Mediterranean Steppe Research Articles

Moderate sheep grazing increases arthropod biomass and habitat use by steppe birds

Open semi-natural ecosystems have been historically shaped by anthropogenic land-use, and the abandonment or intensification of these activities implied a detrimental alteration of their landscapes. Extensive sheep grazing has gradually decreased during the 20th century in Mediterranean steppes, triggering changes across all taxa. Here, we address the effect of sheep grazing on both arthropod biomass and space use by insectivorous steppe birds, using an endangered passerine as a model species. We found that biomass of different arthropod groups peaked at intermediate levels of grazing, and that both short-term grazing (affecting arthropod biomass) and long-term grazing (affecting vegetation structure) explain space use by insectivorous birds, whereas only long-term processes are decisive for bird territory establishment. Our results emphasise the role of sustained moderate grazing intensity in the conservation of steppe biodiversity. In the current decline context of extensive sheep grazing, agricultural policies should prioritise these practices to ensure the persistence of open semi-natural ecosystems

Livestock grazing‐induced large‐scale biotic homogenization in arid Mediterranean steppe rangelands

AbstractDespite many studies that have explored the effect of livestock grazing on plant communities, the response of species composition and diversity to livestock grazing in arid rangelands remains ambiguous. This study examined the effects of livestock grazing on plant communities in arid steppe rangelands of North Africa. Plant diversity of annual species, perennial species, and all species combined were measured and compared between grazed and grazing‐excluded areas. We also examined the relative importance of species turnover and community nestedness. Moreover, the effects of livestock grazing on beta diversity at local among transects and landscape among sites scales were examined using the multiplicative diversity partitioning. Results revealed that livestock grazing significantly decreased the alpha diversity of all species combined and the diversity of annual plants. Livestock grazing induced a shift in plant community composition where most species composition variation (~74%) was due to infrequent species replacement 'turnover' between the two management types rather than nestedness (~26%). Results revealed also that among transects, beta diversity was higher in grazed steppes than in grazing‐excluded steppes. Whereas, among sites, beta diversity was lower in grazed steppes compared to grazing‐excluded steppes. These findings suggest that livestock grazing in arid steppe rangelands increases the variation in plant species composition at a local spatial scale and engenders vegetation homogeneity at a landscape spatial scale. Therefore, the implementation of appropriate management practices such as short‐term grazing exclusion is mandatory to prevent these ecosystems from large‐scale biotic homogenization.

Vegetation Pattern Modulates Ground Arthropod Diversity in Semi-Arid Mediterranean Steppes.

The ecological functioning of dryland ecosystems is closely related to the spatial pattern of the vegetation, which is typically structured in patches. Ground arthropods mediate key soil functions and ecological processes, yet little is known about the influence of dryland vegetation pattern on their abundance and diversity. Here, we investigate how patch size and cover, and distance between patches relate to the abundance and diversity of meso-and microarthropods in semi-arid steppes. We found that species richness and abundance of ground arthropods exponentially increase with vegetation cover, patch size, and patch closeness. The communities under vegetation patches mainly respond to patch size, while the communities in the bare-soil interpatches are mostly controlled by the average distance between patches, independently of the concurrent changes in vegetation cover. Large patches seem to play a critical role as reserve and source of ground arthropod diversity. Our results suggest that decreasing vegetation cover and/or changes in vegetation pattern towards small and over-dispersed vegetation patches can fast lead to a significant loss of ground arthropods diversity in drylands.

