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Agricultural land‐use history and restoration impact soil microbial biodiversity

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Human land uses, such as agriculture, can leave long‐lasting legacies as ecosystems recover. As a consequence, active restoration may be necessary to overcome land‐use legacies; however, few studies have evaluated the joint effects of agricultural history and restoration on ecological communities. Those that have studied this joint effect have largely focused on plants and ignored other communities, such as soil microbes. We conducted a large‐scale experiment to understand how agricultural history and restoration tree thinning affect soil bacterial and fungal communities within longleaf pine savannas of the southern United States. This experiment contained 64 pairs of remnant (no history of tillage agriculture) and post‐agricultural (reforested following abandonment from tillage agriculture >60 years prior) longleaf pine savanna plots. Plots were each 1‐ha and arranged into 27 blocks to minimize land‐use decision making biases. We experimentally restored half of the remnant and post‐agricultural plots by thinning trees to reinstate open‐canopy savanna conditions and collected soils from all plots five growing seasons after tree thinning. We then evaluated soil bacterial and fungal communities using metabarcoding. Agricultural history increased bacterial diversity but decreased fungal diversity, while restoration increased both bacterial and fungal diversity. Both bacterial and fungal richness were correlated with a range of environmental variables including aboveground variables like leaf litter and plant diversity, and belowground variables such as soil nutrients, pH, and organic matter, many of which were also impacted by agricultural history and restoration. Fungal and bacterial community compositions were shaped by restoration and agricultural history resulting in four distinct communities across the four treatment combinations.
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... Not only current but also past land-use can have effects that persist for decades, Romdhane et al. Environmental Microbiome (2022) 17:1 affecting the microbiome in contemporary land use [12,13]. For example, a history of tillage or no tillage 60 years before conversion to longleaf pine savanna was found to differentially affect the diversity and composition of bacterial and fungal communities [13]. ...
... Environmental Microbiome (2022) 17:1 affecting the microbiome in contemporary land use [12,13]. For example, a history of tillage or no tillage 60 years before conversion to longleaf pine savanna was found to differentially affect the diversity and composition of bacterial and fungal communities [13]. Since soil microbes are major players of the biogeochemical cycles and therefore tremendously important for ecosystem functions [14][15][16], it is important to understand how microbial communities are affected by increased land-use intensity, and to what extent the responses are modulated by legacy effects of prior land use. ...
... The impact of land-use history on microbial communities has been investigated in previous studies with large variation in the persistence of the legacy effects [77,78]. For example, past arable farming land resulted in long-lasting legacies on forest microbial communities that were persisting over half a century after agricultural abandonment [13,79]. An explanation for these long-lasting effects is that historical land use caused shifts in soil properties, such as C and N content or pH, which are important drivers of soil microbial communities and may require decades to recover. ...
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Background Soil microbial communities are major drivers of cycling of soil nutrients that sustain plant growth and productivity. Yet, a holistic understanding of the impact of land-use intensification on the soil microbiome is still poorly understood. Here, we used a field experiment to investigate the long-term consequences of changes in land-use intensity based on cropping frequency (continuous cropping, alternating cropping with a temporary grassland, perennial grassland) on bacterial, protist and fungal communities as well as on their co-occurrence networks. Results We showed that land use has a major impact on the structure and composition of bacterial, protist and fungal communities. Grassland and arable cropping differed markedly with many taxa differentiating between both land use types. The smallest differences in the microbiome were observed between temporary grassland and continuous cropping, which suggests lasting effects of the cropping system preceding the temporary grasslands. Land-use intensity also affected the bacterial co-occurrence networks with increased complexity in the perennial grassland comparing to the other land-use systems. Similarly, co-occurrence networks within microbial groups showed a higher connectivity in the perennial grasslands. Protists, particularly Rhizaria, dominated in soil microbial associations, as they showed a higher number of connections than bacteria and fungi in all land uses. Conclusions Our findings provide evidence of legacy effects of prior land use on the composition of the soil microbiome. Whatever the land use, network analyses highlighted the importance of protists as a key element of the soil microbiome that should be considered in future work. Altogether, this work provides a holistic perspective of the differential responses of various microbial groups and of their associations to agricultural intensification.
