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Global change is a multifaceted, unprecedented crisis hitting the life support system of our planet. Among global changes, climate change is regarded as one of the most grave threats to biodiversity because of its direct impacts on species and ecosystems integrity and because of its indirect consequences through synergistic effects with other global change factors such as biological invasions. The challenges presented to either reduce or mitigate this biodiversity crisis derived from climate change require novel synthesis and innovation in ecological and evolutionary theory. Positive species interactions within and between trophic levels can play a key role in the resilience of ecological communities. Depending on the tolerance of nurse species to different aspects of climate change, communities can be more or less resilient to those changes. This knowledge has important implications for both natural communities and agroecosystems. Further, our fundamental understanding of the role of positive interactions can also enable both effective conservation and restoration levers in space and time. This special issue includes studies addressing the role of facilitative interactions on the response of ecological systems to climate change. Key concepts examined included stress, gradients, nurse species, spatial scale, translocation, phylogenetics alongside physiochemicals, and variation in the capacity of species to buffer changes. Alpine, tundra, drylands and temperate forests were directly tested, but salient principles were relevant to all ecosystems including a contribution on soil biota and also a call to more open data and collaborative science. Together, this corpus of work highlighted the significance of facilitative interactions in mitigating many of the effects of climate change on biodiversity. [ABSTRACT FROM AUTHOR]

Our understanding of the fundamental role that soil bacteria play in the structure and functioning of Earth's ecosystems is ever expanding, but insight into the nature of interactions within these bacterial communities remains rudimentary. Bacterial facilitation may enhance the establishment, growth, and succession of eukaryotic biota, elevating the complexity and diversity of the entire soil community and thereby modulating multiple ecosystem functions. Global climate change often alters soil bacterial community composition, which, in turn, impacts other dependent biota. However, the impact of climate change on facilitation within bacterial communities remains poorly understood even though it may have important cascading consequences for entire ecosystems. The wealth of metagenomic data currently being generated gives community ecologists the ability to investigate bacterial facilitation in the natural world and how it affects ecological systems responses to climate change. Here, we review current evidence demonstrating the importance of facilitation in promoting emergent properties such as community diversity, ecosystem functioning, and resilience to climate change in soil bacterial communities. We show that a synthesis is currently missing between the abundant data, newly developed models and a coherent ecological framework that addresses these emergent properties. We highlight that including phylogenetic information, the physicochemical environment, and species‐specific ecologies can improve our ability to infer interactions in natural soil communities. Following these recommendations, studies on bacterial facilitation will be an important piece of the puzzle to understand the consequences of global change on ecological communities and a model to advance our understanding of facilitation in complex communities more generally. [ABSTRACT FROM AUTHOR]

The impact of global change on biodiversity is commonly assessed in terms of changes in species distributions, community richness and community composition. Whether and how much associations between species are also changing is much less documented. In this study, we quantify changes in large‐scale patterns of species associations in bird communities in relation to changes in species composition. We use network approaches to build three community‐aggregated indices reflecting complementary aspects of species association networks. We characterise the spatio–temporal dynamics of these indices using a large‐scale and high‐resolution dataset of bird co‐abundances of 109 species monitored for 17 years (2001–2017) from 1969 sites across France. We finally test whether spatial and temporal changes in species association networks are related to species homogenisation estimated as the spatio–temporal dynamics of species turnover (β‐diversity) and community generalism (community generalisation index). The consistency of these relationships is tested across three main habitats, namely woodland, grassland and human settlements. We document a directional change in association‐based indices in response to modifications in species turnover and community generalism in space and time. Weaker associations and sparser networks were related to lower spatial species turnover and higher community generalism, suggesting an overlooked aspect of biotic homogenisation affecting species associations and may also have an impact on species interactions. We report that this overall pattern is not constant across habitats, with opposite relationships between biotic homogenisation and change in species association networks in urban versus forest communities suggesting distinct homogenisation processes. Although species associations contain only partial signatures of species interactions, our study highlights that biotic homogenisation translates to finer changes in community structure by affecting the number, strength and type of species associations. [ABSTRACT FROM AUTHOR]