Response of dung beetle assemblages to grazing intensity in two distinct bioclimatic contexts

Given the impact of livestock on ecosystems worldwide, it is necessary to understand the effects of grazing practices on biodiversity in order to improve the sustainability of pasture management practices. In a pasture, spatio-temporal variability in livestock activity results in a heterogeneous distribution of defoliation, trampling and excreta. To date, fine-scale analyses of grazing intensity have been rare, and the geographical extent of the studies often limited. In this study, we addressed this gap by analysing the influence of contrasting intra-pasture grazing intensity on the structure and composition of dung beetle assemblages. To do this, we studied a three-level grazing intensity gradient in two distinct bioclimatic contexts, a Mediterranean steppe and the Alps, which also allowed us to determine if dung beetle responses to grazing intensity are related to bioclimatic conditions. The observed dung beetle responses showed an imprint of the bioclimatic context and the local pasture conditions, and species composition and relative abundance showed strong variations along the grazing intensity gradient in both study areas. Species assemblages from the most and least grazed parts of pastures differed strongly. By altering habitat conditions, changing dung availability and modifying competitive interactions, fine-scale heterogeneity in grazing intensity led to substantial variations in the abundance of dung beetle nesting guilds. In both study areas an increase in grazing intensity was detrimental to the largest species and the soil-digging species (which bury dung in underground nests), whereas dung-dwelling species (which reproduce inside dung pads) were favoured. We discuss the combined use of nesting guilds and body mass as potential features to generalize the application of dung beetles as indicators of grazing practices.

Factors limiting early establishment of the Mediterranean grassland species Brachypodium retusum at disturbed sites

In Mediterranean dry grasslands, water availability and grazing strongly influence plant establishment. Although higher water availability and lower grazing pressure usually increase seedling recruitment in the beginning, higher competition may reduce seedling survival. In our study, we analysed this trade-off for the dominant species of Western Mediterranean steppes Brachypodium retusum which hardly recolonises restoration sites degraded by soil disturbance such as arable use.A split-plot experiment was set up on an ex-arable site in the “La Crau” steppe in order to test the effects of initial watering and sheep grazing on seedling recruitment, survival and early growth during two years. The watering treatment was applied in the first autumn and spring doubling the usual precipitation during this period and grazing was tested using exclosures. Survival and growth of seedlings established from field-sown seeds were compared to those of transplanted seedlings pre-grown in a growth chamber.Watering did not affect germination whereas the grazing effect was negative. Initial watering had a positive effect on survival only in grazed plots suggesting a compensatory effect under grazing disturbance. Significant main effects of watering on early growth disappeared in the second season. Grazing significantly reduced most measured growth traits whereas the effect on survival was only marginally significant. Planted seedlings (49%) survived better than seedlings emerged from field-sown seeds (36%). In conclusion, initial fencing increases establishment success of B. retusum in ecological restoration. Initial watering may help to mitigate negative grazing effects when fencing is not possible.

Fire increases the reproduction of the dominant grass Brachypodium retusum and Mediterranean steppe diversity in a combined burning and grazing experiment

AbstractAimsWe assessed what the effects of fire and grazing are on vegetative growth and sexual reproduction of Brachypodium retusum, the dominant species of Mediterranean Thero‐Brachypodietea grasslands (“steppes”) and on species composition of the associated plant community.Location“La Crau”, southeastern France.MethodsWe set up a split‐plot experiment testing the effects of fire season (winter, summer) and grazing on plant cover, inflorescence number, seed set and germination of Brachypodium retusum in traditionally grazed grasslands. We further analyzed plant species composition and diversity in vegetation relevés. The same fire treatments were tested in a second experiment in long‐term grazing exclosures.ResultsBrachypodium retusum showed a rapid post‐fire recovery, but other species of the associated plant community, in particular annuals, recovered as fast or even faster. Fire increased Brachypodium retusum inflorescence production and seed set per inflorescence and this effect was stronger in the summer fire treatment. At the community level, fire significantly increased species richness, evenness and Bray–Curtis dissimilarity in the second post‐fire season and again, the summer fire effect was stronger. Grazing exclusion for two seasons had only a small effect on Brachypodium retusum and the associated plant community. The effect of both fire treatments on Brachypodium retusum was similar in long‐term exclosures. In these exclosures, fire resulted in a community shift towards the species composition of traditionally grazed steppes.ConclusionsThe concomitant positive effects of experimental burning on Brachypodium retusum reproduction and on plant diversity of Mediterranean steppe vegetation suggest that the system is adapted to fire as an important driver of community composition. Annual species surviving as seeds are as successful in post‐fire recovery as perennial resprouters. Prescribed burning may be an alternative strategy to restore community structure in abandoned (ungrazed) steppes showing a decline in typical grassland species after several years of grazing abandonment.

