Branch Wood Research Articles

Rapid mixing between old and new C pools in the canopy of mature forest trees

Stable C isotope signals in plant tissues became a key tool in explaining growth responses to the environment. The technique is based on the fundamental assumption that the isotopic composition of a given unit of tissue (e.g. a tree ring) reflects the specific C uptake conditions in the leaf at a given time. Beyond the methodological implications of any deviation from this assumption, it is of physiological interest whether new C is transferred directly from sources (a photosynthesizing leaf) to structural sinks (e.g. adjacent stem tissue), or inherently passes through existing (mobile) C pools, which may be of variable (older) age. Here, we explore the fate of (13)C-labelled photosynthates in the crowns of a 30-35 m tall, mixed forest using a canopy crane. In all nine study species labelled C reached woody tissue within 2-9 h after labelling. Four months later, very small signals were left in branch wood of Tilia suggesting that low mixing of new, labelled C with old C had taken place. In contrast, signals in Fagus and Quercus had increased, indicating more intense mixing. This species-specific mixing of new with old C pools is likely to mask year- or season-specific linkages between tree ring formation and climate and has considerable implications for climate reconstruction using stable isotopes as proxies for past climatic conditions.

Wood vessel diameter is related to elevation and genotype in the Hawaiian tree Metrosideros polymorpha (Myrtaceae)

We tested the hypothesis that trees growing at high elevations with occasional freezing temperatures have smaller diameter xylem vessels than trees of the same species growing at lower and warmer elevations. The young branch wood of the wide-ranging Hawaiian tree species Metrosideros polymorpha (Myrtaceae) was examined in three natural field populations (high, middle, and low elevations: 2469, 1280, and 107 m a.s.l., respectively) and contrasted with seedlings from these populations that were grown in a common garden at middle elevation (1190 m). Previous studies showed that these populations have some genetic differences and have distinctive leaf structure and ecophysiological traits. Vessel diameter was significantly smaller in the high elevation field and common garden plants than in middle elevation plants. However, high elevation vessels were wider in common garden plants compared to field plants, indicating that vessel diameter is determined both by genotype (parental populations) and environment (growing conditions different from those of parents). Reduced vessel diameter has implications for resistance to cavitation induced by freezing and/or drought in plants growing near tree line in Hawaii.

Biomass and element pools of selected spruce trees in the catchments of Plešné and Čertovo Lakes in the Šumava Mts.

This paper presents detailed data on the biomass and element pools of six sample trees in the catchments of Plešné andČertovoLakes. Diameters and heights of the sample trees ranged from 28.0 to 63.7 cm and from 14.1 to 38.7 m. The age of the sample trees ranged from 84 to 177 years. Total biomass of the sample trees was in the range of 239.4 kg to 2,932.3 kg. Variation of total biomass between the sample trees was a consequence of the tree biometric data (height and dbh) and age differences. The proportion of stem wood and bark ranged from 63.5 to 69.5%, and from 4.6 to 7.2%, respectively. The proportion of foliage and fine branches ranged from 4.3 to 8.4%, and from 0.7 to 1.9%, respectively. The proportion of branch wood and bark ranged from 2.2 to 6.5%, and from 0.8 to 2.2%, respectively. Mean concentrations of C in different tree components were quite similar. Except C and compared to the other elements, N had the highest mean concentrations in tree components in all cases. Concentrations of P, Ca, Mg, and K showed similar patterns. Generally the highest concentrations of these elements were found in foliage, fine branches, fine roots and bark of stem and branches. Fe, Na, Al and Mn showed the lowest mean concentrations in tree components for all the analyzed elements. The total element pools per tree were highly variable because of the differences in total biomass between the individual trees. Generally, stem wood and bark, foliage, and roots contained the highest proportion of the elements. But there were differences between individual elements. Concerning the important nutrients, while the highest proportion of Ca and Mg was contained in stem wood and bark, the highest proportion of P was contained in foliage. The foliage contained a relatively high proportion of P and K, but a relatively low proportion of Ca and Mg.

Do browsing elephants damage female trees more?

