Mapping local density of young Eucalyptus plantations by individual tree detection in high spatial resolution satellite images

Zhou Jia, Proisy Christophe, Descombes Xavier, Le Maire Guerric, Nouvellon Yann, Stape Jose Luiz, Viennois Gaëlle, Zerubia Josiane, Couteron Pierre. 2013. Mapping local density of young Eucalyptus plantations by individual tree detection in high spatial resolution satellite images. Forest Ecology and Management, 301 : 129-141.

https://doi.org/10.1016/j.foreco.2012.10.007

Article de revue ; Article de revue à facteur d'impact

Version publiée - Anglais
Accès réservé aux personnels Cirad
Utilisation soumise à autorisation de l'auteur ou du Cirad.
document_569077.pdf
Télécharger (4MB)

Quartile : Q1, Sujet : FORESTRY

Résumé : Local tree density may vary in young Eucalyptus plantations under the effects of environmental conditions or inadequate management, and these variations need to be mapped over large areas as they have a significant impact on the final biomass harvested. High spatial resolution optical satellite images have the potential to provide crucial information on tree density at an affordable cost for forest management. Here, we test the capacity of this promising technique to map the local density of young and small Eucalyptus trees in a large plantation in Brazil. We use three Worldview panchromatic images acquired at a 50 cm resolution on different dates corresponding to trees aged 6, 9 and 13 months and define an overall accuracy index to evaluate the quality of the detection results. The best agreement between the local densities obtained by visual detection and by marked point process modeling was found at 9 months, with only small omission and commission errors and a stable 4% underestimation of the number of trees across the density gradient. We validated the capability of the MPP approach to detect trees aged 9 months by making a comparison with local densities recorded on 112 plots of ?590 m2 and ranging between 1360 and 1700 trees per hectare. We obtained a good correlation (r2 = 0.88) with a root mean square error of 31 trees/ha. We generalized detection by computing a consistent map over the whole plantation. Our results showed that local tree density was not uniformly distributed even in a well-controlled intensively-managed Eucalyptus plantation and therefore needed to be monitored and mapped. Use of the marked point process approach is then discussed with respect to stand characteristics (canopy closure), acquisition dates and recommendations for algorithm parameterization.

Mots-clés Agrovoc : Eucalyptus, caractéristique du peuplement, plantation forestière, cartographie, télédétection, satellite

Mots-clés géographiques Agrovoc : Sao Paulo

Classification Agris : K10 - Production forestière
F40 - Écologie végétale
U30 - Méthodes de recherche

Champ stratégique Cirad : Axe 1 (2005-2013) - Intensification écologique

Auteurs et affiliations