Recovery of Mediterranean steppe vegetation after cultivation: Legacy effects on plant composition, soil properties and functional traits

AbstractQuestionsAre the vegetation structure and soil properties of fallows similar to adjacent species‐rich Mediterranean steppe communities 35 years after abandonment? Is there a spontaneous redevelopment towards the original steppe vegetation after reintroduction of the traditional grazing system? Can differences in functional trait composition be identified according to different land‐use types? Do traits of selected species affect the ability to recolonize fallow land?LocationMediterranean steppe of La Crau (Southeastern France).MethodsWe conducted 80 vegetation surveys and soil analyses in the steppe and adjacent fallow land in six locations in La Crau in 2015; for three locations, data from 2001 were included. To compare the functional composition of steppe vs fallow land, community‐weighted means (CMW) of specific leaf area (SLA), leaf dry matter content (LDMC) and canopy height were calculated. To test whether trait variability is associated with the recolonization success of 12 selected target species, we measured SLA, LDMC, canopy height, plant width and aboveground biomass on eight replicate individuals per site and species.ResultsFallow land was characterized by lower species richness and elevated phosphorus and potassium content in the soil. Comparing vegetation relevés between 2001 and 2015 revealed that the fallows were developing towards steppe vegetation. CWMs of SLA were significantly lower and CWM of LDMC higher in steppe than in fallow land. There was no similarity in trait composition between steppe species that successfully recolonized the fallow‐land community, and no evidence that intraspecific trait variability is associated with recolonization success of these species.ConclusionsEven after decades of abandonment and reintroduction of the grazing system, the vegetation structure, soil properties and plant functional trait composition of fallows differ from those of adjacent steppe communities. These results illustrate the need for active restoration to accelerate the recovery of former arable land to the target steppe communities.

Prediction of Landscape Function and Soil Surface Condition in the Libyan Rangelands Using Selected Spectral Vegetation Indices

Spectral Vegetation Indices (SVIs) have been used to examine variations in vegetation formation and phenology. Lately, researchers and agricultural practitioners have utilized SVIs to examine various soil properties for instance moisture and nutrients. From our review of the literature, there were few comprehensive studies conducted to know whether it is possible or not to predict landscape function indices by using remote sensing technology, and which spectral vegetation index is the best predictor. It has been shown that landscape function indices can be accurately predicted by Normalized Different Vegetation Index (NDVI). Therefore, we attempted to test the ability of selected SVIs to predict landscape function indices (LFA-SSA) in the Mediterranean steppes of Al-Jabal Al-Akhdar, northeast Libya. We used data collected between May and October of 2006 and 2014. A total of 28 sites were chosen to collect the data for both SVIs and LFA-SSA. Simple linear regression was applied between LFA-SSA and SVIs. The results demonstrated that there is a positive linear relationship between LFA-SSC and the selected SVIs. The findings revealed that the Normalized Different Vegetation Index (NDVI) and Modified Soil Adjusted Vegetation Index (MSAVI) acquired from the Landsat Enhanced Thematic Mapper Plus (ETM+) could be utilized in predicting the variability of significant structural and functional qualities of soil and vegetation in the Mediterranean climate.