AbstractHerbivory in unisexual plants has mainly been assessed in studies of invertebrates, mostly insects. At a different scale of disturbance, browsing by large animals has rarely been studied. Elephants can seriously damage or kill trees by removing parts of the canopy, debark, or break the stem. We compared browsing by African elephants (Loxodonta africana) in male and female Marula trees (Sclerocarya birrea ssp. caffra). We expected females to incur more damage because of their sweet and fleshy fruits, known to attract elephants from far. Following this, we expected females to give more resistance through a denser branch wood that would break off at a larger diameter than in males. We tested this by pulling branches down to simulate elephant browsing as to compare branch resistance and design. All trees showed signs of browsing and females were generally more injured. However, there was no sexual difference in wood density and diameter at breaking point. Female branches were shorter, less ramified and carried fewer reproductive shoots than male branches. This sexual dimorphism could result from costly reproductive allocation in females and sexual selection, promoting intensive male flowering. Indirectly, elephants could reinforce this difference by engaging females more in tissue repair after browsing.

A survey on energy consumption in rural households in the fringes of Xian city

A survey, in the form of a questionnaire, of energy consumption patterns in residential households in the rural fringe of Xian city was undertaken during the winter of 2003/2004. More than 200 households were sampled during the survey. The status of fuel consumption, including the use of biomass fuels for cooking and space heating, was investigated. The types of stoves, purpose of the stove use, and characteristics of the residential houses and residents were also reported and analyzed. The purpose of the survey was to clarify the status of energy consumption and to estimate emissions of greenhouse gases and air pollutants in rural areas of China, from the environmental perspective of climate change and indoor to continental scale air pollution. In rural areas of China, biomass (wood and agricultural waste, such as stalks, corn canes and twigs, branches of wood) is the type of fuel most commonly used. It emits several air pollutants: particulate matter (PM), CO, NMHCs, CH 4 and high levels of black carbon (BC) – a greenhouse effect aerosol, and organic carbon (OC) – a cooling effect aerosol. However, CO 2 emissions from biomass burning are assumed to be zero because of carbon neutrality. From this survey it would then be possible to analyze the fundamentals of emission reduction potential, for air pollutants and greenhouse gases, from the rural household sector in China.

Adaptive genetic variation in water-use efficiency and gum yield in Acacia senegal provenances grown on clay soil in the Blue Nile region, Sudan

The genetic variation in shoot growth, water-use efficiency (as assessed by δ 13C) and gum production was compared among eight Acacia senegal provenances originating from contrasting conditions of the gum arabic belt in central Sudan. The experimental site was in the clay plain region. Carbon isotope ratios were obtained from leaves and branch wood samples of the dissimilar A. senegal provenances. The clay provenances were distinctly superior to the sand provenances in all traits studied but especially in basal diameter and crown width, reflecting their adaptation to the environment. Values of δ 13C were less negative in the sand group compared to the clay both in leaves and in branch wood. This suggests that sand provenances displayed conservative water use and high drought tolerance. Of the clay provenances, the local one displayed a high negative δ 13C value, which indicates less conservative water use that results in high productivity at this particular clay-soil site. Water use appears to correspond to the environmental conditions prevailing at collection sites for these provenances. Results suggest that A. senegal provenances in the clay part of the gum belt are adapted for fast growth rate and high biomass and gum productivity as compared with the provenances from the sand regions: a negative correlation was found between tree gum yield and δ 13C. The variation in water use and gum production was greater among provenance groups than within them, suggesting that selection among rather than within provenances would result in distinct genetic gain in gum yield.

