Dirk Maes

• PhD
• Senior Researcher at Research Institute for Nature and Forest

Background In response to the ongoing biodiversity crisis amongst arthropods, it is essential to implement efficient conservation strategies to safeguard both species diversity and the vital ecosystem services they provide. Developing such strategies requires reliable predictive models that can identify the species that are the most vulnerable to c...

Context Genetic connectivity is often disrupted by anthropogenic habitat fragmentation, and therefore often a focus in landscape-scale conservation. Landscape genetics methods allow for studying functional connectivity in heterogenous landscapes in detail and have the potential to inform conservation measures for a species’ regional persistence. Ye...

Species populations naturally fluctuate, yet long-term trend analysis can reveal patterns of success, decline, or stability under global change pressures. While responses to climate change are well31 documented, its synergy with another major global driver, urbanization, remains understudied. Here, we analyzed long-term monitoring data from over 8,...

Genetic factors can have a major influence on both short‐ and long‐term success of reintroductions. Genomic monitoring can give a range of insights into the early life of a reintroduced population and ultimately can help to avoid wasting limited conservation resources. In this study, we characterise the genetic diversity of a reintroduced Carteroce...

Arthropods, as ectotherms, are experiencing global declines, with many species facing the need to either acclimate or disperse in response to climate change. To generate general insights into such responses, a framework integrating traits on life history, dispersal and thermal niche is currently lacking. In light of this, understanding to which deg...

In response to the ongoing biodiversity crisis among arthropods, it is essential to implement efficient conservation strategies to safeguard both species diversity and the vital ecosystem services they provide. Developing such strategies requires reliable predictive models that can identify the species that are the most vulnerable to current and fu...

The importance of genetic diversity has been recognised by the Convention on Biological Diversity but attempts at monitoring or improving the genetic diversity of populations have been minimal. Here, we investigate changes over time in the genetic diversity of a wild insect species, Maniola jurtina (Lepidoptera: Nymphalidae) and present a large‐sca...

Aim Anthropogenic‐driven biodiversity loss can impact ecosystem stability. However, most studies have only evaluated the diversity–stability relationship at the local scale and we do not fully understand which factors stabilize animal populations and communities across scales. Here, we investigate the role of species dispersal ability, climate, spa...

Arthropod movement has been noticeably understudied compared to vertebrates. A crucial knowledge gap pertains to the factors influencing arthropod movement at habitat boundaries, which has direct implications for population dynamics and gene flow. While larger arthropod species generally achieve greater dispersal distances and large‐scale movements...

Insect abundance and diversity appear to decline rapidly in recent decades, garnering significant media attention, and hence raising public awareness. Macro‐moths—a species‐rich and ecologically diverse insect group—face severe declines, particularly in urbanised and intensively farmed areas in NW Europe. Flanders is a highly anthropogenic region,...

The strong and rapid decline of pollinators and other insects has recently drawn attention from both scientists and the media. The main threats to insects are habitat loss and fragmentation, pesticides, climate change and invasive species (such as the Yellow-legged Hornet Vespa velutina). To halt this decline it is important to conserve and manage...

Habitat loss and fragmentation have caused declines in the abundance and distribution of butterflies, particularly habitat specialists. The Chequered Skipper, Carterocephalus palaemon, has been extinct in England since 1976 after declining from the 1940s predominantly due to changes in woodland management including afforestation and the decline in...

In the NW-European region of Flanders (northern Belgium), wet heathlands harbour several threatened species among which the emblematic Alcon Blue butterfly Phengaris alcon is rapidly declining. Since 1990, the number of occupied grid cells in Flanders has decreased from 61 to only six in 2023, a decline of 90%. Due to the loss of many populations,...

The strong and rapid decline of pollinators and other insects has recently drawn attention from both scientists and the media. The main threats to insects are habitat loss and fragmentation, pesticides, climate change and invasive species (such as the Yellow-legged hornet). To halt this decline, it is crucial to conserve and manage areas that are i...

