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1.
High-density hardwood trees with large diameters have been found to damage manually operated increment borers, thus limiting their use in the tropics. Therefore, we herein report a new, low-cost gasoline-powered sampling system for high-density tropical hardwood trees with large diameters. This system provides increment cores 15 mm in diameter and up to 1.35 m in length, allowing minimally invasive sampling of tropical hardwood tree species, which, up to the present, could not be collected by conventional 5 or 10 mm increment borers. This system provides a single core sample with ample amount of wood for multidisciplinary analyses, including ring width, stable isotope and wood anatomical measurements. The borer never gets stuck inside stems, even in hollowed trees, cores will never twist during coring, and the gasoline drill gives ample flexibility in the field. It is anticipated that the dendrochronological community will find our technique very useful in the pursuit of tropical tree ring research.  相似文献   

2.
A microtome designed for the surface preparation of entire increment cores allows cutting plane surfaces on cores up to a length of 40 cm. Compared to the common sanding procedure, the wood cells of the annual rings remain open, not filled with swarf, and the cell walls are smooth and hence clearly visible. This article aims at describing the functionality of the microtome and the procedures needed for an accurate surface preparation to achieve a good contrast for subsequent image analysis. Possible applications for a more detailed analysis of variations in the tracheid structure of conifers and vessel sizes of oak are presented, which can be included in time series analyses.  相似文献   

3.
《Dendrochronologia》2014,32(2):120-126
The early settlement history of Canada's National Capital Region, including Ottawa (Ontario) and Gatineau (Québec), was shaped in large part by the towering eastern white pine (Pinus strobus) forests that once covered the Ottawa Valley and fuelled a lucrative lumber export industry spanning the 19th and much of the 20th century. Some of the first dwellings and farmsteads of this era are still standing and serve as reminders of this history. A crucial piece of information in the assessment of a structure's heritage value is its date of construction. Unfortunately, this information is not always known and is approximated based on construction styles and other sources of information. In this study, dendroarchaeology methods are applied to constrain the construction dates of six historic structures in the National Capital Region of 19th century vintage. A multi-century (AD 1670–2009) eastern white pine ring-width chronology was developed for dating the study structures using cross sections from sunken logs recovered from the Ottawa River and cores from live trees from the Petawawa Research Forest. The tree-ring inferred construction dates for the six structures ranged from 1830 to 1878. For most structures, historical records about the property or first inhabitants were available to corroborate the results. The ring-width chronologies of the individual structures were well correlated with the regional chronology (ravg = 0.63, p  0.01), and this regional coherence clearly demonstrates the value of tree-rings for heritage structure assessments and reconstructing the settlement history of this region.  相似文献   

4.
Quantitative analysis of wood anatomy is a powerful dendroecological tool to provide new insights into environmental signals encoded in tree-rings. Nevertheless, studies with long time series or large sample sizes are not very common for diffuse-porous tree species due to the laborious sample preparation and image analysis. Finding a compromise between sample size and accuracy of sample estimators is therefore of crucial importance. In this simulation study, we present a subsampling method, which can make the quantitative analysis of wood anatomy of European beech more efficient. Based on our study material we demonstrate that for the parameters vessel size, vessel density, total vessel area and accumulated hydraulic conductivity the environmental signals are captured with high trueness (deviation < 5%) when analysing only a 1 mm wide radial stripe along the increment core. Nevertheless, when information about vessel grouping indices is required, for high trueness of the results a wider radial stripe of ∼2.2 mm needs to be analysed.  相似文献   

5.
The rising discussion on carbon balance of tropical forests often does not consider the sequestration potential of secondary dry forests, which are becoming an increasing importance due to land use change and reforestation. We have developed an easy applicable tool for the estimation of biomass increment of tropical secondary forest stands on the base of tree ring analysis. The existence of annual rings was shown by a combination of anatomical examination and radiocarbon estimations. With tree ring analysis, forest inventories and destructive sampling the above-ground biomass increment of secondary forest stands of age between 9 and 48 years in the dry forest region of Guanacaste, Costa Rica were estimated. The above-ground biomass increment of the tree layer varies between 2.4 and 3.2 Mg/ha yr in different stands. Lianas contribute with up to 23% additional production. Differences in productivity among the stands along a chronosequence were not significant. The measured carbon allocation potential of 1.7–2.1 Mg C/ha yr lies in the range of reported values from other tropical dry forests and old growth humid forests as well.  相似文献   

