A wave of green leaves and multi‐colored flowers advances from low to high latitudes each spring. However, little is known about how flowering offset (i.e., ending of flowering) and duration of populations of the same species vary along environmental gradients. Understanding these patterns is critical for predicting the effects of future climate and land‐use change on plants, pollinators, and herbivores. Here, we investigated potential climatic and landscape drivers of flowering onset, offset, and duration of 52 plant species with varying key traits. We generated phenology estimates using >270,000 community‐science photographs and a novel presence‐only phenometric estimation method. We found longer flowering durations in warmer areas, which is more obvious for summer‐blooming species compared to spring‐bloomers driven by their strongly differing offset dynamics. We also found that higher human population density and higher annual precipitation are associated with delayed flowering offset and extended flowering duration. Finally, offset of woody perennials was more sensitive than herbaceous species to both climate and urbanization drivers. Empirical forecast models suggested that flowering durations will be longer in 2030 and 2050 under representative concentration pathway (RCP) 8.5, especially for summer‐blooming species. Our study provides critical insight into drivers of key flowering phenophases and confirms that Hopkins’ Bioclimatic Law also applies to flowering durations for summer‐blooming species and herbaceous spring‐blooming species.

Insect phenological lability is key for determining which species will adapt under environmental change. However, little is known about when adult insect activity terminates and overall activity duration. We used community-science and museum specimen data to investigate the effects of climate and urbanisation on timing of adult insect activity for 101 species varying in life history traits. We found detritivores and species with aquatic larval stages extend activity periods most rapidly in response to increasing regional temperature. Conversely, species with subterranean larval stages have relatively constant durations regardless of regional temperature. Species extended their period of adult activity similarly in warmer conditions regardless of voltinism classification. Longer adult durations may represent a general response to warming, but voltinism data in subtropical environments are likely underreported. This effort provides a framework to address the drivers of adult insect phenology at continental scales and a basis for predicting species response to environmental change.

Aim: Nitrogen (N)-fixing plants are an important component of global plant communities, but the drivers of N-fixing plant diversity, especially in temperate regions, remain underexplored. Here, we examined broad-scale patterns of N-fixing and non-fixing plant phylogenetic diversity (PD) and species richness (SR) across a wide portion of temperate North America, focusing on relationships with soil N and aridity. We also tested whether exotic species, with and without N-fixing symbiosis, have fewer abiotic limitations compared with native species.Location: USA and Puerto Rico. Time period: Current. Major taxa studied: Vascular plants, focusing on N-fixing groups (orders Fabales, Fagales, Rosales and Cucurbitales). Methods: We subset National Ecological Observatory Network (NEON) plant plot data from all sites along two axes (N fixing-non-N fixing and native-exotic), calculating plot-level SR, PD and mean pairwise phylogenetic distance (MPD). We then used linear mixed models to investigate relationships between diversity values and key soil measurements, along with aridity, temperature and fire frequency. Results: Aridity was the sole predictor of proportional phylogenetic diversity of N fixers. The SR of N fixers still decreased marginally in arid regions, whereas native N-fixer MPD increased with aridity, indicative of unique lineages of N fixers in the driest conditions, in contrast to native non-N fixers. The SR of both native N fixers and non-N fixers increased in low-N soils. Aridity did not affect SR of exotic non-N fixers, unlike other groups, whereas exotic N fixers showed lower MPD in increasingly high-N soils, suggesting filtering, contrary what was found for native N fixers. Main conclusions:Our results suggest that it is not nitrogen, or any soil nutrient, that has the strongest effect on the relative success of N fixers in plant communities.Rather, aridity is the key driver, at least for native species, in line with empirical results from other biomes and increased understanding of N fixation as a key mechanism to avoid water loss.