... There are documented links between agricultural intensification and decreasing microbial diversity, and changing community structures (Turley et al., 2020). Similar to the influence of site aridity, we also found that land use systematically affected the microbial PLFA composition with forest and cropland land uses being diametrically most dissimilar in community composition, with lower intensity agriculture in the form of grassland for grazing, and the recovery of croplands within exclosures, falling in between (Figure 5a). ...
... Similar to the influence of site aridity, we also found that land use systematically affected the microbial PLFA composition with forest and cropland land uses being diametrically most dissimilar in community composition, with lower intensity agriculture in the form of grassland for grazing, and the recovery of croplands within exclosures, falling in between (Figure 5a). The resulting effect of land use on community structure seemed to match that driven by site aridity and was well correlated to soil pH and OM content, consistent with the impacts of land-use intensity previously observed in both temperate (Turley et al., 2020) and tropical environments (Berkelmann et al., 2020). It has previously been shown that the conversion of natural forests and woodlands into agricultural land is detrimental for soil C, nutrient and microbial biomass stocks, as well as for microbial functions in tropical (Paul et al., 2010) and subtropical soils (Brackin et al., 2013;Tosi et al., 2016). ...
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We investigated how legacies of land use and climate affected the microbial use of organic matter (OM) along a tropical climate gradient in Ethiopia. Four levels of land‐use intensity ranging from croplands to pristine forests were assessed along a gradient from cool and moist high altitude (MAT = 16°C, MAP = 2,200 mm) to hot and dry lowland sites (MAT = 20°C, MAP = 1,050 mm). We resolved the biomass, structure, and growth rates of microbial decomposer communities together with the rates of carbon (C) and nitrogen (N) transformation. To target the legacies of climate and land use, samples were assessed at optimal moisture and standardized temperature in the laboratory. Microbial biomass and the fungal‐to‐bacterial ratio increased with both legacies of drier climates and higher land‐use intensities. In contrast, fungal growth rates increased in humid climates, but were unaffected by land use. The ratio of C mineralization to gross N mineralization decreased with higher humidity and more intensive land use, suggesting a change in microbial resource use from more nutrient‐poor to nutrient‐rich OM. Mineralization of nutrient‐poor OM implied a lower nutrient availability to microbes in arid climates and low‐intensity land uses, while the mineralization of nutrient‐rich OM in humid sites and higher intensity land uses implied a higher microbial nutrient availability there. The difference in respiration between land uses increased with ecosystem aridity, suggesting that OM turnover and soil fertility were more impacted by land use in drier climates. Together, our results suggest that drier subtropical climates will exacerbate the negative effects of land‐use intensification on OM turnover and nutrient provisioning for plants.
... Long-term effects on various soil chemical properties of post-agricultural forests and grasslands have been reported to persist for centuries after agricultural activity had ceased (Koerner et al., 1999;Dupouey et al., 2002). Yet very few studies have investigated the legacy of past management practices and past land use on soil microbial biodiversity (Turley et al., 2020). Some studies have explored the long-lasting effects of past agricultural activities on forest recovery after agricultural abandonment (Stockmann et al., 2015;Katulanda et al., 2018). ...
Article
Present-day soil physicochemical characteristics, land use/land cover (LULC), and field management practices are commonly recognised as the main drivers shaping archaeal/bacterial and fungal communities in vineyard soils. Few studies have investigated the legacy of past land uses on soil microbial biodiversity, yet anthropogenic disturbances have already been proven to affect soil characteristics over decades. In this study, we explore the possibility of long-lasting impacts of forest-to-vineyard conversion on present-day soil archaeal/bacterial and fungal communities after 15 years of vine cultivation. The selected study area is in a Burgundian vineyard (Pernand-Vergelesses, Burgundy, France), where it was possible to reconstruct the history of land cover and land use for the past 40 years. Soil samples were collected from five zones managed under similar pedo-climatic conditions but with different land-use histories (a 70-year-old vineyard, a 15-year-old vineyard converted from pine forest, a 15-year-old vineyard converted from mixed forest, a pine forest and a mixed forest). For each zone, basic physicochemical parameters (organic carbon, total nitrogen, copper, C:N ratio, and soil texture) were measured, and DNA was extracted to characterise the microbial biomass, and also the richness and taxonomic composition of archaeal/bacterial and fungal communities (16S and 18S). Our results show that changes in LULC lead to differential responses in soil microbial biomass, and in archaeal/bacterial and fungal richness and taxonomic composition. After 15 years of cultivation, the present-day microbial biomass and indigenous archaeal/bacterial communities of recent vineyard soils are shown to be partly inherited from past LULC, but no evidence was found of long-term impacts of past land use on fungal communities. Past land-use history should therefore be added to the well-established set of environmental drivers, providing valuable information to explain the spatial variability of soil microbiology, observed at intra-plot, plot, and landscape scales. Integrating the history of changes in LULC is therefore recommended to evaluate and adopt the best strategies to develop sustainable management practices.