Habitat management is necessary for the conservation of threatened species, yet best practices in fragmented human-dominated landscapes have remained difficult to generalise. We show that multi-scale vegetation management decisions in heathlands can be supported by integrating opportunistic citizen science data and multispectral satellite data. Opp...

Citizen science is an increasingly powerful tool to gather large quantities of biological data and to engage the public. The number of citizen science initiatives has rapidly increased in the last 15 years. Invasive alien species such as the harlequin ladybird, Harmonia axyridis (Coleoptera, Coccinellidae), provide a particularly good opportunity f...

Despite large numbers of reintroduction projects taking place and the high cost involved, there is a generally low success rate. Insects in particular are understudied within reintroduction ecology, with guidelines focusing on more iconic vertebrate taxa. Species distribution models (SDMs) examine the associations between species observations and e...

Trade‐offs among traits are central to life‐history theory and often closely linked to an organism's fitness. Understanding how these trade‐offs vary among populations and across environments is therefore important to more accurately predict species' responses to future climate change. However, the extent to which responses vary across populations...

Arthropod movement has been noticeably understudied compared to vertebrates. A crucial knowledge gap pertains to the factors influencing arthropod movement at habitat boundaries, which has direct implications for population dynamics and gene flow. While larger arthropod species generally achieve greater dispersal distances and large-scale movements...

Connectivity is a species- and landscape-specific measure that is key to species conservation in fragmented landscapes. However, information on connectivity is often lacking, especially for insects which are known to be severely declining. Patterns of gene flow constitute an indirect measure of functional landscape connectivity. We studied the popu...

NatuurFocus

International and regional legislations require authorities to report regularly on the state of species of conservation concern in their region or country (e.g., the EU Birds and Habitats Directives). Monitoring schemes for species across a variety of taxonomic groups are being set up to estimate abundance trends. In Flanders (northern Belgium), un...

The Red List criteria of the International Union for Conservation of Nature (IUCN) prescribe that Red Lists should preferably be revised every ten years. This is the first Red for macro-moths in Flanders. For this, we used three of the five possible IUCN criteria, i.e., changes in distribution (IUCN criterion A), the extent of occurrence (IUCN crit...

Context Genetic connectivity is often disrupted by anthropogenic habitat fragmentation, and therefore often a focus in landscape-scale conservation. Landscape genetics methods allow for studying functional connectivity in heterogenous landscapes in detail and have the potential to inform conservation measures for a species’ regional persistence. Ye...

Connectivity is a species- and landscape-specific measure that is key to species conservation in fragmented landscapes. However, information on connectivity is often lacking, especially for insects that are known to be severely declining. Patterns of gene flow constitute an indirect measure of functional landscape connectivity. We studied the popul...

The recent decline in insect diversity and abundance and the consequences for associated ecosystem functioning and services have attracted growing attention. Especially highly anthropogenic regions are affected by rapid biodiversity changes including significant losses. Two decades ago, we suggested that Flanders (northern Belgium) was Europe's wor...

Although diversity and abundance of arthropods have been shown to decline globally, they are underrepresented in nature conservation efforts and policies. Belowground taxa are especially neglected, despite their key roles in ecosystem functioning. Terrestrial isopods are litter and soil dwelling and important contributors to litter decomposition an...

Towards a more robust Flemish nature? An exploratory study with recommendations regarding the evaluation of the regional conservation objectives

De Knijf G., Lambrechts J. & Maes D. 2022. A new Red List of the dragonflies and damselflies in Flanders. A dramatic decline of Odonata species of bogs and heathland ponds. Natuurfocus 21(2): 52-61. [In Dutch] The IUCN Red List criteria are intended to be an easily and widely understood system for classifying species the extinction risk of species...

Opportunistic citizen science data are commonly filtered in an attempt to improve their applicability for relating species occurrences with environmental variables. Recommendations on when and how to filter, however, have remained relatively general and associations between species traits and filtering recommendations are sparse. We collected six t...

