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Despite the large contribution of macropores made by soil engineers to the soil macroporosity and water infiltration, few studies have addressed the specific contribution of soil engineer groups, dynamics of biopores and their efficiency in conducting water. Thus, we aimed to investigate the link between soil macrofauna, soil biopores and water infiltration under different pedoclimatic conditions. To do so, we conducted an experimentation in twelve study sites with a large longitudinal gradient from France to Vietnam. The experiment consisted in the field incubation of repacked soil in cores (15 cm in height and 15 cm in diameter) and controlling the activity of soil engineers in the manner of litter bag. For each site, soil columns were: (i) covered with a mesh (200µm) or not and (ii) with or without addition of organic residues to the soil surface. After 12 months, we measured (i) the 3D organization of biopores by X-ray computed tomography and (ii) the saturated hydraulic conductivity by Beerkan method. In addition, soil macrofauna communities and the 3D organization of biopores was measured in each study field. Addition of organic residues increased up to 2-fold the volume percentage of biopores which reached similar values than those observed for each study field. The co-inertia analysis between the data matrix characterizing the shape of biopores and the data matrix of the macrofauna communities showed no statistically significant correlation. Saturated hydraulic conductivity increased with the presence of biopores by 2 to 50-fold with the lowest increased in soils presenting largest saturated hydraulic conductivity. In conclusion, these results demonstrated that biopores are rapidly regenerated regardless the pedoclimatic conditions while the efficiency of biopores in conducting water is related to soil properties.

The availability of globally harmonized standard operating procedures (SOPs) will greatly enhance the ability to provide comparable data. Laboratories are nowadays asked to provide data for traditional services and for the payment of ecosystem services. To ensure the reliability and comparability of data, laboratories should use globally accepted SOPs and apply quality assurance and quality control procedures. The Global Soil Laboratory Network (GLOSOLAN) of the Global Soil Partnership, FAO was established in 2017 to harmonize soil analytical data while building and strengthening the analytical capacity of laboratories worldwide. According to the Global Soil Laboratory Assessment 2018, the few methods used to measure the most common soil parameters (e.g. CNPK) have a large number of modifications resulting in high levels of divergence. According to GLOSOLAN, the methods used by laboratories are the result of geographic isolation, historical circumstances, and technical and economic constraints. The adoption of a common SOP per soil parameter is currently difficult as laboratories select the SOPs to use considering the suitability of the method to their soils and local calibrations to plant response in individual environments. Still, commercially available SOPs are the result of top-down development processes that excluded some countries and regions, and their cost and language sometimes limit their accessibility and use. To overcome these barriers, GLOSOLAN has developed a bottom-up, inclusive approach to harmonize and publish its SOPs that actively involves all its members. When only 29 countries were involved in the ISO technical committee on soil (TC190), GLOSOLAN had 72 contributors from 51 countries in its SOP on Walkley and Black. Individual contributions are processed and harmonized by a dedicated working group that is tasked to write the SOP. Thereafter, the draft SOP is reviewed by a Review Panel, the GLOSOLAN technical committee, and (depending on the topic) experts from other GSP technical networks. GLOSOLAN proficiency tests validate the SOPs. Endorsed SOPs are published open access on the GLOSOLAN webpage in multiple languages including dialects. Up to now, GLOSOLAN has published about 40 SOPs for soil chemical, physical and biological parameters, and another 18 SOPs will be published in 2023. If laboratories’ engagement in GLOSOLAN activities continues at this pace, GLOSOLAN will be in the unique position to affirm its SOPs as the new standard to harmonize soil data globally. Whenever possible, GLOSOLAN encourages national governments to support soil laboratories in order to combine bottom-up and top-down movements for the benefit of all.

This study aimed to compare the properties of the constructions made by Microcerotermes pakistanicus, a wood-feeding termite species building carton nests, to those made by the fungus-growing termite Odontotermes obesus in a secondary forest in the Western Ghats region of Kerala. X-ray computed tomography (X-ray CT) showed that the pinnacle of O. obesus termitaria was very thick and compact with a central cavity and numerous unconnected galleries in its inner part. Conversely, the construction of M. pakistanicus appeared as a very porous media made of abundant and connected galleries following a radial trajectory, and the galleries were separated from the others by a thin wall. Despite significant differences in terms of soil chemical properties, Odontotermes obesus termitaria and sheetings had similar properties to those of the surrounding topsoil. Conversely, M. pakistanicus nest had unique chemical properties distinct from those of O. obesus or the surrounding soil. Moreover, although M. pakistanicus builds carton nests from its faeces, minerals were also measured within its termitaria. In conclusion, this study shows the very different properties of O. obesus and M. pakistanicus constructs. It also suggests the need for soil ecologists to consider carton-nests as a third group of soil-nest type, in addition to those built by soil or litter feeders and fungus-growers which edify termitaria from soil and different amount of organic matter. Further studies are also needed to determine their functional impacts on soil and nutrient dynamics.