... Most of these, however, focus predominately on the response of the plant community and, while important, do not focus the processes that support the plant community, such as key plant-soil feedbacks (Costantini et al. 2016). Including nutrient cycles and the soil microbial community in restoration projects has previously been rarely considered despite the impacts soil degradation can have on grasslands (Jiao et al. 2009) but in recent years it had become more prevalent in grassland restoration studies (Docherty and Gutknecht 2019, Fehmi et al. 2020, Li et al. 2020, Turley et al. 2020, Yang et al. 2021. Erosion has the capability of moving over 20 gigatones of soil globally per year, subsequently transporting a large amount of nutrients (this statistic is just for water transport alone; FAO (Food and Agriculture Orgnaizaton of the United Nations), 2015). ...
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Grasslands are essential natural and agricultural ecosystems that encompass over one-third of global lands. However, land conversion and poor management have caused losses of these systems which contributed to a 10% reduction of net primary production, a 4% increase in carbon emissions, and a potential loss of US $42 billion a year. It is, therefore, important to restore, enhance and conserve these grasslands to sustain natural plant communities and the livelihoods of those that rely on them. We installed low cost rock structures (media lunas) to assess their ability to restore grasslands by slowing water flow, reducing erosion and improving plant establishment. Our treatments included sites with small and large rock structures that were seeded with a native seed mix as well as sites with no seed or rock and sites with only seed addition. We collected summer percent cover for plants, litter, and rock and spring seedling count data. We also collected soil for nutrient, moisture, and microbial analysis. Within the first year, we found no change in plant cover between rock structures of two rock sizes. We did find, however, an increase in soil moisture, litter, fungal richness, and spring seedling germination within the rock structures, despite a historic drought. This work demonstrates that rock structures can positively impact plants and soils of grasslands even within the first year. Our results suggest that managers should seriously consider employing these low-cost structures to increase short-term plant establishment and possibly, soil health, in grasslands.
... In the research of Swamy et al. [96], Singh and Sharma [97], and Gupta et al. [98], they revealed significant improvements in available nitrogen, phosphorus, potassium, and organic carbon content in soil under agroforestry plantations. Turley et al. [99] indicated that the restoration of abandoned land increased bacterial diversity by 13.8% and fungal diversity by 60.1%. Xu et al.'s [100] results indicate that recovery after cropland abandonment causes an increase in microbial activity in the soil and depends on plant characteristics and soil physicochemical parameters. ...
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Bioenergy crops play an ecologically and economically fundamental role as an alternative to agri-food productions and as renewable energy sources. Thus far, less attention has been given to assessing microbiological indicators of soil quality in bioenergy crops on abandoned land. The current study assessed microbial and biochemical properties of two soils with different textures in agroforestry plantations of Paulownia elongata x Paulownia fortunei, with regard to the analysis of potential for the reclamation and redevelopment of abandoned lands. The soil samples were characterised by measuring microbial biomass C and N, key enzyme activities, and determining the community-level physiological profiles (CLPP) using Biolog EcoPlates. Soil texture, sampling time (June and October), and distance of sampling (0.1 m and 1 m from a tree) had significant effects on microbiological properties. Moreover, dehydrogenases and acid phosphatase activities as well as microbial biomass C and N decreased with distance from the trees, and were significantly higher in the October than in the June. The community-level physiological profiles (CLPP) and diversity indices showed a similar trend to other parameters of biological activity. The results showed that there were significant differences in the AWCD (average well-colour development) of all carbon sources among the Paulownia microbial communities (p < 0.05). In summary, already after one year of tree planting, a statistically significant increase in microbial activity was found, regardless of soil texture, when evaluated by various methods. This proves the value of the Paulownia as fast-growing plant for recultivation and improvement of soil quality on abandoned land.