This is a commentary on Hodgson et al., 2022, https://doi.org/10.1111/gcb.16220

In dit rapport geven we voor negen taxonomische groepen (vaatplanten, amfibieën en reptielen, vissen, broedvogels, overwinterende watervogels, zoogdieren, dagvlinders, libellen en sprinkhanen en krekels) een geactualiseerde lijst van soorten die belangrijk zijn voor het provinciale natuurbehoud, -beheer en/of -beleid in Antwerpen. De gegevensbronne...

In dit rapport geven we voor negen taxonomische groepen (vaatplanten, amfibieën en reptielen, vissen, broedvogels, overwinterende watervogels, zoogdieren, dagvlinders, libellen en sprinkhanen en krekels) een geactualiseerde lijst van soorten die belangrijk zijn voor het provinciale natuurbehoud, -beheer en/of -beleid in Vlaams-Brabant. De gegevensb...

In dit rapport, dat samen met de vijf provinciale rapporten één geheel vormt, beschrijven we de procedure voor de afbakening van provinciaal prioritaire soorten, maar ook van andere soorten die voor het provinciale natuurbehoud en/of -beleid van belang kunnen zijn. Naast provinciaal prioritaire soorten sensu Bauwens et al. (2001), waarbij de soorte...

In dit rapport geven we voor negen taxonomische groepen (vaatplanten, amfibieën en reptielen, vissen, broedvogels, overwinterende watervogels, zoogdieren, dagvlinders, libellen en sprinkhanen en krekels) een geactualiseerde lijst van soorten die belangrijk zijn voor het provinciale natuurbehoud, -beheer en/of -beleid in West-Vlaanderen. De gegevens...

In dit rapport geven we voor negen taxonomische groepen (vaatplanten, amfibieën en reptielen, vissen, broedvogels, overwinterende watervogels, zoogdieren, dagvlinders, libellen en sprinkhanen en krekels) een geactualiseerde lijst van soorten die belangrijk zijn voor het provinciale natuurbehoud, -beheer en/of -beleid in Limburg. De gegevensbronnen...

In dit rapport geven we voor negen taxonomische groepen (vaatplanten, amfibieën en reptielen, vissen, broedvogels, overwinterende watervogels, zoogdieren, dagvlinders, libellen en sprinkhanen en krekels) een geactualiseerde lijst van soorten die belangrijk zijn voor het provinciale natuurbehoud, -beheer en/of -beleid in Oost-Vlaanderen. De gegevens...

The Red List criteria of the International Union for Conservation of Nature (IUCN) are intended to be an easily and widely understood system for classifying species at high risk of extinction. However, while the Red List may focus attention on those taxa at the highest risk, it is not a means of setting priorities for conservation measures for thei...

Background To set up successful conservation measures, detailed knowledge on the dispersal and colonization capacities of the focal species and connectivity between populations is of high relevance. We developed species-specific nuclear microsatellite molecular markers for the grayling ( Hipparchia semele ), a butterfly endemic to Europe and of gro...

Nesting in dense aggregations is common in central-place foragers, such as group-living birds and insects. Both environmental heterogeneity and behavioral interactions are known to induce clustering of nests, but their relative importance remains unclear. We developed an individual-based model that simulated the spatial organization of nest-buildin...

1. Insect populations show strong temporal fluctuations in abundance. This renders classical monitoring studies extremely difficult to provide insights into specific management actions. For rare species of conservation concern, it is not an option to develop large scale experiments to assess and steer landscape-level actions such as grazing managem...

Simple Summary The peacock butterfly is abundant and widespread in Europe. It used to have a single generation per year: adults born in summer overwintered and reappeared in spring to reproduce. However, recent flight patterns in western Europe show three peaks during the year: a first one in spring (overwintering butterflies), a second one in earl...

Red Lists are important indicators for nature conservation. They are often used to determine for which species action plans or monitoring schemes are being designed. Flanders has a long tradition in Red List assessments and butterflies are the first group for which a third Red List has been compiled recently. This allows us to analyse shifts in but...