6.
Tree-ring (TR) chronologies are important instruments for the dating and provenance analyses of historical wood, as well as for climate reconstructions. However, radial growth patterns differ between tree species and growing environments. Therefore chronologies are more or less specific for a certain tree species, region and elevation. Chronologies that are restricted to more confined regions could extend the possibilities for dating, dendroprovenancing and regional climate reconstructions.In Southern Germany, the transport of wood by raft – for the supply of towns and cities with timber – has been documented since early mediaeval times. Consequently, not only local timber from the lowlands was used for construction purposes, but also alpine wood originating from sites up to the timberline. Since pronounced altitudinal gradients cause distinct climate differences, elevation-specific chronologies have the potential to improve dating precision in this region.In this contribution, a model is presented and applied in order to separate elevation-specific provenances of Norway spruce (Picea abies L. Karst) and Silver fir (Abies alba Mill.) in Southern Germany. The model is derived from more than 2100 living TR series originating from sites between 200 and 1710 m above see level. Absolute (mean, maximum) ring-width values and the variation of ring-widths (mean sensitivity) show distinct correlations with their altitudinal provenance, reflecting improvements in growth conditions as well as the increase of their yearly variation from high over intermediate to low elevation sites. Mean ring widths and mean sensitivity values were used as independent parameters in an exponential regression model which exhibits a coefficient of determination (r2) of 77% for spruce and 74% for fir. The prediction accuracy of the elevation amounts ±300 m for spruce and ±200 m for fir within the 95% confidence interval.The model was used to estimate the elevation origin of around 5000 historical spruce and 800 historical fir series from buildings located in Southern Germany. The historical TR series covering the AD 990–1800 period were allocated by the model to elevations between 120 and 2090 m. In a second step the individual TR series were combined to elevation-specific chronologies representing low, intermediate, and high altitudinal belts. The chronologies show distinct differences among the altitudinal belts in terms of signatures and pointer years, especially for spruce. Elevation-specific chronologies are assumed to amplify the dating possibilities of ancient timber, to provide valuable evidences for the origin of historical wood, and to offer more specific proxy data for regional climate reconstructions.  相似文献   

7.
For rural populations in Africa, tree bark is widely used for medicinal purposes. Despite its importance, no anatomical studies exist which detail the recovery of medicinal tree species in Africa to bark harvesting. This present study aims to determine the anatomical variable(s) that could help to predict the differing recovery rates of 12 medicinal tree species. Discs of branches were collected from non-harvested trees of 12 different African species. A total of 12 anatomical variables were measured in the wood, the cambium and the phloem zone, and the correlation between the bark recovery rate and each variable was tested. Among the 12 anatomical variables tested, the thickness of the conducting phloem zone emerged as the most important one to explain the bark recovery rate. The presence of sclereids within the conducting phloem zone was also found to be an explanatory variable and was negatively correlated with the bark recovery rate. For 10 out of the 12 species, the thickness of the cambial zone varied significantly with the season. Nevertheless, this variable did not contribute significantly to the explanation of the bark recovery rate. Given that the 12 studied species showed a large range of bark recovery rates (0.1–10.0 cm y?1), we assume that they may be representative of the variety of wound healing responses (i.e. wood and bark tissue production) in many of African tree species. Consequently, our results could offer the advantage to foresee the potential of wound closure in any tree from which bark could be harvested.  相似文献   

