity occurred at the start of the growing season in spring and during late wood formation in summer and (ii) there was no particular shortage in NSC, which caused P. sylvestris to draw upon stem reserves more heavily during the drought in 2009.

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Effect of girdling on cambial activity in white pine

Canadian Journal of Botany ◽

10.1139/b68-024 ◽

1968 ◽

Vol 46 (2) ◽

pp. 141-146 ◽

Cited By ~ 16

Author(s):

Brayton F. Wilson

Keyword(s):

Mitotic Activity ◽

Transport System ◽

Phloem Transport ◽

Cambial Activity ◽

Cell Number ◽

Wall Thickening ◽

White Pine ◽

Cell Dimensions ◽

Cambial Zone ◽

Number Of Cells

There are no changes in cell dimensions more than 10 cm above a girdle in white pine (Pinus strobus L.), but up to 10 cm above, cell radial diameters are less, and at 2 cm cell walls may be thicker. There is an increase in number of cells produced from 2 to 310 cm above girdles, apparently because of a higher mitotic index and longer season for mitotic activity. The radial number of cells in the cambial zone does not change. From 2 to 310 cm below girdles mitotic activity and radial enlargement soon stop, cell wall thickening continues slowly, and there is no change in radial cell number in the cambial zone. These effects above and below girdles appear to be independent of time of girdling. They may be explained by the effect of girdling in blocking both the polarized auxin transport system and the non-polarized phloem transport system.

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Influence of meteorological factors on the formation of radial growth of trees in coniferous stands of the Leningrad region

Известия СПбЛТА ◽

10.21266/2079-4304.2020.232.33-49 ◽

2020 ◽

Author(s):

А.В. Чудаков ◽

Д.А. Данилов ◽

Д.А. Зайцев

Keyword(s):

Picea Abies ◽

Pinus Sylvestris ◽

Climatic Factors ◽

Rank Correlation ◽

Growing Season ◽

Growth Conditions ◽

Monthly Precipitation ◽

Leningrad Region ◽

Spruce Wood ◽

The Impact

Проведено исследование влияния климатических факторов на показатели прироста древостоев сосны (Pinus sylvestris) и ели (Picea abies) естественного происхождения, не затронутых рубками. Объекты исследования – древостои с разной долей участия этих пород в однородных условиях произрастания на почвах с двучленными отложениями. Длительность анализируемого периода составила 54 года, на текущий момент древостои являются спелыми. Была изучена связь прироста со средней температурой воздуха за вегетационный период и суммой осадков за вегетационный период. Анализ связей климата с параметрами древесины хвойных проводили на основе поиска статистически значимых ранговых коэффициентов корреляции между древесно-кольцевыми хронологиями и климатическими факторами в насаждениях с разной долей участия сосны и ели. Вычислялся коэффициент ранговой корреляции Спирмена как количественная оценка связи между исследуемыми явлениями. Ранговый корреляционный анализ позволил на статистически значимом уровне оценить вклад средних температур и суммы осадков по месяцам в формирование макроструктурных элементов древесины сосны и ели. Прослеживается большая метеозависимость элементов годичного прироста древесины ели, чем сосны, в данных условиях. Для соснового элемента смешанных хвойных древостоев наибольшая взаимосвязь с температурными показателями наблюдается в июле–сентябре, тогда как для ели выявлена ярко выраженная зависимость с этим фактором в мае для всех древостоев с ее участием. Проведенное исследование показало, что в зависимости от доли участия ели и сосны образование структурных элементов ксилемы годичного прироста имеет разную степень по силе вязи со средними температурами и суммой осадков по месяцам вегетационного периода. A study was carried out on the impact of climatic factors on the increment rates of pine (Pinus sylvestris L.) and spruce (Picea abies (L.) Karst.) stands of natural origin, not affected by forestry impact. Tree stands with different participation of these species in similar growth conditions on binary deposits soils were reviewed. The duration of the analyzed period was 54 years, at the present time stands are mature. The connection between the growth and average air temperature during the growing season and the amount of precipitation during the growing season was studied. The analysis of climate relationships with coniferous wood parameters was carried out on the basis of searching statistically significant rank coefficients of correlation between wood-ring chronologies and climate factors in stands with different participation shares of pine and spruce. Spearman's rank correlation coefficient was calculated as a quantitative evaluation of the connection between the observed effects. Rank correlation analysis allowed to estimate at statistically significant level the contribution of average temperatures and the sum of monthly precipitation on the formation of macrostructural elements of pine and spruce wood. There is a higher meteorological dependence on the increment rate of spruce wood than pine wood in the given conditions. For the pine element of mixed coniferous trees the greatest correlation of increment with temperature indices is observed in July-September months, while for the spruce a marked dependence with this factor was revealed in May month for all stands with spruce participation. The study showed that depending on the share of conifers, the formation of structural elements of the xylem has a different strength of the relationship with average temperatures and the amount of precipitation in the months of the growing season.

