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Testing the generality of below-ground biomass allometry across plant functional types / Keryn I. Paul in Forest ecology and management, vol 432 (15 January 2019)  

Public [article]  inForest ecology and management > vol 432 (15 January 2019) . - pp 102 - 114 Titre : Testing the generality of below-ground biomass allometry across plant functional types Type de document : Article/Communication Auteurs : Keryn I. Paul, Auteur Année de publication : 2019 Article en page(s) : pp 102 - 114 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Végétation [Termes descripteurs IGN] Acacia (genre) [Termes descripteurs IGN] allométrie [Termes descripteurs IGN] arbuste [Termes descripteurs IGN] Australie [Termes descripteurs IGN] biomasse souterraine [Termes descripteurs IGN] bois sur pied [Termes descripteurs IGN] diamètre des arbres [Termes descripteurs IGN] écosystème forestier [Termes descripteurs IGN] Eucalyptus (genre) [Termes descripteurs IGN] forêt tropicale [Termes descripteurs IGN] modèle fonctionnel [Termes descripteurs IGN] Pinus radiata [Termes descripteurs IGN] puits de carbone [Termes descripteurs IGN] sous-bois Résumé : (auteur) Accurate quantification of below-ground biomass (BGB) of woody vegetation is critical to understanding ecosystem function and potential for climate change mitigation from sequestration of biomass carbon. We compiled 2054 measurements of planted and natural individual tree and shrub biomass from across different regions of Australia (arid shrublands to tropical rainforests) to develop allometric models for prediction of BGB. We found that the relationship between BGB and stem diameter was generic, with a simple power-law model having a BGB prediction efficiency of 72–93% for four broad plant functional types: (i) shrubs and Acacia trees, (ii) multi-stemmed mallee eucalypts, (iii) other trees of relatively high wood density, and; (iv) a species of relatively low wood density, Pinus radiata D. Don. There was little improvement in accuracy of model prediction by including variables (e.g. climatic characteristics, stand age or management) in addition to stem diameter alone. We further assessed the generality of the plant functional type models across 11 contrasting stands where data from whole-plot excavation of BGB were available. The efficiency of model prediction of stand-based BGB was 93%, with a mean absolute prediction error of only 6.5%, and with no improvements in validation results when species-specific models were applied. Given the high prediction performance of the generalised models, we suggest that additional costs associated with the development of new species-specific models for estimating BGB are only warranted when gains in accuracy of stand-based predictions are justifiable, such as for a high-biomass stand comprising only one or two dominant species. However, generic models based on plant functional type should not be applied where stands are dominated by species that are unusual in their morphology and unlikely to conform to the generalised plant functional group models. Numéro de notice : A2019-003 Thématique : FORET Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.foreco.2018.08.043 date de publication en ligne : 15/09/2018 En ligne : https://doi.org/10.1016/j.foreco.2018.08.043 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91596 [article]

Response of Swiss forests to management and climate change in the last 60 years / Meinrad Küchler in Annals of Forest Science [en ligne], vol 72 n° 3 (May 2015)  

Public [article]  inAnnals of Forest Science [en ligne] > vol 72 n° 3 (May 2015) . - pp 311 - 320 Titre : Response of Swiss forests to management and climate change in the last 60 years Type de document : Article/Communication Auteurs : Meinrad Küchler, Auteur ; Helen Küchler, Auteur ; Angéline Bedolla, Auteur ; et al., Auteur Année de publication : 2015 Article en page(s) : pp 311 - 320 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Végétation [Termes descripteurs IGN] analyse diachronique [Termes descripteurs IGN] arbuste [Termes descripteurs IGN] changement climatique [Termes descripteurs IGN] espèce végétale [Termes descripteurs IGN] forêt [Termes descripteurs IGN] herbe [Termes descripteurs IGN] inventaire forestier étranger (données) [Termes descripteurs IGN] plantation forestière [Termes descripteurs IGN] recensement [Termes descripteurs IGN] Suisse [Termes descripteurs IGN] sylviculture [Termes descripteurs IGN] température Résumé : (auteur) Context : Forest vegetation is forecasted to shift upslope several hundred metres by 2100 due to climate warming. However, only a small number of detailed assessments in selected regions have confirmed a climate response on the part of forest vegetation. Aims : This study aimed to analyse the relative contributions of temperature and other factors to range shifts in forest vegetation by comparing old and revisited relevés in Swiss forests. Methods : In order to investigate such range shifts, we revisited 451 relevé plots in forests in all parts of Switzerland. Collected data comprise two independent samples, one dating from the 1950s (age 60 sample) on 126 plots and the other dating from the 1990s (age 15 sample) on 325 plots. We defined an indicator value for elevation to estimate the upslope and downslope range shifts of forest species. The influence of different site factors on range shifts was assessed by variance partitioning using Landolt’s (2010) averaged species indicator values. Vegetation changes were analysed by balancing both increasing and decreasing frequencies of plant species. Results : Our findings show significant differences between the two survey periods, where the averaged species indicator for elevation varied greatly in both the age-60 and the age-15 samples. In addition, a significant upslope shift in the herbaceous forest layer (herbs and tree regeneration) of about 10 m per decade since the mid-twentieth century is evident. Downslope shifts were detected in the shrub/tree layer at lower elevations, which may be explained by factors other than climate warming. Conclusions : To date, the impact of global warming on tree species composition in Swiss forests has been weaker in comparison to the effects arising from forest management and land use change. Understorey vegetation, however, shows a strong signal of upslope shift that may be explained most adequately by a combination of climate change and other factors. Numéro de notice : 2015-453 Thématique : FORET Nature : Article En ligne : http://link.springer.com/article/10.1007/s13595-014-0409-x/fulltext.html Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=77109 [article]