8.
Trees can reach ages that in some cases amount to thousands of years. In the Mediterranean region, olive trees (Olea europaea) have traditionally been considered a particularly long-lived species. The main objective of this study was to assess the age of large olive trees considered to be millenarian and classified as monumental trees in northeastern Spain. We extracted cores of 14 individuals and obtained 8 sections of trees which had already been cut in the area where the largest olive trees in the northeastern Iberian Peninsula are found. The age of the sampled olive trees was assessed by counting the number of annual growth rings. Tree rings did not cross-date well, neither within nor between individuals, but boundaries between likely annual rings were clearly distinct. We found a linear relationship between DBH and tree age (in years) (Age = 2.11 × diameter(cm) + 88.93, R2 = 0.80), which was used to estimate the age of unsampled olive trees. The maximum estimated age (627 ± 110 years) is among the greatest ages reported for olive trees around the world (700 years) and among the oldest trees in Mediterranean ecosystems.  相似文献   

9.
We present a network of thirteen annual ring-width chronologies from high elevation whitebark pine (Pinus albicaulis Engelm.) sites in the western Canadian Cordillera in order to assess the dendroclimatic potential of this long-lived tree species. The temperature signal within the chronologies is complex and strongly influenced by diverging trends in the summer temperature and ring-width records from across the region. A first differences transformation of the tree-ring and temperature records illustrates a loss of frequency coherence in growth response to summer temperatures following reduced radial growth in the 1950s. Prior to reduced growth, we note a positive association with summer temperatures for both first differenced (rd = 0.60) and traditional (r = 0.50) records. Following reduced growth, the association at first differences is maintained (rd = 0.49) whereas there is a change in the lower frequency component of tree growth response to summer temperatures (r = ?0.34). We suggest the cause of this reduced temperature sensitivity is related to the interaction between diurnal temperature and cloud cover patterns, the hydrological regime of snowpack, and site conditions which have been amenable to the initiation of moisture stress during the latter half of the 20th century. Reduced radial growth is coincident with the arrival of white pine blister rust (Cronatium ribicola J.C. Fisch. ex Raben) into the study region which suggests this infestation may be related to the observed reduction in radial growth. Whitebark pine has considerable potential for the field of dendroclimatology. Unfortunately, the decline of the species due to the combined effects of climate change, white pine blister rust, mountain pine beetle (Dendroctonus ponderosae Hopk.), and forest fire exclusion practices indicate this potential may remain unfulfilled.  相似文献   

10.
Ultrasound can be used to study tendon movement. However, measurement of tendon movement is mostly based on manual tracking of anatomical landmarks such as the musculo-tendinous junction, limiting the applicability to a small number of muscle-tendon units. The aim of this study was to quantify tendon displacement without anatomical landmarks using a speckle tracking algorithm optimized for tendons in long B-mode image sequences. A dedicated two-dimensional multi-kernel block-matching scheme with subpixel motion estimation was devised to handle large displacements over long sequences. The accuracy of the tracking on porcine tendons was evaluated during different displacements and velocities. Subsequently, the accuracy of tracking the flexor digitorum superficialis (FDS) of a human cadaver hand was evaluated. Finally, the in-vivo accuracy of the tendon tracking was determined by measuring the movement of the FDS at the wrist level. For the porcine experiment and the human cadaver arm experiment tracking errors were, on average, 0.08 and 0.05 mm, respectively (1.3% and 1.0%). For the in-vivo experiment the tracking error was, on average, 0.3 mm (1.6%). This study demonstrated that our dedicated speckle tracking can quantify tendon displacement at different physiological velocities without anatomical landmarks with high accuracy. The technique allows tracking over large displacements and in a wider range of tendons than by using anatomical landmarks.  相似文献   

11.
A rupture-prone carotid plaque can potentially be identified by calculating the peak cap stress (PCS). For these calculations, plaque geometry from MRI is often used. Unfortunately, MRI is hampered by a low resolution, leading to an overestimation of cap thickness and an underestimation of PCS. We developed a model to reconstruct the cap based on plaque geometry to better predict cap thickness and PCS.We used histological stained plaques from 34 patients. These plaques were segmented and served as the ground truth. Sections of these plaques contained 93 necrotic cores with a cap thickness <0.62 mm which were used to generate a geometry-based model. The histological data was used to simulate in vivo MRI images, which were manually delineated by three experienced MRI readers. Caps below the MRI resolution (n = 31) were (digitally removed and) reconstructed according to the geometry-based model. Cap thickness and PCS were determined for the ground truth, readers, and reconstructed geometries.Cap thickness was 0.07 mm for the ground truth, 0.23 mm for the readers, and 0.12 mm for the reconstructed geometries. The model predicts cap thickness significantly better than the readers. PCS was 464 kPa for the ground truth, 262 kPa for the readers and 384 kPa for the reconstructed geometries. The model did not predict the PCS significantly better than the readers.The geometry-based model provided a significant improvement for cap thickness estimation and can potentially help in rupture-risk prediction, solely based on cap thickness. Estimation of PCS estimation did not improve, probably due to the complex shape of the plaques.  相似文献   