... Here, we show that soil and root mineral nutrients were unaffected in the initial phase, one year after the start of the experimental treatments. This result agrees with other short-term studies, where management was stopped or reduced [51][52][53] and might have been expected because it is well known that agricultural soil usage has long-lasting legacy effects [54,55]. For example, recovery of N cycling takes almost a decade [56,57]. ...
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To secure high yield, tropical oil palm plantations are fertilized, and understory vegetation is controlled by chemical clearing with herbicides. These treatments cause a drastic turnover of soil microbes and cause loss of beneficial mycorrhizal fungi. Here, we tested if reduced fertilization and weeding instead of conventional treatments restored beneficial ecological groups associated with roots. We conducted our study one year after the start of the reduced management in large-scale oil palm plantations. We hypothesized that reduced fertilizer application and weeding result in shifts of the root-associated species composition because changes in the management regimes affect belowground biomass and nutrients in soil and roots. Alternatively, we hypothesized that the legacy of massive soil fertilization and herbicide application preclude compositional shifts of root-associated biota within short time periods. We did not find any significant treatment effects on root nutrient contents, root biomass, and nutrients in soil. At the level of species (based on operational taxonomic units obtained by Illumina sequencing) or phyla, no significant effects of reduced management were observed. However, distinct functional groups showed early responses to the treatments: nematodes decreased in response to weeding; yeasts and ectomycorrhizal-multitrophic fungi increased under fertilizer treatments; arbuscular mycorrhizal fungi increased under fertilizer reduction. Since the responsive ecological groups were represented by low sequence abundances, their responses were masked by very high sequence abundances of saprotrophic and pathotrophic fungi. Thus, the composition of the whole root-associated community was unaffected by reduced management. In conclusion, our results show that changes in management regimes start to re-wire critical constituents of soil–plant food webs.
... Moreover, liming was typically applied in agricultural land to increase the pH, which again favored grasses against heather. Later on, this agricultural history can affect soil microbial communities even 50 years after abandonment (Turley et al., 2020). As heathlands have always been a characteristic part of the mosaic of landscapes in many European countries that have almost disappeared, in order to return them to the Netherlands, restoration of heathlands on ex-arable fields is inevitable. ...
Article
Heathlands are threatened habitats throughout the whole Europe, which have initiated numerous restoration programmes aimed mostly at plant community reconstruction; however, little is known about soil fauna restoration. Here we have studied newly established wet and dry heathlands in the Netherlands after topsoil removal of previously agricultural land, where we manipulated the soil pH (acidification by Sulphur or liming by Ca ions as Dolokal) and introduced plant or soil material to speed up the restoration process. We sampled experimental plots and nearby mature heathlands (used as local reference habitat) over five years (2013–2017) for nematodes, mesofauna (mainly springtails and mites) and macrofauna. Although soil inoculation proved to be a substantive step in target plant community development and also helped to shift soil faunal assemblages towards the target, the latter were still far from reference heathland after five years. Only macrofaunal densities showed similar densities in 2017 as in local reference spots. The succession dynamics of all studied groups and trophic composition of macrofauna and nematodes differed in wet and dry heathlands. Soil amendments improved the initial colonisation as well as liming at the wet sites, which probably created suitable microhabitats for soil fauna development.
... Techniques, such as metabarcoding based on sequences of the internal transcribed spacer (ITS) region, have been recognized as the universal barcode for a correct taxonomic identi cation of fungal community members with potential to detect rare species in samples of different nature, including poor sequenced taxa (Badotti et al. 2017;Forin et al. 2018). Characterization of fungal communities using metabarcoding of ITS region sequences have expanded the capability to identify land use effects that shape these communities across space and time, associated to factors such as leaf litter, soil nutrients, pH and organic matter content (Rosenfeld et al. 2018;Sommermann et al. 2018;Turley et al. 2020). Tropical soils are important units to study fungal ecological preferences and their driving factors, considering that diversity of fungal groups can peak in tropical ecosystems (Tedersoo et al. 2014). ...