Influence of a dense, low-height shrub species on the accuracy of a lidar-derived DEM / Samuel B. Gould in Photogrammetric Engineering & Remote Sensing, PERS, vol 79 n° 5 (May 2013)  

Public [article]  inPhotogrammetric Engineering & Remote Sensing, PERS > vol 79 n° 5 (May 2013) . - pp 421 - 431 Titre : Influence of a dense, low-height shrub species on the accuracy of a lidar-derived DEM Type de document : Article/Communication Auteurs : Samuel B. Gould, Auteur ; Nancy F. Glenn, Auteur ; Temuulen T. Sankey, Auteur ; James P. Macnamara, Auteur Année de publication : 2013 Article en page(s) : pp 421 - 431 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes descripteurs IGN] analyse comparative [Termes descripteurs IGN] arbuste [Termes descripteurs IGN] données GPS [Termes descripteurs IGN] données lidar [Termes descripteurs IGN] erreur de mesure [Termes descripteurs IGN] Idaho (Etats-Unis) [Termes descripteurs IGN] modèle numérique de surface [Termes descripteurs IGN] montagne [Termes descripteurs IGN] signal laser [Termes descripteurs IGN] signal lidar Résumé : (Auteur) Airborne lidar provides an effective platform for collecting elevation data. However, the accuracy of lidar-derived digital elevation models (dbms) can be adversely affected by natural conditions as well as methods used to process the data. Using a lidar dataset from a mountainous region of southwest Idaho, this study extends previous assessments of DEM accuracy with a focused investigation of a specific dense, low-height shrub species (Ceanothus velutinus). Bare-earth elevations were collected using survey-grade GPS and compared to lidar-derived elevations to assess DEM accuracy. Results suggest that the magnitude of elevation error varied depending on morphological characteristics of ceanothus, terrain slope, and filtering parameters used to process the lidar data. When using optimal filtering parameters, root mean square error (RMSEZ) was largest in areas of ceanothus cover, ranging from 0.17 to 0.26m in slopes 25°. An examination of lidar returns found that ceanothus obstructed laser pulse penetration and few returns reached the ground surface. In areas of ceanothus cover, we conclude that the obstruction of the ground surface contributed to filtering errors, which resulted in mislabeled ground returns and decreased accuracy in bare-earth OEMs. These results have implications for the use of lidar-derived OEMs in areas of ceanothus throughout western North America, and in ecosys-tems with similar dense shrub cover. Numéro de notice : A2013-280 Thématique : FORET/IMAGERIE Nature : Article DOI : 10.14358/PERS.79.5.421 En ligne : https://doi.org/10.14358/PERS.79.5.421 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32418 [article]

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Small-footprint Lidar estimations of sagebrush canopy characteristics / J. Mitchell in Photogrammetric Engineering & Remote Sensing, PERS, vol 77 n° 5 (May 2011)  

Public [article]  inPhotogrammetric Engineering & Remote Sensing, PERS > vol 77 n° 5 (May 2011) . - pp 521 - 530 Titre : Small-footprint Lidar estimations of sagebrush canopy characteristics Type de document : Article/Communication Auteurs : J. Mitchell, Auteur ; N. Glenn, Auteur ; et al., Auteur Année de publication : 2011 Article en page(s) : pp 521 - 530 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes descripteurs IGN] arbuste [Termes descripteurs IGN] densité des points [Termes descripteurs IGN] données lidar [Termes descripteurs IGN] données maillées [Termes descripteurs IGN] hauteur de la végétation [Termes descripteurs IGN] plante herbacée [Termes descripteurs IGN] semis de points Résumé : (Auteur) The height and shape of shrub canopies are critical measurements for characterizing shrub steppe rangelands. Remote sensing technologies might provide an efficient method to acquire these measurements across large areas. This study compared point-cloud and rasterized lidar data to field-measured sagebrush height and shape to quantify the correlation between field-based and lidar-derived estimates. The results demonstrated that discrete return, small-footprint lidar with high point density (9.46 points/m2) can provide strong predictions of true sagebrush height (H2 of 0.84 to 0.86), but with a consistent underestimation of approximately 30 percent. Our results provided the first successful lidar-based descriptors of sagebrush shape with R2 values of 0.65, 0.74, and 0.78 for respective predictions of shortest canopy diameter, longest canopy diameter, and canopy area. Future studies can extend lidar-derived shrub height and shape measurements to canopy volume, cover, and biomass estimates. Numéro de notice : A2011-171 Thématique : FORET/IMAGERIE Nature : Article DOI : 10.14358/PERS.77.5.521 En ligne : https://doi.org/10.14358/PERS.77.5.521 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30949 [article]

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