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At the international level, various definitions have been established for the compilation and publication of forest resources assessment results over the last decade. These international definitions frequently rely on terms that are not precisely specified for inventory purposes and do not completely cover the requirements arising from the application of National Forest Inventory (NFI) data. Also, with respect to conventional topics such as forest area and growing stock estimation, several terms and expressions referring to individual trees are not, or are only vaguely, defined until now. Since the individual tree is the basic element of any forest resources assessment, the clarification of tree-related terms is an important part of COST Action E43 to harmonise common reporting of National Forest Inventories. Based on a review of existing definitions and on the requirements for harmonised reporting, common tree-related definitions are established. One objective of this study is to refine and enhance the applicability of available tree and shrub definitions, in particular with regard to the distinction between trees and shrubs. The study also focuses on the parts or âelementsâ of trees and on the distinction between these elements as they are of particular importance in growing stock and biomass definitions. Furthermore, several definitions for tree characteristics such as âlivingâ and âstandingâ, as well as tree variables such as height, length, diameter at breast height, and crown projection area are adjusted with respect to NFI purposes. A concluding discussion reflects upon the reviewed, refined and newly established definitions. The definitions presented in this paper provide a firm basis for a common set of harmonised reference definitions developed by COST Action E43 and contribute to the precise and consistent use of terms.

International agreements such as the Kyoto protocol and Convention on Biological Diversity (1992), as well as, criteria and indicator processes require reports on the status of nationsâ forests. Any comparison of the current status and trends of forest resources among nations presumes that the nationsâ applied definitions and concepts produce comparable estimates of the status of forests. In spite of this, the FAO has already collected global information for 60 years and made noticeable efforts in creating common definitions, but forest related data are still collected using diverse definitions, even regarding basic concepts such as forest and forest area. A simple consequence is that the cross-countries estimates are not comparable. The reasons behind the differences in the definitions are diverse histories, and sometimes different use of forests. In an ideal case, national forest inventories should fulfil both national and international needs. In addition to the FAOâs Forest Resources Assessment process, other efforts are made to assess the status of forests in European countries, e.g. European Forest Information and Communication System (EFICS). EFICS produced reports about forest inventories but does not suggest any common definition or method to convert estimates from one definition to another one. This article presents principles and methods to create commonly acceptable and adoptable definitions for forest inventories. The principles and methods are demonstrated using two examples: the reference definitions of forest and growing stock. The article is based on the work of COST Action E43 (http://www.metla.fi/eu/cost/e43/).

In 2009, the Swiss National Forest Inventory (NFI) turned from a periodic into an annual measurement design in which only one-ninth of the overall sample of permanent plots is measured every year. The reduction in sample size due to the implementation of the annual design results in an unacceptably large increase in variance when using the standard simple random sampling estimator. Thus, a flexible estimation procedure using two- and three-phase regression estimators is presented with a special focus on utilizing updating techniques to account for disturbances and growth and is applied to the second and third Swiss NFIs. The first phase consists of a dense sample of systematically distributed plots on a 500 m x 500 m grid for which auxiliary variables are obtained through the interpretation of aerial photographs. The second phase is an eightfold looser subgrid with terrestrial plot data collected from the past inventory, and the third and final phase consists of the three most recent annual subgrids with the current state of the target variable (stem volume). The proposed three-phase estimators reduce the increase in variance from 294% to 145% compared with the estimator based on the full periodic sample while remaining unbiased. Key words: national forest inventories, three-phase regression, annual (paneled) inventory design, Swiss National Forest Inventory, remote sensing and previous measurement. L'inventaire Forestier National Suisse a change en 2009 d'un systeme periodique (inventaire complet chaque 10 ans) a un releve continu annuel par placettes permanentes sur un neuvieme de l'echantillon total. La taille reduite de l'echantillon annuel conduit a une erreur inacceptablement grande de l'estimateur base sur l'echantillonnage aleatoire simple. Pour remedier a ce probleme nous proposons des estimateurs par regression utilisant un plan de sondage a deux ou trois phase et tres flexibles. La variable cible consideree dans cet article est le volume sur pied. La premiere phase repose sur un reseau dense de photographies aeriennes (500 m x 500 m), dont l'interpretation permet d'obtenir des variables explicatives sur la canopee (en particulier concernant les interventions), la deuxieme phase consiste en placettes terrestres sur un sous-reseau (un huitieme) de la premiere phase, dont les valeurs actualisees servent de variable explicative tres performante, la troisieme et derniere phase consiste des placettes avec les trois plus recentes donnees annuelles. La technique proposee permet d'obtenir des estimateurs sans biais et de reduire l'augmentation de la variance due au changement de systeme de 294 a 145 %. Mots-cles: Inventaire forestier, estimation par regression avec plan d'echantillonnage a trois phases, Inventaire Forestier National Suisse avec releve annuel, teledetection, actualisation de mesures anterieures., 1. Introduction The fourth Swiss National Forest Inventory (NFI) is the first Swiss NFI to implement an annual measurement design in which one-ninth of its permanent remeasured terrestrial plots are [...]

