Published by Springer Nature

Online ISSN: 1432-2285


Print ISSN: 0931-1890


Fig. 1. Time-series plots of key climate variables (anomalies relative to the 1967-2005 average). Climate data from Innsbruck (thick lines) and Mt. Patscherkofel (thin lines) reach back to 1866 and 1967, respectively. Correlation coefficients (r) between climate variables from Innsbruck and Mt. Patscherkofel are indicated (*** = p < 0.001). Climate anomalies in 2003 within the study area are marked by filled circles.
Fig. 2.
Fig. 3.
Fig. 4. A Timberline (TB200, TB100) and B tree line (TR100) ring width chronologies used as predictand in moving response functions.  
Fig. 5. Moving 56-yr response functions between key climate variables and residual chronologies. A TB200, B TB100, C TR100 (pr = previous year climate variable, T = mean temperature, P = precipitation).  


Long-term changes in tree-ring–climate relationships at Mt. Patscherkofel (Tyrol, Austria) since the mid-1980s
  • Article
  • Full-text available

February 2008


146 Reads

Walter Oberhuber



Klaus Pfeifer




Although growth limitation of trees at Alpine and high-latitude timberlines by prevailing summer temperature is well established, loss of thermal response of radial tree growth during last decades has repeatedly been addressed. We examined long-term variability of climate-growth relationships in ring width chronologies of Stone pine (Pinus cembra L.) by means of moving response functions (MRF). The study area is situated in the timberline ecotone (c. 2000 - 2200 m a.s.l.) on Mt. Patscherkofel (Tyrol, Austria). Five site chronologies were developed within the ecotone with constant sample depth (≥ 19 trees) throughout most of the time period analysed. MRF calculated for the period 1866-1999 and 1901-1999 for c. 200 and c. 100 yr old stands, respectively, revealed that mean July temperature is the major and long-term stable driving force of Pinus cembra radial growth within the timberline ecotone. However, since the mid 1980s, radial growth in timberline and tree line chronologies strikingly diverges from the July temperature trend. This is probably a result of extreme climate events (e.g. low winter precipitation, late frost) and/or increasing drought stress on cambial activity. The latter assumption is supported by a < 10 % increase in annual increments of c. 50 yr old trees at the timberline and at the tree line in 2003 compared to 2002, when extraordinary hot and dry conditions prevailed during summer. Furthermore, especially during the second half of the 20(th) century, influence of climate variables on radial growth show abrupt fluctuations, which might also be a consequence of climate warming on tree physiology.

Fig. 1. Plots of single AE energy values (dots) and relative water loss (line) as well as the course of the radial dimensional changes against time of the same fresh (a, c) and pre-dried (b, c) dehydrating wood specimens  
Fig. 2. Courses of radial dimensional changes (a), cumulative acoustic emission (b) and acoustic emission energy (c) in 5% relative water loss steps. Error bars show one standard error. Filled symbols and solid lines represent fresh wood; empty symbols and dashed lines represent pre-dried wood (n = 9, respectively)  
Fig. 3. Relative water loss (a) and percent loss of conductivity plotted against the application of positive pressure (b). Error bars show one standard error. Filled symbols and solid lines represent fresh wood; empty symbols and dashed lines represent pre-dried wood (n = 5, respectively). Hydraulic vulnerability curves were calculated from single measurements using cubic functions (b)
Fig. 4. Semi-thin transverse sections of fresh Norway spruce earlywood (a–c), pre-dried earlywood (d–e) and pre-dried wood from the earlywood-latewood transition zone (f). Arrows point at the darker stained torus of the pit membrane because toluidine blue stained the torus in dark lilac, which gave a strong contrast to the light blue-stained pit chamber walls and secondary cell walls of the tracheids. Reference bars represent 50 μm (a), 30 μm (b–d), 20 μm (e) and 10 μm (f)  
Fig. 5. X-ray CT scans of fresh dehydrated standard beams of Norway spruce. Arrows point at wood rays containing radial resin canals. Reference bars represent 1 mm (a), 200 μm (b, c) and 100 μm (d)  
Radial shrinkage and ultrasound acoustic emissions of fresh versus pre-dried Norway spruce sapwood

October 2010


216 Reads

Acoustic emission (AE) and radial shrinkage were compared between fully saturated fresh and pre-dried Norway spruce sapwood during dehydration at ambient temperature. Hydraulic conductivity measurements, anatomical investigations on bordered pits and X-ray computed tomography (CT) scans were done to search for possible AE sources other than the breakage of the water columns inside the tracheids. Both fresh and pre-dried specimens showed radial shrinkage due to drying surface layers right from the beginning of dehydration, which induced almost no AE. Whereas no dimensional changes occurred in pre-dried wood thereafter, fresh wood showed a rapid shrinkage increase starting at 25% relative water loss. This dimensional change ceased when further moisture got lost and was even partially reversed. AE of fresh wood showed much higher activity and energy, which is a waveform feature that describes the strength of the acoustic signal. Extremely high single AE energy events were detected at this critical stage of dehydration. After partial recovery from shrinkage, neither dimensional changes nor AE activity showed differences between fresh and pre-dried wood after more than 80% relative moisture loss. Our results suggested that fresh sapwood is more prone to dehydration stresses than pre-dried sapwood. Differences in AE and shrinkage behavior might be due to the weakening or distortion of the pit membranes (cavitation fatigue), pit aspiration, structural changes of the cell walls and micro-checks, which occurred during the first dehydration cycle.

