Data from: Species-habitat networks reveal conservation implications that other community analyses do not detect

Grassland restoration is an important conservation intervention supporting declining insect pollinators, particularly in threatened calcareous grassland landscapes. While restoration is often assessed using simple diversity or the similarity to a target community metrics, this can fail to represent key aspects of community reconstruction. Here, we compare a new method, species-habitat networks, with techniques previously relied upon to understand the process of pollinator community restoration. The species-habitat network approach reveals details relevant to insect conservation that are not visible using standard measures of species richness, abundance, community similarity or network metrics. For instance, a shared set of butterflies and bumblebees found in ancient extensively managed grassland, the target community for restoration, were more likely to inhabit previously disturbed grassland than recently disturbed or reverting grasslands. We propose that species-habitat networks should be part of the standard analytical toolkit assessing the effectiveness of restoration, particularly for mobile species such as insects.Funding provided by: China Scholarship CouncilCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100004543Award Number: 202108370189Funding provided by: Natural Environment Research CouncilCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100000270Award Number: NE/V006444/1Funding provided by: Natural Environment Research CouncilCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100000270Award Number: NE/V007548/1Funding provided by: Natural Environment Research CouncilCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100000270Award Number: NE/ W005050/1Funding provided by: Natural Environment Research CouncilCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100000270Award Number: NE/N014472/1The study took place in the Salisbury Plain Training Area, southern England. It covered six distinct grassland habitats across the area, representing a gradient of plant species richness and flower resources. These included ancient grassland, previously disturbed grassland, recently disturbed grassland, reverting grassland, intensive grazing, and ungrazed grassland. In 2010, 36 permanently marked line transects (6 × 85 m) were established, one in the center of each habitat plot. Sampling occurred four times between May 30 and September 19, 2011, monthly. Surveys took place between 10:00 and 17:30, coinciding with major pollinator flight periods. The method followed the UK Butterfly Monitoring Scheme (BMS) and adapted for bumblebee surveys. Surveys occurred under standardized environmental conditions (wind speed 17ºC if cloudy or >13ºC if less than 40% cloud cover). Temperature, sunshine percentage, and wind speed were recorded. It took approximately two days to complete all transect counts for the 36 plots. During each survey, all butterflies and day-flying moths were identified and counted at the species level. Foraging bumblebees were also recorded to species level, and rare species were verified with voucher specimens. Bombus terrestris and B. lucorum were recorded collectively as they couldn't be reliably distinguished in the field. Summed counts were made for honeybees, solitary bees, and hoverflies. The first flowering plant visited by each bee or butterfly was recorded to species, enabling the construction of plant-pollinator interaction webs for each grassland type. Regarding flower resources, during each pollinator survey, eight 0.5 × 0.5 m quadrats were used, spaced equally along each transect. All flowering dicotyledonous plants were identified, and the number of flower units per species was counted. Flower units encompassed single flowers, multi-flowered stems, flower-heads, and umbels, providing estimates of timing, diversity, and abundance of floral resources available to pollinators in each grassland habitat throughout the season