Juan J. Oñate

Environmental effects of agri-environmental schemes in Western Europe

Agri-environmental schemes (AES) have been introduced as part of European Unions (EU) Common Agricultural Policy and are now an important part of this. A methodological approach to analyse the policy effects of AES is outlined, in which we distinguish between performance effects (on agricultural practices) and outcome effects (environmental impact). The performance effects are further approached including measurement of improvement and protection effects based on 12 indicators on changes/maintenance of land use and agricultural management. Data from personal interviews of participating and non-participating farmers in AES measures in nine EU Member States and Switzerland were used to analyse policy effects, including single indicator effects on agricultural practices as well as combined effects at the agreement level. Significant effects were found for mineral N-fertiliser use, stocking density reduction, maintenance of a minimum livestock density and pesticides. For AES agreements regulating grassland management, fertiliser use and pesticides, clear indications of combined improvement and protection effects were found. In addition clear improvement effects of agreements regulating fertiliser and pesticides use on mainly arable lands were revealed. It is concluded that the approach presented including the 12 selected indicators has proven to be operational.

Agricultural intensification and biodiversity partitioning in European landscapes comparing plants, carabids, and birds

Effects of agricultural intensification (AI) on biodiversity are often assessed on the plot scale, although processes determining diversity also operate on larger spatial scales. Here, we analyzed the diversity of vascular plants, carabid beetles, and birds in agricultural landscapes in cereal crop fields at the field (n = 1350), farm (n = 270), and European-region (n = 9) scale. We partitioned diversity into its additive components alpha, beta, and gamma, and assessed the relative contribution of beta diversity to total species richness at each spatial scale. AI was determined using pesticide and fertilizer inputs, as well as tillage operations and categorized into low, medium, and high levels. As AI was not significantly related to landscape complexity, we could disentangle potential AI effects on local vs. landscape community homogenization. AI negatively affected the species richness of plants and birds, but not carabid beetles, at all spatial scales. Hence, local AI was closely correlated to beta diversity on larger scales up to the farm and region level, and thereby was an indicator of farm- and region-wide biodiversity losses. At the scale of farms (12.83-20.52%) and regions (68.34-80.18%), beta diversity accounted for the major part of the total species richness for all three taxa, indicating great dissimilarity in environmental conditions on larger spatial scales. For plants, relative importance of alpha diversity decreased with AI, while relative importance of beta diversity on the farm scale increased with AI for carabids and birds. Hence, and in contrast to our expectations, AI does not necessarily homogenize local communities, presumably due to the heterogeneity of farming practices. In conclusion, a more detailed understanding of AI effects on diversity patterns of various taxa and at multiple spatial scales would contribute to more efficient agri-environmental schemes in agroecosystems.

Assessing vulnerability of functional diversity to species loss: a case study in Mediterranean agricultural systems

Summary Increasing land-use intensification is leading to biodiversity losses world-wide, which can reduce the functioning of ecosystems. However, it is increasingly clear that not all species are equally important for ecosystem processes: whereas the loss of a functionally unique species may reduce the capacity of the community to perform some functions, losing a functionally redundant species should have a much smaller impact. Assessing the vulnerability of functional diversity (FD) to species extinctions can help to predict the impacts of land-use intensification. This approach consists in ranking species according to their risk of extinction and then estimating the trajectory followed by FD as species are lost from local communities. However, the most widely used FD indices are not independent of species richness, being much more sensitive to the loss of species in species-poor than in species-rich sites. This may result in misleading interpretations, affecting our ability to rank communities according to the vulnerability of their FD to species loss, by confounding it with the initial level of species richness. Here, we propose comparing the trajectory of FD under the most plausible order of species loss with that followed under random species losses as an effective way to remove the trivial effect of species richness in the assessments of vulnerability to species loss. After decoupling vulnerability from species richness, we used it to analyse the effect of agricultural intensification on the vulnerability of arable plant communities in Mediterranean agricultural fields. Our results show that management strategies aiming to increase the functionality of these systems should focus on intermediately intensified fields, where small reductions in the level of intensification are likely to benefit arable plant diversity, increasing the number of species and FD and decreasing the vulnerability of FD to species losses. Removing the effect of species richness is essential to attain unbiased estimations of the vulnerability of communities to species loss, especially when species-poor communities are considered. Combining vulnerability with information on taxonomic and functional diversity appears as a promising tool to inform decision-making processes, anticipating the effects of local extinctions.

