RESUMEN
In Europe, agri-environment schemes (AES) are a key instrument to combat the ongoing decline of farmland biodiversity. AES aim is to support biodiversity and maintain ecosystem services, such as pollination or pest control. To what extent AES affect crop yield is still poorly understood. We performed a systematic review, including hierarchical meta-analyses, to investigate potential trade-offs and win-wins between the effectiveness of AES for arthropod diversity and agricultural yield on European croplands. Altogether, we found 26 studies with a total of 125 data points that fulfilled our study inclusion criteria. From each study, we extracted data on biodiversity (arthropod species richness and abundance) and yield for fields with AES management and control fields without AES. The majority of the studies reported significantly higher species richness and abundance of arthropods (especially wild pollinators) in fields with AES (31 % increase), but yields were at the same time significantly lower on fields with AES compared to control fields (21 % decrease). Aside from the opportunity costs, AES that promote out-of-production elements (e.g. wildflower strips), supported biodiversity (29-32 % increase) without significantly compromising yield (2-5 % increase). Farmers can get an even higher yield in these situations than in current conventional agricultural production systems without AES. Thus, our study is useful to identify AES demonstrating benefits for arthropod biodiversity with negligible or relatively low costs regarding yield losses. Further optimization of the design and management of AES is needed to improve their effectiveness in promoting both biodiversity and minimizing crop yield losses.
Asunto(s)
Artrópodos , Ecosistema , Animales , Biodiversidad , Agricultura , Productos AgrícolasRESUMEN
Providing for growing food demand while minimizing environmental degradation is a major contemporary environmental challenge. Agri-environmental schemes (AESs) are often promoted to meet this challenge by providing subsidies to farmers who adopt agri-environmental practices (AEPs). The success of these schemes depends on the ability to engage farmers, thus understanding farmers' perceptions about AEPs is pivotal. Yet, current knowledge is limited as most research explores farmer's attitudes towards existing AESs, often based on subsidies. We explored the attitudes of farmers and their communities towards five different AEPs, and towards a potential AES, in an area of intensive agriculture in Israel, where currently no AES are implemented. We conducted five focus group sessions with 41 farmers, 12 follow-up interviews, and a survey with 296 community members. Findings indicate that farmers' willingness to implement AEPs was driven by environmental, personal, and social considerations, particularly perceptions of "good farming" practices, such as community cohesiveness and maintaining control of one's field. Farmers' lack of trust in the government, and lack of personal or local experience with specific AEPs, are other major barriers for joining a potential AES. Farmers perceived financial compensation as a safety net, but placed social and cultural values on par with, or above, financial considerations for joining an AES. Farmers' communities demonstrated high support for implementing AEPs, indicating that communities could be an asset for AES development. Therefore, while incentives for many AESs are based primarily on monetary compensation, to achieve their desired long-term results they should also focus on farmer resilience, independence, knowledge creation, and socio-cultural capital development.
Asunto(s)
Agricultura , Agricultores , Actitud , Granjas , Humanos , IsraelRESUMEN
A fundamental notion in community ecology is that local species diversity reflects some balance between the contrasting forces of competitive exclusion and competitive release. Quantifying this balance is not trivial, and requires data on the magnitude of both processes in the same system, as well as appropriate methodology to integrate and interpret such data. Here we present a novel framework for empirical studies of the balance between competitive exclusion and competitive release and demonstrate its applicability using data from a Mediterranean annual grassland where grazing is a major mechanism of competitive release. Empirical data on the balance between competitive exclusion and competitive release are crucial for understanding observed patterns of variation in local species diversity and the proposed approach provides a simple framework for the collection, interpretation, and synthesis of such data.
Asunto(s)
Biota , Pradera , Herbivoria , Animales , Biodiversidad , Evolución Biológica , Conducta Competitiva , Modelos Biológicos , Poaceae/fisiologíaRESUMEN
Species diversity has two components - number of species and spatial turnover in species composition (beta-diversity). Using a field experiment focusing on a system of Mediterranean grasslands, we show that interspecific competition may influence the two components in the same direction or in opposite directions, depending on whether competitive exclusions are deterministic or stochastic. Deterministic exclusions reduce both patch-scale richness and beta-diversity, thereby homogenising the community. Stochastic extinctions reduce richness at the patch scale, but increase the differences in species composition among patches. These results indicate that studies of competitive effects on beta diversity may help to distinguish between deterministic and stochastic components of competitive exclusion. Such distinction is crucial for understanding the causal relationship between competition and species diversity, one of the oldest and most fundamental questions in ecology.