Michez Adrien

University of Liège | ulg · Gembloux Agro-Bio Tech

(1) Regular wildlife abundance surveys are a key conservation tool. Manned aircraft flying transects often remain the best alternative for counting large ungulates. Drones have cheaper and safer logistics, however their range is generally too short for large-scale application of the traditional method. Our paper investigates an innovative rosette f...

Unmanned aerial systems (UASs) represent an important tool to characterize vegetation patterns and processes. Their ultrahigh resolution and flexibility may help to bridge the gap between field and satellite remote sensing data. UASs can address a variety of fields, ranging from biodiversity mapping and monitoring through the assessment of ecosyste...

Remote sensing can be used to collect information related to forest management. Previous studies demonstrated the potential of using multispectral satellite imagery for classifying tree species. However, methods that can map tree species in mixed forest stands on a large scale are lacking. We propose an innovative method for mapping the proportions...

Riparian zones are the paragon of transitional ecosystems, providing critical habitat and ecosystem services that are especially threatened by global change. Following consultation with experts, 10 key challenges were identified to be addressed for riparian vegetation science and management improvement: (1) Create a distinct scientific community by...

La surface de la pessière wallonne a diminué de 30 % entre 1980 et 2010. L’exploitation d’un grand nombre de peuplements arrivés à maturité ces deux dernières décennies et un faible taux de replantation expliquent cette tendance. La crise des scolytes que nous avons connue ces dernières années, si elle a accentué la pression sur la ressource en épi...

Managers need to know how to mitigate rising stream water temperature (WT) due to climate change. This requires identifying the environmental drivers that influence thermal regime and determining the spatial area where interventions are most effective. We hypothesized that (i) extreme thermal events can be influenced by a set of environmental facto...

Ecosystem complexity is among the important drivers of biodiversity and ecosystem functioning, and unmanned aerial systems (UASs) are becoming an important tool for characterizing vegetation patterns and processes. The variety of UASs applications is immense, and so are the procedures to process UASs data described in the literature. Optimizing the...

Les écosystèmes riverains constituent un enjeu écologique majeur par les nombreux services écosystémiques qu’ils fournissent à travers le globe. Pour créer ou encourager des projets de préservation et de restauration écologiques, une caractérisation de ces milieux est nécessaire. Une prémisse à cette caractérisation est l’évaluation de la diversité...

The highlighting and study of extreme water temperatures, which endanger numerous species, is of particular interest for river managers planning for future thermal conditions. Extreme water temperatures, defined as temperatures outside the normal range, are predicted to occur more frequently. This range includes seasonality and other trends in temp...

The connectivity of riparian forests can be used as a proxy for the capacity of riparian zones to provide ecological functions, goods and services. In this study, we aim to test the potential of the freely available Copernicus “Riparian Zones” dataset to characterize the connectivity of riparian forests located in two European bioclimatic regions—t...

En application de nouvelles dispositions du Code de l’Eau entrées en vigueur fin 2018, les gestionnaires de cours d’eau publics wallons ont élaboré des programmes d’actions détaillés (PARIS) pour la période 2022-2027, à l’échelle d’unités de gestion physiquement homogènes appelées « secteurs ». Ces PARIS ont pour vocation de contribuer à une gestio...

Riparian ecosystems are home to a remarkable biodiversity, but have been degraded in many regions of the world. Vegetation biomass is central to several key functions of riparian systems. It is influenced by multiple factors, such as soil waterlogging, sediment input, flood, and human disturbance. However, knowledge is lacking on how these factors...

Wildlife monitoring is an important part of the conservation strategies for certain endangered species. Non-invasive methods are of significant interest because they preserve the studied animal. The study of signs, especially tracks, seems to be a valuable compromise between reliability, simplicity and feasibility. The main objective of this study...

In the context of global biodiversity loss, wildlife population monitoring is a major chal-lenge. Some innovative techniques such as the use of drones—also called unmanned aerial vehi-cle/system (UAV/UAS)—offer promising opportunities. The potential of UAS-based wildlife censususing high-resolution imagery is now well established for terrestrial ma...

L’eau, ressource à protéger, est de plus en plus soumise à diverses contraintes liées notamment à la demande croissante en eau et au réchauffement climatique. Dans ce contexte, la gestion durable des cours d’eau est plus que jamais une nécessité. Pour mettre fin à la détérioration de l’état des masses d’eau et les amener à un « bon état », la direc...

Riparian vegetation is a central component of the hydrosystem. As such, it is often subject to management practices that aim to influence its ecological, hydraulic or hydrological functions. Remote sensing has the potential to improve knowledge and management of riparian vegetation by providing cost-effective and spatially continuous data over wide...

