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Intensified agriculture, a driver of biodiversity loss, can diminish ecosystem functions and their stability. Biodiversity can increase functional redundancy and is expected to stabilize ecosystem functions. Few studies, however, have explored how agricultural intensity affects functional redundancy and its link with ecosystem function stability. Here, within a continental-wide study, we assess how functional redundancy of seed predation is affected by agricultural intensity and landscape simplification. By combining carabid abundances with molecular gut content data, functional redundancy of seed predation was quantified for 65 weed genera across 60 fields in four European countries. Across weed genera, functional redundancy was reduced with high field management intensity and simplified crop rotations. Moreover, functional redundancy increased the spatial stability of weed seed predation at the field scale. We found that ecosystem functions are vulnerable to disturbances in intensively managed agroecosystems, providing empirical evidence of the importance of biodiversity for stable ecosystem functions across space.

Intensive agriculture, a driver of biodiversity loss, can diminish ecosystem functions and their stability. Biodiversity can increase functional redundancy and is expected to stabilize ecosystem functions. Few studies however have explored how agricultural intensity affects functional redundancy and its link with ecosystem function stability. Here, within a continent-wide study, we assess how the functional redundancy of seed predation is affected by agricultural intensity and landscape simplification. By combining carabid abundances with molecular gut content data, functional redundancy of seed predation was quantified for 65 weed genera across 60 fields in four European countries. Across weed genera, functional redundancy was reduced with high field management intensity and simplified crop rotations. Moreover, functional redundancy increased the spatial stability of weed seed predation within fields. We found that ecosystem functions are vulnerable to disturbance in intensively managed agroecosystems, providing empirical evidence of the importance of biodiversity for stable ecosystem functions across space.

Assessing effects of climate change on agricultural systems and the potential for ecological intensification to increase food security in developing countries is essential to guide management, policy-making and future research. ‘Push-pull’ technology (PPT) is a poly-cropping design developed in eastern Africa that utilizes plant chemicals to mediate plant–insect interactions. PPT application yields significant increases in crop productivity, by reducing pest load and damage caused by arthropods and parasitic weeds, while also bolstering soil fertility. As climate change effects may be species- and/or context-specific, there is need to elucidate how, in interaction with biotic factors, projected climate conditions are likely to influence future functioning of PPT. Here, we first reviewed how changes in temperature, precipitation and atmospheric CO2 concentration can influence PPT components (i.e., land use, soils, crops, weeds, diseases, pests and their natural enemies) across sub-Saharan Africa (SSA). We then imposed these anticipated responses on a landscape-scale qualitative mathematical model of maize production under PPT in eastern Africa, to predict cumulative, structure-mediated impacts of climate change on maize yield. Our review suggests variable impacts of climate change on PPT components in SSA by the end of the 21st century, including reduced soil fertility, increased weed and arthropod pest pressure and increased prevalence of crop diseases, but also increased biological control by pests’ natural enemies. Extrapolating empirical evidence of climate effects to predict responses to projected climate conditions is mainly limited by a lack of mechanistic understanding regarding single and interactive effects of climate variables on PPT components. Model predictions of maize yield responses to anticipated impacts of climate change in eastern Africa suggest predominantly negative future trends. Nevertheless, maize yields can be sustained or increased by favour

[ES] El control biológico de Rhopalosiphum padi por depredadores de carábidos generalistas es uno de los importantes servicios ecosistémicos en el sistema de producción de cereales de las regiones templadas. Sin embargo, las amenazas debido a la simplificación del paisaje y el cambio climático antropogénico están generando preocupación por la sostenibilidad de estos servicios ecosistémicos. El estudio del nicho térmico y el efecto de las temperaturas extremas en el rendimiento de las especies individuales, así como la respuesta colectiva de los grupos de especies ante las fluctuaciones de temperatura, se ha convertido en importante para conocer la resiliencia y estabilidad que proporcionan los servicios ecosistémicos. Se llevaron a cabo experimentos de depredación sobre pulgón centinela que involucraban a dos depredadores, Poecilus cupreus y Pterostichus melanarius, se realizaron dentro de cámaras climáticas a lo largo de un gradiente de temperaturas para probar la robustez del modelo derivado del patrón de actividad dependiente de la temperatura del campo. Además, se llevó a cabo un experimento en cámaras climáticas para probar si la diversidad de respuesta entre los dos depredadores daba como resultado una depredación estable en un escenario de temperaturas variables. Encontramos que los depredadores consumían más a su temperatura óptima y el consumo disminuía gradualmente fuera de las temperaturas óptimas en los dos depredadores. El modelo es lo suficientemente robusto como para predecir la depredación por P. cupreus y P. melanarius, ya que no se observaron diferencias significativas en la mayoría de los gradientes de temperatura entre la depredación obtenida en las cámaras climáticas y la depredación predicha del modelo. Sin embargo, los montajes de depredadores con respuesta diversa a la temperatura no dieron los resultados esperados para un control biológico estable en este estudio., [EN] Biological control of Rhopalosiphum padi by generalist carabids predators are one of the important ecosystem services in cereal production system of temperate regions. However, threats due to landscape simplification and anthropogenic climate change is raising concern for the sustainability of these ecosystem services. The study of thermal niche and the effect of the temperature extremes on the performance of the individual species as well as collective response of the species assemblages towards temperature fluctuations has become important to know about the resilience and stability of the ecosystem services provided by them. Predation experiments on sentinel aphid cards involving two predators namely- Poecilus cupreus and Pterostichus melanarius was carried inside the climate cabinets along temperature gradient to test the robustness of the model derived from the temperature dependent activity pattern from the field. Also, experiment to test whether the response diversity among the two predators result in stability of the predation under varying temperature scenario was carried out in climate cabinets. We found that predators consumed most at their optimal temperature and the consumption gradually decreased beyond the optimal temperatures for two predators. The model is robust enough to predict the predation by P. cupreus and P. melanarius, as no significant differences was observed in majority of the temperature gradients between the observed predation in climate cabinets and predicted predation from the model. Predator assemblages with diverse response to temperature, however, did not yield expected results for stable biological control in this study.

Understanding the impacts that invasive vertebrates have on terrestrial ecosystems extends primarily to invaders’ impacts on species with which they interact directly through mechanisms such as predation, competition and habitat modification. In addition to direct effects, invaders can also initiate ecological cascades via indirect population level effects on species with which they do not directly interact. However, evidence that invasive vertebrates initiate ecological cascades in terrestrial ecosystems remains scarce. Here, we ask whether the invasion of the cane toad, a vertebrate invader that is toxic to many of Australia’s vertebrate predators, has induced ecological cascades in a semi-arid rangeland. We compared activity of a large predatory lizard, the sand-goanna, and abundances of smaller lizards preyed upon by goannas in areas of high toad activity near toads’ dry season refuges and areas of low toad activity distant from toads’ dry season refuges. Consistent with the hypothesis that toad invasion has led to declines of native predators susceptible to poisoning, goanna activity was lower in areas of high toad activity. Consistent with the hypothesis that toad-induced goanna decline lead to increases in abundance the prey of goannas, smaller lizards were more abundant in areas of high toad activity. Structural equation modelling showed a positive correlation between goanna activity and distance from dry season refuge habitats used by toads. The abundances of small lizards was correlated negatively with goanna activity and distance from dry season refuges of toads. Our findings provide support for the notion that invasions by terrestrial vertebrates can trigger ecological cascades.