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Changes in soil fungal community caused by land use have not been sufficiently studied in South-American Andosols, considered globally as important food production areas. This study analyzed 26 soil samples of Andosols collected from locations devoted to conservation, agriculture and mining activities in the southeastern region of Antioquia, Colombia, to establish differences between fungal communities as indicators of the degree of soil perturbation. The study developed a novel heminested PCR with primers SSUmCf Mix, ITS4 and fITS7 to assess Arbuscular Mycorrhizal Fungi detection in a Illumina MiSeq metabarcoding on nuclear ribosomal ITS2 region. A non-metric multidimensional scaling allowed exploring driver factors of fungal community changes, while fitted Dirichlet-multinomial models and PERMANOVA tests allowed identifying the correlations between alpha diversity indexes and community dissimilarities, as well as the significance of land use effects on fungal community composition. Furthermore, response ratios were determined to assess effect size by land use over relevant taxa. Results suggest a good coverage of fungal diversity with a detection of 10,529 high-quality ITS2 sequences belonged to phylum Glomeromycota. The analysis shows strong correlations of Shannon and Fisher indexes with dissimilarities on fungal communities among land uses (r=0.94), related to variations in temperature, air humidity and organic matter contents that lead to significant responses in abundances of relevant orders (such as Wallemiales and Trichosporonales). The study highlights the rich fungal biodiversity of the tropical Andosols, their specific sensitivities to environmental perturbation factors, and the useful range of a metabarcoding approach to characterize soil fungal communities.
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Restoring habitats degraded by intensive agriculture is challenging, and the resulting communities often have lower quality and host fewer species than reference ecosystems. To improve restoration outputs, we need to understand what limits both establishment and performance of target species in restored populations. In this study, we focused on grassland restoration with regional seeds and compared the performance of two target herbs, Betonica officinalis and Centaurea jacea, between restored and reference populations. We also measured plant functional traits and environmental characteristics to understand which parameters affect population performance. Individual plants of both species were smaller in restored populations, which indicates reduced performance. Leaves of plants from restored populations contained more δ¹⁵N and, in Betonica, also less nitrogen and higher C:N ratio, which suggests that the performance of the target species may be limited by nitrogen. Nitrogen limitation of all restored communities was further corroborated by the low N:P ratio of bulk biomass. In Centaurea, we also recorded massive herbivory damage in restored populations, which likely further reduced this species's performance in restored meadows. In summary, target plants in restored populations showed lower performance than conspecifics in reference sites, probably due to nutrient imbalance (low nitrogen availability) and excessive herbivory damage. This article is protected by copyright. All rights reserved.
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Soil bacteria and understorey plants interact and drive forest ecosystem functioning. Yet, knowledge about biotic and abiotic factors that affect the composition of the bacterial community in the rhizosphere of understorey plants is largely lacking. Here, we assessed the effects of plant species identity (Milium effusum vs Stachys sylvatica), rhizospheric soil characteristics, large-scale environmental conditions (temperature, precipitation and nitrogen (N) deposition), and land-use history (ancient vs recent forests) on bacterial community composition in rhizosphere soil in temperate forests along a 1700 km latitudinal gradient in Europe. The dominant bacterial phyla in the rhizosphere soil of both plant species were Acidobacteria, Actinobacteria and Proteobacteria. Bacterial community composition differed significantly between the two plant species. Within plant species, soil chemistry was the most important factor determining soil bacterial community composition. More precisely, soil acidity correlated with the presence of multiple phyla, e.g. Acidobacteria (negatively), Chlamydiae (negatively) and Nitrospirae (positively), in both plant species. Large-scale environmental conditions were only important in S. sylvatica and land-use history was not important in either of the plant species. The observed role of understorey plant species identity and rhizosphere soil characteristics in determining soil bacterial community composition extends our understanding of plant-soil bacteria interactions in forest ecosystem functioning.
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Agricultural land use is a leading cause of habitat degradation, leaving a legacy of ecological impacts long after agriculture has ceased. Yet the mechanisms for legacy effects, such as altered plant community composition, are not well understood. In particular, whether plant community recovery is limited by an inability of populations to establish within post-agricultural areas, owing to altered environmental conditions within these areas, remains poorly known. We evaluated this hypothesis of post-agricultural establishment limitation through a field experiment within longleaf pine woodlands in South Carolina (USA) and a greenhouse experiment using field-collected soils from these sites. In the field, we sowed seeds of 12 understory plant species associated with remnants (no known history of agriculture) into 27 paired remnant and post-agricultural woodlands. We found that post-agricultural woodlands supported higher establishment, resulting in greater species richness of sown species. These results were context dependent, however, with higher establishment in post-agricultural woodlands only when sites were frequently burned, had less leaf litter, or had less sandy soils. In the greenhouse, we found that agricultural history had no impact on plant growth or survival, suggesting that establishment limitation is unlikely driven by differences in soils associated with agricultural history when environmental conditions are not stressful. Rather, the potential for establishment in post-agricultural habitats can be higher than in remnant habitats, with the strength of this effect determined by fire frequency and soil characteristics.
