Soil type and land use intensity determine the composition of arbuscular mycorrhizal fungal communities

The objective of this study was to test whether soil types can be characterized by their arbuscular mycorrhizal fungal (AMF) communities. To answer this question, a well-defined study area in the temperate climatic zone of Central Europe was chosen with a large spectrum of soils and parent materials. Representative soil samples were taken from three soil types (Cambisol, Fluvisol and Leptosol) at in total 16 sites differing in agricultural land use intensity (9 grasslands and 7 arable lands). AMF spores were isolated and morphologically identified directly from field soils and after reproduction in trap cultures. AMF diversity and community composition strongly depended on soil type and land use intensity, and several AMF species were characteristic for a specific soil type or a specific land use type and hence had a specific niche. In contrast, other AM fungi could be considered as ‘generalists’ as they were present in each soil type investigated, irrespective of land use intensity. An estimated 53% of the 61 observed AMF species could be classified as ‘specialists’ as (almost) exclusively found in specific soil types and/or under specific land use intensities; 28% appeared to be ‘generalists’ and 19% could not be classified. Plant species compositions (either natural or planted) had only a subordinate influence on the AMF communities. In conclusion, land use intensity and soil type strongly affected AMF community composition as well as the presence and prevalence of many AM fungi. Future work should examine how the differences in AMF species compositions affect important ecosystem processes in different soils and to which extent the loss of specific groups of AM fungi affect soil quality.     

Impact of conservation tillage and organic farming on the diversity of arbuscular mycorrhizal fungi

Communities of arbuscular mycorrhizal fungi (AMF) are strongly affected by land use intensity and soil type. The impact of tillage practices on AMF communities is still poorly understood, especially in organic farming systems. Our objective was to investigate the impact of soil cultivation on AMF communities in organically managed clay soils of a long-term field experiment located in the Sissle valley (Frick, Switzerland) where two different tillage (reduced and conventional mouldboard plough tillage) and two different types of fertilization (farmyard manure & slurry, or slurry only) have been applied since 2002. In addition, a permanent grassland and two conventionally managed croplands situated in the neighborhood of the experiment were analyzed as controls. Four different soil depths were studied including top-soils (0–10 and 10–20 cm) of different cultivation regimes and undisturbed sub-soils (20–30 and 30–40 cm). The fungi were directly isolated from field soil samples, and additionally spores were periodically collected from long-term trap culture (microcosm) systems. In total, >50,000 AMF spores were identified on the species level, and 53 AMF species were found, with 38 species in the permanent grassland, 33 each in the two reduced till organic farming systems, 28–33 in the regularly plowed organic farming systems, and 28–33 in the non-organic conventional farming systems. AMF spore density and species richness increased in the top-soils under reduced tillage as compared to the ploughed plots. In 10–20 cm also the Shannon–Weaver AMF diversity index was higher under reduced tillage than in the ploughed plots. Our study demonstrates that AMF communities in clay soils were affected by land use type, farming system, tillage as well as fertilization strategy and varying with soil depth. Several AMF indicator species especially for different land use types and tillage strategies were identified from the large data set.     

Effects of cropping systems under no‐till agriculture on arbuscular mycorrhizal fungi in Argentinean Pampas

Here, we compare arbuscular mycorrhizal fungi (AMF) communities and fatty acids in soils under different no‐till (NT) agricultural managements over two seasons in two consecutive years. Two NT practices with different agricultural managements were compared: crop rotation (CR) and soya bean monoculture (MC). Soils of natural grasslands (NGs) were used as a reference. Treatments were tested along a regional gradient (four geographical locations) across a 400‐km transect of the Argentinean Pampas. We identified 46 morphospecies. Several morphospecies occurred abundantly at all soils; others appeared to be restricted to specific situations. At the regional scale, CR maintained the same richness levels of AMF spores, whereas MC showed less richness, when compared with the NG. Although AMF spore density was clearly affected by cropping practices in the four locations, we could observe some changes in AMF species richness, and similar diversity under agricultural and natural soils. Fatty acid concentrations (whole‐cell, phospholipid and neutral lipid fatty acids) revealed differences between soil managements and showed similar patterns of variation in all locations. Spore density positively correlated with all soil lipids fractions. The results suggest that AMF spore communities and fatty acids in soils are suitable indicators of soil management involving different levels of crop rotation. Spore richness measured at a regional scale proved to be sensitive to different NT agricultural managements. Moreover, certain morphospecies could be good bioindicators for NT practices based on cropping systems on the Argentinean Pampas.     