Drought sensitivity of three co-occurring conifers within a dry inner Alpine environment

February 2013


89 Reads

We applied dendroclimatological techniques to determine long-term stationarity of climate-growth relationships and recent growth trends of three widespread coniferous tree species of the central Austrian Alps, which grow intermixed at dry-mesic sites within a dry inner Alpine environment (750 m asl). Time series of annual increments were developed from > 120 mature trees of Picea abies, Larix decidua and Pinus sylvestris. Calculation of response functions for the period 1911 - 2009 revealed significant differences among species in response to climate variables. While precipitation in May - June favoured radial growth of Picea abies and Larix decidua, Pinus sylvestris growth mainly depended on April - May precipitation. P. abies growth was most sensitive to May - June temperature (inverse relationship). Moving response function coefficients indicated increasing drought sensitivity of all species in recent decades, which is related to a decline in soil moisture availability due to increasing stand density and tree size and higher evapotranspiration rates in a warmer climate. While recent trend in basal area increment (BAI) of L. decidua distinctly declined implying high vulnerability to drought stress, moderately shade-tolerant P. abies showed steadily increasing BAI and quite constant BAI was maintained in drought adapted P. sylvestris, although at lowest level of all species. We conclude that synergistic effects of stand dynamics and climate warming increased drought sensitivity, which changed competitive strength of co-occurring conifers due to differences in inherent adaptive capacity.

Temporal dynamic of wood formation in Pinus cembra along the alpine treeline ecotone and the effect of climate variables

June 2009


72 Reads

We determined the temporal dynamic of cambial activity and xylem development of stone pine (Pinus cembra L.) throughout the treeline ecotone. Repeated micro-sampling of the developing tree ring was carried out during the growing seasons 2006 and 2007 at the timberline (1950 m a.s.l.), treeline (2110 m a.s.l.) and within the krummholz belt (2180 m a.s.l.) and the influence of climate variables on intra-annual wood formation was determined.At the beginning of both growing seasons, highest numbers of cambial and enlarging cells were observed at the treeline. Soil temperatures at time of initiation of cambial activity were c. 1.5 °C higher at treeline (open canopy) compared to timberline (closed canopy), suggesting that a threshold root-zone temperature is involved in triggering onset of above ground stem growth.The rate of xylem cell production determined in two weekly intervals during June through August 2006-2007 was significantly correlated with air temperature (temperature sums expressed as degree-days and mean daily maximum temperature) at the timberline only. Lack of significant relationships between tracheid production and temperature variables at the treeline and within the krummholz belt support past dendroclimatological studies that more extreme environmental conditions (e.g., wind exposure, frost desiccation, late frost) increasingly control tree growth above timberline.Results of this study revealed that spatial and temporal (i.e. year-to-year) variability in timing and dynamic of wood formation of Pinus cembra is strongly influenced by local site factors within the treeline ecotone and the dynamics of seasonal temperature variation, respectively.

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

June 2010


97 Reads

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.

Fig. 2 Morphology (a, d), shoot cross section (b, e) and detail of the outermost layer (c, f) of spring shoots (a-c) and lammas shoots (d-f) of Nicoter. In the lowermost pictures, suberinised phellem cells and the cuticle appear light grey due to staining with sudan-III-glycerol.
Fig. 5 Percentage loss of hydraulic conductivity on-site (i.e. native embolism) on 31 January 2011 and on 21 February 2011 of spring shoots (open bars) and lammas shoots (solid bars) of Gala and Nicoter. Asterisks indicate significant differences between shoot types within each apple variety (P \ 0.05). Mean and SE
Winter peridermal conductance of apple trees: Lammas shoots and spring shoots compared

June 2013


125 Reads

Lammas shoots are flushes formed by some woody species later in the growing season. Having less time to develop, tissue formation is suggested to be incomplete leading to a higher peridermal water loss during consecutive months. In this study, we analysed morphological and anatomical parameters, peridermal conductance to water vapour and the level of native embolism in mid-winter and late-winter of lammas shoots and normal spring shoots of the apple varieties Malus domestica 'Gala' and 'Nicoter'. Lammas shoots showed a significantly higher shoot cross-sectional area due to larger pith and corticular parenchyma areas. In contrast, phloem was significantly thicker in spring shoots. No pronounced differences were observed in xylem and collenchyma thickness or mean hydraulic conduit diameter. The phellem of spring shoots was composed of more suberinised cells compared to lammas shoots, which led to a significantly higher peridermal conductance in the latter. The amount of native embolism in mid-winter did not differ between shoot types, but in late-winter lammas shoots were more embolised than spring shoots. Data show that the restricted vegetation period of lammas shoots affects their development and, in consequence, their transpiration shield. This may also pose a risk for winter desiccation.