International audience; Termites are key soil bioturbators in tropical ecosystems. Apart from mound nests constructed by some advanced lineages, most of the species use their faeces, oral secretions, debris, or soil aggregates to protect themselves from predators and desiccation when they go out to forage. Although this soil ‘sheeting’ is considered to play a key role in soil functioning, the properties of this termite-made material has been poorly studied. The few available data showed that sheeting properties are highly variable with positive, neutral or negative impacts on soil C and clay content, and consequently on soil aggregate stability. Therefore, the objective of this study was to determine the factors controlling the physical (particle size fractions and structural stability) and chemical (pH, electrical conductivity and carbon content) properties of soil sheeting produced by termite species encompassing all feeding and building categories using a dataset representative of an important diversity of biotopes coming from 21 countries from all continents colonized by termites. We showed that sheeting properties were explained by the properties of their environment, and especially by those of the bulk soil (linear relationships), followed in a lesser extent by the mean annual precipitation and biotope. Classic hypotheses related to termite feeding and building strategies were not hold by our analysis. However, the distinction of termites into fungus-growing and non-fungus growing species was useful when differentiating the impact of termites on soil electrical conductivity, C content, and structural stability. The large variability observed suggests the need to redefine termite functional groups based on their impacts on soil properties using a trait-based approach from morphological, anatomical and/or physiological traits.

International audience; Soil macroporosity is a highly dynamic feature driven by numerous physical and biological processes, of which bioturbation, the movement of water in soil and swelling and shrinking cycles are the main processes. To date, the interaction between these factors, especially how galleries produced by soil fauna respond to rainwater percolation and wetting-drying (WD) cycles, remains poorly known. A laboratory experiment was carried out to expose soil macrofauna galleries to 3 different consecutive water flow (simulated rain event of 50, 80 and 110 mm h-1 in one hour) and drying cycles in a clayey soil. X-ray computed tomography and image analyses were used prior and after each exposure to assess the water stabilities of galleries and created cracks. The 3D properties (volume, diameter, specific surface area and density) of the galleries produced by termites or ants were not statistically influenced by rainwater percolation and WD cycles, suggesting a high water stability and life expectancy under natural conditions. Conversely, the crack water stability was variable and was probably influenced by the presence of galleries in the same area. This study emphasizes that the macropores created by soil fauna may persist in clayey soil and that there is a need to better understand how cracks and galleries interact.

Environmental changes are threatening current and future food security. In this context, it is imperative to design agricultural systems that are resilient to increasing frequent climate shocks, losses in biodiversity and soil fertility and to increasing demand from our societies because of population growth and consumption patterns. The emergence of sustainability science reminds us that soil management cannot be successfully approached by the independent actions of individual categories of actors, namely soil researchers or agronomists. Therefore, we advocate for more holistic and transdisciplinary research that takes into account the social, cultural, environmental and economic impacts of agricultural practices. Using examples of agricultural practices that aim to use the activity of termites to improve the services delivered by ecosystems (e.g. the Zai system), rather than considering them pests and trying to eradicate them from lands, we discuss the interest of traditional agricultural practices as sources of inspiration for soil scientists and for the identification of tomorrow's agricultural practices.

Termites are amongst the main macroinvertebrate decomposers in tropical ecosystems and they exert additional impacts through the creation of biostructures (mounds, galleries, sheetings, etc.) with different soil physical and chemical properties, thereby impacting positively on numerous ecosystem services for humankind. Unfortunately, this positive or 'bright' role of termites is often overshadowed by their 'dark' side, that is, their status as pests threatening agriculture and constructions. This article assesses advances in our knowledge of the impact of termites on several sustainable development goals (SDGs 1 'no poverty', 2 'zero hunger', 3 'good health', 9 'innovation', 11 'sustainable cities', 13 'climate action' and 15 'life on land'). Finally, using the Indian myth of Valmiki as a parable, we illustrate that a reconciliation between the termite's dark and bright sides is needed if we want to reduce our dramatic impact on biodiversity and more generally achieve SDGs.

