Biodiversity In Agroecosystems Research Articles

Organic farming supports spatiotemporal stability in species richness of bumblebees and butterflies

The spatiotemporal stability of wild organisms, such as flower-visiting insects, is critical to guarantee high levels of biodiversity in agroecosystems. Whereas the proportion of semi-natural habitats in the landscapes has been shown to stabilize the species richness of flower visitors, the effect of farming intensity has not yet been studied. In this study, we compared the temporal and spatial stability (continuity of species richness in space and time) of two groups of flower-visiting insects (butterflies and bumblebees) between nine conventional and ten organic farms, distributed along a gradient of semi-natural grassland proportion. We surveyed bumblebees, butterflies and local flower cover during the growing season, covering multiple years and several habitat types per farm (cereal fields, temporary grasslands and semi-natural grasslands). At the field scale we found that within-year stability of bumblebee species richness was higher in organic than in conventional temporary grasslands (leys), because of a higher continuity of in-field flower resources. Further analyses showed that late-season flower resources in organic ley fields were critical to maintain a high within-year stability of bumblebee species richness by reducing resource bottlenecks during that period, when most bumblebee colonies produce new queens. The among-year stability of bumblebee species richness was higher in organic than in conventional cereal fields, whereas the within and among-year stability of butterfly species richness was not influenced by farming system. On the farm scale, we found that the spatial stability of butterfly and bumblebee species richness was higher in organic than in conventional farms, but this was not explained by a greater spatial continuity of flower resources. Our study shows that organic farming reduces the spatiotemporal fluctuations in bumblebee and butterfly species richness. In addition, increasing floral resources as such benefits bumblebees and butterflies irrespective of farming system. Organic farming and increasing availability in floral resources therefore contribute to maintaining the within and between-year stability of bumblebees and butterflies in agricultural landscapes.

Landscape composition, configuration, and trophic interactions shape arthropod communities in rice agroecosystems

Abstract Increasing landscape heterogeneity of agroecosystems can enhance natural enemy populations and promote biological control. However, little is known about the multiscale effects of landscape heterogeneity on arthropod communities in rice agroecosystems, especially in combination with trophic interactions. We examined for the first time how landscape heterogeneity, measured by four independent metrics of landscape composition and configuration at three spatial scales, affected species abundance and species richness of rice arthropods within four functional groups and the abundance of the most common species at 28 sites in the Philippines. We additionally examined the influence of trophic interactions among these functional groups. We found that both the compositional and configurational landscape heterogeneity in combination with trophic interactions determined the structure of rice‐arthropod communities. Herbivore abundance decreased with increasing landscape diversity. The abundance of parasitoids and species richness of both parasitoids and predators increased with the structural connectivity of rice bunds. Fragmentation of the rice landscape had a clear negative effect on most arthropod groups, except for highly mobile predatory arthropods. Abundance of common predators and detritivore species decreased with increasing complexity in the shape of rice patches. Trophic interactions, measured as the abundance of prey, outweighed the importance of landscape heterogeneity for predators. In contrast, parasitoids responded positively to configurational landscape heterogeneity but were unaffected by prey abundance. Synthesis and applications. Our research shows how landscape heterogeneity and trophic interactions have different effects on different functional groups. While predator abundance was solely driven by the availability of prey, all other functional groups in the rice‐arthropod community were significantly affected by the composition and configuration of surrounding landscape features. Landscape management aiming to improve biodiversity and biological control in rice agroecosystems should promote a diversity of land uses and habitat types within 100–300 m radii to reduce the presence of pests. Management practices should also focus on maintaining smaller rice patches and the structural connectivity of rice bunds to enhance populations of the natural enemies of rice pests. Future research should focus on the temporal and spatial manipulation of rice fields to maximize the effects of biological control.

