UAV-based canopy textures assess changes in forest structure from long-term degradation

Bourgoin Clément, Betbeder Julie, Couteron Pierre, Blanc Lilian, Dessard Hélène, Oszwald Johan, Le Roux Renan, Cornu Guillaume, Reymondin Louis, Mazzei Lucas, Sist Plinio, Läderach Peter, Gond Valéry. 2020. UAV-based canopy textures assess changes in forest structure from long-term degradation. Ecological Indicators, 115:106386, 11 p.

Quartile : Q2, Sujet : ENVIRONMENTAL SCIENCES

Résumé : Degraded tropical forests dominate agricultural frontiers and their management is becoming an urgent priority. This calls for a better understanding of the different forest cover states and cost-efficient techniques to quantify the impact of degradation on forest structure. Canopy texture analyses based on Very High Spatial Resolution (VHSR) optical imagery provide proxies to assess forest structures but the mechanisms linking them with degradation have rarely been investigated. To address this gap, we used a lightweight Unmanned Aerial Vehicle (UAV) to map 739 ha of degraded forests and acquire both canopy VHSR images and height model. Thirty-three years of degradation history from Landsat archives allowed us to sample 40 plots in undisturbed, logged, over-logged and burned and regrowth forests in tropical forested landscapes (Paragominas, Pará, Brazil). Fourier (FOTO) and lacunarity textures were used to assess forest canopy structure and to build a typology linking degradation history and current states. Texture metrics capture canopy grain, heterogeneity and openness gradients and correlate with forest structure variability (R2 = 0.58). Similar structures share common degradation history and can be discriminated on the basis of canopy texture alone (accuracy = 55%). Over-logging causes a lowering in forest height, which brings homogeneous textures and of finer grain. We identified the major changes in structures due to fire following logging which changes heterogeneous and intermediate grain into coarse textures. Our findings highlight the potential of canopy texture metrics to characterize degraded forests and thus be used as indicators for forest management and degradation mitigation. Inexpensive and agile UAV open promising perspectives at the interface between field inventory and satellite characterization of forest structure using texture metrics.

Mots-clés Agrovoc : forêt tropicale, dégradation des forêts, couvert forestier, texture, télédétection, drone

Mots-clés complémentaires : Canopée

Mots-clés libres : Canopy structure, Forest degradation, Remote Sensing, Texture, Tropical forest, Unmanned aerial vehicle

Classification Agris : K70 - Dégâts causés aux forêts et leur protection
F50 - Anatomie et morphologie des plantes
F40 - Écologie végétale

Champ stratégique Cirad : CTS 4 (2019-) - Santé des plantes, des animaux et des écosystèmes

Agences de financement européennes : European Commission

Programme de financement européen : H2020

Projets sur financement : (EU) Observatory of the Dynamics of Interactions between Societies and Environment in the Amazon

Auteurs et affiliations

• Bourgoin Clément, CIRAD-ES-UPR Forêts et sociétés (FRA) - auteur correspondant
• Betbeder Julie, CIRAD-ES-UPR Forêts et sociétés (CRI)
• Couteron Pierre, IRD (FRA)
• Blanc Lilian, CIRAD-ES-UPR Forêts et sociétés (FRA) ORCID: 0000-0003-3605-4230
• Dessard Hélène, CIRAD-ES-UPR Forêts et sociétés (FRA)
• Oszwald Johan, Université de Rennes 2 (FRA)
• Le Roux Renan, Université de Montpellier (FRA)
• Cornu Guillaume, CIRAD-ES-UPR Forêts et sociétés (FRA) ORCID: 0000-0002-7523-5176
• Reymondin Louis, CIAT (VNM)
• Mazzei Lucas, EMBRAPA (BRA)
• Sist Plinio, CIRAD-ES-UPR Forêts et sociétés (FRA) ORCID: 0000-0002-4565-4417
• Läderach Peter, CIAT (COL)
• Gond Valéry, CIRAD-ES-UPR Forêts et sociétés (FRA) ORCID: 0000-0002-0080-3140

Source : Cirad-Agritrop (https://agritrop.cirad.fr/595499/)

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