This study aimed to understand the relationship between termite food preferences and the ecological benefits derived from their activity in terms of soil dynamics and water infiltration. A field study was carried out for six months with different food baits (elephant dung, Acacia leaves, twigs and leaves of Lantana camara as well as Ficus religiosa, Pterocarpus marsupium, Prosopis juliflora, Michelia champaca, Azadirachta indica and Hevea brasiliensis wood stakes) installed on the soil surface in a semi-deciduous forest in southern India. At the end of the experiment we determined bait consumption rates and the amount of soil sheetings covering the different baits. Water infiltration rates were also measured using the Beerkan method. The initial infiltration rates (i.e. average of the first three infiltration rates) under the baits were compared to those at the end of the experiment (average of the last three infiltration rates when the steady state was reached). Three termite species, Odontotermes obesus, O. feae and Microtermes obesi, were found associated with some of the baits in the study area. Among the different baits, elephant dung and Acacia leaves were the most preferred and a relationship was observed between the quantity of soil sheetings and the bait consumption rate. Termite preference for elephant dung and Acacia leaves was also associated with higher water infiltration rates. However, this difference was only significant at the beginning of the experiment and no significant difference was measured once the steady state was reached. In conclusion, we showed that resource quality was of primary importance for soil sheeting production but that the influence of termites on water infiltration remained limited, most likely because of the low stability of their tunnels in the soil.

Termites are undoubtedly amongst the most important soil macroinvertebrate decomposers in semi-arid environments in India. However, in this specific type of environment, the influence of termite foraging activity on soil functioning remains unexplored. Therefore, this study examines the link between the quality of litter and the functional impact of termite feeding preferences on soil properties and soil hydraulic conductivity in a deciduous forest in southern India. Different organic resources (elephant dung: &ldquo, ED&rdquo, elephant grass: &ldquo, EG&rdquo, acacia leaves: &ldquo, AL&rdquo, and layers of cardboard: &ldquo, CB&rdquo, ) were applied on repacked soil cores. ED appeared to be the most attractive resource to Odontotermes obesus, leading to a larger amount of soil sheeting (i.e., the soil used by termites for covering the litter they consume), more numerous and larger holes in the ground and a lower soil bulk density. As a consequence, ED increased the soil hydraulic conductivity (4-fold) compared with the control soil. Thus, this study highlights that the more O. obesus prefers a substrate, the more this species impacts soil dynamics and water infiltration in the soil. This study also shows that ED can be used as an efficient substrate for accelerating the infiltration of water in southern-Indian soils, mainly through the production of galleries that are open on the soil surface, offering new perspectives on termite management in this environment.

This communication assesses advances in our knowledge of the beneficial influences of termites on ecosystem functioning and services. Termites are amongst the main macroinvertebrate decomposers in arid and semi-arid environments and exert additional impacts through the creation of biostructures (mounds, galleries, sheetings, etc.) with different soil physical and chemical properties . Unfortunately, the positive ‘or bright’ role of termites is often overshadowed by their dark side, i.e. their status as pests threatening agriculture in the tropics (635 vs. 164 articles referenced in WoS with termites and either pest or ecosystem engineer as keywords. Source: WoS, April 2019). Termite impacts on soil properties and water dynamics can be differentiated at four different scales: (i) at the landscape scale, where termites act as heterogeneity drivers; (ii) at the soil profile scale, where termites act as soil bioturbators; (iii) at the aggregate scale, where they act as aggregate reorganizers; (iv) and last, at the clay mineral scale, where they can act as weathering agents [1] . In this communication, two examples of ecosystem services provided by termites are given. The first describes the positive impact of termites on water infiltration and nutrient guidance at small scale through the production of foraging galleries in soil [2] and how this activity can be used to improve agro-ecosystem functioning in arid and semi-arid environments [3] . The second example deals with the construction of mounds and sheeting by termites in “natural” environments [4] and how these “patches of biodiversity and fertility” can be used in the lower Mekong Basin to reduce food insecurity and to provide a better access to health [5] ( Fig. 1 ). Finally, the perception of termite mounds in Southern Indian rural environments ( Fig. 2 ) is discussed and used as example of the cultural services that can be provided by termites in some circumstances. The story of Valmiki, the author of the Ramayana, is explained and used as a parable for highlighting the interconnection between the “bright” and “dark” sides of termites, and more generally that to get the bright we also need the dark.