Cadmium-mediated morphological, biochemical and physiological tuning in three different Anabaena species

Cyanobacteria are a natural inhabitant of paddy field and enhance the crop productivity in an eco-friendly manner. Cadmium (Cd) is a perilous trace metal element which not only limits the crop productivity but also inhibits the growth and nitrogen-fixing ability of these diazotrophs as well as the biodiversity of rice field semiaquatic agroecosystems. However, the impact of Cd toxicity in diazotrophic cyanobacteria is yet not adequately addressed. Therefore, in the present study, three diazotrophic cyanobacterial species, i.e., Anabaena sp. PCC7120, Anabaena L31, and Anabaena doliolum were subjected to their LC50 doses of Cd, and their physiological (PSII, Psi, respiration, energy status and nitrogen fixation rate), biochemical variables (such as antioxidant contents and antioxidant enzymes) together with morphological parameters were evaluated. The results of physiological variables suggested that the Cd exposure adversely affects the photosynthesis, respiration, and biological nitrogen fixation ability across three Anabaena species. The results of biochemical variables in terms of accumulation of antioxidants (glutathione, thiol, phytochelatin and proline) content as well as antioxidant enzymes such as glutathione S-transferase (GST), glutathione reductase (GR), catalase-peroxidase (CAT), ascorbate peroxidase (APX) and superoxide dismutase (SOD) revealed that their inter-species stress tolerance behavior may be attributed to the differential accumulation of antioxidants as well as differential antioxidant enzyme activity in three species. Furthermore, the enhanced antioxidant enzymes activity such as GST, GR, CAT, and SOD in Anabaena L31 advocated significantly higher as compared to Anabaena PCC7120 and Anabaena doliolum. In conclusion, Cd-toxicity assessment regarding physiological, biochemical and morphological aspects across three species identified Anabaena L31 as Cd-resistant species than the other two tested species, i.e., Anabaena PCC7120 and Anabaena doliolum.

<b>Butterfly diversity in human-modified ecosystems of southern Sikkim, the eastern Himalaya, India</b>

Understanding wild biodiversity of agroecosystems and other human dominated landscapes are crucial for the management and conservation of biological resources. Here, we studied the diversity, abundance, similarity and functionality of butterflies in different human modified ecosystems in southern Sikkim, the Eastern Himalaya. The study was conducted from January 2015 to May 2015 by covering three habitat types namely, farm-based agroforestry, large cardamom-based agroforestry and adjacent natural forest ecosystem. We followed point count method along the transect to collect data on butterflies in the study area. A total of 911 individual butterflies representing six families and 44 species were recorded during the present study in southern Sikkim. Species richness and abundances of butterflies were significantly different among the systems. While diversity and abundance were higher in forest patches, each system harbored unique species assemblages with low similarity between habitats. The information on larval host plants were available for 41 butterfly species which depended on 128 plant species belonging to 27 families. The butterfly community was dominated by oligophagous II (19 species) followed by polyphagous (11 species), monophagous (8 species) and oligophagous I (3 species). Similarly, generalist feeders had higher species and abundance compared to specialist feeders. Specialist species were confined to forest habitat, whereas generalist species were mostly restricted to cultivated systems. The findings of the study highlighted the need for conservation of traditionally managed agroecosystems in order to conserve butterflies and other associated biodiversity.

Bee diversity in crop fields is influenced by remotely-sensed nesting resources in surrounding permanent grasslands

Landscape heterogeneity is an important driver of biodiversity in agroecosystems. However, the functional heterogeneity of agricultural landscapes, taking into account the different resources that habitat patches can provide to species, has rarely been studied. In this study, we explored the effect of landscape-scale nest availability provided by permanent grasslands on wild bee communities. Wild bees were sampled in 43 cereal fields in south-western France differing in the surrounding proportion of permanent grasslands. Using remote sensing tools, we measured two parameters of grassland structure known to locally influence bee nest density (slope and proportion of sparse vegetation). We found that mean slope of surrounding grasslands was the factor that most positively influenced bee richness, abundance and trait distribution in bee communities. We also found that mean slope of surrounding grasslands had a better predictive power of bee community structure than the proportion of permanent grasslands. Ground-nesting species, species with high dispersal capacities and species with a generalist diet were positively affected by the availability of sloped ground in the surrounding permanent grasslands. Only bee species with specialized flower requirements responded positively to the proportion of sparse vegetation in grasslands. Our results suggest that landscape-scale availability of nesting resources provided by grasslands affects bee communities in agricultural landscapes and can help sustain functionally diverse bee assemblages. Using simple remote sensing tools, this study highlights the importance of considering nesting resources in agricultural landscapes to maintain wild bee diversity in farmlands.