Species composition of arbuscular mycorrhizal fungi in two mountain meadows with differing management types and levels of plant biodiversity

Species composition of arbuscular mycorrhizal fungi (AMF) was analysed in two differently managed mountain grasslands in Thuringia (Germany). Arbuscular mycorrhizal fungi were studied in the roots of 18 dominant plant species from a total of 56 (32%). Additionally, spores of AMF were isolated from soil samples. Arbuscular mycorrhizal fungi species composition was analysed based on 96 sequences of the internal transcribed spacer of the nuclear ribosomal DNA, 72 originated from mycorrhizal roots, and 24 originated from AMF spores. Phylogenetic analyses revealed a total of 19 AMF species representing all genera of the Glomeromycota except Scutellospora and Pacispora. Despite a different farming intensity, resulting in remarkable differences concerning their plant species diversity (27 against 43 plant species), the diversity of AMF was found to be similar with 11 species on the intensively farmed meadow and ten species on the extensively farmed one. Nevertheless, species composition between both sites was clearly different. It thus seems likely that the AMF species composition, but not necessarily the species number, is related to above ground plant biodiversity in the system under study.     

Contributions of biotic and abiotic factors to soil aggregation across a land use gradient

Soil aggregation is a major ecosystem process that can be impacted by intensified land use directly through soil disturbances, or indirectly through impacts on biotic and abiotic factors that affect soil aggregation. We collected soils from 27 grassland sites across a range of land use intensities including varying levels of mowing, grazing, and fertilization in order to test the importance of selected direct and indirect effects on soil aggregation. We measured root length and mass, root colonization by arbuscular mycorrhizal fungi (AMF), extraradical AMF hyphal length, soil aggregation, and soil hydrophobicity. We also quantified levels of phosphorus, nitrogen, organic carbon, carbonate carbon, and sand in the soil.As land use intensity (defined as a multivariate index combining mowing, grazing, and fertilization intensities) increased, root mass decreased and length of extraradical hyphae increased. Total colonization by AMF was unaffected by land use intensity, but vesicular colonization tended to increase while arbuscular colonization declined. Soil aggregation increased with increasing land use intensity. We used structural equation models to explore mechanisms of soil aggregation and found that extraradical AMF hyphal length contributed to soil aggregation in models containing only biotic explanatory factors. When we also included abiotic factors in the model, no biotic factor was significant, and soil aggregation decreased as levels of sand and carbonate increased, likely due to concurrent decreases in levels of clay in the soil.In summary, we have shown that agricultural measures such as mowing, grazing, and fertilization can increase soil aggregation in managed grasslands. Furthermore, abiotic factors can be more important for determining soil aggregation than biotic factors, especially in highly aggregated soils. Aggregate turnover may be reduced in such highly aggregated soils past the point required to ensure efficient integration of new labile C into stable aggregates.     

Morphological and molecular characterization of arbuscular mycorrhizal fungal communities inhabiting the roots and the soil of saffron (Crocus sativus L.) under different agricultural management practices

Crocus sativus L. cultivation is expanding to areas with low soil fertility, where mycorrhizal fungi are supposed to be essential for plants growth and ecosystems functioning. Agricultural practices applied under these conditions should lead to good saffron productivity and quality. Our objective was to study the density and diversity of mycorrhizal fungi populations associated with saffron grown in Taliouine (Morocco) under different agricultural management practices (fertilization type, age and plantation method). Morpho-anatomical studies identified rhizospheric mycorrhizal spores and assessed root colonization by arbuscular mycorrhizal fungi (AMF). Molecular identification of AMF was realized by sequencing the Large Subunit (LSU) rDNA gene region. Among the eleven species of AMF spores identified, Funneliformis and Rhizoglomus species were the most abundant (> 35%). Modern saffron plantation showed higher roots colonization rates (mycorrhization intensity (100%) and frequency (51.6%)), while in traditional plantations lower mycorrhization frequency values were found (17.4%). LSU sequencing identified five AMF genera and three unknown genomic groups, whereas Shannon diversity index indicated that AMF community composition changed significantly according to plantation age and fertilization type. Our results contribute to a better knowledge of saffron AMF communities and open new perspectives for a rational utilization of the agricultural practices for organic saffron production.     