Inter-specific association and habitat use in a farmland passerine assemblage

We studied the pattern of inter-specific association of breeding territories in a passerine assemblage of dry cereal farmland in central Spain and evaluated the role of the presence of heterospecifics in the habitat use patterns exhibited by different species. Bird territories showed a non-random inter-specific spatial aggregation pattern. We studied territory abundance variation in the three more abundant species: the corn bunting, the crested lark, and the fan-tailed warbler. Crested lark and fan-tailed warbler territories were more abundant in plots where corn bunting territories were present and vice versa, while their respective abundances did not vary with the breeding presence of the other species. We used landscape and agricultural management variables to analyze the relationships between habitat and each species’ breeding territories by means of classification trees. While the corn bunting showed a marked pattern of nesting habitat use, the crested lark and the fan-tailed warbler exhibited a much more generalist one. Corn Bunting presence was affected negatively by intensification-related variables, such as field size and percent cover of cereal crops. Similarly, the presence of crested larks was negatively related to high yielding areas. However, when the presence of hetero-specific territories was considered, the presence of corn bunting territories was the most important variable explaining the occurrence of breeding fan-tailed warblers, and the second most important in the case of the crested lark. These results suggest that inter-specific attraction could play a role in the formation of farmland bird assemblages, while adding further evidence for the detrimental effect of agricultural intensification at the community level.

Towards the identification and assessment of HNV Dehesas: a meso-scale approach

Iberian dehesa and montado are paradigmatic high nature value (HNV) agroforestry systems in Europe. Nevertheless their conservation status is uncertain as a consequence of their typological variety, different intensity of management practices on the ground, and other ongoing processes challenging their long-term sustainability. The existing broad gradients of dehesa and montado types impose difficulties in estimating not only their distribution and extent, but also their condition, since probably not all these agroforestry systems should readily be considered as HNV. Tackling with these difficulties, we explore a methodology based on GIS-analyses of land cover cartographies to estimate the extent and condition of dehesa farmland in an area covering ten municipalities in northern Andalusia region (Spain) based on: (1) integration of available thematic maps to obtain an improved land-use cartography; (2) application of GIS map generalization techniques to delimit potential HNV farmland types; (3) definition and calculation of several indices of ‘structural diversity’ and ‘impact’ within patches of dehesa farmland; (4) automatized weighted integration of indices to obtain a cartography assessing dehesa’s HNV in an ordinal scale from very low to very high. Estimated natural value was significantly worse for cultivated dehesas, with dehesas of pastures showing higher structural diversity and lower impact indices. Weaknesses and strengths of the proposed methodology are discussed.

Influence of Landscape and Field-Level Agricultural Management on a Mediterranean Farmland Winter Bird Community

Summary. We studied the response to agricultural management factors of birds wintering in an unirrigated cereal farmland area of central Spain, examining the influence on species richness, abundance and community composition of different field-level and landscape-level agricultural management variables related to intensification. Our initial hypothesis was that landscape-level management factors exert a stronger effect on wintering bird species richness, total abundance and community composition than field-level ones. The particular responses of the most frequent species (skylark Alauda arvensis, corn bunting Emberiza calandra and meadow pipit Anthus pratensis) were also examined. Richer assemblages were found in more substrate-diverse plots with natural vegetation patches or in plots with higher yield crops, while the more abundant ones, dominated by the skylark, occupied more homogeneous areas dominated by cereals and arable land. As expected, landscape-level management factors explained a much greater proportion of variance in community composition compared to field-level factors (71% vs 29%, respectively). Species richness per se was favoured by substratediverse plots containing patches of natural vegetation, but also by plots where cereal crops were more productive in the previous harvest, declining in more homogeneous plots dominated by cereal crops and arable land in general. Conversely, skylark abundance and total abundance increased as landscapes became more homogeneous and dominated by cereals and arable land, although the relationship for total abundance only approached significance. Results suggest that the current landscape structure and levels of agricultural production of cereal farmland in central Spain can host relatively abundant winter populations of seed-eating and open landscape specialists like the skylark, although certain levels of habitat diversity need to be guaranteed to ensure the maintenance of rich wintering bird communities.

Efectos de la gestión agraria en las aves de los cultivos cerealistas: un proceso multiescalar

Rodriguez Martinez, N., Bordas, P., Pineiro, J., Garcia de Castro, N., Martin, P., Mendez, M. (2013). Meta-analysis of the effects of burnt wood removal on Mediterranean forest regeneration: a step towards an evidence-based management. Ecosistemas 22(1):71-76. Doi.:10.7818/ECOS.2013.22-1.15 Many environmental managers base their decisions on previous field experience, but not on primary scientific literature or advice by academic scientists. Evidence-based management, based on primary scientific literature and meta-analysis, to decide among environmental management options is very infrequent. This paper illustrates this approach using as an example salvage logging in Mediterranean forests. Traditionally, forest management after fire has included salvage logging, i.e., harvest and removal of burnt wood, based on economic, ecological and esthetic grounds. However, salvage logging has also been criticised due to, among other reasons, its potential detrimental effects on forest regeneration. A meta-analysis of the relevant Mediterranean literature suggested no (seedling density and height) or negative (survival) effect of salvage logging on forest regeneration. Although a meta-analysis based on such a small sample size as the one possible in this study does not allow strong conclusions, it suggests that: (1) current management is not consistent with the (scarce) available evidence, at least regarding forest regeneration after fire and (2) stronger evidence should be gathered about this kind of forest management.