Establishment of Grass Strips for Maintaining Biodiversity in Agroecosystems

Main principle of the common agricultural policy of European Union is achievement of high results with the least possible negative impact on the environment, land protection and efficient use of natural resources. For that purpose, a number of studies are carried out, related to the improvement of biodiversity and protection of the pollinators in the areas of production. Two type of grass mixes were observed: “Laitamag” (Hungary) composed of White mustard (Sinapis alba L.), White clover (Trifolium repens L.), Phacelia (Phacelia tanacetifolia Bentham), Crimson clover (Trifolium incarnatum L.), Egyptian clover (Trifolium alexandrinum L.), Red clover (Trifolium pretense L.), Wild oats (Avena sativa L.), Alfalfa (Medicago sativa L.), Buckwheat (Fagopyrum esculentum Moench) and Sainfoin (Onobrychis viciifolia Scop.) and a mix, proposed by the Agrarian University: White mustard (Sinapis alba L.), White clover (Trifolium repens L.), Phacelia (Phacelia tanacetifolia Bentham), Buckwheat (Fagopyrum esculentum Moench), Coriander (Coriandrum sativum L.). The vegetation of the autumn crops began in March, as the blossoming lasts for 60-63 days, from the beginning of April until 24 June. For the spring sowing (18 March), the flowering of the mixes occurred later, in the second 10-day period of May and ended at the end of June. As a result of the low temperatures during winter, the white mustard, buckwheat and sainfoin plants perished. White clover proves to be the most resilient species.

Complejidad y sostenibilidad de dos agroecosistemas con cacao, Siuna 2017

Esta investigación se realizó en la comunidad El Carao-Hormiguero, Siuna, 2017, en las fincas Los Laureles del Sr. German Valerio Pérez y El Encanto del Sr. Carlos López Lagos, con el fin de evaluar la complejidad y sostenibilidad de dos agro ecosistemas con cacao a través de manejo de biodiversidad en los agroecosistemas y determinar el nivel de sostenibilidad en el aspecto sociocultural, económico y agro-ambiental. Se aplicaron dos metodologías, Vázquez (2013) la cual evalúa seis indicativos y 64 indicadores, se miden con un rango de (0-4) siendo este un valor estándar para medir el nivel de complejidad de los sistemas de producción y HESOFI (2015) que evalúa 71 indicadores, 12 componentes y 3 criterios, sociocultural, económicos y agro-ambiental y para cada criterio se asigna un valor de 100. El coeficiente y manejo de la biodiversidad en la finca Los Laureles es medianamente complejo con un nivel del 2.61 (56.71%) con un índice satisfactorio y El Encanto 1.60 (33.44%), determinándose como un sistema de producción poco complejo con índice medianamente satisfactorio. El nivel de sostenibilidad que miden las dimensiones socio-cultural, económica y agro-ambiental para la finca El Encanto fue de 132 de 300, su fuerza radica en lo sociocultural con (66%), agro-ambiental con (41%) y económico con un (25%). Los Laureles presentó un valor de 202 de 300, su mayor fuerte fue lo sociocultural (75%), lo agro- ambiental (69%) y lo económico (58%). Tales resultados indican que Los Laureles cuenta con un grado de sostenibilidad del (67.40%), y El Encanto con (44.19%).

Effects of pasture conversion to sugarcane for biofuel production on stream fish assemblages in tropical agroecosystems

Abstract One of the main causes of biodiversity loss in aquatic ecosystems is instream habitat change associated with land‐use change in the drainage basin. Biofuel crop production is an increasingly important driver of land‐use change in existing agricultural drainage basins. Conceptually, biofuels such as sugarcane (Saccharum spp.: Poaceea) can provide a sustainable alternative to fossil fuels, but little is known about the consequences of biofuel crop production for biodiversity. Thus, our aim was to investigate if and how the degree of further environmental changes at regional and local scales can influence taxonomic and functional structure of fish assemblages in agroecosystem streams. We quantified drainage basin land use, instream and riparian habitat, and fish assemblages in 38 agroecosystem streams in Brazil with drainage basins experiencing rapid expansion of sugarcane production, and calculated degree of environmental change and corresponding response in taxonomic and functional structure of stream fish assemblages. Procrustes and redundancy analyses tested for correlation between land use and instream habitat and environmental factors correlated with fish assemblage structure, respectively. Previous studies demonstrated relationships between land‐use change, instream habitat change and taxonomic and functional structure of stream fish assemblages. Therefore, we used regression to test the hypothesis that degree of environmental change is positively correlated with magnitude of change in taxonomic and functional structure of fish assemblages. Primary gradients of environmental change included conversion of pasture to sugarcane and reduction of stream width, depth and volume. Although drainage basin and instream attributes were not correlated within a year, we detected a legacy effect of land use on instream habitat. The degree of environmental change was not significantly correlated with taxonomic or functional changes in stream fish assemblages in most cases. However, abundances of resistant taxa increased, whereas nektonic functional groups decreased, and the biological response also presented evidence of a legacy effect. Our findings demonstrate that instream habitat and aquatic biodiversity in streams with agricultural drainage basins undergoing rapid conversion to biofuel production likely will not experience the full magnitude of responses in the short term. Therefore, repeated sampling of sufficient duration to account for legacy effects or time lags is needed to test for effects of biofuel expansion on biodiversity, and similarly to assess whether management practices such as riparian zone preservation can benefit biodiversity in agroecosystems.

