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Forest biomass is an essential resource in relation to the green transition and its assessment is key for the sustainable management of forest resources. Here, we present a forest biomass dataset for Europe based on the best available inventory and satellite data, with a higher level of harmonisation and spatial resolution than other existing data. This database provides statistics and maps of the forest area, biomass stock and their share available for wood supply in the year 2020, and statistics on gross and net volume increment in 2010–2020, for 38 European countries. The statistics of most countries are available at a sub-national scale and are derived from National Forest Inventory data, harmonised using common reference definitions and estimation methodology, and updated to a common year using a modelling approach. For those counties without harmonised statistics, data were derived from the State of Europe's Forest 2020 Report at the national scale. The maps are coherent with the statistics and depict the spatial distribution of the forest variables at 100 m resolution. [ABSTRACT FROM AUTHOR]

This article presents the methodological approach of age estimation of juvenile Socotra dragon's blood trees (Dracaena cinnabari Balf. F., DBT) for the first time. To date, only the model for the age estimation of the tree crown after the first flowering event has been published. The DBTs were measured on Socotra Island (Yemen), on the Firmihin Plateau. A set of three indirect growth models was used for the estimation of the juvenile phase duration. The first model shows the relationship between the proportion of stem cavities and diameter at breast height (DBH). The second model describes the relationship between the DBH and stem height of juvenile trees. The third model expresses the radial stem increment with an increasing number of branch orders. The first model estimates the ratio of the stem cavity and secondary vascular tissue. The second model serves to retrospectively estimate the DBH of the tree at the time of the first flowering event according to the height of the stem. Extrapolation of the third model enabled us to estimate the duration of the juvenile phase that corresponds to the thickness of the secondary vascular tissue. A non-destructive methodology for juvenile DBT age estimation was developed, although the calculated absolute values are not precise. The same approach can also be used for the other arborescent dragon tree species. The validity of our assumption should be verified by repeated measurements on trees from different age groups. And thus, more precise model with less uncertainty about the parameter estimates could be obtained in the future. [ABSTRACT FROM AUTHOR]

Unique woodlands of Dracaena cinnabari (DC) are at risk throughout most of their range (Socotra Island, Yemen) as a result of missing regeneration and overmaturity. Effective conservation measures depend on reliable predictions of future population dynamics, which depend on accurate data on current age structure. However, age determination of Dracaena sp. has long been a scientific challenge, because the common method of tree ring counts cannot be applied to this or to most other monocotyledonous trees. In the present study, the indirect method for crown age estimation proposed by Adolt and Pavlis (Trees 18:43-53, ) was further developed using a more appropriate statistical technique and an intuitive model formulation. This new technique is based on the relationship between the number of branching orders and the number of flowering events that result from a specific growth pattern. We used logistic regression to directly model annual flowering probability, the reciprocal value of which corresponds to the length of the interval between flowering events. Our methodology was applied to data sets collected at two ecologically distinct sites. In Firmihin, the time between flowering events decreases from 28 years between the first and second event to 10 years between the 25th and 26th event. The length of time between flower events in Skant, however, was estimated to be a constant value of 6.5 years. We propose the application of generalised mixed-effects models and methods of survey sampling to improve the accuracy of crown age estimation in DC. Our methodology may also be useful for age estimations of other tree species with similar growth patterns, such as Dracaena draco and Aloe dichotoma. [ABSTRACT FROM AUTHOR]