Agriculture is known to strongly influence soil functioning. Nevertheless, its long-term effects remain not well documented in the Mediterranean region, which has a long history of human land use. The “Parc Naturel Régional du Luberon” is a good illustration of these land use changes, as its territory is now covered with forests of differing ages and histories. This study investigates the effect of past land use (agricultural terraces) on microarthropods of current forest soils. In this way, Acari and Collembola of soils from ancient forests, recent forests (developed before 1958), and very recent forests (developed after 1958) were analysed. Different pedoclimatic conditions (Meso-Mediterranean vs. Supra-Mediterranean) and two contrasted seasons (winter and summer) were taken into account in mesofauna responses. A negative effect of past agricultural land use was observed on soil microarthropod abundance in very recent forests only, whatever the pedoclimatic conditions. After at least 60 years of reforestation, this negative effect was no longer observed, indicating a recovery of these communities. Land use legacy effect on oribatid mites in post-agricultural forests depended on the pedoclimatic conditions considered, suggesting that the recovery of microarthropod communities takes more time under more arid conditions. Microarthropods can be considered as good bioindicators of past land use effects depending on pedoclimatic conditions in forest soils.

This article applies the tools of bibliometric analyses to explore the evolution and strategic orientation of research focusing on the temporal dynamics of land use, which can be considered as an important proxy to assess soil vulnerability. With 1416 papers published in 417 different journals, the investigation showed a growing interest in the subject during the period ranging from 2001 to 2020. The main countries working on that topic are the USA, China, and certain countries of the European Union with a worldwide collaboration regarding coauthors. A cluster analysis of the keywords generated 6 main themes of research, each focusing on different issues and approaches, that is, greenhouse gas emissions, soil nutrients, climate change, erosion risk, human disturbances as well as resilience of soil functioning. Finally, it appears that the effect of land use legacy is poorly considered in the context of climate change, which could represent a future line of research.

Land use is known to be one of the major factors driving soil microbial and physico‐chemical properties. Understanding its long‐term effect remains a major challenge in assessing current soil functioning. Here, soil microbial and physico‐chemical properties of recent and very recent forests (forests developed in 1958 vs. after 1958) were compared with those of ancient forests (present in 1860 and 1958) to assess the effect of Land Use Legacy (LUL). LUL effects were further analysed depending on contrasting (i) climate conditions (sub‐humid vs. humid Mediterranean climates) and (ii) seasons (winter and summer), to examine whether LUL modified microbial responses to different spatio‐temporal climate conditions. Microbial indicators (lignocellulolytic activities, basal respiration, and microbial biomass) and physico‐chemical properties (C and N contents, mineralogical analyses, pH and conductivity) were assessed. A strong effect of past agricultural practice (terrace cultivation) was observed in soils from very recent forests: reduced microbial biomass and activities as well as number of Quercus pubescens stems together with increased phosphorous content and pH. Interestingly, LUL effect did not affect microbial and physico‐chemical responses to seasonal contrasts (winter vs. summer). Microbial response to LUL was not influenced by climate while climate modified LUL effects on some physico‐chemical properties (CaCO₃, C_org, and K content). Moreover, soil recovered “pristine” physico‐chemical and microbial functional properties after at least 60 years of reforestation.

L'utilisation des terres est l'un des principaux facteurs déterminant les propriétés physico-chimiques et biologique des sols. Comprendre son effet à long terme est un défi majeur pour évaluer le fonctionnement actuel des sols et leurs vulnérabilités face aux changements globaux. Dans la région méditerranéenne, l'abandon de l'agriculture en terrasse à partir du XIXème siècle a entraîné la coexistence de forêts présentant des continuités temporelles (historique d’usage et âge) différentes. L’objectif de cette thèse est de déterminer si, dans le cas de sols d’écosystèmes forestiers, l’usage antérieur des sols (i) produit une signature chimique spécifique et (ii) conduit à des propriétés physico-chimiques et biologiques différentes modifiant son fonctionnement actuel. Pour ce faire, le potentiel analytique de la spectroscopie FTIR a permis de réaliser un référentiel des signatures chimiques des sols en fonction de leurs usages actuels (forêts vs agrosystèmes) dépendamment des pratiques associées et du climat. Puis cette technique a été testée pour discriminer des sols ayant une histoire d’occupation des terres différente (forêts anciennes, récentes et très récentes du Parc Naturel Régional du Luberon) en fonction de différentes profondeurs et conditions climatiques. L’incidence des usages antérieurs sur le fonctionnement actuel des sols a ensuite été appréhendée par le biais d’analyses des communautés microbiennes et de la mésofaune ainsi que par des analyses physico-chimiques complémentaires. Cette étude confirme ainsi que l’historique d’usage doit être pris en compte dans l’évaluation de la vulnérabilité des sols, notamment dans un contexte de changement climatique

Viticulture is a major agricultural sector in France, which ranks third worldwide in terms of vineyard surface area. Productivity-oriented practices in this sector have negatively affected soils and their biodiversity. In response, alternative practices to conventional viticulture have gained increasing attention. This study assessed the effects of different soil management practices on key organisms for soil ecosystem functioning across 37 vineyards in southern France. Vineyards were selected to encompass various agricultural practices, including variation in inter-row vegetation cover, presence or absence of organic matter input, and tillage intensity. A multi-taxa, integrative approach was employed to investigate the responses to management practices of three soil fauna groups (spiders, ants and Collembola), while also taking into account soil and landscape properties that shape these communities. Spiders and ants were sampled using pitfall traps, and Collembola were extracted from soil cores. Generalised linear models showed that the predominant factor in structuring soil fauna communities was agricultural practices more than soil and landscape properties. All soil fauna groups studied responded negatively to soil tillage intensity, while ant communities were negatively affected by pesticide intensity, and Collembola density increased with organic matter inputs. Overall, these findings highlight a convergent response of soil fauna to tillage intensity, alongside taxon-specific responses to soil properties and organic matter input. We found that only spider communities were influenced by landscape properties. These results demonstrate that integrated, multi-scale and multi-taxa approaches are valuable tools to develop relevant, sustainable management practices that preserve soil biodiversity and their associated functions in vineyards.