Impact of agricultural practices on earthworm biodiversity in different agroecosystems

The diversity of Earthworms in agro-ecosystems is less studied and the modern agriculture which involve different agricultural practices like crop rotation, tillage and application of synthetic fertilizer leads to pollute the soil ecosystem as a result the highly sensitive soil micro and macro faunal diversity is in threaten condition. This investigation was an attempt to assess the diversity of different native species of earthworms from five different agro-ecosystems. The diversity of earthworms reveals that the diversity of earthworms from rice field recorded higher number followed by turmeric field. Eiesnia foetida and Periyonx excavates were the local earthworm species recorded during the entire investigation. The investigation reveals the impact of different agricultural practices on the soil faunal diversity and its importance in the context of soil organic matter.

Effectiveness of the system of protected areas of Lombardy (Northern Italy) in preserving breeding birds

SummaryNetworks of protected areas (PAs) where human activities are allowed at different degrees are fundamental to ensure the long-term conservation of biological diversity and ecological processes. However, studies aimed at assessing their effectiveness, focusing on several species simultaneously are scarce. We assessed the effectiveness of the system of protected areas (PAs) of Lombardy, Northern Italy, in conserving bird populations by comparing the changes from 1992 to 2013 in the occurrence of 54 breeding bird species censused in areas classified in different protection categories, namely Nature Reserves (NRs), areas designed predominantly for the protection of nature; Regional Parks (RPs), naturally valuable areas where human activities, including intensive agriculture, are allowed; and non-protected areas (NPAs). Overall, occurrence of common birds increased in Lombardy in the last 20 years and farmland and long-distance migrants (LDMs), which suffered sharp declines at a continental scale, showed stable and increasing trends, respectively. These trends were, however, the balance between those of species whose occurrence markedly increased, and those of species that dramatically declined. Species occurred more often in PAs than in NPAs, while temporal trends in occurrence were significantly more positive in RPs than in both NRs and NPAs. Hence, PAs seemed effective in preserving common bird communities. Occurrence of woodland and short-distance migrant species was higher in PAs than in NPAs, while occurrence of farmland species and LDMs was similar in all protection categories. PAs of Lombardy appear therefore effective only in protecting some categories of birds. Farmland and LDM birds would benefit more from ecologically sustainable land-use policies aiming at improving agro-ecosystem biodiversity than from protected areas.

Metagenomic analysis of oomycete communities from the rhizosphere of field pea on the Canadian prairies.

Oomycetes are a diverse group of microorganisms; however, little is known about their composition and biodiversity in agroecosystems. Illumina MiSeq was used to determine the type and abundance of oomycetes associated with pea root rot in the Canadian prairies. Additional objectives of the study were to identify differences in oomycete communities associated with pea root health and compare oomycete communities among the 3 prairie provinces, where field peas are commonly cultivated. Samples of soil from the rhizosphere of field pea (Pisum sativum L.) were collected from patches of asymptomatic or diseased plants from 26 commercial fields in 2013 and 2014. Oomycete communities were characterized using metagenomic analysis of the ITS1 region on Illumina MiSeq. From 105 identified operational taxonomic units (OTUs), 45 and 16 oomycete OTUs were identified at species and genus levels, respectively. Pythium was the most prevalent genus and Pythium heterothallicum the most prevalent species in all 3 provinces in both 2013 and 2014. Aphanomyces euteiches, a very important pea root rot pathogen in regions of the prairies, was detected in 57% of sites but at very low abundance (<0.2%). Multivariate analysis revealed differences in the relative abundance of species in oomycete communities between asymptomatic and diseased sites, and among years and provinces. This study demonstrated that deep amplicon sequencing can provide information on the composition and diversity of oomycete communities in agricultural soils.