Returning home after fire: how fire may help us manage the persistence of scrub-steppe specialist bird populations

Semi-natural open habitats have drastically changed in the last few decades due to agricultural intensification and rural depopulation. Steppe-birds, and especially those adapted to primary stages of vegetation succession, are threatened by an increase in scrub cover, and management actions are being applied to reverse scrub encroachment and restore habitat suitability in semi-natural open habitats. In this paper we evaluated for the first time, the long-term effects of a wildfire on habitat structure, vegetation productivity, and the associated response of an endangered scrub-steppe specialist bird, the Dupont’s Lark Chersophilus duponti. Wildfire occurred in a Mediterranean steppe of central Spain dominated by permanent community of dwarf cushions scrubs. Bird abundance was evaluated by line transects in the burnt and unburnt areas 3 years prior to the fire and 4 and 7 years after the fire. We quantified changes in habitat structure at fine scale level through vegetation sampling points and in vegetation productivity by estimating the Normalized Difference Vegetation Index (NDVI). Fire had strong effects for at least up to 4 years after the fire, when lower NDVI values, less scrub cover and fewer, but not significant, number of males were detected in the burnt area with respect to the pre-fire conditions. Seven years after fire most vegetation variables measured did not differ between areas, number of males detected within the burnt area was recovered and NDVI values in burnt area were slightly recovered but were significantly lower than in control area. Slow regeneration of the scrub cover after fire explained the unsuccessful occupation of the burnt area by the Dupont’s Lark up to several years after fire. The more dispersed and shorter habitat created by fire 7 years after the fire seems to be more suitable for the species than that in control areas. The large number of males around the burnt area may have played a role in the recolonization process. In sum, vegetation recovery and the presence of a low scrub-steppe specialist, as the Dupont’s lark, suggests that fire management could be integrated into conservation plans to effectively manage scrub encroachment processes in Mediterranean scrub-steppes.

Runoff from biocrust: A vital resource for vegetation performance on Mediterranean steppes

AbstractDryland vegetation is limited by water scarcity, and usually appears in the form of sparsely distributed patches within a heterogeneous unvegetated matrix often covered by biological soil crust. Biocrusts usually act as runoff sources, whereas vegetation acts as sinks, reinfiltrating most of the run‐on from upstream biocrusted areas. Alteration of biocrusts by human disturbances or climate change may exert a strong impact on soil erosion, promoting rill formation, increasing flow connectivity between source areas and reducing run‐on inputs to vegetation, strongly affecting ecosystem functioning. The role of biocrust runoff in vegetation productivity, which to date has not been studied in depth, must therefore be understood to predict the consequences of such changes. In this study, we analysed the response of Machrochloa tenacissima to run‐on exclusion for two years and compared it to the performance of plants of the same species receiving runoff from biocrusted source patches. The results showed that plants receiving run‐on had more photosynthetically active biomass, net C uptake rates and water‐use efficiency than plants under run‐on exclusion. Differences between treatments became wider over time, especially after rainfall, when the differences in water availability were greatest. These results lead to the conclusion that run‐on is a crucial water input for dryland vegetation. Any alteration of unvegetated areas usually covered by biocrust may have important effects on vegetation productivity similar to those from changes in precipitation pattern, and would result in a new, eco‐hydrological equilibrium of the whole ecosystem.

Effects of ecological restoration on beetle assemblages: results from a large-scale experiment in a Mediterranean steppe rangeland

Given that biological conservation cannot prevent the full range of negative impacts on biodiversity, ecological restoration is nowadays commonly acknowledged as a necessary tool for conservation purposes. Here, we report on an ecological rehabilitation project in the La Crau area (south-eastern France), beginning in 2009 when a former industrial orchard (357 ha) was rehabilitated into a Mediterranean rangeland. We assessed the effect of ecological rehabilitation and different additional restoration treatments on beetle assemblages. Seven treatments were considered: the reference steppe, the rehabilitated treatment alone, three additional experimental restoration treatments (soil transfer; nurse species seeding and hay transfer), the control and the edge between the steppe and the former industrial orchard area. All beetle families were considered. Beetles were sampled with pitfall traps for 3 years (2011–2013). Our major finding was a positive effect of soil transfer and nurse species seeding treatments, which promote the characteristic beetle composition of the reference steppe. Nevertheless, strong differences remain between the steppe and the various assessed treatments in terms of composition. Long-term monitoring should therefore now focus on particular beetle indicator species that could reflect the response of the overall characteristic beetle assemblage of the reference steppe.

