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While the importance of permanent grasslands (PG) for the conservation of high nature value habitats is often acknowledged, their role in most of the main sustainable food system scenarios published in the last few years is less explicit. In the best case, the place of permanent grassland in scenarios and policy agendas is their conservation; in the worst one, they are simply replaced by afforested land or cropland, considered as a better option when the focus is on GHG emissions only. In this paper, we defend the idea that several misinterpretations of the positive and negative impacts of ruminants, the 'natural' users of PG, explain why ruminants are poorly addressed by most scenarios. Based on the findings of an agroecological scenario for Europe—TYFA, standing for Ten Years For Agroecology—in which extensive permanent grassland and ruminants together play a prominent role for biodiversity conservation, nitrogen cycling and climate change mitigation and adaptation, we call for a research agenda that would better inform the specific role of PG in the provision of ecosystem services—and in particular those that depend on nitrogen management. [ABSTRACT FROM AUTHOR]

Persian walnut (Juglans regia L.), which is native to Central Asia, has been widely cultivated throughout Europe over millennia as a multipurpose tree. However, only recently the naturalization process outside cultivation has been studied, mostly in temperate Europe, with no information regarding the Mediterranean region. Here we provide the first field investigations about the natural regeneration of walnut in two traditional Mediterranean agroecosystems: an irrigated mixed orchard in suburban areas and a non-irrigated prickly pear (Opuntia ficusindica [L.] Mill.) orchard. The natural regeneration densities were statistically different in the two agroecosystems, ranging from 75 individuals per hectare in the prickly pear orchard to 200 individuals per hectare in the mixed orchard. Crows were frequently observed actively carrying walnuts in both environments. The irrigation practices and the shade provided by larger trees in the mixed orchard, and the potential benefits provided by prickly pear individuals, seemed to be crucial for seedling establishment and development in the two orchards, respectively. On the other hand, climate does not seem to represent a constraint for walnut recruitment, even if the mean annual temperature at the mixed orchard is slightly above the optimal temperature for walnut. Other biotic and abiotic factors that may trigger or hamper the naturalization process are also discussed in this paper, which explores the research needs for better understanding the naturalization potential of the Persian walnut in Mediterranean agroecosystems, as well as the effects of different land uses and future climate change on this process. [ABSTRACT FROM AUTHOR]