Carbon allocation in a Costa Rican dry forest derived from tree ring analysis

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.     

A method for determining knotty core sizes of standing Pinus patula trees based on tree ring sampling

The objectives of this study were to develop and assess a method of using tree ring measurements in standing pruned Pinus patula trees for modelling the knotty core of the pruned section of a tree and to assess variability in knotty core diameters in the tree stem. A total of 170 trees from 17 compartments on a wide variety of growth sites from the Mpumalanga escarpment in South Africa were selected and destructively sampled. We show that ring width measurements at breast height can be used to predict growth in the upper pruned section which in turn can be used to reconstruct the internal knotty core through the full pruned section of the log.Analysis of variation for the entire data set from ring width measurements showed that there was far greater variation in knotty core percentages (the percentage of diameter occupied by knotty core) between different compartments than within compartments. Within a tree, the knotty core percentages between three stem sections, 0.0–2.4 m, 2.4–4.8 m, and 4.8–7 m, differed significantly. As expected the knotty core percentages were found to increase from the bottom section (49.1%) to the top section (65.4%).A comparison of the actual measured knotty core size and the modeled knotty core size of a sub-sample of trees showed only a modest relationship (R² = 0.62). Reasons for this might be variability in pruning quality, inaccurate pruning records, nodal swellings, and the methodology used to measure the actual knotty core sizes.Knowledge of knotty core sizes can be used as a decision aid in the forest and forest products industry.     

Toward consistent measurements of carbon accumulation: A multi-site assessment of biomass and basal area increment across Europe

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.     

Simulation study to determine necessary sample sizes for image analysis-based quantitative wood anatomy of vessels of beech (Fagus sylvatica)

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.     

Loss of aboveground forest biomass and landscape biomass variability in Missouri,US

Disturbance regimes and forests have changed over time in the eastern United States. We examined effects of historical disturbance (circa 1813 to 1850) compared to current disturbance (circa 2004 to 2008) on aboveground, live tree biomass (for trees with diameters ≥13 cm) and landscape variation of biomass in forests of the Ozarks and Plains landscapes in Missouri, USA. We simulated 10,000 one-hectare plots using random diameters generated from parameters of diameter distributions limited to diameters ≥13 cm and random densities generated from density estimates. Area-weighted mean biomass density (Mg/ha) for historical forests averaged 116 Mg/ha, ranging from 54 Mg/ha to 357 Mg/ha by small scale ecological subsections within Missouri landscapes. Area-weighted mean biomass density for current forests averaged 82 Mg/ha, ranging from 66 Mg/ha to 144 Mg/ha by ecological subsection for currently forested land. Biomass density of current forest was greater than historical biomass density for only 2 of 23 ecological subsections. Current carbon sequestration of 292 TgC on 7 million ha of forested land is less than half of the estimated historical total carbon sequestration of 693 TgC on 12 million ha. Cumulative tree cutting disturbances over time have produced forests that have less aboveground tree biomass and are uniform in biomass compared to estimates of historical biomass, which varied across Missouri landscapes. With continued relatively low rates of forest disturbance, current biomass per ha will likely increase to historical levels as the most competitive trees become larger in size and mean number of trees per ha decreases due to competition and self-thinning. Restoration of large diameter structure and forested extent of upland woodlands and floodplain forests could fulfill multiple conservation objectives, including carbon sequestration.     

Diversity and spatial clustering of shade trees affect cacao yield and pathogen pressure in Costa Rican agroforests

The importance of the spatial organisation of individuals in explaining species coexistence within a community is widely recognised. However, few analyses of spatial structure have been performed on tropical agroforests.The main objective of this study was to highlight the links between spatial organisation of shade trees on the one hand, and shade tree species richness and cacao yield on the other, using data from 29 cacao agroforests in Costa Rica.A method of spatial statistics, Ripley's K-function, was used to analyse the spatial organisation of shade and cacao trees in the study plots. For each stand, the X and Y coordinates of ≥2.5-m-tall trees were recorded. In each plot we also assessed shade tree species richness and cacao yield (with total number of pods = number of pods damaged by frosty pod rot + number of healthy pods).Three types of stands were identified: the first was characterised by significant clustering of shade trees, the highest shade tree species richness (S = 6), and the highest number of damaged pods (139 pods ha^?1 year^?1). The second type was characterised by random spatial organisation of shade trees. The third type showed a trend towards regular organisation. Species richness of shade trees did not differ significantly between the last two types (S = 4 for both), nor did the number of damaged pods (56 pods ha^?1 year^?1 and 67 pods ha^?1 year^?1 respectively).Although the trends were not statistically significant for all the variables in our data set, the clustered spatial structure appears to favour a synergy between environmental (tree species richness), and provisioning (cacao production) services.     