The Red List criteria of the International Union for Conservation of Nature (IUCN) prescribe that Red Lists should preferably be revised every ten years. The previous Red List dated from 2011 and, therefore, the current state of butterflies in Flanders was again tested against the international IUCN Red List criteria. For this, we used four of the...

In de bijdrage van Hendrik Schoukens wordt herstelbeheer als een van de werven voor een (juridisch) houdbare Vlaamse Programmatische Aanpak Stikstof (PAS) naar voor geschoven (Schoukens 2021 in dit nummer). Tegelijkertijd geeft de auteur ook aan dat dit geen gemakkelijkheidsoplossing of substituut mag zijn voor het terugdringen van de stikstofemiss...

Apart from the annual garden butterfly-counting weekend, Natuurpunt (the largest nature NGO in Flanders, northern Belgium) also organizes monthly counts of butterflies in gardens since 2007. In this report, we analyse these citizen science data from the period 2007-2019. Volunteers were asked to record the monthly maximum number of individuals per...

Opportunistically collected species occurrence data are often used for species distribution models (SDMs) when high-quality data collected through standardized recording protocols are unavailable. While opportunistic data are abundant, uncertainty is usually high, e.g. due to observer effects or a lack of metadata. To increase data quality and impr...

We review changes in the status of butterflies in Europe, focusing on long-running population data available for the United Kingdom, the Netherlands, and Belgium, based on standardized monitoring transects. In the United Kingdom, 8% of resident species have become extinct, and since 1976 overall numbers declined by around 50%. In the Netherlands, 2...

Bij gebrek aan of in afwachting van grootschalige zandverstuivingsdynamiek in de duinen focust duinbeheer in natuurgebieden vaak op het herstel van habitattypen en maatregelen voor bescherming van specifieke soorten. Begrazing is hierbij een cruciaal beheerinstrument om een dynamisch duinlandschap te behouden of te creëren. Insecten en andere ongew...

Van Klink et al. (Reports, 24 April 2020, p. 417) argue for a more nuanced view of insect decline, and of human responsibility for this decline, than previously suggested. However, shortcomings in data selection and methodology raise questions about their conclusions on trends and drivers. We call for more rigorous methodology to be applied in meta...

In this report, we update the European Grassland Butterfly Indicator, present new butterfly indicators for widespread species, woodland butterflies, as well as butterflies in urban environments, in Natura 2000 areas and as climate change indicators. The indicators use field data up to and including the 2018 field season. The method for calculating...

Asking authors who have tested interventions to explain how they have placed their paper in context will help ensure conservation science reduces the perils of cherry picking scientific evidence and will improve the design of future work. It will not provide a complete remedy to bias in conservation articles. Ideally, the impact of this measure wil...

Sinds 1991 wordt er aan dagvlindermonitoring gedaan in Vlaanderen. Het aantal vlinderroutes is altijd vrij bescheiden geweest en haalde nooit de aantallen van Groot-Brittannië of Nederland. Dankzij nieuwe statistische technieken kunnen we nu echter ook in Vlaanderen trends bereken, zij het alleen voor de meer algemene soorten. In totaal werden in V...

2010 was het Internationaal Jaar van de Biodiversiteit. Dat jaar genoot het veelvormige leven op onze planeet bijzondere aandacht. Het was de start van het Decennium van de Biodiversiteit. Nieuwe akkoorden werden gesmeed, doelstellingen vooropgesteld en strategieën uitgerold. We zijn nu tien jaar later. Tijd voor een nieuwe balans. Natuur.focus bes...

The fate of humans and insects intertwine, especially through the medium of plants. Global environmental change, including land transformation and contamination, is causing concerning insect diversity loss, articulated in the companion review Scientists' warning to humanity on insect extinctions. Yet, despite a sound philosophical foundation, recog...