End of season carbon supply status of woody species near the treeline in western China

As trees and shrubs approach the high elevation tree limit, it is often assumed that they fall short in photosynthate (source [imitation). Alternatively, tow temperature may restrict carbon investment (growth, sink Limitation). The content of mobile nonstructural. carbohydrates (NSC) in tissues is considered a measure of the carbon source-sink balance. To test the source vs. sink Limitation hypothesis, we compared tate-season NSC concentrations of various woody taxa. across attitudinal gradients from the subalpine forest to the treeline at the eastern edge of the Tibetan Plateau. Since we were interested in the generality of trends, we present community trends across four taxa, namely Quercus aquifolioides, Abies faxoniana, Rhododendron fabri subsp. prattii and Sorbus rufopilosa. NSC concentrations increased significantly with attitude in branch wood, current-year and last-year leaves, while there were no significant trends in stem sapwood and root xylem. The sugar to starch ratio was roughly 1:1 in branches and evergreen leaves, white stems and roots showed a higher starch fraction. Analyses of total nitrogen in leaves and wood tissues indicated no change in the trees' nitrogen supply with elevation. The overall attitudinal. trends of NSC in this group of woody plant species revealed no depletion of carbon reserves near the tree Limit, suggesting that sink limitation predominates woody plant Life across this treeline ecotone community.. (c) 2005 Published by Elsevier GmbH on behalf of Gesellschaft fur Okologie.

Chironomidae (Diptera) em substratos artificiais num pequeno reservatório: Represa do Monjolinho, São Carlos, São Paulo, Brasil

O presente estudo teve como objetivo verificar possíveis diferenças taxonômicas e funcionais entre as assembléias de Chironomidae que colonizam substratos orgânicos e inorgânicos estruturalmente distintos. Substratos poliméricos (isopor e tela de náilon), minerais (pedra de argila expandida e areia grossa) e orgânicos vegetais (detritos de Scirpus cubensis e Cabomba piauhyensis; detritos de madeira), contidos em sacos de náilon, foram submersos na Represa do Monjolinho. Estes, após 30 dias, foram retirados, lavados em peneira de malha de 0,21 mm e os organismos retidos identificados sob microscópios estereoscópicos e/ou óptico. A análise de 3432 larvas indicou a presença de 17 unidades taxonômicas das quais Goeldichironomus neopictus foi predominante, com expressiva participação em todos os substratos (>73%). As análises de agrupamentos quantitativa (Distância Euclidiana) e qualitativa (Coeficiente de Jaccard) apontaram para diferentes arranjos. A primeira agrupou as assembléias que colonizaram areia e madeira (com maiores densidades numéricas e riqueza de táxons), os substratos poliméricos (isopor e tela de náilon) e os detritos de macrófitas. A segunda indicou maior semelhança entre as assembléias presentes nos substratos orgânicos vegetais e nos minerais. Em contraposição, devido à elevada representatividade de coletores em todos os substratos (>95%), as assembléias apresentaram-se funcionalmente similares.

Mating Behavior of Oemona hirta (F.) (Coleoptera: Cerambycidae: Cerambycinae) in Laboratory Conditions

Oemona hirta (F.) is a New Zealand longicorn beetle. Its larvae are known to bore into wood of branches and stems of living trees and vines of over 50 species, most of which are exotic such as citrus, apple, persimmon, cherry, chestnut, almond, walnut, grape and poplar, causing serious damage (Miller, 1925; Hudson, 1934; Dumbleton, 1937; Clearwater, 1981; Spiller and Wise, 1982; Rohitha et al., 1992). Adults are flower feeders (Dye, 1950). Control of this pest is still very difficult. Knowledge of mating behavior may provide information for the future development of monitoring and control measures for the pest, and enhance our understanding of the biology and ecology of cerambycid beetles. Several attempts were made to observe mating activities of O. hirta beetles in the field but all failed (Dye, 1950; Clearwater and Muggleston, 1985; Q. Wang, unpublished data). Previous studies show that (1) caged virgin males and females and black light failed to attract any adult of either sex in the field (Clearwater and Muggleston, 1985; Q. Wang, unpublished data), (2) adults of both sexes were attracted to fermenting plant materials (Dye, 1950), and (3) females preferred wounds on trees as oviposition sites (Dye, 1950; Clearwater and Muggleston, 1985). These observations appear

Growth and productivity assessment of Casuarina glauca Sieb. ex. Spreng on sodic soil sites

