A machine learning approach to fill gaps in dendrometer data.

Key Message: The machine learning algorithm extreme gradient boosting can be employed to address the issue of long data gaps in individual trees, without the need for additional tree-growth data or climatic variables.

Abstract: The susceptibility of dendrometer devices to technical failures often makes time-series analyses challenging. Resulting data gaps decrease sample size and complicate time-series comparison and integration.

The oldest known clones of Salix herbacea growing in the Northern Apennines, Italy are at least 2000 years old.

Premise: Dominant in many ecosystems around the world, clonal plants can reach considerable ages and sizes. Due to their modular growth patterns, individual clonal plants (genets) can consist of many subunits (ramets). Since single ramets do not reflect the actual age of genets, the ratio between genet size (radius) and longitudinal annual growth rate (LAGR) of living ramets is often used to approximate the age of clonal plants.

Global wood anatomical perspective on the onset of the Late Antique Little Ice Age (LALIA) in the mid-6th century CE.

Linked to major volcanic eruptions around 536 and 540 CE, the onset of the Late Antique Little Ice Age has been described as the coldest period of the past two millennia. The exact timing and spatial extent of this exceptional cold phase are, however, still under debate because of the limited resolution and geographical distribution of the available proxy archives. Here, we use 106 wood anatomical thin sections from 23 forest sites and 20 tree species in both hemispheres to search for cell-level fingerprints of ephemeral summer cooling between 530 and 550 CE.

Hidden fairy rings and males-Genetic patterns of natural Burgundy truffle (Tuber aestivum Vittad.) populations reveal new insights into its life cycle.

Burgundy truffles are heterothallic ascomycetes that grow in symbiosis with trees. Despite their esteemed belowground fruitbodies, the species' complex lifecycle is still not fully understood. Here, we present the genetic patterns in three natural Burgundy truffle populations based on genotyped fruitbodies, ascospore extracts and ectomycorrhizal root tips using microsatellites and the mating-type locus.

The influence of decision-making in tree ring-based climate reconstructions.

Tree-ring chronologies underpin the majority of annually-resolved reconstructions of Common Era climate. However, they are derived using different datasets and techniques, the ramifications of which have hitherto been little explored. Here, we report the results of a double-blind experiment that yielded 15 Northern Hemisphere summer temperature reconstructions from a common network of regional tree-ring width datasets.

Tree rings reveal signs of Europe's sustainable forest management long before the first historical evidence.

To satisfy the increasing demand for wood in central Europe during medieval times, a new system of forest management was developed, one far superior to simple coppicing. The adoption of a sophisticated, Coppice-with-Standards (CWS) management practice created a two-storey forest structure that could provide fuelwood as well as construction timber. Here we present a dendrochronological study of actively managed CWS forests in northern Bavaria to detect the radial growth response to cyclical understorey harvesting in overstorey oaks (Quercus sp.

Higher groundwater levels in western Europe characterize warm periods in the Common Era.

Hydroclimate, the interplay of moisture supply and evaporative demand, is essential for ecological and agricultural systems. The understanding of long-term hydroclimate changes is, however, limited because instrumental measurements are inadequate in length to capture the full range of precipitation and temperature variability and by the uneven distribution of high-resolution proxy records in space and time. Here, we present a tree-ring-based reconstruction of interannual to centennial-scale groundwater level (GWL) fluctuations for south-western Germany and north-eastern France.

Ecological and conceptual consequences of Arctic pollution.

Although the effect of pollution on forest health and decline received much attention in the 1980s, it has not been considered to explain the 'Divergence Problem' in dendroclimatology; a decoupling of tree growth from rising air temperatures since the 1970s. Here we use physical and biogeochemical measurements of hundreds of living and dead conifers to reconstruct the impact of heavy industrialisation around Norilsk in northern Siberia. Moreover, we develop a forward model with surface irradiance forcing to quantify long-distance effects of anthropogenic emissions on the functioning and productivity of Siberia's taiga.

Stable body size of Alpine ungulates.