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Underestimated effects of low temperature during early growing season on carbon sequestration of a subtropical coniferous plantation

Biogeosciences ◽

10.5194/bg-8-1667-2011 ◽

2011 ◽

Vol 8 (6) ◽

pp. 1667-1678 ◽

Cited By ~ 29

Author(s):

W.-J. Zhang ◽

H.-M. Wang ◽

F.-T. Yang ◽

Y.-H. Yi ◽

X.-F. Wen ◽

...

Keyword(s):

Carbon Sequestration ◽

Air Temperature ◽

Growing Season ◽

Carbon Uptake ◽

Summer Drought ◽

Eddy Flux ◽

Season Length ◽

Growing Season Length ◽

Coniferous Plantation ◽

The Impact

Abstract. The impact of air temperature in early growing season on the carbon sequestration of a subtropical coniferous plantation was discussed through analyzing the eddy flux observations at Qianyanzhou (QYZ) site in southern China from 2003 to 2008. This site experienced two cold early growing seasons (with temperature anomalies of 2–5 °C) in 2005 and 2008, and a severe summer drought in 2003. Results indicated that the low air temperature from January to March was the major factor controlling the inter-annual variations in net carbon uptake at this site, rather than the previously thought summer drought. The accumulative air temperature from January to February showed high correlation (R2=0.970, p<0.001) with the annual net ecosystem production (NEP). This was due to the controls of early-month temperature on the plant phenology developing and the growing season length at this subtropical site. The cold spring greatly shortened the growing season length and therefore reduced the carbon uptake period. The eddy flux observations showed a carbon loss of 4.04 g C m−2 per growing-season day at this coniferous forest site. On the other hand, the summer drought also reduced the net carbon uptake strength because the photosynthesis was more sensitive to water deficit stress than the ecosystem respiration. However, the impact of summer drought occurred within a relatively shorter period and the carbon sequestration went back to the normal level once the drought was relieved.

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Intra-annual dynamics of cambial and xylem phenology in subalpine conifers at Deogyusan National Park in the Republic of Korea

Journal of Wood Science ◽

10.1186/s10086-021-01950-2 ◽

2021 ◽

Vol 67 (1) ◽

Author(s):

Jun-Hui Park ◽

En-Bi Choi ◽

Hong-Chul Park ◽

Na-Yeon Lee ◽

Jeong-Wook Seo

Keyword(s):

Cell Wall ◽

National Park ◽

Cambial Activity ◽

Republic Of Korea ◽

Pinus Koraiensis ◽

Wall Thickening ◽

Cell Enlargement ◽

Xylem Development ◽

The Republic ◽

Number Of Cells

AbstractSubalpine conifers are highly sensitive to climatic changes. In these trees, the intra-annual dynamics of cambial activity and phenological process in xylem development are closely associated with climatic conditions. However, these scientific findings have not been verified for subalpine conifers in the Republic of Korea. Therefore, we initiated such a study with four subalpine conifers, viz. Abies koreana, Pinus koraiensis, Taxus cuspidata, and Picea jezoensis, growing between 1573 and 1594 m a.s.l. at Deogyusan National Park. Microcores (Ø 2 mm) of these trees were obtained using a mini borer, called as Trephor, every week between April 7 and September 25 in 2017 to monitor their growing seasons, the intra-annual dynamics of the cambial activity, and the number of cells during phenological phases of cell enlargement and cell-wall thickening. For the study, five trees were selected for each conifer species. Results showed that the cambial activity of A. koreana, P. koraiensis, and P. jezoensis required at least 73.8 heat-sum values, whereas the T. cuspidata needed 109.6 heat-sum. The durations of cambial activity of A. koreana, P. koraiensis, T. cuspidata, and P. jezoensis were 134 (127–144), 113 (92–128), 113 (106–120), and 100 (76–128) days, respectively. The intra-annual variations of the number of cells in the cambium, during the cell enlargement phase and cell-wall thickening phase showed predominantly a bell-shaped curve, with a delay of approximately 2–4 weeks between each other. On the other hand, the number of cumulated mature cells showed an S-shaped curve. Through this study, the first fundamental data on phenological process in xylem development of subalpine conifers in the Republic of Korea have been successfully presented.