Casuarina glauca is an introduced tree species to India. It is one the few species that can grow successfully in salt effected sites. C. glauca was investigated for biomass production at highly sodic soil sites (pH 8.6–10.5); it was found to be promising in terms of growth and productivity. Average height of plants in an 8-yr-old trial of Casuarina glauca was 1033.3 ± 270 cm, however diameter at breast height (dbh) remained at 8.59 ± 2.0 cm with a basal area of 6.68 ± 1.6 cm 2 per plant. High plant survival and establishment (75%) indicate its potential for afforestation of degraded soil sites. Linear regression equations ( Y = a + bx) were developed to predict biomass of standing stocks defining relationships between growth parameters ( x) as independent variable and productivity ( Y) as dependent variable. Both uni-factor equations based on one independent variable (height or diameter alone), and multifactors involving both height and diameter together ( d 2 h) were derived to predict biomass of different plant components. Coefficient of correlation and regression coefficients were found to be highly significant ( p < 0.001) in all the equations irrespective of independent variable such as plant height, diameter or both ( d 2 h). There were marginal differences in r 2 value (0.78–0.8) among equations derived by using d 2 or d 2 h as independent variables. Height alone had relatively poor functional correlation with yield ( r 2 = 0.45). Accordingly, uni-factor linear equations with diameter ( d 2) were used for computing stand biomass with reasonably good accuracy. At the age of 8 years, stand productivity was 68.2 t ha −1 (oven dry biomass) out of which relatively a very high proportion (80.3%) of biomass was allocated to stem wood (54.8 t ha −1). Both branch wood (8.4 t ha −1) and leaves (5 t ha −1) contributed marginally. Casuarina glauca can be recommended as a promising species for biomass production on sodic soil sites as is evident from its performance.

Multivariate NIR spectroscopy models for moisture, ash and calorific content in biofuels using bi-orthogonal partial least squares regression

The multitude of biofuels in use and their widely different characteristics stress the need for improved characterisation of their chemical and physical properties. Industrial use of biofuels further demands rapid characterisation methods suitable for on-line measurements. The single most important property in biofuels is the calorific value. This is influenced by moisture and ash content as well as the chemical composition of the dry biomass. Near infrared (NIR) spectroscopy and bi-orthogonal partial least squares (BPLS) regression were used to model moisture and ash content as well as gross calorific value in ground samples of stem and branches wood. Samples from 16 individual trees of Norway spruce were artificially moistened into five classes (10, 20, 30, 40 and 50%). Three different models for decomposition of the spectral variation into structure and noise were applied. In total 16 BPLS models were used, all of which showed high accuracy in prediction for a test set and they explained 95.4-99.8% of the reference variable variation. The models for moisture content were spanned by the O-H and C-H overtones, i.e. between water and organic matter. The models for ash content appeared to be based on interactions in carbon chains. For calorific value the models was spanned by C-H stretching, by O-H stretching and bending and by combinations of O-H and C-O stretching. Also -C=C- bonds contributed in the prediction of calorific value. This study illustrates the possibility of using the NIR technique in combination with multivariate calibration to predict economically important properties of biofuels and to interpret models. This concept may also be applied for on-line prediction in processes to standardize biofuels or in biofuelled plants for process monitoring.

A Study of Eucalyptus Grandis and Eucalyptus Globulus Branch wood Microstructure

Experimental measurements of cellulose crystallite width and microfibril angle (MFA) by X-ray diffractometry on SilviScan-2 and by conventional microtechniques revealed that the branch wood of the two species exhibited very similar trends in cellulose crystallite width and MFA. Cellulose crystallite width was greater on the upper side of the branches. Tension wood, as defined by the occurrence of gelatinous fibres, was found where cellulose crystallite width was greater than 3.0 nm and 3.1 nm in Eucalyptus grandis and E. globulus respectively. In the tension wood zones, MFA was lower than in the rest of the samples and so could be used to differentiate tension wood. On the lower side of the branches MFA determined from X-ray diffractometry unexpectedly exceeded 40° and fibres were often buckled in both the tangential and radial directions in both species. This local variation in the direction of the fibre axes contributed only slightly to the magnitude of the MFA determined by SilviScan-2. Even given this misalignment, the additional evidence gained from pit angles and cracks in fibre walls suggested that the MFA was indeed around 40° in the lower radius of the branches. This MFA is considerably larger than would be expected for eucalypt stem wood and it is suggested that opposite wood in eucalypt branches may provide a complimentary structural role to that of the tension wood. Experimental measurements of crystallite width produced by SilviScan-2 may be used to accurately locate tension wood zones in both species.