Winter is coming: plant freezing resistance as a key functional trait for the assembly of annual Mediterranean communities.

In Mediterranean annual plants, germination mainly occurs during the autumn and only those seedlings that survive winter freezing can flower and produce seedlings in spring. Surprisingly, the effect of freezing events as an abiotic determinant of these communities remains unexplored. The present study aimed to investigate how freezing events affect annual Mediterranean communities and whether their functional structure as related to freezing resistance is linked to the main biotic and abiotic determinants of these communities. In 120 plots located on a semi-arid Mediterranean steppe (Spain), the community functional structure related to the lethal temperature causing 50 % frost damage (LT50 trait) in seedlings was estimated and summarized as the community-weighted mean (CWM-LT50) and its functional diversity (FD-LT50). Plots were stratified according to distance to rabbit shelters and latrines as a proxy for rabbit density, proximity to Stipa tenacissima and spring water availability, where annual species abundance was recorded in all plots over three consecutive years. Annual species were able to resist a threshold temperature of -4 °C and most had LT50 values around the absolute minimum temperature (-9.5 °C) in the three years. Higher rabbit densities led to lower CWM-LT50 and higher FD-LT50 values. Plots close to Stipa tussocks had higher CWM-LT50 values whereas water availability had no effects. High freezing resistance was extended among winter annual species, suggesting the presence of an association between historical environmental filtering and low winter temperatures. However, the community functional structure related to freezing resistance remained variable among scenarios with differences in herbivory pressure and distance to perennial vegetation. The trends observed indicate that traits that allow plants to deal with herbivory may also promote freezing resistance, and that tussocks can act as nurses via microclimatic amelioration of harsher winter conditions.

Plant community structure and diversity under grazing gradient in arid Mediterranean steppe of Algeria

Plant community structure and diversity under grazing gradient in arid Mediterranean steppe of Algeria

Impacts of future climate scenarios on hypersaline habitats and their conservation interest

This study is focused on determining the response behaviour of five saline plant communities to two environmental variables: flooding and salinity. Also, total soil organic carbon, diversity, plant cover and vegetation height were measured. Once this behaviour is known, the impacts of future climate scenarios may be approached. Since some of these variables could be altered by climate change, the future vegetation dynamics might indicate the trending of change, so plant communities can be used as bioindicators. The investigation was carried out in some small coastal wetlands located in a semiarid Mediterranean region. Low values of diversity were found in these plant communities due to a great effect of flooding, followed by salinity. ‘Reed beds’ are bioindicators of flooding and environmental disturbance. ‘Saline rushes’ are also flooding bioindicators and efficient accumulators of organic matter. ‘Mediterranean halophilous scrubs’ are bioindicators of seasonal flooding and changes to salinity. ‘Mediterranean halo-nitrophilous scrubs’ might be considered as bioindicators of low flooding and low salinity in anthropic environment while ‘Mediterranean salt steppes’ bioindicate driest conditions. At present, Mediterranean halophilous scrubs are the most widely extended community, which could be interpreted as a consequence of a changing and sharply seasonal climate. Our research suggests that future climate change scenarios involving flooding increases would support the proliferation of the lowest diversity and thus lower ecological value plant communities (i.e. reed beds). Conversely, a future scenario of decreasing flooding would benefit the most diverse and valuable conservation community actually priortized by European Habitats Directive (Mediterranean salt steppes, Limonietalia).

Vertical sheep mobility along the altitudinal gradient through stable isotope analyses in tooth molar bioapatite, meteoric water and pastures: A reference from the Ebro valley to the Central Pyrenees