Soil and Foliar Arthropod Abundance and Diversity in Five Cropping Systems in the Coastal Plains of North Carolina.

Soil and foliar arthropod populations in agricultural settings respond to environmental disturbance and degradation, impacting functional biodiversity in agroecosystems. The objective of this study was to evaluate system level management effects on soil and foliar arthropod abundance and diversity in corn and soybean. Our field experiment was a completely randomized block design with three replicates for five farming systems which included: Conventional clean till, conventional long rotation, conventional no-till, organic clean till, and organic reduced till. Soil arthropod sampling was accomplished by pitfall trapping. Foliar arthropod sampling was accomplished by scouting corn and sweep netting soybean. Overall soil arthropod abundance was significantly impacted by cropping in corn and for foliar arthropods in soybeans. Conventional long rotation and organic clean till systems were highest in overall soil arthropod abundance for corn while organic reduced till systems exceeded all other systems for overall foliar arthropod abundance in soybeans. Foliar arthropod abundance over sampling weeks was significantly impacted by cropping system and is suspected to be the result of in-field weed and cover crop cultivation practices. This suggests that the sum of management practices within production systems impact soil and foliar arthropod abundance and diversity and that the effects of these systems are dynamic over the cropping season. Changes in diversity may be explained by weed management practices as sources of disturbance and reduced arthropod refuges via weed reduction. Furthermore, our results suggest agricultural systems lower in management intensity, whether due to organic practices or reduced levels of disturbance, foster greater arthropod diversity.

The Role of Traditional Communities n the Management of Diversity of Sheep Populations in Caras - Severin County

Abstract Modernization of agriculture has led to the erosion of biodiversity of agroecosystems with implications for productivity in the sector. Degradation of genetic resources of plants, animals, insects and soil organisms causing economic losses threatening the food security of the population. This study is based on biodiversity in sheep populations in Caras - Severin and brings attention to traditional practices in the management of animal genetic resources. In the agroecosystem, maintaining the biodiversity is a guarantee for future challenges (growth and diversification of consumer demand, climate change, possible calamities) provided that at the consumer level there is an increased preference to traditional and organic products. From this point of view, it is remarkable the effort of private breeders in Caras - Severin to maintain the rustic varieties of sheep, but we think it requires a more resolute stand of the government and academic organisations for identification, preservation and support of such genetic resources valuable for all species. In Caras-Severin County, diversity of sheep populations is maintained in household or pastoral system in small and medium farms, the animal selection being based on the interest and preferences.

Spider community responds to litter complexity: insights from a small-scale experiment in an exotic pine stand

ABSTRACT Conservation of biodiversity in agroecosystems is an urgent need, and a suitable approach to maximize animal biodiversity and their services is the restoration of habitat heterogeneity. Here we investigated the value of increasing litter complexity in tree plantations of exotic pine for ground spiders. We hypothesized that increasing the litter complexity of these systems, as it would be the case in ecologically designed plantations, would increase spider aggregations. We performed a small-scale litter manipulation experiment within an exotic pine stand in the municipality of Minas do Leão, Rio Grande do Sul, Brazil, and compared spider diversity in simple (only pine needles) and complex substrates (with the addition of diverse native broadleaves). We found 1,110 spiders, 19 families and 32 morphospecies. The most abundant families were Linyphiidae, Theridiidae and Salticidade, and the dominant morphospecies were Thymoites sp. 2 and Lygarina sp. Web-building spiders represented 61% of total spider abundance, and 17 species, while hunting spiders, 49% and 15 species. As expected, densities of spider individuals and species from both web-building and hunting spiders were higher in complex litter substrate. Potential preys (Collembola) also responded positively to the treatment, and had influence of spider community patterns. Our results suggest that ensuring some degree of plant and litter diversity within pine stands (e.g. understory establishment) might foster spider aggregations and possibly help to conserve their diversity at local-scales.