Tracking devices have become small enough to be widely applied to arthropods to study their movement. However, possible side effects of these devices on arthropod performance and behaviour are rarely considered. We performed a systematic review of 173 papers about research in which tracking devices—radio frequency identification (RFID), harmonic ra...

The Silver-studded Blue Plebejus argus is a threatened butterfly in Flanders. It is typical for early successional stages of both dry and wet heathlands. The species used to occur in the eastern half of Flanders, but is now completely restricted to the Campine region in the north east. Since the middle of the 20th century, the species is declining...

By realising the conservation objectives for European habitats it is assumed that a large number of species will benefit from these measures as well. In this analysis, we test this hypothesis for 142 species of conservation priority in Flanders. To do so, we use the potential habitat approach, i.e. mechanistic models that translate the ecological p...

Each Member State needs to report every 6 years (2013-2019, 2025…) to the European Commission (EC) about the conservation status of habitats and species present in each biogeographical region. This document presents the applied method and results for the period 2013-2018 of the species present in Flanders (northern Belgium). Flanders is nearly comp...

Each Member State needs to report every 6 years (2013-2019, 2025…) to the European Commission (EC) about the conservation status of habitats and species present in each biogeographical region. This document presents the reporting files for the different insect sepcies (beetles, dragonflies, butterflies) and molluscs for the period 2013-2018 of the...

Red Lists estimate the extinction risk of species at global or regional levels and areimportant instruments in conservation policies. Global Red List assessments are readilyavailable via the IUCN website (https://www.iucnredlist.org) and are regularly updated by(taxonomic) experts. Regional Red Lists, however, are not always easy to find and oftenu...

Red Lists are very valuable tools in nature conservation at global, continental and (sub-) national scales. In an attempt to prioritise conservation actions for European butterflies, we compiled a database with species lists and Red Lists of all European countries, including the Macaronesian archipelagos (Azores, Madeira and Canary Islands). In tot...

The Chequered Skipper Carterocephalus palaemon inhabits a variety of habitats in NW Europe: heathlands, wet grasslands and chalk grasslands, usually at woodland edges and wide rides and glades in different types of woodlands. It mainly uses broadleaved grasses such as Molinia, Calamagrostis and Brachypodium as host plants. The species became extinc...

The range of hosts exploited by a parasite is determined by several factors, including host availability, infectivity and exploitability. Each of these can be the target of natural selection on both host and parasite, which will determine the local outcome of interactions, and potentially lead to coevolution. However, geographical variation in host...

Het natuurbeleid, -beheer en -behoud baseerde zich vroeger vaak op de kennis of ervaring van mensen in het veld. De vraag naar een meer door gegevens onderbouwde aanpak is in de loop der jaren echter steeds groter geworden. Omwille van het grote aantal gebieden, biotopen en soorten en de vraag naar gebiedsdekkende inventarisaties, is het verzamelen...

Vooraleer de monitoring te kunnen aanvatten moet de kennis over de verspreiding van 4 soorten mollusken voldoende zijn om een goed steekproefkader te kunnen opstellen. Vooral voor de Nauwe korfslak (Vertigo angustior), de Zeggekorfslak (Vertigo moulinsiana), de Platte schijfhoren (Anisus vorticulus) en de Bataafse stroommossel (Unio crassus) dient...

This annual report provides a summary of the status of the indicators concerning the European Biodiversity Strategy targets. For Target 1, the conclusions at the Flemish level are in line with the EU Mid Term Review. For example, a small number of habitats and species of the Habitat Directive are improving slightly, but the majority are still in...

Aim Species distribution models built with geographically restricted data often fail to capture the full range of conditions experienced by species across their entire distribution area. Using such models to predict distribution shifts under future environmental change may, therefore, produce biased projections. However, restricted‐scale models hav...

This report describes the monitoring networks for the mammals European hamster (Cricetus cricetus), Common dormouse (Muscardinus avellanarius), European badger (Meles meles) and European otter (Lutra lutra). The aim of the monitoring is to obtain a population trend estimate on a Flemish scale. Common dormouse is counted annually along transects. Eu...