Fig. 2. Wood anatomical characteristics change with cambial age. Transverse sections of juvenile (a, b) and mature (c, d) Norway spruce wood. Reference bars represent 50 μm (a, d) and 1,000 μm (b, c) 
Fig. 5. 
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Figure 4 of 4
Hydraulic efficiency compromises compression strength perpendicular to the grain in Norway spruce trunkwood

April 2011


132 Reads

The aim of this study was to investigate bending stiffness and compression strength perpendicular to the grain of Norway spruce (Picea abies (L.) Karst.) trunkwood with different anatomical and hydraulic properties. Hydraulically less safe mature sapwood had bigger hydraulic lumen diameters and higher specific hydraulic conductivities than hydraulically safer juvenile wood. Bending stiffness (MOE) was higher, whereas radial compression strength lower in mature than in juvenile wood. A density-based tradeoff between MOE and hydraulic efficiency was apparent in mature wood only. Across cambial age, bending stiffness did not compromise hydraulic efficiency due to variation in latewood percent and because of the structural demands of the tree top (e.g. high flexibility). Radial compression strength compromised, however, hydraulic efficiency because it was extremely dependent on the characteristics of the "weakest" wood part, the highly conductive earlywood. An increase in conduit wall reinforcement of earlywood tracheids would be too costly for the tree. Increasing radial compression strength by modification of microfibril angles or ray cell number could result in a decrease of MOE, which would negatively affect the trunk's capability to support the crown. We propose that radial compression strength could be an easily assessable and highly predictive parameter for the resistance against implosion or vulnerability to cavitation across conifer species, which should be topic of further studies.

Fig. 1 Location of the experimental site in Hunshandak Sandland 
Fig. 2 Osmotic potentials of different plant functional types (PFTs) in Hunshandak ( AG annual grasses, PG perennial grasses). The mean values of all plants with the same PFT are presented 
Table 2 (continued)
Fig. 3 Regression relationship between rooting depth and osmotic potential of all tested plants in three different habitats in Hunshandak Sandland. The relationship is correlate significant at P <0.001 level and equation is expressed as Y =0.0146 X 1.1289 ( r 2 =0.42, n =104). The osmotic potential values were obtained through three replications of each plant 
Fig. 4 The average leaf osmotic potential of all species in three habitats in the Hunshandak Sandland. The mean values of all plants in the same habitats are presented 
Leaf osmotic potentials of 104 plant species in relation to habitats and plant functional types in Hunshandak Sandland, Inner Mongolia, China

January 2003


794 Reads

Leaf osmotic potentials ( s) of 104 plant species from different habitats, i.e., fixed sand dunes, lowland and wetlands in Hunshandak Sandland, Inner Mongolia, China, were investigated. The values of s were strongly species-specific, and varied from –6.54MPa ( Caragana microphylla), to –0.44MPa ( Digitaria ischaemum); 75% of plants investigated had s from –1.01 to –3.0MPa. Shrubs were found to have the lowest s, with an average value of –3.19MPa, while grasses showed the highest s. The order of plant s is shrubs<trees<grasses. The result may relate to anatomical features of shrubs. C4 photosynthetic pathway plants showed lower s values. The s values of 104 species were negatively correlated with their rooting depths ( r 2=0.42; P <0.001). High hydraulic pressure resulting from the deep roots may well explain this trend. The value of s increased as the environment became wetter, ranging from –0.79MPa in wetlands to –2.09MPa in fixed sand dunes. Although soil salt content was higher in wetlands, we did not find any effect on s.

Ecophysiology of mangroves. Trees Struct Funct 2:129-142

November 1988


302 Reads

Mangrove forests are of major ecological and commercial importance, yet the future of these resources is threatened by pollution, development and over-exploitation. There is an urgent need to develop sound management practices based on a functional understanding of the physical and biological processes underlying mangrove ecosystem dynamics. Such biological processes include dispersal (Rabinowitz 1978), herbivory (Smith 1987) and the physiological bases of species interactions and responses to environmental factors. Understanding these processes is essential for the development of more comprehensive and predictive modelling of mangrove ecosystem dynamics than has previously been possible.

Fig. 1 Raw ring-width chronologies (dashed lines) and index ring values (continuous lines) built for site AOC (a) and AOB (b). Year of fire is 1995  
Table 1 Dendrochronological characteristics of the raw ring-width data
Fig. 2 Raw ring-width chronologies (dashed lines) and index ring values built for site MCB. Year of fire is 1990  
Fig. 3 The mean d 13 C-values of the tree rings (5-year intervals) measured for sites AOB, AOC (a) and MCB (b). Groups of years 1991-1995 and 1985-1989 are before fire, intervals 1996-2000, 2001-2005, 1990-1994, 1995-1999 are after fire. Bars are standard deviation
Tree-ring growth and stable isotopes (13C and 15N) detect effects of wildfires on tree physiological processes in Pinus sylvestris L

August 2011


487 Reads

Forest fires may alter the physiological and growth processes of trees by causing stress in trees and modifying the availability of soil nutrient. We investigated if, after a high-severity fire, changes in tree-ring growth can be observed, as well as changes in the nitrogen and carbon isotope composition of tree rings of surviving trees. Two wildfires that occurred in Pinus sylvestris L. stands in Northern Italy, one at the beginning and one at the end of the vegetative season, were chosen as the focus of this study. After the fires, the surviving trees showed growth suppression with very narrow tree rings or locally absent rings. The carbon isotope ratio was more negative in tree rings formed in the 5years following fire, indicating better water supply in a situation of less competition. The nitrogen isotope ratio followed opposite trends in the two wildfire stands. In trees cored in the stand where the fire happened at the beginning of the vegetative season, there was no change in the nitrogen isotope ratio, whereas in samples collected in the other fire site, higher nitrogen isotope ratios were observed in the tree rings formed after the fire, reflecting changes in the soil nitrogen supply. Modifications in the growth and isotope composition of the fire-stressed trees disappeared from 6 to 10years after the fire. By studying trees before and after fire, we were able to show that fire affects not only the growth of surviving trees, but also their physiological processes. KeywordsWildfires–Tree rings–δ13C–δ15N– Pinus sylvestris L.

