Pierre Defourny

Pierre Defourny
Université Catholique de Louvain - UCLouvain | UCLouvain · Earth and Life Institute

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335
Publications
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Publications

Publications (335)
Article
Managed grasslands cover about one third of the European utilized agricultural area. Appropriate grassland management is key for balancing trade-offs between provisioning and regulating ecosystem services. The timing and frequency of mowing events are major factors of grassland management. Recent studies have shown the feasibility of detecting mowi...
Article
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Mapping crop within-field yield variability provide an essential piece of information for precision agriculture applications. Leaf Area Index (LAI) is an important parameter that describes maize growth, vegetation structure, light absorption and subsequently maize biomass and grain yield (GY). The main goal for this study was to estimate maize biom...
Chapter
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Le rapport État des forêts 2021 (EDF 2021) est le septième de la série publiée depuis 2005. Le rapport précédent a été publié en 2015 lors de la quinzième Conférence des Parties de la Convention-cadre des Nations Unies sur les changements climatiques (CCNUCC) tenue à Paris. Le présent rapport a été élaboré lors de la pandémie de la COVID-19 qui s'e...
Article
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As a place to live, work and play, urban spaces are the nerve centers of human activity. The urban spaces, which are becoming increasingly extensive and dense, are particularly sensitive to the effects of climate change. Greening cities has been identified as one of the most effective ways to mitigate one of these effects, the urban heat island. In...
Book
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The 2021 State of the Forest (SOF 2021) report is the seventh in the series published since 2005. The previous report was released in 2015 during the fifteenth Conference of the Parties to the United Nations Framework Convention on Climate Change (UNFCCC) held in Paris. This report was prepared during the COVID-19pandemic, which imposed itself as...
Article
[Full-text in "View-only" : https://rdcu.be/cJ2Go] For a conventional potato crop, splitting nitrogen (N) application is recognised as an efficient strategy to improve tuber yield and quality and to mitigate N losses to the environment. This approach requires the assessment of in-season crop N status for decisions on supplemental mineral N fertili...
Article
The green area index (GAI) and the soil moisture under the canopy are two key variables for agricultural monitoring. The current most accurate GAI estimation methods exploit optical data and are rendered ineffective in the case of frequent cloud cover. Synthetic aperture radar (SAR) measurements could allow the remote estimation of both variables a...
Article
Full-text available
The availability of crop type reference datasets for satellite image classification is very limited for complex agricultural systems as observed in developing and emerging countries. Indeed, agricultural land use is very dynamic, agricultural censuses are often poorly georeferenced and crop types are difficult to interpret directly from satellite i...
Poster
Full-text available
WalOUS - Land cover and land use maps for Wallonia Owner : Wallonia Public Service Spatial resolution : 1m - Formats : Raster & Vector
Article
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Agricultural landscapes are characterized by diversity and complexity, which makes crop mapping at a regional scale a top priority for different purposes such as administrative decisions and farming management. Project 32194 of the Dragon 4 Program was implemented to meet the requirements of crop mapping, with the specific objective to develop suit...
Article
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In this upcoming Common Agricultural Policy (CAP) reform, the use of satellite imagery is taking an increasing role for improving the Integrated Administration and Control System (IACS). Considering the operational aspect of the CAP monitoring process, the use of Sentinel-1 SAR (Synthetic Aperture Radar) images is highly relevant, especially in reg...
Preprint
Full-text available
The availability of crop type reference datasets for satellite image classification is very limited for complex agricultural systems as observed in developing and emerging countries. Indeed, agricultural land use is very dynamic, agricultural census are often poorly georeferenced, and crop types are difficult to photo-interpret directly from satell...
Article
Full-text available
Winter cover crops, used as green manure, can supply up to 45 units of nitrogen per hectare to the following summer crops. In order to contribute to the establishment of the nitrogen balance sheet for fertilisation recommendation of subsequent main crop at field scale, this supply is currently derived from the biomass production, classically estima...
Conference Paper
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Wallonia wishes to acquire reproducible methodologies for mapping Land Cover (LC) and Land Use (LU) in order to meet, by 2020, the requirements of the European INSPIRE Directive. To this end, the regional authorities are financing the development of automatized, scalable and high quality open-source methodologies, making the most of the rich catalo...
Article
Full-text available
Crop type classification with satellite imageries is widely applied in support of crop production management and food security strategy. The abundant supply of these satellite data is accelerating and blooming the application of crop classification as satellite data at 10 m to 30 m spatial resolution have been made accessible easily, widely and fre...
Article
Full-text available
Grasslands encompass vast and diverse ecosystems that provide food, wildlife habitat and carbon storage. Their large range in land use intensity significantly impacts their ecological value and the balance between these goods and services. Mowing dates and frequencies are major aspects of grassland use intensity, which have an impact on their ecolo...
Article
Full-text available
Land cover maps contribute to a large diversity of geospatial applications, including but not limited to land management, hydrology, land use planning, climate modeling and biodiversity monitoring. In densely populated and highly fragmented landscapes as observed in the Walloon region (Belgium), very high spatial resolution is required to depict al...
