Radial Growth Dynamics Research Articles

Climatic influences on intra-annual stem radial increment of Pinus sylvestris (L.) exposed to drought

Within a dry inner Alpine valley in the Eastern Central Alps (750 m a.s.l., Tyrol, Austria) the influence of climate variables (precipitation, air humidity, temperature) and soil water content on intra-annual dynamics of tree-ring development was determined in Scots pine (Pinus sylvestris L.) at two sites differing in soil water availability (xeric and dry-mesic site). Radial stem development was continuously followed during 2007 and 2008 by band dendrometers and repeated micro-sampling of the developing tree rings of mature trees. Daily and seasonal fluctuations of the stem radius, which reached almost half of total annual increment, primarily reflected changes in tree water status and masked radial stem growth especially during drought periods in spring. However, temporal dynamics of intra-annual radial growth determined by both methods were found to be quite similar, when onset of radial growth in dendrometer traces was defined by the occurrence of first enlarging xylem cells. Radial increments during the growing period, which lasted from early April through early August showed statistically significant relationships with precipitation (Kendall τ = 0.234, p < 0.01, and τ = 0.184, p < 0.05, at the xeric and dry-mesic site, respectively) and relative air humidity (Pearson r = 0.290, p < 0.05, and r = 0.306, p < 0.05 at the xeric and dry-mesic site, respectively). Soil water content and air temperature had no influence on radial stem increment. Culmination of radial stem growth was detected at both study plots around mid-May, prior to occurrence of more favourable climatic conditions, i.e. an increase in precipitation during summer. We suggest that the early decrease in radial growth rate is due to a high belowground demand for carbohydrates to ensure adequate resource acquisition on the drought prone substrate.

Cdc42 and Gsk3 modulate the dynamics of radial glial growth, inter-radial glial interactions and polarity in the developing cerebral cortex

Cdc42 and Gsk3 modulate the dynamics of radial glial growth, inter-radial glial interactions and polarity in the developing cerebral cortex

Dinamismi di accrescimento e sensitività climatica dell’abete bianco (Abies alba Mill.) nel SIC Alpe della Luna-Bocca Trabaria (PU)

Abstract: A dendroecological and dendroclimatic analysis was carried out in silver fir stand of Fonte Abeti, in the Apennines of central Italy. This small forest is the only one present in the northern side of the Marche region and it is currently included as a priority habitat in the Site of Community Interest “ Luna-Bocca Trabaria”. The study aimed to assess the sensitivity of silver fir to the current climate variability and was carried out on 40 dominant trees, for which we reconstructed radial growth dynamics, pointer years and climate-growth relationships. These were computed for the period 1892-2003, using monthly mean temperatures and precipitation drawn from the ALP-IMP climate dataset using simple and moving correlations in order to verify response stationarity through time.

Spatial dynamics of radial growth and growth efficiency in residualPinus resinosafollowing aggregated retention harvesting

Variable retention harvest systems are encouraged to promote complexity in managed forests, and aggregated retention has been suggested as a means of reducing moisture stress in residual trees. We studied the impacts of within-aggregate position on growth and foliar physiology to better understand the spatial dynamics of residual-tree responses to aggregated retention harvests in even-aged Pinus resinosa Ait. stands. Distance from edge and edge aspect influenced radial growth, volume increment, and growth efficiency, but only edge aspect affected foliar nitrogen content. Spatial variables had no significant relationships with foliar carbon isotope ratios (δ13C). Increases in radial growth, volume increment, and growth efficiency following harvesting were greatest near edges and in the northeastern quadrants of aggregates that received mechanical understory release treatments, and lowest in the southeastern quadrant of aggregates and near aggregate centers. Foliar nitrogen content was highest in the southwestern quadrants of aggregates that received understory release treatments, and lowest in the northwestern quadrants of aggregates. Our results suggest spatial relationships are important determinants of residual-tree responses to aggregated retention harvests.