12.
13.
Smoke stimulates seed germination of a range of species from ecosystems that may or may not be fire prone. We evaluated the effects of smoke-water on germination of ten tree species of economic value in the Amazon region. Two materials were burnt to produce smoke-water: germination paper and the wood of Cecropia palmata Willd. Seven dilutions of the solutions were tested. Seeds of nine forest trees were germinated under controlled laboratory conditions (25 °C ± 2 °C) in the laboratory. Bertholletia excelsa Humb. & Bonpl., was tested in the nursery (approximately 25–36 °C) because of its large seeds. Irrespective of the material burned, smoke-water significantly increased seed germination of three species: Cordia goeldiana Hub., Ochroma pyramidale (Cav. ex Lam.) Urb. and Jacaranda copaia (Aubl.) D. Don. and there was a significant inhibitory effect on Swietenia macrophylla King. Germination was accelerated by smoke in J. copaia, B. excelsa and Bellucia grossularioides (L.) Triana. The most pronounced effect was observed in B. excelsa, as the mean germination time of 108 d (control) was reduced to 76 d with smoke-water made from germination paper (dilution of 1:25) and to 61 d with the one from Cecropia wood (dilution of 1:250). For five of the ten species studied, smoke-water either increased or accelerated seed germination, irrespective of the materials used for its production. Seeds with low vigour and prolonged germination time seemed to be more receptive to smoke.  相似文献   

14.
QuestionsUncertainty in detecting disturbance histories has long been ignored in dendrochronological studies in forest ecosystems. Our goal was to characterize this uncertainty in relation to the key parameters of forest ecosystems and sample size. In addition, we aimed to provide a method to define uncertainty bounds in specific forest ecosystems with known parameters, and to provide a required (conservative) minimal sample size to achieve a pre-defined level of uncertainty if no actual key forest parameters are known.LocationTraining data were collected from Žofínský Prales (48°40′N, 14°42′E, 735–830 m a.s.l., granite, Czech Republic).MethodsWe used probability theory and expressed uncertainty as the length (the difference between the upper and lower bounds) of the 95% confidence interval. We studied the uncertainty of (i) the initial growth of trees – if they originated under canopy or in a gap; and (ii) the responses to disturbance events during subsequent growth – on the basis of release detection in the radial growth of trees. These two variables provide different information, which together give a picture of the disturbance history. While initial growth date the existence of a gap in a given decade (recent as well as older gaps are included), release demonstrates the moment of a disturbance event.ResultsWith the help of general mathematical deduction, we have obtained results valid across vegetation types. The length of a confidence interval depends on the sample size, proportion of released trees in a population, as well as on the variability of tree layer features (e.g., crown area of suppressed and released trees).ConclusionsMost studies to date have evaluated the initial growth of trees with higher uncertainty than for canopy disturbed area. The length of the 95% confidence interval for detecting initial growth has been rarely shorter than 0.1 (error ± 5%) and has mostly been much longer. To reach 95% confidence interval length of 0.1 (error ± 5%) when detecting the canopy disturbed area, at least 485 tree cores should be evaluated in studied time period, while to reach a 0.05 interval length (error ± 2.5%) at least 1925 tree cores are required. Our approach can be used to find the required sample size in each specific forest ecosystem to achieve pre-defined levels of uncertainty while detecting disturbance history.  相似文献   