Arbuscular mycorrhizal fungal communities in changing environments: The effects of seasonality and anthropogenic disturbance in a seasonal dry forest

The landscape of Mexican seasonal dry forests is affected by various periodic (long and drastic drought) and random (elimination of the forest coverage for agricultural purposes) disturbance events. The community of arbuscular mycorrhizal fungi (AMF) responds to these changes, sporulating and reducing its activity during the dry season, and slowly reestablishing itself following abandonment of cultivated fields. To determine the dynamics of the AMF community in response to natural phenomena and anthropogenic disturbances, we collected soil samples during the wet and dry seasons from plots with different time periods since abandonment of agricultural activity, categorized as early (less than 5 years), middle (11–23 years), and late (over 30 years) age plots. From each plot, AMF spores were isolated and identified in order to estimate abundance, richness and diversity. In addition, the number of infective propagules and value of mycorrhizal inoculum potential were calculated for each plot. Twenty-three species were recorded, for which Glomeraceae and Acaulosporaceae were the most commonly represented families. Significant differences were found in AMF species richness among plots and seasons and the diversity index of AMF was higher than 1.0 in most cases. There were no significant differences in spore abundance. Viable propagules were observed in all soil samples, with fluctuations relating mainly to time since abandonment. Overall, seasonality has a strong influence on AMF diversity but not on AMF infectivity, while time since abandonment had a more important impact.     

Mycorrhizal activity and diversity in a long-term organic Mediterranean agroecosystem

In organic agriculture, soil fertility and productivity rely on biological processes carried out by soil microbes, which represent the key elements of agroecosystem functioning. Arbuscular mycorrhizal fungi (AMF), fundamental microorganisms for soil fertility, plant nutrition and health, may play an important role in organic agriculture by compensating for the reduced use of fertilizers and pesticides. Though, AMF activity and diversity following conversion from conventional to organic farming are poorly investigated. Here we studied AMF abundance, diversity and activity in short- and long-term organically and conventionally managed Mediterranean arable agroecosystems. Our results show that both AMF population activity, as assessed by the mycorrhizal inoculum potential (MIP) assay, the percentage of colonized root length of the field crop (maize) and glomalin-related soil protein (GRSP) content were higher in organically managed fields and increased with time since transition to organic farming. Here, we showed an increase of GRSP content in arable organic systems and a strong correlation with soil MIP values. The analysis of AMF spores showed differences among communities of the three microagroecosystems in terms of species richness and composition as suggested by a multivariate analysis. All our data indicate that AMF respond positively to the transition to organic farming by a progressive enhancement of their activity that seems independent from the species richness of the AMF communities. Our study contributes to the understanding of the effects of agricultural managements on AMF, which represent a promising tool for the implementation of sustainable agriculture.     

Optimization of land use structure and spatial pattern for the semi-arid loess hilly–gully region in China

The semi-arid loess hilly–gully region in China has an extremely vulnerable ecological environment. Inappropriate land use — crop farming, overgrazing, and plantation forestry - has worsened soil erosion, intensified water shortage, and hence impeded the ecological conservation and agricultural development of the entire region in the past. Optimizing land use and vegetation cover and spatial pattern is conducive to achieving both ecological and economic goals in terms of controlling soil erosion, using water resources rationally and raising agricultural productivity. Changchuan Watershed, a typical small catchment in the semi-arid loess hilly region, was selected as the case study area to analyze the impacts of land use and land cover structure and associated spatial pattern on soil erosion and water consumption in the Watershed, through field investigation and model simulation. Land use structure was optimized by multi-objective programming, using remote sensing (RS) and geographical information system (GIS) techniques, analytic hierarchical programming (AHP) and expert consultancy. The digitized optimum spatial pattern embodying rationally-proportioned land use structure was obtained through GIS-aided redistribution of land use types. The optimized land use structure re-apportioned woodlands, shrublands, grasslands, and croplands at 3.7%, 38.6%, 49.4%, and 6.3% of the land area respectively, compared to the current land use structure of 2.4%, 38.6%, 24.0%, and 12.6%, respectively, in the Changchuan Watershed. In the optimized land use spatial pattern, croplands are mainly located in the riverside plain and check-dammed valleys and grasslands are widely distributed in the lower reaches of the basin, while shrublands are appropriately established in the middle and upper reaches of the river. A comparative analysis shows that the optimized land use structure, with well-designed spatial pattern is able to reduce soil erosion, enhance the utilization of water resources and raise agricultural productivity.     

矿区土壤丛枝菌根真菌对采陷时间序列的响应

煤炭井工开釆造成大面积的地表塌陷,破坏了原有地表植被、土壤结构和地貌,影响土壤微生物群落结构和组成.为了研究井工矿开釆沉陷区丛枝菌根真菌(AMF)多样性与开采时间序列的相关性,本文以补连塔矿区不同开采年份的采煤沉陷区作为样地,以AMF和土壤因子为研究对象,探索随着采煤沉陷时间的延续,AMF物种多样性、种群结构变化规律及...     

