The enigma on the date of the 79 AD Vesuvius eruption: lesson from grape archaeobotanical remains

<p>The sites destroyed by the eruption of Mt. Vesuvius (southern Italy) in AD 79 provide a complete picture of life in Campania during the 1<sup>st</sup> century AD. Among the archaeological areas, the Vesuvian region constitutes an exceptional case for the wealth of botanical remains. The presence and quantity of these materials in the Vesuvian area depend on the heat of volcanic materials such as the fallout of pumice, ash and gas emitted during the eruption. Therefore, this eruption has determined, together with archaeological finds, the preservation of thousands of botanical remains represented especially by food plants like cereals (i.e. T<em>riticum dicoccum; Hordeum vulgare; Setaria italica</em>) and pulses (i.e. <em>Vicia faba</em> var. <em>minor</em>; <em>Lens culinaris</em>), olive (<em>Olea europaea</em> var. <em>europaea</em>) and grape remains (<em>Vitis vinifera</em> subsp. <em>vinifera</em>). The eruption date is still matter of discussion. Indeed, the classical theory according to the story described by Pliny the Young indicates the 24 August as the date of eruption, while recently some scholars hypothesize that the correct day is the 24 October 79 AD. The discrepancy is probably due to a wrong medieval transcription of the original text by Pliny. Some botanical remains might help solve this  dispute. For example, the analysis of wood anatomical traits can be targeted to detect how much of the yearly wood increment had been produced at the time of eruption. Also the variation of the conduit anatomical traits in the last wood increment might be an indicator to reconstruct the season when the vines were destroyed. In this study, we used leaf and wood remnants of <em>V. vinifera</em> to determine the phenological phase of the vines at the time of eruption in order to provide evidence for supporting one of the two hypotheses. More specifically, a morpho-anatomical characterization was carried out on wood samples coming from Herculaneum ruins (Ercolano), and on tendrils and leaves with evidence of pruning coming from Oplontis site (Torre Annunziata). This study case is a proof of concept of the application potential of a trait-based approach in palaeobotany.</p>

Components of the Increment Dynamics of Early and Late Wood of Quercus robur Stem in the Upland Oak Forest of the Southern Forest-Steppе

The stem radial increment contains information on the tree growth, development, and condition. The early and late wood increment has essential features. The increment dynamics contains monotonous and cyclic components. Retrospective and predictive assessments of growth and development of a tree and a stand based on the patterns of radial increment are possible. The purpose of the article is to analyze the properties of the components and their contribution to the increment dynamics of oak early and late wood, depending on the favorability of growth period and the crown development. The research object was the artificial upland oak forest of the first quality class (pure in composition). Two periods of growth were considered: 1st – favorable (1968–1996) and 2nd – unfavourable (1997–2014). We studied three groups of oak, each group of 10 trees. The groups were distinguished by the development of crown (original classification) and its dynamics. The stem cores were taken at a height of 1.3 m from the southeast side. Indicators of radial increment were defined in the images of cores scanned at 1200 dpi resolution. Three components of the dynamics were identified: a long-term trend and cyclic components with 12- and 2–5-year cycles. The variability of cyclic components of the dynamics of early wood increment was more than twice lower, than that of the late wood. The contribution of the component with 2–5-year cyclicity to the dynamics of early and late wood increment prevails during the favorable period of growth. The contribution of the component with 12-year cyclicity increases during the unfavorable period and the more, the less developed the crowns. The transition of the radial increment to a lower level occurred during the minimum of the component with 12-year cyclicity. There is no significant correlation between early and late wood increment of the component with 2–5-year cyclicity, which makes the major contribution to their ratio. The correlation between early and late wood increment of other components is closer during the unfavorable period and with a decline in crown development. The correlation between the early and late wood increment of the previous year is closer than that of the same year.

Wood properties and transcriptional responses of poplar hybrids in mixed cropping with the nitrogen-fixing species Robinia pseudoacacia