15.
Live oak (Quercus virginiana Mill.) is a long lived, broadleaf, evergreen species native to the lower Coastal Plain of the southern and southeastern United States and is frequently planted in the urban environment. However, live oak has received limited attention for its potential for dendrochronological analyses possibly because its growth-ring boundaries may be less defined due to the absence of a distinct dormancy period. The objective of this explorative study was to determine whether live oak rings in both urban and historic trees could be accurately identified and measured for dendrochronological applications. One hundred urban live oaks were assessed as well as four cross-sectional specimens from historic sites in the southeastern United States. Age of all cored live oak ranged from 7 to 29 (average = 16.8 rings), while cross-sections were taken from trees with an average age of 175 years. A chronology was created from cores that had the highest interseries correlations (n = 27), resulting in an average interseries correlation of 0.654. The analysis of live oak cross sections revealed that the rings on live oak are very faint and barely discernible, delimited mainly by a faint row of earlywood vessels with no or barely visible terminal parenchyma. Rings on these sections were erratic (i.e., fading out along the circumference) and non-concentric (i.e., a particular ring could be both wide and narrow at certain points along the circumference) so that any attempt to measure the rings on opposing radii would have produced meaningless results. However, based on the results of this study, we conclude that the dendrochronological analysis of live oak is possible with careful sample preparation and analysis and that results would be reliable, even for urban trees. Results of this study suggest that urban tree-ring series with higher interseries correlations were more vigorous than those with lower values, suggesting that urban environmental stresses related to individual sites may decrease the usefulness of crossdating techniques for evaluating annual rings on younger, urban trees.  相似文献   

16.
《Dendrochronologia》2014,32(2):153-161
The use of tree-ring data in carbon cycle research has so far been limited because traditional study designs are not geared toward quantifying forest carbon accumulation. Existing studies that assessed biomass increment from tree rings were often confined to individual sites and used inconsistent sampling schemes. We applied a consistent biomass-oriented sampling design at five managed forest sites located in different climate zones to assess the annual carbon accumulation in above-ground woody tissues (i.e. stems and branches) and its climate response. Radial growth and biometric measurements were combined to reconstruct the annual biomass increment in individual trees and upscaled to the site level. In addition to this, we estimated that 32–60 trees are required at these five sites to robustly quantify carbon accumulation rates. Tree dimensions and growth rates varied considerably among sites as a function of differing stand density, climatic limitations, and management interventions. Accordingly, mean site-level carbon accumulation rates between 65 g C m−2 y−1 and 225 g C m−2 y−1 were reconstructed for the 1970–2009 period. A comparison of biomass increment with the widely used basal area increment (BAI) revealed very similar growth trends but emphasized the merits of biomass assessments due to species-specific BAI/biomass relationship. Our study illustrates the benefits and challenges of combining tree-ring data with biometric measurements and promotes the consistent application of a standardized sampling protocol across large spatial scales. It is thus viewed as a conceptual basis for future use of tree-ring data to approach research questions related to forest productivity and the terrestrial carbon balance.  相似文献   

17.
This study aimed to identify some socioeconomic factors affecting local people in central Riyadh area for the utilization of wood and other energy sources in cooking and heating in order to develop some recommendations for conserving woodlands. The study results revealed that gas is the most common energy source used for cooking with a mean usage level of 2.79 (SD = 0.58). On the other hand, wood ranked first for heating with the highest mean, usage level of 1.90 (SD = 1.06). However, electricity and gas as sources of energy for heating ranked second and third with mean usage level of 1.81 and 0.80 respectively. The study revealed that local people with the university education were significantly making higher use of electricity for both cooking and heating and those with no formal education ranked the highest on wood use for both cooking and heating. In addition, those living in traditional houses significantly used more wood for cooking than those living in villas and apartments. Also, local people with high income levels significantly were using more electricity for heating than others. The study recommended conducting extension and environmental awareness raising programs to enhance local residents’ adoption of wood substitutes, promoting employment opportunities for unemployed locals, and subsidizing prices of alternative energy sources.  相似文献   