Although the frequency of pastoral activities involving vertical sheep mobility has decreased over the last century, this is a herding strategy still used in the Ebro basin, where animals move from overwintering valley locations up to the Pyrenees from late spring to early autumn. Such practice allows herders to avoid the worst climatic conditions, seasonally balancing the great contrast between ecological zones in this region, from dry lowland Mediterranean steppe to wet mountain subalpine grasslands. As recent regional archaeological works have suggested, the altitudinal movement of flocks may have begun with the first early Neolithic groups settled in this territory. Here we investigate through stable isotope analyses one of the last flocks that still performs this activity. Sheep specimens were analyzed by sequential analyses (δ13C and δ18O) in bioapatite of tooth enamel, allowing detection of seasonal changes. Tooth series are interpreted according to rainfall distribution, seasonal patterns in δ 18O of meteoric water, vegetation changes and δ13C values in pastures along the altitudinal gradient in the area. Vertical movements in sheep sequential series are recognized by an inverse relationship between δ13C and δ18O values. Monthly δ18O values in meteoric water obtained in valley and mountain locations describe the same type of seasonal oscillation, with high values during the warm months and low values during the cold months. Pastures analyzed along the altitudinal gradient showed a decrease in δ13C values with altitude, linked to the seasonal availability of precipitation and vegetation differences among locations. These results define a new analytical and conceptual framework for the interpretation of archaeological samples in this region.

The Palaearctic steppe biome: a new synthesis

The Palaearctic steppes range from the Mediterranean basin towards China, forming one of the largest continuous terrestrial biomes. The literature on steppe ecology and conservation is vast but scattered and often not available in English. We provide a review of some key topics based on a new definition of steppes, which includes also Mediterranean steppes and alpine rangelands of the Asian Highlands. Revisiting the terrestrial ecoregions of the world, we estimate that the Palaearctic steppe biome extends over ca. 10.5 million km2. Major chorological regions differ in their macroclimatic niche with a clear distinction between Middle Asia with its winter precipitation and the Central Asian summer-rain regions of the Mongolian plateau and of Tibet. Steppe soils store large amounts of carbon, yet the sequestration potential is debated and depends on land use. Major physiognomic-ecological steppe types include forest-, typical-, desert-, and alpine-steppe, which vary in the importance of grasses, mainly C3 species. The steppes host a specialised fauna, and Middle Asia, Tibet, and especially Mongolia, have large herds of migrating ungulates. The share of pristine and protected sites is low in the steppe regions, with conversion into croplands being the most important land use impact in Europe, Middle Asia, and the Mediterranean, while grazing has a severe impact in some parts of Mongolia and Tibet. There are major gaps in our knowledge on: (1) the effects of climate change on the crucial seasonal patterns; (2) the role of steppe soils in the global carbon budget; and (3) the ecology and distribution of most animal groups except vertebrates.

The Contribution of Photodegradation to Litter Decomposition in Semiarid Mediterranean Grasslands Depends on its Interaction with Local Humidity Conditions, Litter Quality and Position

Understanding how UV radiation interacts with prevailing climatic conditions and litter quality to determine leaf litter decomposition is fundamental for understanding soil carbon cycling pathways and ecosystem functioning in drylands. We carried out a field manipulative experiment to investigate how litter quality (labile and nitrogen-rich Retama sphaerocarpa vs. recalcitrant and nitrogen-poor Stipa tenacissima), position (on the ground vs. standing) and different UV radiation levels (UV pass vs. UV block) affect litter decomposition rates at two semiarid Mediterranean steppes with contrasting climates (continental vs. maritime) in a fully factorial experimental design. As expected, Retama litter decomposed faster than that of Stipa, and litter placed on the ground decayed faster than standing litter. However, and surprisingly, contrasting effects of UV radiation on litter decomposition were observed between the two sites. At the continental site, UV radiation increased litter decay constants by 21% on average, although the contribution of photodegradation was larger when litter was placed on the ground rather than in standing litter. At the maritime site, decay constants were 15% larger in the absence of UV radiation regardless of litter position. Significant litter type × UV exposure radiation and litter type × position interactions indicate that photodegradation contributes more to litter decomposition under less favorable moisture and substrate availability conditions for microbial decomposers. Our results emphasize the need to consider interactions between moisture availability, litter quality and UV radiation in litter decomposition models to fully understand litter decomposition impacts on soil carbon cycling and storage in drylands under climate change.