International audience; In the tropics, termites are key litter decomposers and soil bioturbators. Termite foraging activity involves the production of sheetings and galleries that influence the physical, chemical and hydraulic properties of soils. The functional impacts of these biogenic structures and biopores have been acknowledged for a long time in soils dominated by 1:1 minerals. Less is known, however, on their functional impacts in soils dominated by 2:1 minerals, such as vertisol which represent 22% of the land surface in India. Therefore, an experiment was carried out in a vertisol in southern India where elephant (Elephas maximus) dung pats (ED) and Lantana camara twigs (LT) were applied on the ground and protected (+) or not (−) from termite activity. Termite activity was only measured below ED−, showing a clear preference for organic matter derived from elephant dung. Soil sheetings had similar properties to the surrounding topsoil, with the exception of their C content that was reduced. This result raised the question of the origin of the soil used by termites for covering ED. ED− was also associated with the presence of effective macropores up to 5 cm depth and a significant increase in water hydraulic conductivity (12-fold). However, the utilization of the coefficient of linear extensibility showed that these galleries were unstable and most likely short-lived. In conclusion, this study confirmed that the structure of soils dominated by 2:1 minerals is mainly controlled by physical processes (i.e., the shrinking and swelling of soils). This study also stresses the need to better understand the dynamic of termite galleries in soil and to quantify the origin and fate of organic matter in soil sheetings.

International audience; In the tropics, termites are known to be key litter decomposers and soil bioturbators. Their foraging activity in the soil leads to the production of galleries with specific soil physical, chemical and biological properties. This study investigates the influence of these foraging galleries on water infiltration and soil properties in south-Indian woodlands. A significant increase in water infiltration (× 3 that of control plots) was measured in soil as a result of Odontotermes spp. activities, likely because of the production of galleries in the first cm of the soil. Termite foraging activity was also associated with a significantly greater amount of clay in soil, probably because termites cover the wall of their galleries with fine-size particles, resulting in an increased saturated soil water content. Conversely, no differences in C content, CO2 emission and soil bulk density were measured in comparison with the surrounding soil. Consequently, this study confirms the beneficial impact of termites on water infiltration in soil but suggests a rather low local impact on soil chemical and biological functioning.

International audience; This study investigated the origin of the soil termites used to build their above-ground mounds. Termite mounds were surveyed in a ferralsol and a vertisol in a dry deciduous forest in Karnataka, southern India. In these environments, two types of above-ground termite mounds are observed which we describe here as CATHEDRAL and LENTICULAR mounds. Partial Least Squares Regression models (PLSR) were computed from the physical and chemical properties of the soil sampled down to 4 and 2.5 m in the ferralsol and vertisol, respectively. Soils from CATHEDRAL mounds had the same signatures as soils collected at approximately 100 and 50 cm deep in the ferralsol and vertisol, respectively. On the other hand, soil from LENTICULAR mounds had the same signature as soil sampled at 30 and 60 cm deep in the ferralsol and vertisol, respectively. In conclusion, this study highlighted that the source of the soil termites use to build their mounds can be soil (ferralsol vs vertisol) and species (CATHEDRAL vs LENTICULAR) specific. In light of these findings, we conclude that the impact of CATHEDRAL mounds on soil dynamics appears to be smaller than that of LENTICULAR mounds in terms of soil volume at the landscape scale but it is higher in terms of soil translocation from deeper soil layers to the surface.

Termites are considered soil engineers and key bioturbators in tropical and subtropical soils. A large number of studies have described the specific properties of the aboveground mounds that termites construct to protect their colonies from environmental hazards. However, there is a paucity of information on properties of soil sheetings; more temporary but often extensive structures are covering over or inserted within substrates on the ground such as leaves and woody materials or components of arboreal runways. Such sheetings are conspicuously produced not only by the Macrotermitinae but also by many other unrelated taxa. Here, we review the available literature and discuss (i) the relationship between rainfall and soil sheeting production and (ii) how termites affect the clay and C contents in soil sheetings. This reveals that sheeting production is highly variable and site specific. We also found that soil sheetings are always enriched in clay, but their impacts on soil C content are variable and related to the C content of the parent soil and to the quality of the substrates consumed by termites.