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The Impact of Changing Climate on the Cambial Activity during Radial Growth in Some Citrus Species

Plant Stress Physiology ◽

10.5772/intechopen.93202 ◽

2021 ◽

Author(s):

Moin Ahmad Khan ◽

M. Badruzzaman Siddiqui

Keyword(s):

Radial Growth ◽

Cambial Activity ◽

Age Effects ◽

Vascular Cambium ◽

Citrus Species ◽

The Third ◽

Changing Climate ◽

Fusiform Initials ◽

Cambial Cells ◽

The Impact

This study on radial growth in the stem of Citrus was carried out with an aim to notice the behavior of vascular cambium with respect to climatic and age effects. The fusiform initials vary in length from 137 to 363 μm in C. limon, 100 to 463 μm in C. paradisi, 137 to 413 μm in C. reticulata var. kinnow, and 137 to 375 μm in C. sinensis. The length rises with age, followed by decline and then again increase in C. limon. In C. paradisi, there is increase up to maximum and after decline is soon followed by constancy. In C. reticulata var. kinnow, increase in length from top to base in C. sinensis, increase up to maximum followed by a decline. Swelling of cambial cells occurs in the third week of March in C. limon, last week of March in C. paradisi, third week of April in C. reticulata var. kinnow, and second week of April in C. sinensis. The cambium turns dormant in early October in C. limon, late December in C. paradisi, early December in C. reticulata var. kinnow, and early November in C. sinensis. Thus, the cambium remains active for about 6 months in C. limon and C. sinensis, 9 months in C. paradisi, and 7 months in C. reticulata var. kinnow.

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Underestimated effects of low temperature during early growing season on carbon sequestration of a subtropical coniferous plantation

Biogeosciences Discussions ◽

10.5194/bgd-8-1411-2011 ◽

2011 ◽

Vol 8 (1) ◽

pp. 1411-1444

Author(s):

W.-J. Zhang ◽

H.-M. Wang ◽

F.-T. Yang ◽

Y.-H. Yi ◽

X.-F. Wen ◽

...

Keyword(s):

Carbon Sequestration ◽

Air Temperature ◽

Growing Season ◽

Carbon Uptake ◽

Summer Drought ◽

Eddy Flux ◽

Season Length ◽

Growing Season Length ◽

Coniferous Plantation ◽

The Impact

Abstract. The impact of air temperature in early months on the carbon sequestration of a subtropical coniferous plantation was discussed by analyzing the eddy flux observations at Qianyanzhou (QYZ) site located in southern China from 2003 to 2008. This site experienced two cold early growing seasons (with temperature anomalies of 2–5° C) in 2005 and 2008, and also a severe summer drought in 2003. Results indicated that the low air temperature from January to March was the major factor controlling the inter-annual variations in net carbon uptake at this site, rather than the previously thought summer drought. The accumulative air temperature from January to February showed high correlation (R2 = 0.970, p < 0.001) with the annual net ecosystem production (NEP). This was due to the controls of early-months temperature on the plant phenology developing and the growing season length at this subtropical site. The cold spring greatly shortened the growing season length and therefore reduced the carbon uptake period. The eddy flux observations showed a carbon loss of 4.04 g C m−2 per growing-season day at this coniferous forest site. On the other hand, the summer drought also reduced the net carbon uptake strength because the photosynthesis was more sensitive to water deficit stress than the ecosystem respiration. However, the impact of summer drought occurred within a relatively shorter period and the carbon sequestration went back to the normal level once the drought was relieved.

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