InterRest is an interdisciplinary project with project partners from six different countries requiring intensive coordination and effective communication. The project coordination team (C. Westphal and junior coordinator A. Hass) ensures effective collaboration between all partners. Furthermore, the experienced coordinators monitor the progress throughout the project including completion and submission of milestones, deliverables and dissemination tasks.

Task 1.1 Study site selection (responsible: C. Westphal, A. Hass, A. Helm, D. Giralt, Ö. Bodin)
Task 1.2 Site mapping and characterization (responsible: C. Westphal, A. Hass, A. Helm, D. Giralt)

In each of the three study regions in Germany, Spain and Estonia, we will select 32 calcareous grasslands as study sites that differ at the local scale from degraded to effectively restored. A restoration intensity index will be developed based on the implemented restoration activities, e.g. shrub removal, grazing regimes. The study sites will be established along two independent landscape heterogeneity gradients, cover of agri-environment schemes (AES) and connectivity to other calcareous grasslands (Fig. 1).

Task 2.1 Plant sampling (responsible: A. Helm, T. Aavik)
In each calcareous grassland, we will establish 5 permanently marked plant diversity sampling plots to characterize plant community structure and diversity at different scales from plot to community level.

Task 2.2 Soil and root organism sampling (responsible: A. Helm, T. Aavik)
To characterize associations between plants and soil organisms, soil samples from each plot will be collected for molecular identification of soil fungi. In addition, we will select a focal plant species for each region. For the focal species, specific interactions between plant individuals and soil fungi will be assessed through identification of root-inhabiting fungi. Soil functional properties will be assessed by characterizing composition of functional groups of soil organisms (guild, trophic level).

Task 2.3 Soil geochemical properties (responsible: A. Helm, T. Aavik)
Topsoil geochemical properties, including bulk density, texture, pH, and soil organic carbon, N, P, K, Mg and Ca content, will be characterised as relevant factors for diversity and composition of soil microorganisms, plants and potentially also for other interacting taxa (e.g. ground nesting pollinators).

Task 3.1 Pollinator sampling (C. Westphal, A. Hass, F. Librán Embid)
We will conduct transect walks to catch pollinators and record the visited plants on each calcareous grassland. Floral resource availability will be quantified for each transect. Based on this, we will study the abundance, richness and functional diversity of pollinators. Moreover, we will analyse the stability, specialization and robustness of the plant-pollinator networks.

Task 3.2 Pollen resource use analyses (responsible: H. Jacquemyn, A. Keller)
To assess pollen resources and plant-pollinator interactions not only in transect walks, we will collect pollen samples from the bodies of focal pollinator species which belong to functionally different pollinator groups (i.e. social bumblebees and honeybees, oligolectic and polylectic wild bee species with different body sizes). We will use DNA metabarcoding to identify plant species exploited by pollinators on the grasslands and in the wider landscape. The effects of landscape types, habitat connectivity and region on the pollen composition and network indices (nestedness, modularity and specialization) will be analysed.

Task 3.3 Pollination function (responsible: C. Westphal, A. Hass, F. Librán Embid)
To study pollination functions, we will select 1-2 insect-pollinated characteristic plant species present in all study sites of one region. Pollinator exclusion and open pollination treatments will be used to analyse their effects on seed and fruit set. Pollinator observations will be conducted to sample their main flower visitors. After seed ripening, we will harvest seeds of experimental and control plants to count the number of seeds as measure of pollination function. We will analyse pollination function in relation to functional pollinator diversity (Task. 3.1), plant-pollinator interaction network metrics (Task 3.2) and local and landscape restoration.

Task 4.1 Bird sampling (responsible: D. Giralt, G. Bota)
To sample bird diversity and abundance in calcareous grasslands, we will use point-count surveys and acoustic monitoring via Autonomous Recording Units (ARUs). The exact number of sampling points and ARUs per site will be established depending on the calcareous grassland size to be representative.

Task 4.2 Bird food resource sampling (responsible: J. Traba)
To investigate the interactions of birds with their food resources, we will collect faeces of two common bird species per region that use calcareous grasslands for nesting and/or foraging. Faeces will be analysed using metabarcoding to identify plant and animal food items consumed. Diets will be compared with food availability (arthropod biomass). Available arthropod food resources will be sampled with pitfall traps and sweep netting to estimate the arthropod biomass of a wide spectrum of epigean and flying arthropods, respectively, including beneficial ones in agroecosystems. We will also use metabarcoding to identify the arthropod taxa complementing the faeces analysis. Finally, we will compare the food resources consumed by birds with the available food resources and analyse how these change with local and landscape restoration. We will analyse the proportion of crops (seeds) and crop pest species consumed by the birds on the calcareous grasslands to estimate their contribution to ecosystem services and disservices in the surrounding landscapes.