Vertical canopy gradients in ??13C correspond with leaf nitrogen content in a mixed-species conifer forest

June 2006


132 Reads

Stable carbon isotope composition varies markedly between sun and shade leaves, with sun leaves being invariably more enriched (i.e., they contain more13C). Several hypotheses have emerged to explain this pattern, but controversy remains as to which mechanism is most general. We measured vertical gradients in stable carbon isotope composition (δ13C) in more than 200 trees of nine conifer species growing in mixed-species forests in the Northern Rocky Mountains, USA. For all species except western larch, δ13C decreased from top to bottom of the canopy. We found that δ13C was strongly correlated with nitrogen per unit leaf area (N area), which is a measure of photosynthetic capacity. Usually weaker correlations were found between δ13C and leaf mass per area, nitrogen per unit leaf mass, height from the ground, or depth in the canopy, and these correlations were more variable between trees than for N area. Gradients of δ13C (per meter canopy depth) were steeper in small trees than in tall trees, indicating that a recent explanation of δ13C gradients in terms of drought stress of upper canopy leaves is unlikely to apply in our study area. The strong relationship between N area and δ13C here reported is consistent with the general finding that leaves or species with higher photosynthetic capacity tend to maintain lower CO2 concentrations inside leaves. We conclude that photosynthetic capacity is a strong determinant of δ13C in vertical canopy profiles, and must be accounted for when interpreting δ13C values in conifer forests.

Fig. 3 d 13 C cor chronologies of beech (period 1926–2005) corrected for changes in atmospheric d 13 C (lines) in three different neighborhood categories (only conspecific neighbors: Fagus100, few  
Fig. 4 Ring-width chronologies (w) in three different neighborhood categories (only conspecific neighbors: Fagus100, few allospecific neighbors, many Fagus neighbors: Fagus70-99, many allospecific and also Fagus neighbors: Fagus\70) and corresponding precipitation in July (bars)  
Fig. 5 Mean annual radial increment (w) and d 13 C cor in annual rings of Fagus trees in the periods 1926–1975 and 1976–2005 in aggregated neighborhood categories (relative contribution of Fagus to competition index (CI) 70-100%: Fagus70-100, n = 9; relative contribution of Fagus to competition index CI \ 70%: Fagus\70, n = 7). Different letters indicate significant differences at p \ 0.05 (one-sided, non-parametric two-sample test after Hothorn et al. 2008)  
Fig. 6 Mean annual radial increment (w) and d 13 C cor in annual rings of Fagus trees in the periods 1926–1975 and 1976–2005 in two categories of competition intensity. Different letters indicate significant differences at p \ 0.05 (one-sided, non-parametric two-sample test after Hothorn et al. 2008)  
??13C signature of tree rings and radial increment of Fagus sylvatica trees as dependent on tree neighborhood and climate

April 2010


145 Reads

We conducted dendroecological analyses in 80-year-long tree ring chronologies to detect neighborhood effects (competition intensity, species identity) on the δ13C signature of tree rings and radial stem increment of Fagus sylvatica trees growing either in monospecific or mixed patches of a temperate forest. We hypothesized that tree ring δ13C is a more sensitive indicator of neighborhood effects and the impact of climate variability on growth than is ring width. We found a closer correlation of summer precipitation to δ13C than to ring width. While the ring width showed a decline over the test period (1926–2005), the mean curve of δ13C increased until the mid of the 1970s, remained high until about 1990, and markedly decreased thereafter. Possible explanations related to ontogeny and environmental change (‘age effect’ due to canopy closure; elevated atmospheric SO2 concentrations in the 1960s–1980s) are discussed. Beech target trees surrounded by many allospecific trees had a significantly lower mean δ13C in the period 1926–1975 than beech with predominantly or exclusively conspecific neighborhood, possibly indicating a more favorable water supply of beech in diverse stands. Contrary to expectation, trees subject to more intense competition by neighboring trees (measured by Hegyi’s competition index) had lower δ13C values in their tree rings, which is thought to reflect denser canopies being linked to increased shading. We conclude that tree ring δ13C time series represent combined archives of climate variability, stand history and neighborhood effects on tree physiology and growth that may add valuable information to that obtained from conventional tree ring analysis. KeywordsAllospecific neighbor–Cambial age–Conspecific neighbor–Dendrochronology–Forest management–Mixed stand

Fig. 2 A comparison of simulated (filled symbols) versus empirical (open symbols) estimates of PAR transmission through the profile of control (circles) and fertilized (triangles) plots. Empirical estimates are from one sampling date in September of 1996 while simulated were calculated using the yearly sum
Light attenuation in a 14-year-old loblolly pine stand as influenced by fertilization and irrigation