Community attributes determine facilitation potential in a semi-arid steppe

a b s t r a c t Studies on positive plant-plant relations have traditionally focused on pair-wise interactions. Conversely, the interaction with other co-occurring species has scarcely been addressed, despite the fact that the entire community may affect plant performance. We used woody vegetation patches as models to eval- uate community facilitation in semi-arid steppes. We characterized biotic and physical attributes of 53 woody patches (patch size, litter accumulation, canopy density, vegetation cover, species number and identity, and phylogenetic distance), and soil fertility (organic C and total N), and evaluated their relative importance for the performance of seedlings of Pistacia lentiscus, a keystone woody species in western Mediterranean steppes. Seedlings were planted underneath the patches, and on their northern and south- ern edges. Woody patches positively affected seedling survival but not seedling growth. Soil fertility was higher underneath the patches than elsewhere. Physical and biotic attributes of woody patches affected seedling survival, but these effects depended on microsite conditions. The composition of the community of small shrubs and perennial grasses growing underneath the patches controlled seedling performance. An increase in Stipa tenacissima and a decrease in Brachypodium retusum increased the probability of survival. The cover of these species and other small shrubs, litter depth and community phylogenetic dis- tance, were also related to seedling survival. Seedlings planted on the northern edge of the patches were mostly affected by attributes of the biotic community. These traits were of lesser importance in seedlings planted underneath and in the southern edge of patches, suggesting that constraints to seedling estab- lishment differed within the patches. Our study highlights the importance of taking into consideration community attributes over pair-wise interactions when evaluating the outcome of ecological interac- tions in multi-specific communities, as they have profound implications in the composition, function and management of semi-arid steppes.

Effects of ecological restoration on Orthoptera assemblages in a Mediterranean steppe rangeland

In the last century, human activities have contributed to the fragmentation and the loss of 80 % of the original surface of a Mediterranean steppe rangeland in south-eastern France. In a recent ecological restoration project, an intensively cultivated orchard of 357 ha planted in 1987 among the steppe vegetation was rehabilitated as a herbaceous habitat for steppe birds after its abandonment in 2006. In addition, three experimental restoration treatments (nurse species seeding, hay transfer; soil transfer) were applied at large scale to test the restoration of the original steppe vegetation. Our four-year study aimed to assess the effect of this rehabilitation and the restoration treatments on Orthoptera assemblages. Capturing the Orthoptera with sweep nets, we measured species richness, abundance, Shannon index, Shannon evenness, Renkonen similarity index and two community structure indices. Our results reveal no significant differences in Orthoptera species richness, abundance and diversity between control and reference steppe after 4 years, indicating that the rehabilitation and the three restoration treatments did not significantly accelerate natural recolonization. In the last year of survey, Orthoptera abundances were still significantly lower in the restored treatments than in the original steppe. Thus, future monitoring will need to determine whether abundance and structure similar to that of the reference steppe is achieved in these restored treatments.

A comparison of different soil transfer strategies for restoring a Mediterranean steppe after a pipeline leak (La Crau plain, South-Eastern France)

Among the techniques used for the restoration of terrestrial ecosystems, soil transfer has already produced encouraging results for re-establishing species-rich grassland plant communities. On August 7 2009, a serious oil pipeline leak occurred in the La Crau steppe in south-eastern France. In 2010, more than 5ha of steppe vegetation were then destroyed by the excavation, and removal of polluted soil. Restoration of the site was achieved by transferring 72000t of identical soil from a nearby quarry. Soil was applied in four treatments, each with a different degree of profile complexity. After three years (2011, 2012 and 2013), our results show that the replacement of the soil to include horizon similar to the reference steppe allows recovery of the vegetation in terms of composition, similarity and species richness of the steppe vegetation during this period. The ecological engineering guidelines aimed at limiting the transit time of the soil and the reconstitution of its vertical layer organisation resulted in the improved recovery of the vegetation without colonisation by non-target species. This system may further benefit from reintroduction of traditional sheep grazing to promote sustainability following the restoration of the steppe vegetation.