Cultivation of fast growing tree species is often confined to marginal land. Mixed cropping with Robinia pseudoacacia, a legume tree species that forms a symbiosis with N2-fixing bacteria, has been proposed to be a measure to improve soil fertility and to achieve beneficial effects on the cocultivated tree species. The goal of our study was to examine the influence of a Robinia mixture on wood chemistry, anatomy, and gene expression in poplar. We hypothesized that annual wood growth is stimulated in species mixtures due to the positive effects of Robinia on N availability and complementary resource use. Alternatively, we hypothesized that competition, especially for water, has negative effects on the wood growth of poplar. We used two commercial biomass clones, Hybride 275 (H275, P. trichocarpa × P. maximowiczii) and Max1 (P. nigra × P. maximowiczii), which were planted at two locations with contrasting soil fertility in monoculture or mixed plots with Robinia to investigate the annual wood increment, wood N and δ13C, wood anatomy (length, cell wall thickness, lumina and frequencies of fibers and vessels) and transcriptional profiles in the developing xylem of 4-year-old stems. In a mixture with Robinia, the annual stem increment was reduced, nitrogen in wood was enhanced, δ13C in wood was decreased, vessel and fiber frequencies were increased, and fiber lengths and fiber lumina were decreased. Transcriptional profiles showed stronger differences between the genotypes and sites than between mono and mixed cultivation. The transcriptional abundances of only one gene (the putative nitrate transporter, NRT1.2) and one gene ontology term (“immune system process”) were significantly enriched in wood-forming tissues in response to the mixture, irrespective of the poplar genotype and growth location. Weighted gene coexpression network analyses extracted gene modules that linked wood nitrogen mainly to vessel traits and wood δ13C with fiber traits. Collectively, molecular and anatomical changes in poplar wood suggest beneficial effects on the water and N supply in response to the mixture with Robinia. These alterations may render poplars less drought-susceptible. However, these benefits are accompanied by a reduced wood increment, emphasizing that other critical factors, presumably light competition or allelopathic effects, overrule a potential growth stimulation.

Forest Plantations and Water Consumption: A Strategy for Hydrosolidarity

A case study of a deliberate change in the design of a new Eucalyptus plantation, aimed at alleviating water impacts, was carried out in an experimental catchment located in the center part of the State of São Paulo, Brazil. It involved the identification of saturated areas in the catchment, based essentially on topographic analysis, as a tool to help in zoning of the new forest plantation, with the objective of improving the flow of water to downstream users, as well as to avoid water quality changes. The design involved the allocation of part of the identified saturated areas as water conservation areas, as well as a change in the spacing of the planting. Measurements of tree growth at the age of two years of the new plantation reveal that the forest productivity of the new plantation design, in terms of projected annual wood increment at the end of the rotation, will be similar to the old plantation scheme, despite the loss of planted area. Preliminary results of the continuous monitoring of the catchment water balance appear to indicate that the objective of increasing the catchment water yield may possibly also be achieved.

An economic aspect of conversion of Scots pine (Pinus sylvestris L.) stands in the Polish Lowland

Pine stands at fertile sites need conversion into broadleaved or mixed forests. Yet, according to the age of stand, conversion may have different economic results. Therefore, in order to reduce costs of the process, the analysis on the basis of the potential income from wood sale has been done. The aim of the analysis has been to find an optimal date of conversion beginning. The date of conversion beginning has been fixed on the basis of the relation of the value of wood increment from the stands which need conversion to the value of average wood increment from stands conformable to the sites. By this means, three age intervals have been appointed.

Radiocarbon Analysis of Pinus Lagunae Tree Rings: Implications for Tropical Dendrochronology

A promising species for tropical dendrochronology is Pinus lagunae, a pine tree found in Baja California Sur (Mexico) around lat 23.5°N. In 1995, we sampled a total of 27 wood cores from 13 Pinus lagunae trees in Sierra La Victoria (23°36'N, 109°56'W), just north of Sierra La Laguna, at an elevation of 1500–1600 m. Selected trees were locally dominant, but their ring-width patterns could not be crossdated. To test the hypothesis that visible growth layers in Pinus lagunae are formed annually, we measured radiocarbon amounts in individual rings by means of accelerator mass spectrometry (AMS). Twenty-three 14C measurements were used to trace the location of the 1963–64 “bomb spike” in 3 wood increment cores. By comparing the location of that δ14C extreme with the number of visible radial wood increments, it was possible to conclude that 2 cores had a number of locally absent rings, while the 3rd one included a few years with more than one growth layer. Therefore, ring-width patterns of sampled Pinus lagunae were not consistent from one tree to another, most likely because of climatic regime in combination with microsite features. While the possibility of generating Pinus lagunae tree-ring chronologies cannot entirely be ruled out, the development of dendrochronological proxy records of climate from coniferous species in tropical North America should focus on species and sites that experience a more pronounced seasonality.

Effect of drought stress and infestation by the balsam woolly adelgid (Homoptera: Adelgidae) on abnormal wood production in Fraser fir

Fraser fir (Abiesfraseri (Pursh) Poir.) seedlings were artificially infested with balsam woolly adelgid, Adelgespiceae (Ratz.), then subjected to drought-stress treatments. Infestation caused a distinct swelling in the main stem, caused by the accumulation of abnormal wood (i.e., "rotholz"). As expected, drought stress reduced diameter growth in the main stem. However, the reduction in wood increment caused by drought stress was relatively small for infested seedlings as compared with uninfested seedlings, owing to the production of rotholz. This implies that infested trees expend considerable energy and nutrients for the production of poorly functioning wood even during periods of stress. The implications of this research for interpreting patterns of tree mortality in the southern Appalachian Mountains are discussed.