November 1998


78 Reads

 We examined empirical and simulated estimates of canopy light attenuation at SETRES (Southeast Tree Research and Education Site), a 2×2 factorial study of water and nutrients. Fertilized plots had significantly lower under-canopy PAR transmittance (TC) when compared to non-fertilized plots. Light interception efficiency, as measured by the canopy cosine-corrected light extinction coefficient, G, was significantly lower in irrigated plots for all dates examined. Estimates of G ranged from a low of 0.36 in irrigated plots in September to a high of 0.64 in March for control plots. Study-wide analyses indicate that a G of 0.50 and a k (uncorrected light extinction coefficient) of 0.69 may be reasonable parameter estimates of canopy light extinction in intermediate-aged loblolly pine plantations across a range of stand conditions and seasons when site-specific data are unavailable. Simulated TC from our version of the BIOMASS model corresponded well to the empirical estimates. Varying the vertical distribution of foliage in simulations (from 10:60:30 to 40:40:10% in the upper, middle, and lower canopy positions, respectively) resulted in only a ±7% change in total PAR intercepted, whereas varying G from 0.3 to 0.7 resulted in a 67% and 31% increase in light intercepted for control and fertilized plots, respectively. Decreased G resulted in an increased proportion of beam radiation intercepted – 63–67% of total PAR intercepted – by the middle canopy where 55–60% of the foliage was found. We hypothesize that proportionally increased productivity observed in irrigated treatments may be attributed to increased beam radiation intercepted deeper into the canopy by a greater foliage area.

Dendroecological reconstruction and interpretation of larch budmoth (Zeiraphera diniana) outbreaks in two central Alpine valleys of Switzerland from 1470-1990

January 1997


26 Reads

 Outbreaks of the larch budmoth (LBM) (Zeiraphera diniana) recur cyclically approximately every 7 to 10 years in subalpine larch-cembran pine and montane to subalpine larch-Norway spruce forests of the relatively dry valleys of the European Alps. By dendroecologically analyzing increment cores from 570 host (European larch –Larix decidua) and non-host trees (cembran pine –Pinus cembra, Norway spruce –Picea abies) through the use of skeleton plots, at least 57 (59) outbreaks could be reconstructed in the optimum Upper Engadine Valley (suboptimum Goms Valley), Switzerland, during the time period 1503 (1472) to 1990. The average interval between initial years of successive outbreaks was 8.58 (8.95) years, SD 1.66 (2.13) years. Over the centuries spatial shifts of LBM activity between the two study areas occurred, probably due to climatic changes. Clear, site-specific differences in LBM attack could only be found in the suboptimum area where high-lying (>1800 m) and/or south-facing stands were infested most. LBM-afflicted trees proved to be unsuitable for climate reconstructions because the impact of the persistently recurring outbreaks on tree growth is dominant. In order to provide sufficient information for a detailed ecological interpretation of the course of an outbreak, latewood widths and/or densities have to be analyzed in addition to the ring-widths.

Seasonal course of translocation and distribution of 14C-labelled photoassimilate in young trees of Larix decidua Mill

December 1989


19 Reads

Young trees of Larix decidua, in their 4th and 5th year of development, were permitted to photoassimilate a pulse of 14CO2 at different times throughout the growing season. After chase periods between 1 h and 7 days, the distribution of 14C in these plants was determined. CO2 fixation followed a maximum curve with highest rates of photosynthesis of 123 4 mol CO2h-1mg chl-1 in June. Translocation of 14C assimilate was observed throughout the growing season. The main quantity of fixed 14C was always retained in the fed leaves. Radiocarbon moved basipetally into the roots at all times, particularly in spring and late summer. Sprouting young shoots and leaves at the stem apex attracted assimilate in spring. Incorporation of 14C into soluble low-molecular-weight substances prevailed; less radioactivity was incorporated into insoluble polymeric compounds. Distribution of 14C among the sugar, amino acid and organic acid fraction was determined. Labelled free sugars were analysed.

Fig. 1 Uptake of the 15 N tracer in fine roots, split by the different 
Fig. 2 The 15 N uptake of the 
Fig. 3 Biomass ( a ) and nitrogen content ( b ) of 100 current-year needles in winter and tree-ring width ( c ), separated by the treatments control ( C ), wood ash ( A ), irrigation ( W ) and liquid fertilization ( LF ) for the years 1997–2000. 15 N pulse labelling was 
Wood ash treatment affects seasonal N fluctuations in needles of adult Picea abies trees: A 15N-tracer study

July 2004


94 Reads

A 15N-tracer experiment was carried out in a stand of adult spruce trees [Picea abies (L.) Karst.] located on the Swiss Plateau in order to investigate the effects of wood ash treatment on seasonal nitrogen fluctuations in fine roots and needles. Treatments included irrigation (W), liquid fertilization (LF) and wood ash (A) application. 15N fluctuation in fine roots and current to 3-year-old needles was studied after one 15N pulse for 2consecutive years (1999, 2000). 15N tracer was rapidly incorporated into the fine roots of adult trees, and 15N values reached similar levels in all treatments 2months after the pulse. In the needles, the largest increase in 15N was observed in those of the current year. Following the initial peak during spring growth, 15N values in needles of control trees showed an oscillating pattern through the season. This oscillation is attributed to the increased use of internal N sources, as soon as the roots can no longer meet the increased N demand during the sprouting phase. However, W-, LF- and A-treated trees no longer showed the oscillation in 15N. Additional water (W and LF) as well as fertilizer (A and LF) may have induced shifts in the microbial flora, thus increasing the unlabelled N release from the soil. The strongest dampening was observed for the A treatment, indicating sufficient N availability from the soil, and making intensive use of the internal N sources unnecessary. Treatment with wood ash thus resulted in a similar fertilizer response to liquid fertilization.