DENDROCHRONOLOGICAL RESEARCH OF SCOTS PINE (PINUS SYLVESTRIS L.) GROWING IN VILNIUS AND KAUNAS FOREST PARKS/PAPRASTOSIOS PUŠIES (PINUS SYLVESTRIS L.), AUGANČIOS VILNIAUS IR KAUNO MIESTŲ MIŠKO PARKUOSE, DENDROCHRONOLOGINIAI TYRIMAI/ ДЕНДРОХРОНОЛОГИЧЕСКИЕ ИССЛЕДОВАНИЯ СОСНЫ ОБЫКНОВЕННОЙ (PINUS SYLVESTRIS L.), ПРОИЗРАСТАЮЩЕЙ В ЛЕСНЫХ ПАРКАХ ГОРОДОВ ВИЛЬНЮСА И КАУНАСА

This study is aimed at dendrochronological indication of unfavourable environmental conditions in Vilnius and Kaunas cities on Scots pine's (Pinus sylvestris L.) radial increment and comparison of city trees growth with the tree growth in relatively unpolluted areas (control forest stands). 330 sample trees in Kaunas and 456 sample pines in Vilnius city and forest parks, 72 sample pines in 3 control forest stands at the distance of 30 km west from Kaunas city were chosen for the radial growth analysis. It was determined that tree radial increment (in per cent) of transformed pine dendro‐scales is lower in cities than in control stands. These alterations were caused by environmental disturbances: exceptionally cold winter in 1979/1980 and air pollution level which was considerably higher in cities than in controlled stands. Though transport emission has constantly been growing since 2000, no clear difference between pine radial growth dynamics in controll stands in Kaunas and Vilnius sample plots was detected. Santrauka Dendrochronologiniai tyrimai, atlikti Vilniaus ir Kauno miestų miško parkuose augančiuose paprastosios pušies (Pinus sylvestris L.) medynuose ir kontroliniuose medynuose, sąlygiškai neužterštoje aplinkoje (Lekėčių girininkijoje; 30 km į vakarus nuo Kauno), indikuoja blogesnes medžių augimo sąlygas miesto aplinkoje nei vietovėje, kurioje nėra vietinės taršos, tuo laikotarpiu, kai miestų tarša buvo gerokai didesnė ir jos poveikį sustiprino ekstremaliai šalta žiema. Tyrimo tikslas – palyginti paprastosios pušies medžių metinio radialiojo prieaugio dinamiką nepalankiomis miestų taršos sąlygomis su gerokai švaresnėje aplinkoje augančių medžių radialiojo prieaugio rodikliais. Analizei buvo parinkta 330 apskaitos medžių Kauno, 456 apskaitos medžiai Vilniaus miestų parkuose bei miško parkuose ir 72 apskaitos medžiai kontroliniuose medynuose teritorijoje, kurioje nėra vietinės taršos. Nustatyta, kad metinis radialusis prieaugis patikimai skyrėsi tik 1981– 1995 m., kai buvo išskirtinai šalta 1979–1980 m. žiema ir oro tarša miestuose buvo daug didesnė nei vietovėje, kurioje nėra vietinės taršos. Nors automobilių transporto emisija nuolat didėja nuo 2000 m., tačiau aiškių skirtumų tarp paprastosios pušies radialiojo augimo kaitos kontroliniuose medynuose bei Kauno ir Vilniaus miestų tyrimo objektuose nenustatyta. Резюме Дендрохронологические исследования сосны обыкновенной (Pinus sylvestris L.) были проведены в лесных парках городов Вильнюса, Каунаса и контрольных древостоях в относительно чистой окружающей среде (в лесничестве Лекечай в 30 км от г. Каунаса). Целью исследования был сравнительный анализ годичного радиального прироста сосны, произрастающей в неблагоприятной для роста городской среде, по сравнению с произрастающей на территории без локального загрязнения. Для анализа годичного радиального прироста в городских парках г. Каунаса были подобраны 330 учетных деревьев, г. Вильнюса – 456 учетных деревьев и на контрольных участках в лесничестве Лекечай – 72 учетных дерева. Значительное различиe в радиальном приросте сосны обыкновенной, произрастающей в городских парках, по сравнению с произрастающей в контрольных древостоях установлено лишь в 1981–1995 гг. (при неблагоприятных для роста климатических условиях экстремально холодной зимы 1979–1980 гг.), когда загрязнение городского воздуха было значительно выше, чем в лесах. Несмотря на увеличение автотранспортной эмиссии с 2000 г., существенных различий в радиальном приросте сосны обыкновенной (Pinus sylvestris L.), произрастающей в городских условиях и на территории без локального загрязнения, не установлено.