The age of monumental olive trees (Olea europaea) in northeastern Spain

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.     

Effects of experimental stem burial on radial growth and wood anatomy of pedunculate oak

In dendrogeomorphology, abrupt changes in wood anatomy are frequently used to date the exact year of burial and exposure events. However, few studies have addressed the precision and underlying mechanisms of these changes. In a field experiment, performed in a drift-sand area in the Netherlands, we buried the stems of mature pedunculate oak trees (Quercus robur L.) up to a height of 50 cm and analysed the responses in ring width and earlywood-vessel characteristics, while monitoring the course of temperature above and below the soil surface.After 3 years of stem burial, we found no significant differences in ring width and earlywood-vessel characteristics between control and buried trees both above and below the burial level. Burial however strongly reduced temperature amplitude and the occurrence of sub-zero temperatures around the buried stems. All buried trees formed epitropic roots that grew upward into the new sediment layer, but no adventitious roots were formed on the buried stems. Irrespective of the burial treatments, we found that the mean ring width was largest at the original stem base and lowest at breast height. In contrast, vessel sizes were significantly larger at breast height compared with the stem base. Differences in vessel density barely differed between years and heights.In our field experiment on mature pedunculate oak trees, the burial of stems by 50 cm of drift sand did not induce any local growth suppression or detectable changes in wood anatomy. As wood-anatomical changes in response to burial have previously been reported for trees that had formed adventitious roots, we stress the role of adventitious-root formation as a possible trigger behind the local changes in wood anatomy, reflecting a functional change of a buried stem towards a root. Based on our field experiment, it seems unlikely that years of shallow or moderate burial events (≤50 cm) can be reconstructed using the wood structure of buried stems. As epitropic roots develop quickly after burial, dating such roots may potentially yield better estimates of burial events. Further research on the relation between adventitious root and changes in stem anatomy is needed to ascertain the precision of dating sand-burial events using tree rings.     

Tree age,site and climate controls on tree ring cellulose δ18O: A case study on oak trees from south-western France

A main concern of dendroclimatic reconstruction is to distinguish in the tree ring proxy the influence of the climate variables of interest from other controlling factors. In order to investigate age, site and climate controls on tree ring width and cellulose δ¹⁸O, measurements have been performed in nearby groups of young (145 years old) and older (310–405 years old) oak trees in south-western France, covering the period 1860–2010.Within a given site, inter-tree deviations are small, pointing to a common climatic signal. Despite a similar inter-annual variability, the average level of cellulose δ¹⁸O in the young tree group is ∼0.8‰ higher than in the old trees. Such offsets might be caused by different soil properties and differences in the fraction of the source water used by trees from different depths. The δ¹⁸O of water in the top soil layer is directly related to the current growing season precipitation, while deeper water can have a lower and more constant δ¹⁸O. Local cave drip waters at 10 m depth indeed show a constant isotopic composition, which corresponds to pluri-annual mean precipitation.A 2‰ increasing trend is observed in cellulose δ¹⁸O of young trees in the first 30 years of growth, during a period when no trend is visible in older trees. This increase can be quantitatively explained by humidity gradients under the forest canopy, and a changing microclimate around the crown as trees grow higher.While relationships between tree ring width and climate appear complex, the isotopic composition of cellulose is strongly correlated with summer maximum temperature, relative humidity and evapotranspiration (r ≈ 0.70). Weaker correlations (r ≈ 0.40) are identified with precipitation δ¹⁸O from a 15-year long local record and from the REMOiso model output. These results imply that leaf water enrichment has a stronger control on the inter-annual variability of cellulose δ¹⁸O than the δ¹⁸O of precipitation.This study demonstrates the suitability of oak tree ring cellulose δ¹⁸O for reconstructing past summer climate variability in south-western France, provided that the sampling and pooling strategy accounts for the fact that trees from different sites and of different age can introduce non-climatic signals.     

