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Auteur Juha Heikkinen |
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Tree mortality in the dynamics and management of uneven-aged Norway spruce stands in southern Finland / Sauli Valkonen in European Journal of Forest Research, vol 139 n° 6 (December 2020)
[article]
Titre : Tree mortality in the dynamics and management of uneven-aged Norway spruce stands in southern Finland Type de document : Article/Communication Auteurs : Sauli Valkonen, Auteur ; Lucie Aulus Giacosa, Auteur ; Juha Heikkinen, Auteur Année de publication : 2020 Article en page(s) : pp 989 – 998 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] analyse diachronique
[Termes IGN] diamètre des arbres
[Termes IGN] Finlande
[Termes IGN] forêt inéquienne
[Termes IGN] mortalité
[Termes IGN] neige
[Termes IGN] Picea abies
[Termes IGN] vent
[Vedettes matières IGN] SylvicultureRésumé : (auteur) This study focused on tree mortality in spruce-dominated stands managed using the single-tree selection method in southern Finland. Together with regeneration and tree growth, mortality is one of the basic elements of the stand structure and dynamics in selection stands. The study was based on data acquired from a set of 20 permanent experimental plots monitored with repeated measurements for 20 years. The average mortality in the number of stems (N) was 4.45 trees ha−1a−1, in basal area (G) 0.07 m2 ha−1a−1, and in stemwood volume (V) 0.56 m3 ha−1a−1. In relative terms it was 0.50% of N, 0.30% of G and 0.27% of V, respectively. Wind and snow were the most common causes of mortality, while deaths by biotic causes (mammals, insects, pathogens) were extremely rare. Some 6–10% of the total loss in the number of stems and volume was attributable to the loss or removal of trees that sustained serious damage in harvesting. Most of the mortality occurred in the smallest diameter classes of up to 20 cm. Such a high mortality among small trees can have an adverse influence on the sustainability of selection structures if not successfully checked in harvesting and management. Numéro de notice : A2020-746 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article DOI : 10.1007/s10342-020-01301-8 Date de publication en ligne : 30/06/2020 En ligne : https://doi.org/10.1007/s10342-020-01301-8 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96394
in European Journal of Forest Research > vol 139 n° 6 (December 2020) . - pp 989 – 998[article]Efficiency of post-stratification for a large-scale forest inventory : case Finnish NFI / Helena Haakana in Annals of Forest Science, vol 76 n° 1 (March 2019)
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Titre : Efficiency of post-stratification for a large-scale forest inventory : case Finnish NFI Type de document : Article/Communication Auteurs : Helena Haakana, Auteur ; Juha Heikkinen, Auteur ; Matti Katila, Auteur ; Annika S. Kangas, Auteur Année de publication : 2019 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] carte de la végétation
[Termes IGN] densité de la végétation
[Termes IGN] Finlande
[Termes IGN] image Landsat
[Termes IGN] inventaire forestier (techniques et méthodes)
[Termes IGN] inventaire forestier étranger (données)
[Termes IGN] ressources forestières
[Termes IGN] stratification
[Termes IGN] volume en bois
[Vedettes matières IGN] Inventaire forestierRésumé : (auteur) Key message : Post-stratification based on remotely sensed data is an efficient method in estimating regional-level results in the operational National Forest Inventory. It also enables calculating the results accurately for smaller areas than with the default method of using the field plots only.
Context : The utilization of auxiliary information in survey sampling through model-assisted estimation or post-stratification has gained popularity in forest inventory recently. However, post-stratification at a large scale involves practical concerns such as the availability of auxiliary data independent of the sample at hand, and a large number of variables for which the results are needed.
Aims : We assessed the efficiency of two different types of post-stratification, either post-stratifying for each variable of interest separately or using one post-stratification for all variables, compared to the estimation based on the field sample plots only. In addition, we examined the precision of area and volume estimates, and the efficiency of post-stratification at different spatial scales.
Methods : For post-stratification, we used the volume maps based on Landsat satellite imagery, digital map data, and the sample plot data of the previous inventory. The efficiencies of post-stratifications based on the mean volume and the mean volumes by tree species were compared.
Results : In estimating the total volume, the relative efficiency of post-stratification compared to field plot based estimation was 1.54–3.54 over the provinces in South Finland. In estimating the volumes by tree species groups, the relative efficiency was 0.93–2.39. The gain with a separate stratification compared to the stratification based on total mean volume for all variables was at largest 0.69. In the small test areas, the relative standard errors of the total volume estimates decreased on average by 33% by using post-stratification instead of sample plots only. The mean relative efficiency was 2.36.
Conclusion : The utilization of an old forest resources map and post-stratification based on the mean volume is an operational approach for the National Forest Inventory. Post-stratification also enables calculating the results accurately for markedly smaller areas than with the field plots only. Post-stratification reduced the probability of very high sampling variances, making the results more robust.Numéro de notice : A2019-042 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s13595-018-0795-6 Date de publication en ligne : 30/01/2019 En ligne : https://doi.org/10.1007/s13595-018-0795-6 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=92040
in Annals of Forest Science > vol 76 n° 1 (March 2019)[article]Close-range constrained image sequences / Juha Heikkinen in ISPRS Journal of photogrammetry and remote sensing, vol 64 n° 3 (May - June 2009)
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Titre : Close-range constrained image sequences Type de document : Article/Communication Auteurs : Juha Heikkinen, Auteur Année de publication : 2009 Article en page(s) : pp 267 - 274 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s)
[Termes IGN] cohérence géométrique
[Termes IGN] espace objet
[Termes IGN] estimation de précision
[Termes IGN] méthode des moindres carrés
[Termes IGN] modélisation géométrique de prise de vue
[Termes IGN] orientation relative
[Termes IGN] séquence d'imagesRésumé : (Auteur) This paper deals with a novel imaging arrangement for special modeling purpose. The method introduced here will take care of the geometrical consistence of photography. It is based on image ray bundles and is meant for conditions where imaging is accomplished inside the object space (e.g. in case of interior model reconstruction). Imaging is designed to be contrained in terms of camera position and orientation and to consist of two image sequences. The image orientation will be resolved by use of LSQ-estimation in heavily overdetermined conditions. The benefits of overdetermination are discussed and the accuracy assessment in a real experiment is published. The accuracy assessment is accomplished with help of exterior reference and stochastic error programmation. Copyright ISPRS Numéro de notice : A2009-246 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2008.10.001 En ligne : https://doi.org/10.1016/j.isprsjprs.2008.10.001 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29876
in ISPRS Journal of photogrammetry and remote sensing > vol 64 n° 3 (May - June 2009) . - pp 267 - 274[article]Réservation
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