Climate and forest management affect 15N-uptake, N balance and biomass of European beech seedlings

March 2004


58 Reads

We investigated the effect of (a) different local climate and (b) thinning of the forest canopy on growth and N status of naturally regenerated European beech seedlings in a beech forest on shallow rendzina soil in southern Germany. For this purpose, a 15N-tracing experiment was conducted during the growing season of the year 2000 with beech seedlings growing on a warm, dry SW-exposed site and a cooler, moist NE-exposed site, and in a thinned and a control stand at each site. Biomass, 15N uptake and partitioning and total N concentrations of beech seedlings were determined. Site and thinning produced clear differences, particularly at the end of the growing season. Biomass and cumulative 15N uptake of beech seedlings then increased due to thinning on the NE site and decreased on the SW site. Total N concentrations in leaves, roots and stems of beech seedlings responded similarly. Therefore, growth and N status of beech seedlings are found to be favoured by thinning under cool-moist conditions. However, under higher temperature and reduced water availability—conditions that are prognosticated in the near future—thinning reduces N uptake and plant N concentration and, thus, impairs N balance and growth of beech regeneration.

A dendroecological reconstruction of western spruce budworm outbreaks (Choristoneura occidentalis) in the Front Range, Colorado, from 1720 to 1986

January 1995


20 Reads

Radial increment cores from Douglas-fir (Pseudotsuga menziesii) and blue spruce (Picea pungens), defoliated by western spruce budworm (Choristoneura occidentalis), were analyzed by means of dendrochronological methods and compared with cores from undefoliated ponderosa pine (Pinus ponderosa) and lodgepole pine (Pinus contorta) growing on the same sites in the Front Range, Colorado. Extensive deforestation during the gold and silver booms in the second part of the nineteenth century led to dense and almost pure stands of shadetolerant budworm host species. By using the skeleton plot method, the number of trees with clear growth reductions is obtained, thus representing an exact record of forest insect attacks. The analysis of abrupt growth reductions revealed at least nine outbreaks of western spruce budworm between 1720 and 1986, the majority occurring in the nineteenth century. The outbreaks were graphically compared with periods of attack in New Mexico and Colorado which were detected by other scientists employing tree-ring measurement techniques. No increase in the frequency of severe outbreaks during the twentieth century was observed, yet there is some evidence that the most recent outbreak might be the most severe ever recorded. Open Douglas-fir stands on higher sites were more susceptible to heavy budworm attack than dense stands on lower sites. Blue spruce was less frequently and less severely attacked than Douglas-fir. The spatial pattern of historical outbreaks generally was very patchy.

Fig. 1 Map of localisation of the sampled sites in the French Alps, in Belledonne, Moyenne-Tarentaise, Haute-Maurienne and Briançonnais areas. Climatic diagrams from four meteorological stations with mean monthly values of temperature (minimum, mean and maximum) in °C and precipitation in mm per month (1951-1990)& / f i g. c :
Fig. 6 Comparison of the regional growth trends of four subalpine species since 1800 in four regions of the French Alps. N=Number of cores, I=growth indices with moving averages in bold& / f i g. c :
Changes in radial tree growth for Picea abies, Larix decidua, Pinus cembra and Pinus uncinata near the alpine timberline since 1750

September 1998


410 Reads

 Changes in radial growth of the four coniferous species growing in the French Alps near the upper treeline are investigated. Thirty-seven populations of Norway spruce [Picea abies (L.) Karst.], European larch (Larix decidua Mill.), Swiss stone pine (Pinus cembra L.) and mountain pine (Pinus uncinata Mill. ex Mirb.) were sampled by taking 1320 cores and analysing tree-ring widths. Sites were chosen in various climatic conditions (macroclimate and aspect) and on two kinds of bedrock in order to take into account the ecological behaviour of these species. Belledonne, Moyenne-Tarentaise, Haute-Maurienne and Briançonnais areas were sampled along increasing gradients of summer aridity and winter continentality. The calculation of time series after removing the age trend brings strong evidence for an increase in radial growth during the two last centuries, but with different stages and fluctuations for each species. This growth trend is significantly enhanced since 1860 for the spruce, and since 1920 for the two pine species. Furthermore, it also appears on Larix decidua with the same pattern despite periodical growth reduction due to attacks of the larch bud moth (Zeiraphera diniana Gn.). The analysis of ring-widths at a given cambial age reveals that this enhanced phenomenon is observed especially during the tree’s early years (25–75 years). The analysis of four regional climatic series, and three longer series of temperature (in farther single sites) reveals synchronous decadal fluctuations and an evident secular increase in minimum temperatures (especially in January and from July to October), that may be involved in tree-growth enhancement. Thermic amplitudes are significantly reduced during the whole growing period, what is more pronounced in Belledonne, the most oceanic region. Long term growth changes are well described by stepwise regression models, especially for the pine species. These models involved both a linear trend (CO2 concentration or N-deposition) and low frequency of Turin monthly temperatures. However, they show different patterns than those observed from response functions at a yearly scale.