Land use changes and raptor conservation in steppe habitats of Eastern Kazakhstan

Steppe habitats in central Asia have suffered important land use changes during this century which are similar to those that have been pointed out as the causes of the decline of steppe birds in western Europe. During June 1999 we conducted road surveys of raptors in Eastern Kazakhstan to detect specific and community responses to land use changes. We detected 11 species of raptors. Kestrels (Falco naumanni and tinnunculus) were the most common species in grasslands and agricultural landscapes, harriers (Circus pygargus and macrourus) were dominant in saline steppes and steppe eagles (Aquila nipalensis) were dominant in dry steppes. There were fewer species in agricultural habitats than in grassland and steppe habitats. Ground-nesting raptors were negatively affected by land use changes and four species were never detected in agricultural zones. Raptor abundance patterns differed between natural steppe habitats and human-transformed habitats, where a patchy distribution was detected. The future of raptor communities in Kazakhstan seems uncertain although the progressive abandonment of intensive agriculture may benefit species sensitive to human presence. The long-term conservation of vertebrate communities may depend upon the maintenance of ecologically and socially sustainable grazing systems.     

Changing soil characteristics alter the arbuscular mycorrhizal fungi communities of Arabica coffee (Coffea arabica) in Ethiopia across a management intensity gradient

Coffee is the most important tropical agricultural commodity worldwide, cultivated in more than 70 countries. Despite the plant's huge economic importance, there is very limited knowledge on the association of arbuscular mycorrhizal fungi (AMF) with coffee roots. We investigated the environmental drivers affecting the diversity and community composition of AMF on Arabica coffee in its Ethiopian center of origin. We used 454 amplicon pyrosequencing to describe AMF communities in the roots of Arabica coffee plants that were sampled along a large management intensity gradient, covering the major Ethiopian coffee production systems. We identified AMF genera that have not been reported before in Arabica coffee production regions elsewhere in the world and show that high soil phosphorus availability decreases AMF diversity and that soil pH, nitrogen and phosphorus availability strongly affect AMF community composition. At the scale of our study (max. 82 km distance between sampling points, and 770 m altitude difference), no effect was found of spatial location or altitude on AMF communities. This is the first study analyzing the drivers of naturally occurring AMF in the roots of a globally important tropical crop, providing preliminary data to improve coffee production in its native and introduced range, through targeted intervention in coffee AMF communities.     

Protected areas do not fulfil the wintering habitat needs of the trans-Saharan migratory Montagu’s harrier

Populations of migratory birds can be affected by events happening at both breeding and wintering grounds. The Sahel is a vast region holding a large number of wintering trans-Saharan migratory European birds, and current land-use changes there may represent a threat for these species. We used satellite tracking data from the migratory Montagu’s harrier to evaluate habitat use of the species during the wintering season, and whether the current network of protected areas is effective to provide their habitat needs during that season. We also developed an ecological niche model for the species in Western-Central Sahel to check if the most suitable sites are included within current protected areas. Tracked harriers occupied a large region encompassing a total of eight countries. The most preferred habitats during winter were croplands and some natural vegetation habitats, especially grasslands. Protected areas only covered a small proportion of the overall wintering grounds of tracked harriers and the most suitable areas for the species in Western-Central Sahel. Increasing the extent of preferred natural habitats within protected areas should benefit the conservation of this and probably other insect-eating raptors. However, substantial increases in extent and number of protected areas in sub-Saharan Africa are very unlike to occur. Conservation actions in the region should therefore be mostly focused on improving land use planning and management outside protected areas, specially enhancing agricultural practices to make biodiversity conservation compatible with poverty alleviation. These can be chiefly targeted at an area of <20,000 km² of very suitable habitat for these species.     