Intercropping Empower Reduces Insect Pests and Increases Biodiversity in Agro-Ecosystem

Currently insect pest management solely depends on chemical pesticide that continuously affects on environment, biodiversity, animal as well as human health. Outbreak of secondary insect pest is also the cost of pesticide use in field leading crop more vulnerable to more pests. These negative impacts of pesticides have provoked growing interest in the adoption of multi-function agricultural biodiversity that promote pest management, creating interesting challenge for traditional approaches to regulatory compliance. To address multi-function agricultural practice, we tested several intercropping systems with mustard and their effect on pest management. Our results revealed that intercropping systems mustard with onion, garlic, radhuni and coriander significantly reduced pest population over sole crop. However, intercropping mustard with wheat and gram increased pest population in mustard field. This result indicated that all crops are not suitable for intercropping system. Among the tested intercropping systems, mustard with onion and coriander significantly reduced branch and flower infestation and increased pod formation per plant. These four intercropping systems did not significantly affect on honeybee pollinator which are crucial for mustard crop yield. A significant linear relationship was also found between honeybee population and pod formation. Our results indicate that suitable intercropping system can be a potential multi-functional agricultural practice for pest management in mustard crop.

Plant diversity and determinant factors across smallholder agricultural management units in Central Ethiopia

Forests in the highlands of Ethiopia have declined considerably, and the supply of forest-based ecosystem services is eroding. Managing agricultural landscapes as well as enhancing plant biodiversity in agro-ecosystems is and will continue to be one possible strategy to preserve biodiversity, ensure an ecosystem service supply and sustain agricultural productivity. This study investigated the current status and prospects of plant diversity and its determinants in an agricultural landscape dominated by smallholder farmers in Southern Ethiopia. Specifically, the study investigated effects of land use, altitudinal gradient, wealth status and household attributes on plant diversity in agricultural landscapes. A complete count, Y-frame transect sampling method and household interviews were used for the study involving 39 households and 115 sample plots. A total of 166 plant species belonging to 134 genera and 56 families were recorded in all land use types. Of these, 101 were woody plant species (51 trees and 50 shrubs), while 65 were cultivated herbs and grasses. Land use, altitude and household wealth status significantly influenced tree and shrub species richness. Among land uses, home gardens hosted the highest number of tree and shrub species. Upper altitudes and rich households also had the highest tree and shrub species richness compared to others. Plant diversity indices (Shannon, Simpson and Margalef) were affected by altitude, wealth status and land use types. Household location, wealth status, the household attributes of landholding and family size had strong and positive influences on the tree species diversity and woody stem density of households, while educational background and off-farm income were negatively related with household-owned tree stem density. Species preference ranking, seedling demand and importance value index computations indicated the dominance of exotic tree species, which may suggest their economic importance over indigenous tree species. In the long term, this might lead to dominance of exotic tree species in the landscapes, which could cause a potential future threat to the remnant indigenous plant diversity that is currently finding refuge in the agricultural landscapes.

Response-based selection of barley cultivars and legume species for complementarity: Root morphology and exudation in relation to nutrient source

Phosphorus (P) and nitrogen (N) use efficiency may be improved through increased biodiversity in agroecosystems. Phenotypic variation in plants’ response to nutrient deficiency may influence positive complementarity in intercropping systems. A multicomponent screening approach was used to assess the influence of P supply and N source on the phenotypic plasticity of nutrient foraging traits in barley (H. vulgare L.) and legume species. Root morphology and exudation were determined in six plant nutrient treatments. A clear divergence in the response of barley and legumes to the nutrient treatments was observed. Root morphology varied most among legumes, whereas exudate citrate and phytase activity were most variable in barley. Changes in root morphology were minimized in plants provided with ammonium in comparison to nitrate but increased under P deficiency. Exudate phytase activity and pH varied with legume species, whereas citrate efflux, specific root length, and root diameter lengths were more variable among barley cultivars. Three legume species and four barley cultivars were identified as the most responsive to P deficiency and the most contrasting of the cultivars and species tested. Phenotypic response to nutrient availability may be a promising approach for the selection of plant combinations for minimal input cropping systems.