Table 1 Stand characteristics (basal area and volume over bark) (Soares et al., 2004), total tree height and diameter at breast height (dbh) of 18-year-old Eucalyptus globulus trees sampled from five different spacings
, sapwood and total cross-sectional area, heartwood percentage in total cross-sectional area and sapwood width at 1.30 m of 18-year-old Eucalyptus globulus trees sampled from two blocks with different spacings
Variation of heartwood and sapwood in 18-year-old Eucalyptus globulus trees grown with different spacings

April 2009


809 Reads

Heartwood and sapwood development was studied in 18-year-old Eucalyptus globulus trees from pulpwood plantations with different spacings (3×2, 3×3, 4×3, 4×4 and 4×5m), on cross-sectional discs taken at breast height. The trees possessed a large proportion of heartwood, on average 60% of the wood cross-sectional surface. Spacing was a statistically significant source of variation of heartwood area, which ranged between 99 and 206cm2 for the closer (3×2) and wider (4×5) spacings, respectively. There was a positive and high statistical significant correlation between heartwood diameter and tree diameter (heartwood diameter=−0.272+0.616dbh; r 2=0.77; P<0.001), and larger trees contained more heartwood regardless of spacing. Heartwood proportion in cross-section remained practically constant between spacings but increased with tree diameter class: 55.1, 62.2, 65.0 and 69.5% for diameter at breast height classes <15, 15–20, 20–25 and >25cm, respectively. The sapwood width did not depend on tree diameter growth and remained practically constant at an average of 18mm (range 15–21mm), but sapwood area showed a good linear regression with tree diameter. Therefore, tree growth enhancement factors, such as wide spacings, will induce formation of larger heartwoods that can negatively impact raw-material quality for pulping. The increase in heartwood in relation with tree dimensions should therefore be taken into account when designing forest management guidelines.

Fig. 1 Vertical distribution of particle size (5 fractions: clay, fine silt, coarse silt, coarse sand, fine sand) and bulk density (cm 3 /g) for every 10-cm soil layer. For a given soil layer, values shown are the mean of two analyses. Thresholds of pedological horizons (named according to Hodgson 1978) are indicated  
Table 1 Characteristics of the four investigated trees: height, cir- cumference at breast height (CBH), and crown class of the tree in the canopy
Fig. 2 Mean vertical profiles of soil water potential (W soil , MPa) measured during each sampling campaign at two locations in the studied plot (horizontal bars represent standard error; n = 2). Filled triangle: reference and 1st campaign (DOY 178–179); open square: 2nd campaign (DOY 184); filled circle: 3rd campaign (DOY 206)  
Fig. 6 Oxygen isotope composition (d 18 O, %) of xylem sap in beech (Fs, triangles) and oak (Qp, squares) as measured in collars (white symbols) and branches (grey symbols). The grey area represents the range of the base-line oxygen isotope composition of soil water at this site before labelling (Fig. 5a). The vertical arrow represents the time of injection of 18 O-labelled water
Evidence of hydraulic lift in a young beech and oak mixed forest using 18O soil water labelling

October 2011


841 Reads

Hydraulic lift (HL) by tree roots in a young, broad-leaved, mixed temperate European forest was investigated during the 2008 growing season by injecting 18O-enriched soil water at a depth of 75–90cm under drought conditions experimentally imposed in a rain-exclusion system. Based on sap flow, leaf water potential, 2-D root distribution measurements, soil isotope profiles, and xylem water isotope composition, water acquisition and use by two tree species, beech (Fagus sylvatica) and oak (Quercus petraea) was compared. We showed that, unlike oak, beech experienced a marked decrease in sap flow and predawn leaf water potential with increasing soil drought. This behaviour was logical considering the shallower root system in beech than in oak. Six days after 18O-labelling, we observed isotopic enrichment in the shallower soil layers. Since the intermediate soil layers did not display any enrichment, our results clearly pointed to hydraulic lift by tree roots. The superficial enrichment that was observed in the vicinity of oak trunks and the increase in the isotopic signature of xylem sap in the oak trees but not in the beech trees confirmed the predominant role of oak in the hydraulic lift at our site. Even though facilitation for water acquisition among species was not observed here, our results suggest a potential positive contribution of species like oak toward maintaining species diversity in mixed forest ecosystems submitted to severe drought events. KeywordsDeciduous mixed forest–Drought– Fagus sylvatica –Isotopic labelling– Quercus petraea –Tree roots

Development of needle retention in Scots pine (Pinus sylvestris) in 1957-1991 in northern and southern Finland

December 1995


7 Reads

The needle trace method was used to study retrospectively the long-term latitudinal variation in needle retention in Scots pine (Pinus sylvestris L.) in Finland. The mean annual summer needle retention (ANR) along the main stem varied from 3.4 to 6.0 needle sets during the period 1957–1991. The lowest values were observed in southern and the highest in northern Finland. The length of the growing season, expressed as the thermal sum (threshold value +5 C), was negatively correlated with the mean ANR (r=-0.96). The geographical needle retention pattern (NRP) for the period 1957–1991 showed a clearly increasing trend from 1957 to 1969 (southern Finland) and to 1975 (northern Finland); thereafter, the NRP tended to decrease close to its minimum value recorded in 1991. The general level of the NRP was approximately 5.0 needle sets in northern Finland and 3.5–4.0 needle sets in southern Finland. The NRP, with its 6–12 year cycle for southern Finland, was clearly periodical. Differences in the NRP among the ten stands in southern Finland were small, whereas the said periodicity was missing and the differences were high among the stands in northern Finland. The results indicate that variation in the number of needle sets, viz. defoliation of pines, is a normal phenomenon. The role of net carbon assimilation as a regulator of the number of needle sets is discussed.

