As climate change shifts the timing of life events — phenology— in organisms across the globe, there is increasing interest in how these shifts vary across space. Complex phenological landscapes create patchy and dynamic resource environments that are tracked by consumers at a wide variety of spatial and temporal scales. These tracking behaviors can have large consequences for the population and community dynamics of both resource producers and consumers. Despite their demonstrated importance across regions and continents, we know relatively little about phenological landscapes at spatial grains of meters to hundreds of meters, the scales over which the vast majority of the earth’s terrestrial consumers forage and disperse. Here we use field data, dense time-series of fine-scale imagery collected with UAVs, and behavioral simulations to explore the causes and consequences of fine-scale spatial variation in leafing and flowering phenology in a rugged subalpine landscape in Western Colorado, USA. Specifically, we ask three important questions: 1) how much variability is there in green-up and flowering phenology at fine scales?, 2) what are the most important abiotic and biotic drivers of this variability?, and 3) How does this variation influence the energetics of foraging for mobile consumers such as pollinators?
Results/Conclusions
We found dramatic fine-scale variability in leafing and flowering phenology over distances of meters to hundreds of meters in our focal landscapes. This meant that there was nearly half as much variability within small sites (ranging from 22 to 62 ha in size), as between sites, which differ in elevation by up to 900m. Small-scale variation in phenology was driven in roughly equal measure by local environmental differences such as snow melt timing and species turnover between microsites. These sources of variation were also strongly correlated, resulting in local-scale phenological variability within plant species that was lower than expected given environmental variability alone. Behavioral simulations suggest that resource surfing behaviors in these landscapes could allow mobile foragers such as pollinators to boost their energetic returns and potentially avoid phenological mismatch by tracking resources spatially, but only if they are able to efficiently shift between resources offered by different plant species. If the cost of shifting resources is high, then these behaviors provide little energetic benefit. Overall, our results suggest that understanding how fine-scale phenological variability across landscapes interacts with the behavioral ecology of foraging can provide powerful insights into the resilience of trophic interactions in the face of global change.