Tree species diversity and community composition in a human-dominated tropical forest of Western Ghats biodiversity hotspot,India

The structure, function, and ecosystem services of tropical forest depend on its species richness, diversity, dominance, and the patterns of changes in the assemblages of tree populations over time. Long-term data from permanent vegetation plots have yielded a wealth of data on the species diversity and dynamics of tree populations, but such studies have only rarely been undertaken in tropical forest landscapes that support large human populations. Thus, anthropogenic drivers and their impacts on species diversity and community structure of tropical forests are not well understood. Here we present data on species diversity, community composition, and regeneration status of tropical forests in a human-dominated landscape in the Western Ghats of southern India. Enumeration of 40 plots (50 m × 20 m) results a total of 106 species of trees, 76 species of saplings and 79 species of seedlings. Detrended Correspondence Analysis ordination of the tree populations yielded five dominant groups, along disturbance and altitudinal gradients on the first and second axes respectively. Abundant species of the area such as Albizia amara, Nothopegia racemosa and Pleiospermum alatum had relatively few individuals in recruiting size classes. Our data indicate probable replacement of rare, localized, and old-growth ‘specialists’ by disturbance-adapted generalists, if the degradation is continuing at the present scale.     

Biomass storage and stand structure in a conservation unit in the Atlantic Rainforest—The role of big trees

This study represents a small-scale approach to forest structure and biomass in the Atlantic Rainforest in Brazil and provides information on an ecosystem in which there still is a lack of data in this regard.The project was carried out in the National Park “Serra dos Orgãos” in the state of Rio de Janeiro, which is one of the largest remnants of continuous forest in this area. This forest is marked by a mosaic of forest types differing in tree composition and structure. Within this heterogeneous habitat the stand structure in three investigation plots was assessed to estimate the above-ground dry biomass (AGB) for all trees with a dbh ≥ 5 cm.This study indicates the structural diversity of the Atlantic Rainforest. Trees with a dbh > 30 cm were represented by 6% of all sampled individuals (18 out of 318 trees), but contributed 72% of total estimated AGB. The results suggest that big trees in the Atlantic Rainforest may contribute more into total AGB as reported for other tropical rainforests. Small-scale structural approaches like this study are able to form an initiating framework of more detailed results and help to improve estimates on biomass amounts and therefore on carbon storage capacity.     

The historical dendroarchaeology of two log structures at the Wynnewood State Historic Site,Castalian Springs,Tennessee, USA

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.     

Ecology and evolution of Devonian trees in New York,USA

The first trees in New York were Middle Devonian (earliest Givetian) cladoxyls (?Duisbergia and Wattieza), with shallow-rooted manoxylic trunks. Cladoxyl trees in New York thus postdate their latest Emsian evolution in Spitzbergen. Progymnosperm trees (?Svalbardia and Callixylon–Archaeopteris) appeared in New York later (mid-Givetian) than progymnosperm trees from Spitzbergen (early Givetian). Associated paleosols are evidence that Wattieza formed intertidal to estuarine mangal and Callixylon formed dry riparian woodland. Also from paleosols comes evidence that Wattieza and Callixylon required about 350 mm more mean annual precipitation than plants of equivalent stature today, that Wattieza tolerated mean annual temperature 7 °C less than current limits of mangal (20 °C), and Callixylon could tolerate temperatures 14 °C less than modern mangal. Devonian mangal and riparian woodland spread into New York from wetter regions elsewhere during transient paleoclimatic spikes of very high CO₂ (3923 ± 238 ppmv), and subhumid (mean annual precipitation 730 ± 147 mm) conditions, which were more likely extrinsic atmospheric perturbations rather than consequences of tree evolution. For most of the Middle Devonian CO₂ was lower (2263 ± 238 ppmv), and paleoclimate in New York was semiarid (mean annual precipitation 484 ± 147 mm). Such transient perturbations and immigration events may explain the 40 million year gap between the late Emsian (400 Ma) evolution of trees and Famennian (360 Ma) CO₂ drawdown and expansion of ice caps.     

Uncertainty in detecting the disturbance history of forest ecosystems using dendrochronology

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.     

Preparing micro sections of entire (dry) conifer increment cores for wood anatomical time-series analyses

The type of samples most commonly used in dendro sciences are increment cores of conifers. These cores allow for an easy determination and measurement of ring-width variations over long time periods. For wood anatomical analyses, the cores have to be split into pieces to enable the preparation of high quality micro sections for detailed measurements of cell properties. A major drawback of this procedure is the fact that it is labor intensive and time consuming. We present a new technique enabling the preparation of micro sections of entire increment cores up to a length of 40 cm. For that purpose we combined standard wood-anatomical techniques with the application of Mowiol glue and common Tesa tape. We tested the introduced method on increment cores of Larix decidua Mill. sampled years ago for ring-width analyses to reanalyze them on a microscopic level. The ability to cut these long sections will tremendously reduce the time needed to prepare micro sections. This is of special interest for wood anatomical image analyses of cores used before to create long ring-width chronologies for any kind of environmental reconstructions.     

