Reference : UMR7263-KHEBOU-010
Workplace : AIX EN PROVENCE
Date of publication : Monday, June 20, 2022
Scientific Responsible name : Co-supervision of the thesis by Cécile ALBERT (CR CNRS), Olivier BLIGHT (MC Univ Avignon) and Benoit GESLIN (MC AMU).
Type of Contract : PhD Student contract / Thesis offer
Contract Period : 36 months
Start date of the thesis : 1 October 2022
Proportion of work : Full time
Remuneration : 2 135 €
Description of the thesis topic
Response of arthropod populations and communities to the loss and fragmentation of pebble cover in the Crau steppe. The loss and fragmentation of natural habitats represent a major threat to biodiversity on a global scale . While there is a strong consensus that conserving biodiversity requires preserving a large amount of natural habitats (i.e. reducing or even halting habitat loss) , the optimal spatial arrangement of these habitats has been the subject of intense debate since the 1970s [3,4]. More precisely, for a certain quantity of habitats in a landscape, are there spatial configurations that are really more favourable than others for maintaining biodiversity? This debate is extremely lively in the current literature with two opposing scientific communities: those who defend the fact that managing the spatial configuration of habitats is essential for conservation versus those who assert that managing the configuration is of little interest and that conservation requires first and foremost the preservation and restoration of natural habitats. The two phenomena, habitat loss and fragmentation, are not independent: as the amount of habitat in a landscape decreases, the remaining 'pieces' of habitat become smaller and more widely spaced, making the debate difficult to resolve . Given the high land pressure on ecosystems today, the opportunities to maintain or restore habitats in large quantities are limited. In this context, planning territories to optimise the spatial configuration of habitats appears to be the only option for conserving biodiversity . Resolving the debate on habitat fragmentation has therefore become a priority.
The SCALED project, funded by the European Research Council (ERC), aims to address this debate. In this context, we are setting up an in situ experimental approach that aims to characterise the response of populations and communities of arthropods in the dry grasslands of the Crau plain and of different arthropod species, including apterous beetles (Asida sericea, Poecilus sericeus and Acinopus picipes) and top predators such as Lycosa tarentula and Scolopendra cingulata, to the quantity and spatial organisation of their habitat. In this system, typical grasslands are ~50% covered by large pebbles from the former Durance river bed; pebbles that provide beetles with shelter from extreme temperatures and predators . Many areas of the plain have been cleared to make way for agricultural activities, thus drastically reducing the abundance and richness of the beetle communities . However, we do not know how the intensity of cobble removal and the spatial organisation of the remaining cobbles may or may not mitigate these effects on beetles.
The objectives of this thesis are more specifically to: 1) temporal monitoring of population dynamics of target species and arthropod communities in the field in different artificial landscapes already set up, 2) analysis of the effect of the pebble cover on the whole ecosystem, 3) monitoring of individual movements and behaviours on some taxa.
The student will therefore be required to carry out trapping in the field (barber traps), determination and counting in the laboratory as well as statistical analysis in R.
1. IPBES. Global Assessment Report on Biodiversity and Ecosystem Services. (2019).
2. Fletcher Jr, R. J. et al. Is habitat fragmentation good for biodiversity? Biol. Conserv. 226, 9–15 (2018).
3. Fahrig, L. et al. Is habitat fragmentation bad for biodiversity? Biol. Conserv. 230, 179–186 (2019).
4. Diamond, J. M. The island dilemma: lessons of modern biogeographic studies for the design of natural reserves. Biol. Conserv. 7, 129–146 (1975).
5. Villard, M. & Metzger, J. P. Beyond the fragmentation debate: a conceptual model to predict when habitat configuration really matters. J. Appl. Ecol. 51, 309–318 (2014).
6. Albert, C. H., Rayfield, B., Dumitru, M. & Gonzalez, A. Applying network theory to prioritize multispecies habitat networks that are robust to climate and land‐use change. Conserv. Biol. 31, 1383–1396 (2017).
7. Buisson, E. & Dutoit, T. Creation of the Natural Reserve of la Crau: implications for the creation and management of protected areas. J. Environ. Manage. 80, 318–326 (2006).
8. Blight, O. et al. Using stone cover patches and grazing exclusion to restore ground-active beetle communities in a degraded pseudo-steppe. J. Insect Conserv. 15, 561–572 (2011).
Constraints and risks
Fieldwork, laboratory work, statistical analysis, scientific writing and presentation.
- Good level in entomology (particularly Mediterranean arthropods, Crau plain)
- Good level of programming and analysis in R
- Good level in English
- Autonomy and initiative
- Team work
We talk about it on Twitter!