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The soil microbial community is essential for maintaining ecosystem functioning and is intimately linked with the plant community. Yet, little is known on how soil microbial communities in the root zone vary at continental scales within plant species. Here we assess the effects of soil chemistry, large-scale environmental conditions (i.e. temperature, precipitation and nitrogen deposition) and forest land-use history on the soil microbial communities (measured by phospholipid fatty acids) in the root zone of four plant species (Geum urbanum, Milium effusum, Poa nemoralis and Stachys sylvatica) in forests along a 1700 km latitudinal gradient in Europe. Soil microbial communities differed significantly among plant species, and soil chemistry was the main determinant of the microbial community composition within each plant species. Influential soil chemical variables for microbial communities were plant species-specific; soil acidity, however, was often an important factor. Large-scale environmental conditions, together with soil chemistry, only explained the microbial community composition in M. effusum and P. nemoralis. Forest land-use history did not affect the soil microbial community composition. Our results underpin the dominant role of soil chemistry in shaping microbial community composition variation within plant species at the continental scale, and provide insights into the composition and functionality of soil microbial communities in forest ecosystems.
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Ecological restoration efforts can increase the diversity and function of degraded areas. However, current restoration practices cannot typically reestablish the full diversity and species composition of remnant plant communities. We present evidence that restoration quality can be improved by reintroducing key organisms from the native plant microbiome. In particular, root symbionts called arbuscular mycorrhizal fungi are crucial in shaping grassland communities, but are sensitive to anthropogenic disturbance, which may pose a problem for grassland restoration. In the present article, we highlight the conceptual motivation and empirical evidence evaluating native mycorrhizal fungi, as opposed to commercial fungi. Reintroduction of the native microbiome and native mycorrhizal fungi improves plant diversity, accelerates succession, and increases the establishment of plants that are often missing from restored communities. The example of mycorrhizal fungi serves to illustrate the value of a more holistic view of plant communities and restoration that embraces the intricacies and dynamics of native microbial communities. © 2018 Published by Oxford University Press on behalf of American Institute of Biological Sciences.
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Human land use, including agriculture, is a leading contributor to declining biodiversity worldwide and can leave long‐lasting legacies on ecosystems after cessation. Ecological restoration is an approach to mitigate these impacts. However, little is known about how animal communities and plant–animal interactions respond to the combined effects of land‐use legacies and restoration. We investigated how restoration and agricultural history affect bee (Hymenoptera: Apoidea: Anthophila) communities and pollination function. In 27 paired remnant (no history of agriculture) and post‐agricultural longleaf pine (Pinus palustris Mill.) woodlands, we established 4–10 1‐ha plots (126 total) and experimentally restored half of them, while the other half were left as unrestored controls. Restoration was accomplished through canopy thinning which reinstates open savanna‐like conditions. We collected bees in each plot using a combination of bowl trapping and standardized netting transects. Thinning increased bee abundance by 169% and bee richness by 110%, but agricultural land use had no effect on these variables. Bee community composition was affected by restoration and was marginally affected by agricultural history. To measure pollination function, we conducted a sentinel plant experiment in which potted black mustard (Brassica nigra L.) plants were placed out in a subset of these sites (n = 10) and either bagged to exclude pollinators or left open for pollinator access. Then, we measured fruit and seed set of sentinel plants to compare pollination function among the restoration and land‐use history treatments. Seed set and fruit set of sentinel plants were higher in open than bagged plants, indicating that this model system effectively measured pollination, but we found no differences in pollination based on restoration or agricultural history. These results indicate that although pollinator communities may show clear responses to restoration that are largely independent of prior land‐use impacts, this does not necessarily translate into differences in pollination function after restoration.