Task 4.3 Predation function (responsible: D. Giralt, G. Bota)
To study the predation function, we will establish a predation experiment using dummy caterpillars. We will quantify arthropod predation in relation to the functional diversity of birds of calcareous grasslands using experimental exposure of artificial (plasticine), caterpillar-like prey to imitate natural prey (lepidopteran larvae) of avian predators. This experiment will allow us to obtain an index of predation function exerted by birds on surrounding crops of calcareous grasslands and analyse how it is affected by restoration, habitat connectivity and the proportion of AES.

Task 5.1 Perceptions and motivations by key actors and stakeholders across regions (responsible: Ö. Bodin, P. Gorris)
For restoration initiatives to be efficient and long-lasting, they need to be acknowledged as legitimate and being supported by local and regional stakeholders, public agencies and other relevant actors. Thus, the project will investigate factors that enhance or suppress legitimacy and support of local and landscape restoration. We will conduct semi-structured interviews with stakeholders on their motivations, perceived obstacles, perceived benefits and their understandings of the habitat types. Besides farmers and other landowners residing in the study areas, we will also include a selection of public officials, visitors organizations, environmentally oriented non-governmental organizations and local businesses in our study population. The aim of this task is to unravel obstacles that limit the success of various restoration projects, but also to identify factors that facilitate the implementation of restoration projects. Further, the multi-regional approach will allow the project to start identifying if and to what extent certain finding appears as generic, and what findings are more bound to the specifics of the local contexts (and also what those contextual factors could be).

Task 5.2 Social-ecological network analysis of key actors and stakeholders, and key biophysical components (responsible: Ö. Bodin, P. Gorris)
In one in-depth case study in Germany, we will extend these analyses by explicitly considering how actors interact with each other, and how they have different stakes and interests in the various natural resources in the landscape. This research approach makes it possible to more deeply integrate key socio-economic and biophysical factors of relevance in restoration projects and to both ask and answer research questions that are inherently interdisciplinary by nature. This in-depth study involves conducting empirical inquiries to define relevant system boundaries, actors, types of interactions and conceptualization of the resources in the landscape, including how they depend on each other. Based on that we will construct a social-ecological network, which will form the basis for further analyses aiming to unravel important and coupled social-ecological dynamics of the study area, including if and to what extent the social and the ecological structures and processes are well aligned across spatial and temporal scales.

Task 6.1 Metanetworks (responsible: C. Westphal, A. Hass, F. Librán Embid)
Here we will comprehensively synthesize the output of WP1-5. We will use the metanetwork approach across restored and degraded calcareous grasslands to analyse modularity and to identify the most central interactions across the different taxa. Metanetworks are an emerging approach to study the consequences of habitat fragmentation on ecological networks at landscape and regional scales. From a conservation perspective, it is fundamental to identify and protect the most important nodes within a metanetwork (i.e. central interactions or habitats) as it can guide environmental policy and conservation efforts.

Task 6.2 Multifunctionality and trade-offs (responsible: D. Kleijn)
We will analyse multitrophic diversity and multifunctionality across the different trophic levels and investigate possible trade-offs with respect to local and landscape scale restoration priorities. We will collate data collected in WP2-4 on biodiversity and ecosystem function provided by soil, plants, beneficial insects and birds. We will test whether the effects on diversity and ecosystem functions of calcareous grassland restoration and cover of AES and connectivity interact with the effects of species groups providing the services. Responses of different species groups and ecosystem functions across the three countries will be scored using meta-analysis approaches to examine whether restoration at different scales generally results in the same responses (multifunctionality) or in different responses (trade-offs).

Task 6.3 Integration of social and ecological data (responsible: C. Westphal, A. Hass)
We will also combine analyses of social and ecological interaction networks to identify social interactions that are crucial for successful restoration at the local and landscape scale and to better understand the fit between social and ecological processes across the different regions. In this task, we will use data compiled in WP1-4 and in WP5 Task 5.1 to compare stakeholder perceptions including motivations, perceived obstacles and perceived benefits as well as ecological effectiveness of restoration measures at the local and landscape scale between the three different study regions. This integration of social and ecological data will give vital insights to which degree stakeholder perceptions influence restoration outcomes and if there are certain groups of stakeholders that are crucial for the effectiveness of restoration measures across different regions.