This study introduces five facets that can improve inference in small area estimation (SAE) problems: (1) model groups, (2) test of area effects, (3) conditional EBLUPs, (4) model selection, and (5) model averaging. Two contrasting case studies with data from the Swiss and Norwegian national forest inventories demonstrate the five facets. The target variable of interest was mean stem volume per hectare on forested land in 108 Swiss forest districts (FD) and in 14 Norwegian municipalities (KOM) in the County of Vestfold. Auxiliary variables from airborne laser scanning (Switzerland) and photogrammetric point clouds (Vestfold) with full coverage and a resolution of 25 m x 25 m (Switzerland) and 16 m x 16 m (Vestfold) were available. Only the data metric mean canopy height was statistically significant. Ten linear fixed-effects models and three mixed linear models were assessed. Area effects were statistically significant in the Swiss case but not in Vestfold case. A model selection based on AIC favored separate linear regression models for each FD and a single common regression model in Vestfold. Model averaging increased, on average, an estimated variance by 15%. Reported estimates of uncertainty were consistently larger than corresponding unconditional EBLUPs. Key words: model groups, tests of area effect, model selection, model averaging, conditional EBLUP. Cette etude presente cinq aspects qui peuvent ameliorer l'inference dans les cas d'estimations pour de petites regions geographiques: (1) les groupes de modeles; (2) les tests de l'effet de region; (3) les meilleures predictions empiriques lineaires sans biais (EBLUP) conditionnelles; (4) la selection de modeles; et (5) la combinaison de modeles. Deux etudes de cas contrastantes, utilisant des donnees des inventaires forestiers nationaux de la Suisse et de la Norvege sont utilisees pour demontrer ces cinq aspects. La variable d'interet ciblee etait le volume moyen a l'hectare par tige des terrains forestiers de 108 Districts forestiers (DF) de la Suisse et de 14 municipalites du Comte de Vestfold en Norvege. Des variables auxiliaires provenant de couvertures completes de balayage laser aeroporte (Suisse) et de nuages de points photogrammetriques (Vestfold), avec une resolution de 25 m x 25 m (Suisse) et de 16 m x 16 m (Vestfold) etaient disponibles. La hauteur moyenne du couvert forestier etait la seule donnee metrique statistiquement significative. Dix modeles lineaires a effets fixes et trois modeles lineaires mixtes ont ete evalues. Les effets de region etaient statistiquement significatifs dans le cas de la Suisse mais pas dans le cas du Vestfold. Une selection de modele sur la base du critere d'information d'Akaike a prefere des modeles de regression lineaires separes pour chaque DF, mais un seul modele de regression commun pour le Vestfold. La combinaison de modeles a augmente la variance estimee de 15 % en moyenne. Les estimations d'incertitude rapportees etaient toujours plus grandes que les meilleures predictions empiriques lineaires sans biais non conditionnelles correspondantes. [Traduit par la Redaction] Mots-cles: groupes de modeles, tests de l'effet de region, selection de modeles, combinaison de modeles, meilleure prediction empirique lineaire sans biais (EBLUP) conditionnelle., Introduction National forest inventories (NFIs) with sample plots established on a national grid provide accurate national and regional (statewide) estimates of important forest resource variables (McRoberts et al. 2010). In [...]

Uneven-aged forests are assumed to have a high stability against storm damage but have rarely been analysed for vulnerability to storm damage due to a lack of a sufficient empirical database. Here we model storm damage in uneven-aged forest to analyse major factors that may determine the sensitivity of this type of forests to storms based on a broad database. Data are derived of public forests in the canton Neuchâtel in West Switzerland that are dominated by silver fir and Norway spruce and managed since the beginning of the 20th century following a single-tree selection system. A unique dataset of periodical (every 5–10 years) full inventories measuring the diameter of every single tree including salvage cuttings was available for the investigation. The time series reached back until 1920 and covered an area of 16 000 ha divided into 3000 divisions. The effect of a major winter storm (‘Lothar’) in December 1999 on these forests was investigated using a subset of 648 divisions. The influence of the vertical stand structure on the vulnerability of storm damage was studied using logistic regression models. To facilitate the analyses, an index of closeness to a J-shaped distribution (LikeJ) based on the number of trees in different diameter classes was developed. Besides structural indices, variables representing stand characteristics, soil-related and topography-related variables were included. The results of our study show that the overall damage level of the investigated forests was rather low. The variables that entered the model for the uneven-aged stands were different to those that are normally significant for even-aged stands. While variables like stand structure, the timing of the harvesting and topographic variables entered a multivariate statistical model as significant predictors, standard predictors for storm damage in even-aged stands such as stand density, thinning intensity or species composition were not significant. We hypothesize that the uneven-aged structure of the investigated forests may be one reason for the low damage level we observed but emphasize the need for more detailed research to support this conclusion. [ABSTRACT FROM PUBLISHER]