Technical Report
Full-text available
This report D11.2 “D41.1b Time Series Derived Indicators and Variables” constitutes methods developed and applied for the Work Package (WP) 41 of ECoLaSS Task 4 targeting filling the thematic gaps in the current Copernicus Land Service Portofolio of the phenology and Agriculture services. In particular, providing indicators and variables of high sp...
Technical Report
Full-text available
This Deliverable “D.44.1b – Prototype Report: Crop Area and Crop Status Parameters” is a deliverable of the WP 44 targeting capturing the phenology of the different crop types as well as the crop type mapping based on S-1 and/or S-2 time series.
Technical Report
Full-text available
This report constitutes a methods compendium for the investigated approaches of the work package 33 “Time Series Analysis for Thematic Classification” of ECoLaSS Task 3 (Automated High Data Volume Processing Lines). The objective of this WP to develop a framework for time series analysis for thematic classification based on Sentinel multi-sensor co...
Chapter
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Volume N°13 de la collection « Monographies des provinces de la République démocratique du Congo ». La Flore du Nord-Ubangi
Technical Report
Full-text available
Within the Copernicus Land Monitoring Services, methodological approaches for change detection and tracking are increasingly being demanded to update existing LC/LU maps and to shorten the timespan between image acquisition and final LC/LU products (e.g. for updating of CORINE LC, Urban Atlas, HRLs, for identification of permanent grasslands, for c...
Technical Report
Full-text available
This Deliverable D16.4: “D51.1d - Stakeholder Consultation Report” is the fourth and final Deliverable of Work Package (WP) 16: “WP 51 – Stakeholder Consultation”, and as such an update of the third issue D16.3: “D51.1c - Stakeholder Consultation Report”. WP 51 aims to ensure the proper involvement of main stakeholders and decision makers in this a...
Technical Report
Full-text available
A record breaking warm month of February: early emerging spring species. In the end of February, an unusually warm weather enveloped Western Europe, breaking monthly temperature records in several regions. Temperatures up to 20°C were recorded in the UK and France for example. Such high temperatures this early in the season caused spring species, a...
Chapter
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Volume n° 12 de la collection « Monographies des provinces de la République démocratique du Congo ». La Flore du Mai-Ndambe
Article
Full-text available
Global land cover information is required to initialize land surface and Earth system models. In recent years, new land cover (LC) datasets at finer spatial resolutions have become available while those currently implemented in most models are outdated. This study assesses the applicability of the Climate Change Initiative (CCI) LC product for use...
Article
Full-text available
The Walloon region of Belgium has launched a research project that aims at elaborating a methodology for automated, high-quality land cover mapping, based primarily on its yearly 0.25m orthophoto coverage. Whereas in urban areas an object-based (OBIA) approach has been the privileged path in the last years as it allows taking into account shape inf...
Article
Free access to the paper for 50 days: https://authors.elsevier.com/a/1YvAs14ynSEen9 -------Cropland maps derived from satellite imagery have become a common source of information to estimate food production, support land use policies, and measure the environmental impacts of agriculture. Cropland classification models are typically calibrated with...
Preprint
Full-text available
Early warning systems for food security rely on timely and accurate estimations of crop production. Several approaches have been developed to get early estimations of area and yield, the two components of crop production. The most common methods, based on Earth observation data, are image classification for crop area and correlation with vegetation...
Poster
Full-text available
High-resolution land cover database are necessary for land use planning and natural resources management. Despite the increasing performances of machine learning methods to extract valuable information from very high-resolution images, combining several sources of information has a greater potential than the optimization of the classifier. Indeed,...
Poster
Full-text available
The Horizon2020 research project “Evolution of Copernicus Land Services based on Sentinel data” (ECoLaSS) aims to improve existing and develop next-generation Copernicus Land Monitoring Service (CLMS) products, with a targeted implementation schedule from 2020 onwards, focusing mainly on the High Resolution Layers (HRLs). Innovative methods and alg...
Article
Full-text available
Ecotopes are the smallest ecologically distinct landscape features in a landscape mapping and classification system. Mapping ecotopes therefore enables the measurement of ecological patterns, process and change. In this study, a multi-source GEOBIA workflow is used to improve the automated delineation and descriptions of ecotopes. Aerial photograph...
Article
With the unprecedented availability of satellite data and the rise of global binary maps, the collection of shared reference data sets should be fostered to allow systematic product benchmarking and validation. Authoritative global reference data are generally collected by experts with regional knowledge through photo-interpretation. During the las...
Article
Full-text available
In this study, we assess the validity of an African-scale groundwater pollution model for nitrates. In a previous study, we identified a statistical continental-scale groundwater pollution model for nitrate. The model was identified using a pan-African meta-analysis of available nitrate groundwater pollution studies. The model was implemented in bo...
Article
Full-text available
The convergence of new EO data flows, new methodological developments and cloud computing infrastructure calls for a paradigm shift in operational agriculture monitoring. The Copernicus Sentinel-2 mission providing a systematic 5-day revisit cycle and free data access opens a completely new avenue for near real-time crop specific monitoring at parc...