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Soil microbial communities directly affect soil functionality through their roles in the cycling of soil nutrients and carbon storage. Microbial communities vary substantially in space and time, between soil types and under different land management. The mechanisms that control the spatial distributions of soil microbes are largely unknown as we have not been able to adequately upscale a detailed analysis of the microbiome in a few grams of soil to that of a catchment, region or continent. Here we reveal that soil microbes along a 1000 km transect have unique spatial structures that are governed mainly by soil properties. The soil microbial community assessed using Phospholipid Fatty Acids showed a strong gradient along the latitude gradient across New South Wales, Australia. We found that soil properties contributed the most to the microbial distribution, while other environmental factors (e.g., temperature, elevation) showed lesser impact. Agricultural activities reduced the variation of the microbial communities, however, its influence was local and much less than the overall influence of soil properties. The ability to predict the soil and environmental factors that control microbial distribution will allow us to predict how future soil and environmental change will affect the spatial distribution of microbes.
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Background and Aims Although soil-inhabiting fungi can affect tree health and biomass production in managed and pristine forests, little is known about the sensitivity of the plant-fungal associations to long-term changes in land use. We aimed to investigate how reforestation of farmlands change soil characteristics and affected the recovery of soil fungal functional guilds. Methods We examined edaphic conditions and fungal communities (Illumina Sequencing) in three land-use types: primary forests (PF), secondary forests (SF, established over two decades ago) and active farmlands during May, July and September in Wuying, China. Results Edaphic conditions and general fungal communities varied with land-use. Interestingly, overall fungal diversity was higher in soils at the farmland than at the forested sites, possibly as a result of recurring disturbances (tilling) allowing competitive release as described by the intermediate disturbance hypothesis. Although ectomycorrhizal fungal diversity and richness were marginally higher in PF than in SF, the latter still hosted surprisingly diverse and abundant ectomycorrhizal fungal communities. Conclusions Reforestation largely restored fungal communities that were still in transition, as their composition in SF was distinct from that in PF. Our results highlight the ability of fungi grown in previously strongly managed agricultural land to rapidly respond to reforestation and thus provide support for forest trees.
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Rationale: Pyrogenic savannas with a tree-grassland "matrix" experience frequent fires (i.e. every 1-3 years). Aboveground responses to frequent fires have been well-studied, but responses of fungal litter decomposers, which directly affect fuels, remain poorly known. We hypothesized that each fire reorganizes below-ground communities and slows litter decomposition, thereby influencing savanna fuel dynamics. Methods: In a pine savanna, we established patches near and away from pines that were either burned or unburned in that year. Within patches, we assessed fungal communities and microbial decomposition of newly deposited litter. Soil variables and plant communities were also assessed as proximate drivers of fungal communities. Results: Fungal communities, but not soil variables or vegetation, differed substantially between burned and unburned patches. Saprotrophic fungi dominated in unburned patches but decreased in richness and relative abundance after fire. Differences in fungal communities with fire were greater in litter than soils, but unaffected by pine proximity. Litter decomposed more slowly in burned than unburned patches. Conclusions: Fires drive shifts between fire-adapted and sensitive fungal taxa in pine savannas. Slower fuel decomposition in accordance with saprotroph declines should enhance fuel accumulation and could impact future fire characteristics. Thus, fire-reorganization of fungal communities may enhance persistence of these fire-adapted ecosystems. This article is protected by copyright. All rights reserved.
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Although plant-soil interactions are increasingly recognized as an important factor in ecosystem restoration, their effects on community assembly during de novo ecosystem establishment are largely unknown. In a heathland restoration trial after topsoil removal we introduced either only aboveground heathland species with fresh herbage or both above- and belowground heathland species with sods to facilitate community assembly. Sod inoculation increased resemblance of the microbial community to the reference system, with a higher fungal and lower bacterial proportion to the community structure. Also densities of bacteriophagous and phytophagous nematodes, Acari and Collembola increased after sod inoculation. The cover of heathland plant species increased by 49% after sod inoculation. The introduction of solely aboveground heathland species increased the cover of these species by only 13%, and did not affect soil community assembly. Additionally, the increase in cover of heathland species over time was inversely correlated to the cover of mesotrophic grassland species. Inverse correlations were also observed between changes in fungal and bacterial abundances. Simultaneous introduction of key species of both above- and below-ground communities had a critical effect on the establishment of both communities, providing a potential shortcut for successful restoration of target ecosystems on disturbed soils.