Managing agricultural change for biodiversity conservation in a Mediterranean upland

In Europe, land use changes follow public policies, and particularly the Common Agricultural Policy. To predict the effect of policies on agricultural practices, landscape, and ultimately biodiversity, requires understanding of the interactions between social, economic and ecological dynamics at regional scale. We studied by means of prospective scenarios the possible effects of agricultural changes on biodiversity in a Mediterranean upland. This area is characterised by extensive grasslands that have been maintained for centuries by agriculture and are now threatened by tree and shrub encroachment. We built four scenarios that describe possible changes in agricultural EU policies by 2030. We selected 15 bird species on the basis of a high natural heritage responsibility of the study area for these species and 45 plant species on the same basis plus local rarity and habitat vulnerability. We analysed how these species were affected by the four scenarios by considering changes in their habitats. For each scenario, we analysed the driving forces that determine land use changes. Landscape dynamics was modelled with a Generalised Linear Model combining environmental and land use factors. Most of the 60 selected species depend on open habitats. Only the scenario where public support was only granted if it provided environmental services had a positive impact on open habitats and their associated biodiversity. This ‘natural heritage’ scenario was also rated positively by local stakeholders. This approach sheds light on the interest of inter/transdisciplinary studies, scenarios, and stakeholder involvement in the definition of public policies for biodiversity conservation.     

Plant species richness in midfield islets and road verges - The effect of landscape fragmentation

Small marginal habitats in the rural landscape may play an important role for plant species richness as refugias. Little is known how the surrounding landscape and landscape history influence these patterns. I analysed how plant species richness was affected by isolation, habitat area, past and present land use, and if landscape context matters. Plant species occurrence in two different types of small marginal habitats were analysed, road verges and midfield islets. The study was conducted in two different agricultural landscapes in Sweden; one open modern agricultural landscape and one traditional rural landscape, and the results compared. Present and past land use, and landscape change was analysed using aerial photographs and old maps. There was a large grassland reduction more than 50 years ago in the modern landscape, when there still were quite a lot of grasslands left in the traditional landscape. Area and connectivity were more important for plant incidence in small remnant habitats in the modern landscape, compared to the less fragmented, traditional rural landscape. On the other hand there were more grassland specialists, 23% in the traditional landscape compared to 16%. Species richness became higher on midfield islet if grazing was re-introduced. The legacy of surrounding landscape remains in the species pool for a long time, atleast 50 years, even in small grassland fragments. Although small grassland remnants are more sensitive to fragmentation effects compared to larger grasslands, they still encompass a substantial part of the grassland species pool and may be valuable for reconstructing grassland management at a landscape scale.     

Historical influences on the vegetation and soils of the Martha’s Vineyard, Massachusetts coastal sandplain: Implications for conservation and restoration

Both disturbance history and previous land use influence present-day vegetation and soils. These influences can have important implications for conservation of plant communities if former disturbance and land use change species abundances, increase colonization of nonnative plant species or if they alter soil characteristics in ways that make them less suitable for species of conservation interest. We compared the plant species composition, the proportion of native and nonnative plant species, and soil biogeochemical characteristics across seven dominant land use and vegetation cover types on the outwash sandplain of Martha’s Vineyard that differed in previous soil tillage, dominant overstory vegetation and history of recent prescribed fire. The outwash sandplain supports many native plant species adapted to dry, low nutrient conditions and maintenance of native species is a management concern. There was broad overlap in the plant species composition among pine (Pinus resinosa, P. strobus) plantations on untilled soils, pine plantations on formerly tilled soils, scrub oak (Quercus ilicifolia) shrublands, tree oak (Q. velutina, Q. alba) woodlands, burned tree oak woodlands, and sandplain grasslands. All of these land cover categories contained few nonnative species. In contrast, agricultural grasslands had high richness and cover of nonnative plants. Soil characteristics were also similar among all of the woodland, shrubland and grassland land cover categories, but soils in agricultural grasslands had higher pH, extractable Ca²⁺ and Mg²⁺ in mineral soils and higher rates of net nitrification. The similarity of soils and significant overlap in vegetation across pine plantations, scrub oak shrublands, oak woodlands and sandplain grasslands suggests that the history of land use, current vegetation and soil characteristics do not pose a major barrier to management strategies that would involve conversion among any of these vegetation types. The current presence of high cover of nonnative species and nutrient-enriched soils in agricultural grasslands, however, may pose a barrier to expansion of sandplain grasslands or shrublands on these former agricultural lands if native species are not able to outcompete nonnative species in these anthropogenically-enriched sites.     