Forest monitoring tools are needed to promote effective and data driven forest management and forest policies. Remote sensing techniques can increase the speed and the cost-efficiency of the forest monitoring as well as large scale mapping of forest attribute (wall-to-wall approach). Digital Aerial Photogrammetry (DAP) is a common cost-effective al...

Applied to grazing management, unmanned aerial systems (UASs) allow for the monitoring of vegetation at the level of each individual on the pasture while covering a significant area (>10 ha per flight). Few studies have investigated the use of UASs to describe the forage quality in terms of nutritive value or chemical composition, while these param...

The use of unmanned aerial systems (UASs) has rapidly grown in many civil applications since the early 2010s. Nowadays, a large variety of reliable low-cost UAS sensors and controllers are available. However, contrary to ultralight aircrafts (ULAs), UASs have a too small operational range to efficiently cover large areas. Flight regulations prevail...

In the context of the climate and biodiversity crisis facing our planet, tropical forests playing a key role in global carbon flux and containing over half of Earth's species are important to preserve. They are today threatened by deforestation but also by forest degradation, which is more difficult to study. Here, we performed a systematic review...

Nous avons utilisé le réseau wallon de surveillance du niveau d’eau des cours d’eau non navigables (réseau Aqualim) afin d’étudier leur régime thermique. Le réseau Aqualim enregistre, en plus de la hauteur d’eau, la température de l’eau toutes les 10 minutes afin de calibrer les données de hauteur d’eau. Nous nous sommes donc intéressés à ces donné...

Ce guide concerne la gestion de toute végétation ligneuse présente sur les berges et les rives des cours d’eau, qui a une influence directe sur le cours d’eau ou qui est directement influencée par celui-ci. Il a été réalisé par la faculté de Gembloux- Agro-Bio Tech de l’Université de Liège à la demande de la Direction des Cours d’eau non navigables...

Many studies focus on stream water temperature (WT) because it is considered a key ecological factor. However, few of them have investigated the use of WT data from water level monitoring networks, which often measure WT as ancillary data. Our study was conducted in southern Belgium at a high temporal resolution with continuous data recorded at int...

Trees have important and diverse roles that make them essential outside of the forest. The use of remote sensing can substantially support traditional field inventories to evaluate and characterize this resource. Existing studies have already realized the automated detection of trees outside the forest (TOF) and classified the subsequently mapped T...

The tools available to farmers to manage grazed pastures and adjust forage demand to grass growth are generally rather static. Unmanned aerial systems (UASs) are interesting versatile tools that can provide relevant 3D information, such as sward height (3D structure), or even describe the physical condition of pastures through the use of spectral i...

In recent decades, remote sensing has increasingly been used to estimate the spatio-temporal evolution of crop biophysical parameters such as the above-ground biomass (AGB). On a local scale, the advent of unmanned aerial vehicles (UAVs) seems to be a promising trade-off between satellite/airborne and terrestrial remote sensing. This study aims to...

Description of the subject. Understanding the current situation and evolution of forests is essential for a sustainable management plan that maintains forests’ ecological and socio-economic functions. Remote sensing is a helpful tool in developing this knowledge. Objectives. This paper investigates the new opportunities offered by using Sentinel-2...

La température des cours d’eau est un facteur central pour la compréhension du fonctionnement des écosystèmes aquatiques. La Wallonie (Sud de la Belgique) dispose d’un réseau permanent de monitoring de hauteur d’eau d’environ 140 stations mesurant également la température de l’eau à intervalles de 10 minutes. L’objectif de cette communication est...

Forested catchments are generally assumed to provide higher quality water in opposition to agricultural and urban catchments. However, this should be tested in various ecological contexts and through the study of multiple variables describing water quality. Indeed, interactions between ecological variables, multiple land use and land cover (LULC) t...

Sous l'impulsion de son administration, la Wallonie a entamé un processus de révision des modalités de gestion de ses cours d'eau publics, notamment à travers le projet des Programmes d'actions sur les rivières par une approche intégrée et sectorisée (PARIS). Les PARIS ont pour but d'intégrer dans le temps et dans l'espace l'ensemble des mesures de...

Le ministère en charge de l'environnement et l'Office national de l'eau et des milieux aquatiques (Onema, intégré à l'Agence française pour la biodiversité depuis le 1er janvier 2017) ont organisé le 10 juin 2016, à Paris, une journée d'échanges sur les avancées techniques et scientifiques et leurs applications opérationnelles offertes par la téléd...