Article
Groundwater management decisions require robust methods that allow accurate predictive modeling of pollutant occurrences. In this study, random forest regression (RFR) was used for modeling groundwater nitrate contamination at the African continent scale. When compared to more conventional techniques, key advantages of RFR include its nonparametric...
Chapter
Full-text available
Le Haut-Katanga s'étend aux confins sud-est de la République démocratique du Congo sur 132 425 km². C'est l'une des provinces les plus richement dotées par la nature. Et l'une des plus convoitées pour ses gisements miniers. Lubumbashi, son chef-lieu, est la deuxième ville du pays et occupe à la fois des fonctions administratives, économiques et cul...
Article
Full-text available
In Mali's cotton belt, spatial variability in management practices, soil fertility and rainfall strongly impact crop productivity and the livelihoods of smallholder farmers. To identify crop growth conditions and hence improve food security, accurate assessment of local crop production is key. However, production estimates in heterogeneous smallhol...
Article
One of the most common approaches to reducing the environmental impact of nitrogen (N) fertilisation in intensive agrosystems is to adjust the N input of the crop requirement. This adjustment is frequently related to the nitrogen nutrition index (NNI) based on the concepts of the critical and actual N absorbed (kg/ha) in the crop canopy (respective...
Article
Sentinel-2 has opened a new era for the remote sensing community where 10-m imagery is freely available with a 5-day revisit frequency and a systematic global coverage. Having both frequent and detailed observations across large geographic areas are ideal characteristics that can potentially revolutionize applications such as crop mapping and monit...
Article
Full-text available
This study evaluates the potential of high resolution hyperspectral airborne imagery to capture within-field variability of durum wheat grain yield (GY) and grain protein content (GPC) in two commercial fields in the Yaqui Valley (northwestern Mexico). Through a weekly/biweekly airborne flight campaign, we acquired 10 mosaics with a micro-hyperspec...
Technical Report
Full-text available
The second half of 2017 was mainly marked by dramatic forest fire and some sparse vegetation anomalies: - The fire of Pedrógão Grande in Portugal was one of the most dramatic fire event of summer 2017 - A fire in Var, France, endangered the last population of Hermann’s tortoise of the country - Dryness influenced the water bird’s population in Cama...
Technical Report
Full-text available
The method to derive the ecotope database 2015 is briefly described and a validation report is provided. The overall accuracy of the underlying pixel-based classification is 94.5 +/- 1.5%
Article
Full-text available
In the last few decades, researchers have developed a plethora of hyperspectral Earth Observation (EO) remote sensing techniques, analysis and applications. While hyperspectral exploratory sensors are demonstrating their potential, Sentinel-2 multispectral satellite remote sensing is now providing free, open, global and systematic high resolution v...
Article
Full-text available
In sub-Saharan Africa, transaction costs are believed to be the most significant barrier that prevents smallholders and farmers from gaining access to markets and productive assets. In this study, we explore the impact of social capital on millet prices for three contrasted years in Senegal. Social capital is approximated using a unique data set on...
Presentation
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The Horizon2020 research project, "Evolution of Copernicus Land Services based on Sentinel data" (ECoLaSS) aims at developing innovative methods, algorithms and prototypes to improve and develop next-generation operational Copernicus Land services from 2020 onwards, for the pan-European and Global Components. One new envisaged pan-European service...
Article
Full-text available
Abstract Crowdsourcing, understood as outsourcing tasks or data collection by a large group of non-professionals, is increasingly used in scientific research and operational applications. In this paper, we reviewed crowdsourcing initiatives in agricultural science and farming activities and further discussed the particular characteristics of this a...
Article
Full-text available
A global reference data set on cropland was collected through a crowdsourcing campaign using the Geo-Wiki crowdsourcing tool. The campaign lasted three weeks, with over 80 participants from around the world reviewing almost 36,000 sample units, focussing on cropland identification. For quality assessment purposes, two additional data sets are provi...
Article
Full-text available
Building on the availability of high revisit frequency Earth Observation satellites at medium spatial resolution (250 m), this study investigates the feasibility of temporal monitoring of water bodies at a continental scale with MODIS. A 2004–2010 time series of twice-daily observations covering the whole African continent was systematically proces...
Article
Pixel counting is probably the most popular way to estimate class areas from satellite-derived maps. It involves determining the number of pixels allocated to a specific thematic class and multiplying it by the pixel area. In the presence of asymmetric classification errors, the pixel counting estimator is biased. The overarching objective of this...
Article
Full-text available
The lack of sufficient ground truth data has always constrained supervised learning, thereby hindering the generation of up-to-date satellite-derived thematic maps. This is all the more true for those applications requiring frequent updates over large areas such as cropland mapping. Therefore, we present a method enabling the automated production o...
Data
Gini analysis per province. The file shows the Gini index fall all bands of the spectral-temporal features for the nine provinces. (CSV)