Age, and radial growth dynamics of Pterocarpus angolensis in southern Africa

Pterocarpus angolensis D.C. is a highly valuable and sought after timber species across much of its range in southern Africa. Attempts at plantation cultivation of this species have not been successful, suggesting that sustainable management of natural populations is necessary for the continued utilization of this resource. Such management will require reliable age and long-term growth data. Despite the value of P. angolensis, few long-term studies of the species’ growth rate have been conducted, and some of these studies indicate that current harvest schemes may be inappropriate. This paper presents results of tree-ring analyses of P. angolensis from nine locations across southern Africa. The analyses include estimates of: (1) tree age, (2) diameter increment, (3) the relationship between tree diameter and the percentage of heartwood, and (4) the relationship between mean diameter increment and local rainfall. The mean annual diameter increment averaged over all nine sites was generally lower than other published values, though the range of values was within that of published figures. Cumulative diameter as a function of age indicates that radial growth can be quite variable, both within and among stands. These variable age–diameter relationships within and across the nine sites suggest that diameter may be a reasonable indicator of tree age at the stand level but not across the species’ range. The relationship between stem diameter and percentage heartwood is significantly positive, suggesting that optimal harvesting diameters may be reliably determined. Average annual diameter increment is significantly positively correlated with mean seasonal rainfall, which explains about half of the variance in mean diameter increment. These findings should be helpful for the sustainable management of this important species.

Effect of tapping activity on the dynamics of radial growth of Hevea brasiliensis trees

Rubber tree (Hevea brasiliensis Müll. Arg.) radial growth dynamics were monitored with displacement sensors, together with latex production, to investigate three aspects of the dual production of latex and wood: (1) the usefulness of fine-scale dendrometric measurements as a physiological tool to detect water shortage through radial growth; (2) the dynamic aspects, both at the seasonal and at the multi-year scale, of the competition between latex and wood production; and (3) the spatial distribution of radial growth rates around the tapping cut. Radial growth of untapped control trees started with the onset of the rainy season and lasted until the onset of the dry season, ceasing completely during the driest period. Displacement sensors provided a sensitive means of detecting water shortage, with a clear correlation between diameter variations and changes in water availability (both daily evapotranspiration and monthly rainfall) over the whole annual cycle. However, the correlation was significantly disturbed in tapped trees. After resumption of tapping, the radial growth rate dropped sharply within two weeks and the effect persisted throughout the whole season, so that the cumulative growth of tapped trees was about half that of untapped trees, with the cumulative growth deficit reaching 80% for the period from mid-June to November. This long-known negative impact of tapping on growth was much stronger in the second year of tapping than in the first, whereas latex production increased significantly between the first and second year of tapping. The increased latex production, which could not be ascribed to climatic conditions, shows that the establishment of an artificial latex sink is a progressive, long-term process likely involving many aspects of metabolism. As expected, ethylene significantly increased latex production in both years; however, ethylene had no effect on the growth rates of tapped trees. Radial growth was differentially affected at different locations around the tapping cut, with growth rates significantly lower in the tapped panel than in the untapped panel, and higher above the cut than below the cut. Thus, caution is needed when deriving whole stem wood production from girth measurements at one location on the stem, especially from girth measurements made close to the tapping cut. This also provides new evidence for the location of the latex regeneration area in the tapped panel, below the cut.