Field measurements in the ICOS program are spatially limited whereas the monitored gas fluxes may have a large footprint. Aerial remote sensing has the advantage to monitor large areas. The main goal of our research was to test the potential of unmanned aerial vehicles (UAV) to upscale parameters monitored through the ICOS program. In this study, w...

Forested catchments are generally assumed to provide higher quality water. However, this hypothesis must be validated in various contexts as interactions between multiple land use and land cover (LULC) types, ecological variables and water quality variables render this relationship highly complex. This paper applies a straightforward multivariate a...

Riparian buffers are of major concern for land and water resource managers despite their relatively low spatial coverage. In Europe, this concern has been acknowledged by different environmental directives which recommend multi-scale monitoring (from local to regional scales). Remote sensing methods could be a cost-effective alternative to field-ba...

Michez Adrien (2016) Caractérisation multi-échelle des bandes riveraines des cours d'eau wallons par télédétection active et passive. Thèse de doctorat. Université de Liège-Gembloux Agro-Bio Tech. 159 p. Résumé Les bandes riveraines des cours d'eau constituent des milieux d'une richesse exceptionnelle aux multiples facettes, comportant les habitats...

Damage caused by ungulates to agricultural areas are difficult to evaluate because the real extent of the damage remains usually poorly described and potentially arising conflicts. Recent advances in unmanned aerial system (UAS) provide new versatile mapping and quantification possibilities in a wide range of applications. We used crop fields (Zea...

Forest surfaces on a global scale represent one-third of the world land area. Human civilizations have always interacted closely with these ecosystems, notably through the broad range of environmental services that they provide: protection of water resources, soil protection, mitigation of the excesses of local climate, reduction of impacts of gas...

Riparian forests are critically endangered many anthropogenic pressures and natural hazards. The importance of riparian zones has been acknowledged by European Directives, involving multi-scale monitoring. The use of this very-high-resolution and hyperspatial imagery in a multi-temporal approach is an emerging topic. The trend is reinforced by the...

Riparian zones are key landscape features, representing the interface between terrestrial and aquatic ecosystems. Although they have been influenced by human activities for centuries, their degradation has increased during the 20th century. Concomitant with (or as consequences of) these disturbances, the invasion of exotic species has increased thr...

In forestry, top height is a common parameter used as indicator of the stand development stage. It can be used to estimate the potential production of monospecific even-aged stands. However, accurate field estimation of top height is time-consuming and expensive. Since the last two decades, LiDAR has proven to be very useful in estimating forest he...

Technology advances can revolutionize Precision Forestry by providing accurate and fine forest information at tree level. This paper addresses the question of how and particularly when Unmanned Aerial System (UAS) should be used in order to efficiently discriminate deciduous tree species. The goal of this research is to determine when is the best t...

La hauteur dominante est une information souvent utilisée en gestion forestière. Il s'agit d'un bon indicateur du niveau de développement des peuplements, pouvant être employé pour estimer le niveau de productivité des peuplements purs équiennes. Cependant, son estimation à partir de mesures de terrain est relativement fastidieuse et coûteuse. Depu...

The present study proposes an innovative approach to automatically extract riparian zone characteristics in order to assess its quality, from pre-determined river management reaches (1-3 km long) to regional scale (ca. 13,000 km for 1,000 management sectors). The aim of this remotely sensed monitoring is to improve river and riparian zone managemen...

Wild boar ability to cause important damages to agricultural lands is not anymore to be demonstrated. These damages often raise conflicts between farmers and hunters due to the associated economic losses. Objective and accurate method for real impact assessment of losses suffered by farmers is thus needed. Currently,in Wallonia damage assessment is...

D’une invention initialement militaire, les drones - et les applications qui dérivent de leurs utilisation - tendent à se banaliser au sein du domaine civil. En terme d’applications géographiques, les micro-drones (< 2 kg) occupent un segment nouveau dans les techniques d’acquisition d’informations, à mi-chemin entre deux segments plus classiques,...

Introduction : Despite their relatively low area coverage, riparian forests are central landscape features providing several ecosystem services. Nevertheless, they are critically endangered in European countries by human pressures (livestock grazing, land use conflicts, canalizations, waste water, ...) andalso by natural hazards such as the recent...

Due to the paucity of suitable habitat, hippos are very rare in the Congo Bassin. Compared to East-African populations, Central African populations of hippos have been less studied. Information found in the literature regarding the animal’s basic ecology is limited. This study focuses on the description of the diet of an isolated hippo population i...