In many species, decreasing body size has been associated with increasing temperatures. Although climate-induced phenotypic shifts, and evolutionary impacts, can affect the structure and functioning of marine and terrestrial ecosystems through biological and metabolic rules, evidence for shrinking body size is often challenged by (i) relatively short intervals of observation, (ii) a limited number of individuals, and (iii) confinement to small and isolated populations. To overcome these issues and provide important multi-species, long-term information for conservation managers and scientists, we compiled and analysed 222 961 measurements of eviscerated body weight, 170 729 measurements of hind foot length and 145 980 measurements of lower jaw length, in the four most abundant Alpine ungulate species: ibex (), chamois (), red deer () and roe deer ().

New Evidence of Thermally Constrained Plant Cell Wall Lignification.

Lignin enhances the mechanical strength of plants and enables their intrinsic water transport. Dendrochronological, wood anatomical, and plant physiological evidence now suggests that the degree of lignin deposition is constrained by low temperature. Placing these findings in an ecological context implies rethinking of the global treeline position.

Dendrochronological evidence for long-distance timber trading in the Roman Empire.

An important question for our understanding of Roman history is how the Empire's economy was structured, and how long-distance trading within and between its provinces was organised and achieved. Moreover, it is still unclear whether large construction timbers, for use in Italy, came from the widespread temperate forests north of the Alps and were then transported to the sparsely-wooded Mediterranean region in the south. Here, we present dendrochronological results from the archaeological excavation of an expensively decorated portico in the centre of Rome.

No radioactive contamination from the Chernobyl disaster in Hungarian white truffles (Tuber magnatum).

Despite being one of the most expensive gourmet foods, it remains unclear if the iconic White Truffle (Tuber magnatum Pico; hereinafter WT) accumulates radioactivity at harmful levels comparable to other fungal species. Here, we measure the active radiocaesium-137 concentration (Cs) in ten hypogeous WT fruitbodies from southern Hungary, and the soils in which they were growing. All WTs reveal non-significant Cs values, thus providing an 'all clear' for WT hunters in the species' northernmost habitats, where corresponding soil samples occasionally exhibit slight Cs concentrations.

Different effects of alpine woody plant expansion on domestic and wild ungulates.

Changes in land-use and climate affect the distribution and diversity of plant and animal species at different spatiotemporal scales. The extent to which species-specific phenotypic plasticity and biotic interactions mediate organismal adaptation to changing environments, however, remains poorly understood. Woody plant expansion is threatening the extent of alpine grasslands worldwide, and evaluating and predicting its effects on herbivores is of crucial importance.

A risk assessment of Europe's black truffle sector under predicted climate change.

The black truffle (Tuber melanosporum) is a highly revered culinary icon species that grows symbiotically with its host trees across several parts of southern Europe. Where harvested under natural or cultivated conditions, truffles can have a significant socioeconomic impact and may even form a key component of cultural identity. Although some aspects of truffle biology and ecology have been elucidated recently, the role of abiotic, environmental and climatic factors in the production and maturation of their fruitbodies is still largely unknown.

A universal protocol for the combined isolation of metabolites, DNA, long RNAs, small RNAs, and proteins from plants and microorganisms.

Here, we describe a method for the combined metabolomic, proteomic, transcriptomic and genomic analysis from one single sample as a major step for multilevel data integration strategies in systems biology. While extracting proteins and DNA, this protocol also allows the separation of metabolites into polar and lipid fractions, as well as RNA fractionation into long and small RNAs, thus allowing a broad range of transcriptional studies. The isolated biomolecules are suitable for analysis with different methods that range from electrophoresis and blotting to state-of-the-art procedures based on mass spectrometry (accurate metabolite profiling, shot-gun proteomics) or massive sequencing technologies (transcript analysis).

Ultradian metabolic rhythm in the diazotrophic cyanobacterium Cyanothece sp. ATCC 51142.

The unicellular cyanobacterium Cyanothece sp. American Type Culture Collection (ATCC) 51142 is capable of performing oxygenic photosynthesis during the day and microoxic nitrogen fixation at night. These mutually exclusive processes are possible only by temporal separation by circadian clock or another cellular program.

On the dynamics and constraints of batch culture growth of the cyanobacterium Cyanothece sp. ATCC 51142.

The unicellular, nitrogen fixing cyanobacterium Cyanothece sp. ATCC 51142 is of a remarkable potential for production of third-generation biofuels. As the biotechnological potential of Cyanothece 51142 varies with the time of the day, we argue that it will, similarly, depend on the phase of the culture growth.