Conifers in cold environments synchronize maximum growth rate of tree‐ring formation with day length

Intra-annual radial growth rates and durations in trees are reported to differ greatly in relation to species, site and environmental conditions. However, very similar dynamics of cambial activity and wood formation are observed in temperate and boreal zones. Here, we compared weekly xylem cell production and variation in stem circumference in the main northern hemisphere conifer species (genera Picea, Pinus, Abies and Larix) from 1996 to 2003. Dynamics of radial growth were modeled with a Gompertz function, defining the upper asymptote (A), x-axis placement (beta) and rate of change (kappa). A strong linear relationship was found between the constants beta and kappa for both types of analysis. The slope of the linear regression, which corresponds to the time at which maximum growth rate occurred, appeared to converge towards the summer solstice. The maximum growth rate occurred around the time of maximum day length, and not during the warmest period of the year as previously suggested. The achievements of photoperiod could act as a growth constraint or a limit after which the rate of tree-ring formation tends to decrease, thus allowing plants to safely complete secondary cell wall lignification before winter.

Identification of biomechanical factors involved in stem shape variability between apricot tree varieties.

Stem shape in angiosperms depends on several growth traits such as elongation direction, amount and position of axillary loads, stem dimensions, wood elasticity, radial growth dynamics and active re-orientation due to tension wood. This paper analyses the relationship between these biomechanical factors and stem shape variability. Three apricot tree varieties with contrasting stem shape were studied. Growth and bending dynamics, mechanical properties and amount of tension wood were measured on 40 1-year-old stems of each variety during one growth season. Formulae derived from simple biomechanical models are proposed to quantify the relationship between biomechanical factors and re-orientation of the stems. The effect of biomechanical factors is quantified combining their mechanical sensitivity and their actual variability. Re-orientations happened in three main periods, involving distinct biomechanical phenomena: (a) passive bending due to the increase of shoot and fruit load at the start of the season; (b) passive uprighting at the fall of fruits; (c) active uprighting due tension wood production at the end of the season. Differences between varieties mainly happened during periods (a) and (b). The main factors causing differences between varieties are the length/diameter and the load/cross-sectional area ratios during period (a). Wood elasticity does not play an important role because of its low inter-variety variability. Differences during period (b) are related to the dynamics of radial growth: varieties with early radial growth bend weakly upward because the new wood layers tend to set them in a bent position. The action of tension wood during period (c) is low when compared with passive phenomena involved in periods (a) and (b).

Radial growth dynamics of nanowires

In this brief paper, we address the problem of the radial growth dynamics of a nanowire due to the vapor–solid (VS) process while at the same time it grows along its axial direction due to vapor–liquid–solid (VLS) process. We show that there exists a critical radius at a certain saturation and that the nanowire will thicken if its initial radius is larger than the critical radius and vice versa. Only when its initial radius is equal to the critical radius will the radius of the nanowire be uniform along its axial direction. In all other cases, the nanowire is tapered with a certain slope. The slope is relevant to the initial radius. The closer it is to the critical radius, the smaller is the slope and vice versa. Although the slope may be generally very small, it still does exist. This suggests that it is difficult to grow long nanowires with a uniform radius.

Radial Growth Dynamics of Spruce (Picea Abies) Measured by Micro-Cores

Using medical cannulas of 0.5 mm inside diameter, micro-cores were taken at three circurnferential heights from five spruce trees [Picea abies (L.) Karst.] in the Ore Mountains (Germany). The micro-cores were taken every second week during the growing seasons of 1996 and 1997 and light-microscopy studies were made on the micro-cores. The number of xylem and phloem cells, and total cell count in the cambial zone, were tabulated for each sampIe. Determination of the intra-annual cellular growth rate of conifers is simplified and will be possible also in long-term experiments. Preliminary evaluations of the wound response indicate that this micro-coring technique causes minimal injury.

Daily dynamics in xylem cell radial growth of Scots pine (Pinus sylvestris L.)