Developing general allometric relationships for regional estimates of carbon sequestration—an example using Eucalyptus pilularis from seven contrasting sites

General non-site-specific allometric relationships are required for the conversion of forest inventory measurements to regional scale estimates of forest carbon sequestration. To determine the most appropriate predictor variables to produce a general allometric relationship, we examined Eucalyptus pilularis aboveground biomass data from seven contrasting sites. Predictor variables included diameter at breast height (dbh), stem volume, dbh 2 × H, dbh × H and height ( H). The data set contained 105 trees, ranging from 6 to over 20,000 kg tree −1, with dbh ranging from 5 to 129 cm. We observed significant site differences in (1) partitioning of biomass between the stem, branch wood and foliage; (2) stem wood density and (3) relationship between dbh and height. For all predictor variables, site had a significant effect on the allometric relationships. Examination of the model residuals of the site-specific and general relationship indicated that using dbh alone as the predictor variable produced the most stable general relationship. Furthermore, the apparent site effect could be removed by the addition of a constant value to the measured diameter (dbh + 1), to account for the differing diameter distribution across the seven sites. Surprisingly, the inclusion of height as a second predictor variable decreased the performance of the general model. We have therefore demonstrated that for E. pilularis a general allometric relationship using dbh alone as the predictor variable can be as accurate as site-specific allometry, whilst being applicable to a wide range of environments, management regimes and ages. This simplifies regional estimates of aboveground biomass from inventory measurements, eliminating the need for site-specific allometric relationships or modifiers such as height, wood density or expansion factors.

A Bit of History About Edwin A. Link

I was interested to read the News Focus discussion regarding the fiscal and educational challenges being undertaken by many U.S. marine laboratories, including the Scripps Institution of Oceanography (SIO), Harbor Branch Oceanographic Institution (HBOI) and Woods Hole Oceanographic Institution (WHOI) (“Saving Scripps,” D. Malakoff, 9 July, p. [166][1]). It is important that the contributions of the pioneering engineers and scientists who helped found these institutions not be overlooked, though. For example, the photo caption accompanying the sidebar on p. [167][2] notes that the Harbor Branch submersibles were named after Seward Johnson Sr., but neglects to mention that they were also named after the late Edwin A. Link (1904–81), the engineer and inventor who designed the Johnson-Sea-Link (JSL) submersibles, as well as many other novel marine engineering devices (e.g., the submersible decompression chamber and the first pressurized diver lockout small submersible). Link and Johnson worked hand in hand from their respective engineering and financial backgrounds during the founding and initial operation of HBOI, and the name of the submersibles reflects the importance of their dual contributions. The Link Foundation, established by Ed Link and his wife, Marion, continues to provide vital financial support to Harbor Branch, including sponsorship of their Summer Internship program, which this year celebrates its 30th year of launching the careers of future marine scientists and ocean engineers. [1]: /lookup/doi/10.1126/science.305.5681.166 [2]: /lookup/doi/10.1126/science.305.5681.167

A UV resonance Raman (UVRR) spectroscopic study on the extractable compounds of Scots pine ( Pinus sylvestris) wood : Part I: Lipophilic compounds

The wood resin in Scots pine ( Pinus sylvestris) stemwood and branch wood were studied using UV resonance Raman (UVRR) spectroscopy. UVRR spectra of the sapwood and heartwood hexane extracts, solid wood samples and model compounds (six resin acids, three fatty acids, a fatty acid ester, sitosterol and sitosterol acetate) were collected using excitation wavelengths of 229, 244 and 257 nm. In addition, visible Raman spectra of the fatty and resin acids were recorded. Resin compositions of heartwood and sapwood hexane extracts were determined using gas chromatography. Raman signals of both conjugated and isolated double bonds of all the model compounds were resonance enhanced by UV excitation. The oleophilic structures showed strong bands in the region of 1660–1630 cm −1. Distinct structures were enhanced depending on the excitation wavelength. The UVRR spectra of the hexane extracts showed characteristic bands for resin and fatty acids. It was possible to identify certain resin acids from the spectra. UV Raman spectra collected from the solid wood samples containing wood resin showed a band at ∼1650 cm −1 due to unsaturated resin components. The Raman signals from extractives in the resin rich branch wood sample gave even more strongly enhanced signals than the aromatic lignin.