The seasonal variation of 20 elements in 1st and 2nd year needles of Norway spruce, Picea abies (L.) Karst

January 1988


7 Reads

The concentration of 20 elements (including eight nutritional elements) in spruce needles was monitored by taking samples at nine different dates in a single year. On each date the youngest and the 1-year-old needles were collected at four different sites. The needles were washed with an organic solvent to remove surface contamination before analysis by instrumental neutron activation. Although the sites showed widely different concentrations for the same element, they could be treated as a uniform population using normalized concentration values. Taking the time dependence of the concentration and the ratio of the concentrations in new and old needles as criteria, the following three groups of elements could be distinguished: 9 group I —Ca, Sr, Ba, and Mn; group II — Al, Br, Co, Fe, Hg, La, Sc, Sb, and Zn; group III — K, Rb, Cs, P, and Cl. Mg and Na did not fit into any of these groups. Within group I and III elements the strongest variations occur during the growing season (late spring and early summer) and the weakest during the dormant season; the variation is greater in the younger needles. Group II elements show an approximately linear increase throughout the year in both the younger and older needles. The concentrations of elements of groups I and II increase with time, while those of group III decrease. Na is unique insofar as its concentration is influenced by foliar uptake of road de-icing salt. The concentration of elements belonging to the same group shows strong inter-element correlations. The grouping of elements deduced here shows similarities with the chemical nature of the elements and with their transportability within the plant.

Carbon partitioning in Norway spruce: Amounts of fructose 2,6-bisphosphate and of intermediates of starch/sucrose synthesis in relation to needle age and degree of needle loss

June 1990


11 Reads

Intermediates involved in carbon partitioning between starch and sucrose [dihydroxyacetone phosphate + glyceraldehyde 3-phosphate (TP), 3-phosphoglyceric acid, fructose 6-phosphate (F6P), fructose 2,6-bisphosphate (F26BP), in addition to glucose, fructose, sucrose and starch] were analysed in lyophilized needles of Norway spruce (Picea abies L. Karst). Samples were taken from all distinct parts of first and second order branches and the analysed data related to season, needle age, needle position and degree of needle loss (control and class 2 approx. 30%–40% needle loss). Positive and inverse correlations of F26BP, an important regulator of carbon partitioning between starch and sucrose, and F6P or TP existed in all samples. F26BP levels were highest in developing needles and gradually decreased during maturation, which is possibly indicative of changes in the relative sink strength during development (switch from import to export of sucrose). In class 2 needles the amount of F26BP was significantly increased. Together with nearly unaltered levels of sucrose but only slightly decreased amounts of starch the results can be taken as evidence for impaired carbon export in our class 2 samples. The data are discussed with respect to needle development and a possible impact of both air pollutants and mineral deficiency at the location from which the samples were taken.

Fig. 1 
Fig. 2 
Fig. 4 
Fig. 6 Seasonal variation of total soluble non-protein N (TSNN) concentrations and its compound profiles in different beech tissues. The samples were collected at four beech forest stands located along a North–South gradient including a site close to Mühlhausen in Central Germany (Mühl), a north-easternly and a south-westernly exposed beech stand close to Tuttlingen (TUT-NE and TUT-SW, respectively) 
Fig. 8 
Seasonal courses of key parameters of nitrogen, carbon and water balance in European beech (Fagus sylvatica L.) grown on four different study sites along a European North–South climate gradient during the 2003 drought

January 2007


269 Reads

During the growing season of the exceptionally dry and warm year 2003, we assessed seasonal changes in nitrogen, carbon and water balance related parameters of mature naturally grown European beech (Fagus sylvatica L.) along a North–South transect in Europe that included a beech forest stand in central Germany, two in southern Germany and one in southern France. Indicators for N balance assessed at all four sites were foliar N contents and total soluble non-protein nitrogen compounds (TSNN) in xylem sap, leaves and phloem exudates; C and water balance related parameters determined were foliar C contents, δ13C and δ18O signatures. Tissue sampling was performed in May, July and September. The N related parameters displayed seasonal courses with highest concentrations during N remobilization in May. Decreased total foliar N contents as well as higher C/N ratios in the stands in central Germany and southern France compared to the other study sites point to an impaired N nutrition status due to lower soil N contents and precipitation perception. TSNN concentrations in leaves and phloem exudates of all study sites were in ranges previously reported, but xylem sap content of amino compounds in July was lower at all study sites when compared to literature data (c. 1 μmol N mL−1). In September, TSNN concentrations increased again at the two study sites in southern Germany after a rain event, whereas they remained constant at sites in central Germany and southern France which hardly perceived precipitation during that time. Thus, TSNN concentrations in the xylem sap might be indicative for water balance related N supply in the beech trees. TSNN profiles at all study sites, however, did not indicate drought stress. Foliar δ13C, but not foliar C and δ18O followed a seasonal trend at all study sites with highest values in May. Differences in foliar δ13C and δ18O did not reflect climatic differences between the sites, and are attributed to differences in altitude, photosynthesis and δ18O signatures of the water sources. Except of low TSNN concentrations in the xylem sap, no physiological indications of drought stress were detected in the trees analysed. We suppose that the other parameters assessed might not have been sensitive to the drought events because of efficient regulation mechanisms that provide a suitable physiological setting even under conditions of prolonged water limitation. The uniform performance of the trees from southern France and central Germany under comparably dry climate conditions denotes that the metabolic plasticity of mature beech from the different sites studied might be similar.

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