Daily dynamics of radial cell expansion during wood formation within the stems of 25-year-old Scots pine trees (Pinus sylvestris L.), growing in field conditions, were studied. The samples of forming wood layers were extracted 4 times per day for 3 days. Possible variations in the growth on different sides of the stem, duration of cell development in radial cell expansion phase and dynamics of cell growth in this phase were taken into account. The perimeters of tracheid cross-sections as a reflection of primary cell wall growth were the criterion of growth in a radial direction. For the evaluation of growing cell perimeters a special system for digital processing and image analysis of tracheid cross-sections of the forming wood was used. Growth rate for certain time intervals was estimated by the change in the relation of the perimeter of each observed cell in each of ten tracheid rows in each of 12 trees to the perimeter of the xylem cell of the same row before the expansion. Temporal differences in average values of the relations were estimated by Analyses of Variance. The existence of daily dynamics of Scots pine xylem cell radial growth has been proved. Intensive growth of pine tracheids has been shown to occur at any time of the day and to depend on the temperature regime of the day and the night as well as water supply of stem tissues. Moreover, reliable differences (P = 0.95) in the increment of cell walls during tracheid radial expansion have been found. Pulsing changes of the water potentials both of the cell and the apoplast, as the reason for the fluctuations of radial cell growth rate, were discussed.

Structure, radial growth dynamics and recent climatic variations of a 320-year-old Pinus rigida rock outcrop community.

The composition, structure and dendroecology of a 320-year-old Pinus rigida rock outcrop community was studied in the Shawangunk Mountains of southeastern New York. This represents one of the oldest known examples of this forest type and it is located on one of the most extreme sites in the northeastern United States. P. rigida represented 88% of all sampled trees, which typically grew on individual soil islands with soil depths of 8-35 cm surrounded by exposed bedrock. The forest was uneven-aged and P. rigida exhibited continuous recruitment into the tree size classes since the late 1600s, suggesting that it represents a physiographic climax for this species. However, a limited amount of Nyssa sylvatica and Quercus prinus recruitment started after 1830. Peak recruitment of P. rigida trees in 1720-1760 and 1860-1890 coincided with parabolic-shaped releases in their radial growth, possibly in response to disturbances. Tree ring growth was typically <0.4 mm/year since the 1850s and <0.3 mm/year during a prolonged and severe drought in the 1960s. However, large increases in precipitation and temperature from 1970 to 1993 were correlated with a dramatic post-drought growth response producing the highest ring width index values throughout the life of 260 to 280-year-old trees. Thus, we attribute certain moderate growth releases (>50%) lasting 10-15 years to climate, rather than disturbance. Tree growth and recruitment at the study site were influenced by a complex interaction of climate, soil and disturbance factors. Coupling of species recruitment, tree ring and climatic data in this study provided an improved technique for understanding forest growth and dynamics.

Seasonal patterns of radial root growth and starch dynamics in plantation-grown Sitka spruce trees of different ages.

Seasonal patterns of radial root growth within 1 m of tree stems were examined in Scottish plantations of Sitka spruce trees aged 9, 15 and 20 years. Results were compared with parallel measurements of shoot extension, radial growth of stems and amounts of starch stored in tissues external to root wood. Youngest trees produced the largest annual increments in root cross-sectional area and numbers of new cells along radial files of tracheids. Irrespective of tree age, new cells were present in roots before bud burst and the onset of radial growth occurred progressively later with increasing distances from the stems. At ages 15 and 20, both stem cross-sectional area and radial root growth up to 0.5 m from the stem base had a minor peak of activity preceding and a major peak following shoot elongation. Further than 0.5 m from the stem, root growth was frequently restricted to the period following shoot extension. Starch storage in the roots reached a maximum in April and May, which was greatest for 9-year-old trees and least for 20-year-old trees. At all ages, radial root growth in early spring occurred concurrently with increased starch storage. Later in the season starch reserves declined rapidly during the period of shoot elongation and root growth occurred whilst reserves were low. At all ages for positions on the root at the base of the stem and 0.25 m from it, starch depletion, at its maximum rate during June, accounted for less than the measured increment of root wood growth at that point. This indicates a substantial translocation of substrates to these zones during growth. At the same time, the reduction in starch concentrations at more distal points from the stem far exceeded that required for local root thickening.