Differential growth response of Curculigo orchioides to native arbuscular mycorrhizal fungal (AMF) communities varying in number and fungal components

The study reports diversity of arbuscular mycorrhizal fungal (AMF) species in the rhizosphere of an endangered anticancerous herb – Curculigo orchioides Gaertn. in its natural habitat. A total of 18 species of AMF, belonging to three genera (Acaulospora, Glomus and Gigaspora) were recorded, with Glomus microcarpum being the most abundant species type. The AMF species composition across the study sites appeared to be influenced by soil pH rather than soil P and vegetation. Acaulospora laevis spores were restricted to sites where the soil pH was acidic. The effectiveness of these native AMF species on growth performance of C. orchioides plants was compared under experimental conditions. In general, the mycorrhizal plants were superior in most of the evaluated parameters, but the extent to which the growth of mycorrhizal plants was influenced varied with the inocula used. The plants inoculated with mixed consortia containing maximum AMF species richness exhibited improved growth in comparison to consortia containing lower AMF diversity and monospecies cultures. The variable plant responses observed with any two consortia having same species richness in the present study could be due to variable component AMF species and their relative abundance. These results emphasize the need to protect the below-ground diversity of AMF and recommend their usage for restoration practices.     

Remnant grassland habitats as source communities for plant diversification in agricultural landscapes

Lately there has been a shift in Sweden from grazing species-rich semi-natural grasslands towards grazing ex-arable fields in the modern agricultural landscape. These fields normally contain a fraction of the plant species richness compared to semi-natural grasslands. However, small remnant habitats have been suggested as important for plant species diversity and conservation as they may function as refugia for grassland specialists in fragmented and highly modified agricultural landscapes. In this study, we examined whether plant communities on small remnant habitats, i.e. midfield islets, can function as sources for grassland species to disperse out into surrounding grazed ex-fields (former arable fields). We examined species richness and grassland specialists (species favoured by grazing) and their ability to colonize fields after 5 and 11 years of grazing. The fields that had been grazed for a shorter time were fairly species-poor with few grassland specialists. A longer period of grazing had a positive effect on total and small-scale species diversity in both islets and fields. Species composition became more similar with time, and the number of grassland specialists in both habitats increased. We found that grassland specialists dispersed step-wise into the fields, and the number of grassland specialists decreased with distance from the source. Our study suggests that remnant habitats, such as midfield islets, do function as a source community for grassland specialists and enhance diversification of grassland species when grazing is introduced. For long-term conservation of plant species, incorporating small refugia into larger grazing complexes may thus enhance species richness.     

藏北高寒草原土壤活性有机碳对AM真菌物种多样性的影响

基于孢子形态学鉴定,通过研究土壤活性有机碳（ASOC）质量分数对丛枝菌根真菌（AMF）物种多样性及侵染效应的影响,为基于土壤环境调控的菌根生物技术的应用探寻新的途径和方法。结果表明,ASOC质量分数在0.30～0.80、0.81～1.40、1.41～4.00 g/kg范围内,Glomus属真菌对AMF的种群构成均具重要作用,且其影响随ASOC质量分数的增加而提高;由Glomus属真菌构成的优势种,特别是一些共有优势种对AMF的种群发育具有主导作用;ASOC质量分数与孢子密度呈显著正相关,较低的ASOC质量分数极显著促进了菌根侵染。从综合影响看,调控ASOC质量分数至较低（0.81～1.40 g/kg）水平,可能充分发挥AMF在高寒草原中的重要作用,这为探寻适度的农业工程调控措施,以强化ASOC对AMF物种多样性及菌根侵染的重要影响,促进多菌种以及多优势种的协同作用,稳定高寒草原环境提供了重要信息。     

Responses of birds of different biogeographic origins and habitat requirements to agricultural land abandonment in northern Spain

Agricultural land-use changes in Europe have taken two opposing directions: towards agricultural intensification or land abandonment. While in the Mediterranean region land abandonment is a main cause of avian diversity decline, in northern Europe species diversity often increases with successional age. We examined the hypothesis that the biogeographic origin of the avifauna determines whether abandonment brings conservation benefits or detriment by studying the bird community of agricultural land in northern Spain, at the boundary of the Mediterranean and Eurosiberian regions. Using a successional gradient, we examined landscape-scale effects of agricultural abandonment on birds during the breeding and non-breeding seasons.The trend in avian diversity with successional stage differed little between Mediterranean and Eurosiberian species in winter. In the spring, however, there was an increase in diversity with stage in abandonment for Eurosiberian birds but not for Mediterranean species. Analysis of individual species showed a preference among Eurosiberian birds for more wooded habitats whereas Mediterranean birds preferred open areas and shrubland.The introduction of agricultural policies to geo-political units that do not coincide with eco-regions cannot be assumed to bring uniform conservation benefits. In the Mediterranean region, agricultural mosaics of low intensity cultivation maintain the highest diversity of priority bird species. Agricultural land abandonment should not be assumed to benefit conservation.