18.
Loss of nitrate in subsurface drainage water from agricultural fields is an important problem in the Midwestern United States and elsewhere. One possible strategy for reducing nitrate export is the use of denitrification bioreactors. A variety of experimental bioreactor designs have been shown to reduce nitrate losses in drainage water for periods up to several years. This research reports on the denitrification activity of a wood chip-based bioreactor operating in the field for over 9 years. Potential denitrification activity was sustained over the 9-year period, which was consistent with nitrate removal from drainage water in the field. Denitrification potentials ranged from 8.2 to 34 mg N kg?1 wood during the last 5 years of bioreactor operation. Populations of denitrifying bacteria were greater in the wood chips than in adjacent subsoil. Loss of wood through decomposition reached 75% at the 90–100 cm depth with a wood half-life of 4.6 years. However, wood loss was less than 20% at 155–170 cm depth and the half-life of this wood was 36.6 years. The differential wood loss at these two depths appears to result from sustained anaerobic conditions below the tile drainage line at 120 cm depth. Pore space concentrations of oxygen and methane support this conjecture. Nitrous oxide exported in tile water from the wood chip bioreactor plots was not significantly higher than N2O exports in tile water from the untreated control plots, and loss of N2O from tile water exiting the bioreactor accounted for 0.0062 kg N2O-N kg?1 NO3-N.  相似文献   

19.
We used formalin-fixed paraffin-embedded (FFPE) materials for biomarker discovery in cases of lung cancer using proteomic analysis. We conducted a retrospective global proteomic study in order to characterize protein expression reflecting clinical stages of individual patients with stage I lung adenocarcinoma without lymph node involvement (n = 7). In addition, we studied more advanced stage IIIA with spread to lymph nodes (n = 6), because the degree of lymph node involvement is the most important factor for staging. FFPE sections of cancerous lesions resected surgically from patients with well-characterized clinical history were subjected to laser microdissection (LMD) followed by Liquid Tissue? solubilization and digestion trypsin. Spectral counting was used to measure the amounts of proteins identified by shotgun liquid chromatography (LC)/tandem mass spectrometry (MS/MS). More than 500 proteins were identified from IA and IIIA cases, and non-parametric statistics showed that 81 proteins correlated significantly with stage IA or IIIA. A subset of those proteins were verified by multiple-reaction monitoring mass spectrometric quantitation (MRM assay), described in other paper in this issue. These results demonstrated the technical feasibility of a global proteomic study using clinically well documented FFPE sections, and its possible utility for detailed retrospective disease analyses in order to improve therapeutic strategy.  相似文献   

20.
Tree rings of eastern red cedar (Juniperus virginiana L.) were examined from cores extracted from two log cabins located at the Wynnewood State Historic Site in Castalian Springs, Sumner County, Tennessee. One cabin was reportedly built by the first explorer in the area, Isaac Bledsoe, sometime between 1772 and his death in 1793. The second cabin was known as Spencer's Cabin after the first settler of the region, Thomas Sharp Spencer, who lived in the immediate vicinity from 1776 to 1779. The goal of this research was to determine the probable construction year(s) for both cabins and determine whether Bledsoe and Spencer did indeed build these structures. Forty-one cores were extracted from Bledsoe's Cabin, and 30 were used for crossdating and building a floating chronology using COFECHA. The Bledsoe's Cabin chronology was then statistically and graphically crossdated using the eastern red cedar reference tree-ring chronology (ITRDB #TN031) from Norris Dam, Tennessee. We found a statistically significant correlation (r = 0.42, t = 4.18, n = 85, p < 0.0001) between the Bledsoe's Cabin chronology and the reference chronology, anchoring the chronology between 1720 and 1804, with nearly all cores indicating tree harvesting between February and April 1805. Twenty-two cores were extracted from Spencer's Cabin, and 17 were used to build a floating chronology for the cabin. Again, we found a statistically significant correlation (r = 0.44, t = 4.85, n = 100, p < 0.00001) with the reference chronology, which anchored the Spencer's Cabin chronology between 1726 and 1825. All trees appear to have been harvested between February and August in 1826. Therefore, neither structure was built by its historical namesake. No known historical documents suggest who the potential builders were, although the property was owned between ca. 1797 and 1829 by General James Winchester. He and his family, however, never resided on the Wynnewood property because Winchester had built a large multi-room structure in nearby Gallatin, Tennessee, by 1802.  相似文献   

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