Soil microbial biomass and function are altered by 12 years of crop rotation

Abstract. Declines in plant diversity will likely reduce soil microbial biomass, alter microbial functions, and threaten the provisioning of soil ecosystem services. We examined whether increasing temporal plant biodiversity in agroecosystems (by rotating crops) can partially reverse these trends and enhance soil microbial biomass and function. We quantified seasonal patterns in soil microbial biomass, respiration rates, extracellular enzyme activity, and catabolic potential three times over one growing season in a 12-year crop rotation study at the W. K. Kellogg Biological Station LTER. Rotation treatments varied from one to five crops in a 3-year rotation cycle, but all soils were sampled under a corn year. We hypothesized that crop diversity would increase microbial biomass, activity, and catabolic evenness (a measure of functional diversity). Inorganic N, the stoichiometry of microbial biomass and dissolved organic C and N varied seasonally, likely reflecting fluctuations in soil resources during the growing season. Soils from biodiverse cropping systems increased microbial biomass C by 28–112 % and N by 18–58 % compared to low-diversity systems. Rotations increased potential C mineralization by as much as 53 %, and potential N mineralization by 72 %, and both were related to substantially higher hydrolase and lower oxidase enzyme activities. The catabolic potential of the soil microbial community showed no, or slightly lower, catabolic evenness in more diverse rotations. However, the catabolic potential indicated that soil microbial communities were functionally distinct, and microbes from monoculture corn preferentially used simple substrates like carboxylic acids, relative to more diverse cropping systems. By isolating plant biodiversity from differences in fertilization and tillage, our study illustrates that crop biodiversity has overarching effects on soil microbial biomass and function that last throughout the growing season. In simplified agricultural systems, relatively small increases in crop diversity can have large impacts on microbial community size and function, with cover crops appearing to facilitate the largest increases.

Conservation tillage reduces the negative impact of urbanisation on carabid communities

Abstract Urban sprawl has been widely recognised as major cause of biodiversity decline across multiple taxonomic levels. Nevertheless, comprehensive studies investigating the effects of landscape urbanisation and farming practices on arthropod biodiversity in agroecosystems are still scarce. We explored the combined effect of urbanisation in the landscape and tillage management (conservation vs. conventional tillage) on predatory carabid beetle communities (Coleoptera: Carabidae) in 10 pairs of winter cereal fields in the agricultural landscape of Udine province (north‐east Italy). Urbanisation (at 750 m scale) strongly decreased carabid activity density, species richness, functional richness and increased functional divergence. We, however, found an interaction between tillage system and the proportion of urban areas in the landscape, i.e., the negative effects of urbanisation on carabid communities were more evident in the fields managed under conventional tillage, while conservation tillage supported more diverse (both taxonomically and ecologically) and abundant beetle communities also in highly urbanised landscapes. We also found that different functional groups differently responded to tillage management. The better local habitat quality provided by conservation tillage may mitigate the negative effects of urbanisation on carabid communities. Our study stresses the importance of considering both local management and landscape composition when planning strategies to support farmland biodiversity.

Multi-scale effects of agri-environment schemes on carabid beetles in intensive farmland

Agri-environment schemes (AESs) were implemented to reduce the loss of biodiversity in agro-ecosystems. This study aimed to assess whether AESs at either local or landscape scale increase the carabid abundance-activity and species richness. Carabids were sampled in 496 fields in a 430km2 study area of central-western France. Based on the extensiveness of the agricultural practices involved, the different AES types were aggregated into three categories (AESEXT+, AESEXT++ and AESEXT+++) forming a gradient of extensiveness in farming practices. We sampled 20 fields in each of the three AESs categories. Each AES fields was paired with conventional fields. A series of statistical models were built to test the balance between the effects of AESs on either the carabid abundance-activity or species richness. AESs affected carabid abundance-activity and species richness both locally and at landscape scale (local characteristics having a greater effect than landscape composition). Carabid diversity benefited from AESs only when the most extensive practices were implemented, i.e. organic farming in cereal crops and delayed cutting in alfalfa. In addition, the local effects of organic farming and delayed cutting coverage interacted positively with these AESs at landscape scale. These results demonstrate that non-targeted organisms can benefit from AES management. They further emphasize the need to consider both local and landscape conditions when studying the effects of AESs on biodiversity. As only the most extensive practices had significant effects at both local and landscape scales, management must be planned strategically in space to ensure that AESs are distributed within the landscape to amplify their positive effects.