Biomass and nutrient pools of canopy and terrestrial components in a primary and a secondary montane cloud forest, Costa Rica

Canopy-dwelling epiphytes and their associated dead organic matter exist as complex subsystems of many forests, but they have only rarely been quantified in the context of the whole ecosystem. We assessed the biomass and nutrient capital of canopy-dwelling and terrestrially rooted components of a primary and an adjacent secondary montane forest in Monteverde, Costa Rica. Total aboveground terrestrially rooted biomass (dry weight) was 490.1 and 151 t ha −1 in the primary and secondary forest, respectively. The primary forest supported a total canopy biomass of 33.1 t ha −1; the secondary forest supported only 0.5% of that, 0.2 t ha −1. Trunk and branch epiphyte biomass in the primary forest was over 40 times and 100 times greater than trunk and branch epiphyte biomass in the secondary forest. The bulk (ca. 95%) of the ecosystem biomass is trunk and branch wood, which is slower to decompose than the non-woody, labile components of foliage and non-woody epiphytes. In contrast to the primary forest, where dead organic matter (crown humus, intercepted litterfall) comprised over 60% of the total epiphytic material, there were only trace amounts in the secondary forest. The important ecosystem roles performed by this material in the primary forest (e.g., retention of atmospheric nutrients, habitat for canopy invertebrates, and substrate for wildlife and bird foraging) are virtually absent in the secondary forest canopy.

Adaptive Growth of Gymnosperm Branches-Ultrastructural and Micromechanical Examinations

The top, the lateral and the underside of basal branch segments of two gymnosperm species, spruce (Picea abies [L.] Karst.) and yew (Taxus baccata L.), were studied with respect to possible adaptation in structural and mechanical properties. Microtensile tests were performed on thin wet foils, which were removed from the periphery of the branches. Structural parameters such as density and the microfibril angle in the S2-layer were examined to investigate the structure-function relationships of the branch wood. The top, the lateral and the underside of both branches showed significant differences in their structural and mechanical properties. However, no significant variations were observed as a function of age and size development. The findings were discussed in view of adaptive growth strategies of trees, including biomechanical constraints of a horizontally growing branch.

Breakdown rates of wood in streams

The breakdown rates of natural branch wood were studied in 2 streams (lowland and upland), and the current knowledge on breakdown rates of wood in streams was reviewed. The breakdown coefficient of natural alder branches, k 5 0.0650/y, in an unpolluted upland stream cor- responded well to the few published data on breakdown rates of natural wood substrates in streams. Breakdown rates of Scots pine (Pinus sylvestris, k 5 0.0698/y), bark-covered black alder (Alnus gluti- nosa, k 5 0.0859/y), and debarked black alder branches (k 5 0.0717/y) in a nutrient-rich sandy lowland stream indicated that breakdown rates differ among tree species. Data from the present and previous studies on the breakdown of natural wood and commercial wood products (wood veneer, tongue depressors, ice-cream sticks) showed that breakdown is slower for natural wood than for commercial wood products, in part because the commercial wood products used in the studies had high surface to volume ratios. A strong relationship exists between surface to volume ratio of the substrate and breakdown rates. The breakdown rates of wood in streams were associated with several abiotic factors, including the physical and chemical properties of the wood substrates used, dissolved nutrients, and water temperature. Overall, the review of published breakdown rates emphasized that the current knowledge on the breakdown rates of wood in streams, especially the temporal patterns of microbial activities, is very limited, and heterogeneous experimental designs in previous studies prevent general conclusions. Nevertheless, measuring wood breakdown rates could be a promising tool for practical application in assessment of the ecological integrity of streams.

