Co-Mast: Harmonized seed production data for woody plants across U.S. long term research sites

Plants display a range of temporal patterns of inter-annual reproduction, from relatively constant seed production to ‘mast seeding’, the synchronized and highly variable interannual seed production of plants within a population. Previous efforts have compiled global records of seed production in long-lived plants to gain insight into seed production, forest and animal population dynamics, and the effects of global change on masting. Existing datasets focus on seed production dynamics at the population scale, but are limited in their ability to examine community-level mast seeding dynamics across different plant species at the continental scale. We harmonized decades of plant reproduction data for 141 woody plant species across nine Long-Term Ecological Research (LTER) or long-term ecological monitoring sites from a wide range of habitats across the United States. Plant reproduction data are reported annually between 1957 and 2021 and based on either seed-traps or seed and/or cone counts on individual trees. A wide range of woody plant species including trees, shrubs, and lianas are represented within sites allowing for direct community-level comparisons among species. We share code for filtering of data that enables the comparison of plot and individual tree data across sites. For each species, we compiled relevant life history attributes (e.g., seed mass, dispersal syndrome, seed longevity, sexual system) that may serve as important predictors of mast seeding in future analyses. To aid in phylogenetically-informed analyses, we also share a phylogeny and phylogenetic distance matrix for all species in the dataset. These data can be used to investigate continent-scale ecological properties of seed production, including individual and population variability, synchrony within and across species, and how these properties of seed production vary in relation to plant species traits and environmental conditions. In addition, these data can be used to assess how annual variability in seed production is associated with climate conditions and how that varies across populations, species, and regions.

Methods
Data on plant reproduction were either downloaded directly from the Environmental Data Initiative Data Portal or recieved from a scientist affiliated with a Long-Term Ecological Research (LTER) site. Data on species attributes were compiled from various sources, referenced in the file called "attribute-citations.csv". Our aim was to create a dataset that harmonizes different sampling methods used to estimate plant reproduction, enabling cross-species comparisons of reproduction across multiple species at sites and incorporating attributes of species such as reproductive cycle length, leaf longevity, and mode of dispersal. The data were filtered as described in the metadata to eliminate dubious seed production time series, including data from rare species, species whose identification was questionable, and seeds identified only to genus rather than species.