Advances in increment coring system for large tropical trees with high wood densities

Incremental coring of trees is the key method used in non-destructive dendrochronological sampling. Despite the advances in developing such methods, the sampling of large, high-density trees still poses a challenge in remote tropical forests. Manually operated incremental drills, while easy to transport across difficult terrain, limit sample size and can often get damaged in the sampling process, especially when trees have wood densities above 0.8 g/cm³. Here, we discuss the existing available alternatives and present an up-to-date incremental coring system composed of a borer coupled to a hand-held drilling machine and a support attached to the tree which can collect incremental cores of 1.5 mm in diameter and over 1.0 m in length. The support ensures stability for the drill throughout the sampling process. This system is relatively lightweight and portable, offering field flexibility and suitability for sampling in remote locations. It provides a core sample of an appropriate diameter and amount for carrying out ring-width measurements, stable isotope and radiocarbon analyses on some of the large, older trees which are now being found in the tropics. We expect that this methodology will broaden the possibilities in the now-blossoming sub-field of tropical dendrochronology.     

Pacemaker Failure Due to Loss of Fluid Seal in a Patient with a 5/6 mm Pacemaker Header Port and a 5 mm Unipolar Lead

IntroductionBefore IS-1 (3.2 mm) standardization of pacemaker leads and connectors, 5/6 mm connector ports accomodated 5 mm or 6 mm diameter lead connector pins.Case reportA patient with sick sinus syndrome underwent implantation of a 5 mm unipolar atrial lead, mated to a 5/6 mm connector port Medtronic Spectrax Sx 5985 pacemaker. Pulse generator reached ERI in 2006, with change out to a Medtronic Sigma SSR306 (5/6 mm connector port) and preservation of the 5 mm lead. She was admitted in 2010 for atrial lead non capture from blood leak and corrosion of the header-connector pin apparatus.Discussion5/6 mm pacemaker header ports have a 5 mm flexible sealing ring at the port entrance to seal 5 mm or 6 mm lead connector pins. The inner barrel diameter of the connector port is 6 mm and insertion of a 5 mm lead results in a 0.5 mm tolerance circumferentially. Should the seal be compromised, blood can corrode the apparatus. To minimize this, we can employ (a) a cinching tie to further seal the silicone ring (b) universal adaptor sleeves (c) splice kits (d) lead adaptor kits. Aging leads, adaptor kits or sleeves themselves can result in lead failure. It may be safer to re-implant the entire system.ConclusionA 5/6 mm configuration pacemaker header connector port allows for significant tolerances when a 5 mm lead is used. Consideration must be made to prevent leaks.     

Tree species composition rather than diversity triggers associational resistance to the pine processionary moth

The reduction of insect herbivory is one of the services provided by tree diversity in forest ecosystems. While it is increasingly acknowledged that the compositional characteristics of tree species assemblages play a major role in triggering associational resistance to herbivores, underlying mechanisms are less well known. We addressed this question in the ORPHEE experiment by assessing pine processionary moth infestations (Thaumetopoea pityocampa) across a tree diversity gradient from pine monocultures to five species mixtures. We showed that tree species richness per se had no effect on the probability of attack by this pest. By contrast, the infestation rate was strongly dependent on plot composition. Mixtures of pines (Pinus pinaster) and birches (Betula pendula) were less prone to T. pityocampa infestations, whereas mixtures of pines and oaks (Quercus spp.) were more often attacked than pine monocultures. By taking into account the relative height of pines and associated broadleaved species, this effect could be explained by pine apparency. Pines were on average 343 ± 5 cm height. Birches, as fast growing trees, were slightly taller than pines (363 ± 6 cm), while oak trees were significantly smaller (74 ± 1 cm). Host trees of T. pityocampa were then partly hidden in mixtures of pines and birches but more apparent in mixtures with oaks. We suggest that reduced pine apparency disrupted visual cues used by female moths to select host trees prior to oviposition. This study highlights the need to take into account tree traits such as growth rate when selecting the tree species that have to be associated in order to improve forest resistance to pest insects.