Tree growth, biomass, allometry and nutrient distribution in Gmelina arborea stands grown in red lateritic soils of Central India

Abstract A chronosequence of Gmelina arborea Roxb. stands ranging from 1 to 6 years old was measured to document changes in growth, biomass and nutrient (N, P and K) contents for three red lateritic sites in Chhattisgarh, India. The stand's density, survival and growth parameters (DBH, total height, crown diameter and number of branches) varied significantly with age and site. The number of stems was highest (789 trees/ha ) in a 1-year-old plantation at site 3 (Kusumi) and lowest (724 trees/ha ) in a 6-year-old stand at site 2 (Anandgoan). Allometric equations for stem wood, branches, leaves and roots to tree diameter at breast height were developed to estimate above ground and below ground tree biomass. The total biomass ranged from 3.9 Mg ha −1 in 1-year-old to 53.7 Mg ha −1 in 6-year-old stand. The stem wood contributed from 55.3% (site 3) to 56.3% (site 1), branch wood from 18.3% (site 2) to 19.8% (site 3), roots from 17.9% (site 3) to 18.5% (site 2) and foliage from 6.6% (site 2) to 7.0% (site 3) of the total biomass. The growth and biomass production were poor from establishment to 3 years age and it increased by 1.5–2 times as the plantation aged from 4–6 years. Nutrient accumulation in tree biomass increased with stand age, following the pattern of biomass accumulation. The total nitrogen accumulation in 6-year-old stands at three sites ranged from 212.9 to 279.5 kg ha −1 with a mean annual storage of 238.4 kg ha −1 and total K ranged from 170.8 to 220.5 kg ha −1 with a mean annual storage of 189.9 kg ha −1 . Phosphorous storage was lowest which ranged from 15.0 to 19.6 kg ha −1 with a mean storage of 16.8 kg ha −1 . The organic matter and nutrients in the soils improved significantly after 6 years of planting. Available N enhanced by 14.9%, 12.0% and 11.3%, K by 10.0%, 9.1% and 10.6%, whereas phosphorous declined by 2.6%, 23.0% and 20.0%, respectively, at soil depths of 0–20, 21–40 and 41– 60 cm . The paper discusses the implications of whole tree harvest at 6 years age for fire/pulpwood.

Non‐structural carbon compounds in temperate forest trees

ABSTRACTThe current carbon supply status of temperate forest trees was assessed by analysing the seasonal variation of non‐structural carbohydrate (NSC) concentrations in leaves, branch wood and stem sapwood of 10 tree species (six deciduous broad‐leafed, one deciduous conifer and three evergreen conifer trees) in a temperate forest that is approximately 100 years old. In addition, all woody tissue was analysed for lipids (acylglycerols). The major NSC fractions were starch, sucrose, glucose and fructose, with other carbohydrates (e.g. raffinose and stachyose) and sugar alcohols (cyclitols and sorbitol) playing only a minor quantitative role. The radial distribution of NSC within entire stem cores, assessed here for the first time in a direct interspecific comparison, revealed large differences in the size of the active sapwood fraction among the species, reflecting the specific wood anatomy (ring‐porous versus diffuse‐porous xylem). The mean minimum NSC concentrations in branch wood during the growing season was 55% of maximum, and even high NSC concentrations were maintained during times of extensive fruit production in masting Fagus sylvestris. The NSC in stem sapwood varied very little throughout the season (cross species mean never below 67% of maximum), and the small reductions observed were not significant for any of the investigated species. Although some species contained substantial quantities of lipids in woody tissues (‘fat trees’; Tilia, Pinus, Picea, Larix), the lipid pools did not vary significantly across the growing season in any species. On average, the carbon stores of deciduous trees would permit to replace the whole leave canopy four times. These data imply that there is not a lot of leeway for a further stimulation of growth by ongoing atmospheric CO2 enrichment. The classical view that deciduous trees rely more on C‐reserves than evergreen trees, seems unwarranted or has lost its justification due to the greater than 30% increase in atmospheric CO2 concentrations over the last 150 years.