Phylogenetic datasets are now commonly generated using short-read sequencing technologies unhampered by degraded DNA, such as that often extracted from herbarium specimens. The compatibility of these methods with herbarium specimens has precipitated an increase in broad sampling of herbarium specimens for inclusion in phylogenetic studies. Understanding which sample characteristics are predictive of sequencing success can guide researchers in the selection of tissues and specimens most likely to yield good results. Multiple recent studies have considered the relationship between sample characteristics and DNA yield and sequence capture success. Here we report an analysis of the relationship between sample characteristics and sequencing success for nearly 8,000 herbarium specimens. This study, the largest of its kind, is also the first to include a measure of specimen quality (“greenness”) as a predictor of DNA sequencing success. We found that taxonomic group and source herbarium are strong predictors of both DNA yield and sequencing success and that the most important specimen characteristics for predicting success differ for DNA yield and sequencing: greenness was the strongest predictor of DNA yield, and age was the strongest predictor of proportion-on-target reads recovered. Surprisingly, the relationship between age and proportion-on-target reads is the inverse of expectations; older specimens performed slightly better in our capture-based protocols. We also found that DNA yield itself is not a strong predictor of sequencing success. Most literature on DNA sequencing from herbarium specimens considers specimen selection for optimal DNA extraction success, which we find to be an inappropriate metric for predicting success using next-generation sequencing technologies.

Insect phenological lability is key for determining which species will adapt under environmental change. However, little is known about when adult insect activity terminates, and overall activity duration. We used community-science and museum specimen data to investigate the effects of climate and urbanization on timing of adult insect activity for 101 species varying in life history traits. We found detritivores and species with aquatic larval stages extend activity periods most rapidly in response to increasing regional temperature. Conversely, species with subterranean larval stages have relatively constant durations regardless of regional temperature. Multivoltine and univoltine species both extended their period of adult activity similarly in warmer conditions. Longer adult durations may represent a general response to warming, but voltinism data in subtropical environments is likely underreported. This effort provides a framework to address drivers of adult insect phenology at continental scales, and a basis for predicting species response to environmental change.

Aim: Quantifying the phylogenetic diversity of temperate trees is essential for understanding what processes are implicated in shaping the modern distribution of temperate broadleaf forest and other major forest biomes. Here we focus on Fagales, an iconic member of forests worldwide, to uncover global diversity and endemism patterns and investigate potential drivers responsible for the spatial distribution of fagalean forest communities. Location: Global. Taxon: Fagales. Methods: We combined phylogenetic data covering 60.2% of living species, fine-scale distribution models covering 90% of species, and nodulation data covering all species to investigate the distribution of species richness at fine spatial scales and compare this to relative phylogenetic diversity (RPD) and phylogenetic endemism. Further, we quantify phylogenetic betadiversity and bioregionalization of Fagales and determine hotspots of Fagales species engaging in root nodule symbiosis (RNS) with nitrogen-fixing actinomycetes. Results: We find the highest richness in temperate east Asia, eastern North America, and equatorial montane regions of Asia and Central America. By contrast, RPD is highest at higher latitudes, where RNS also predominates. We found a strong spatial structuring of regionalizations of Fagales floras as defined by phylogeny and traits related to RNS, reflecting distinct Northern and Southern Hemisphere floras (with the exception of a unique Afro-Boreal region) and highly distinct tropical montane communities. Main conclusions: Species richness and phylogenetic regionalization accord well with traditional biogeographic concepts for temperate forests, but RPD does not. This may reflect ecological filtering specific to Fagales, as RNS strategies are almost universal in the highest RPD regions. Our results highlight the importance of global-scale, clade-specific spatial phylogenetics and its utility for understanding the history behind temperate forest diversity.

The iNaturalist platform generates millions of research-grade biodiversity records via a system in which users collectively reach consensus on taxonomic identification. In the present article, we examine how identifiers and their efforts, an understudied component of the platform, support data generation. Identification is keeping pace with rapid growth of observations, assisted by a small subset of highly active users who tend to be taxonomically specialized. Identifier experience is the primary determinant of whether records reach research grade, and the time it takes to do so. Time to reach research grade has fallen rapidly with growing identification effort and use of computer vision, and research-grade identifications are generally stable. Most observations are vetted by experienced identifiers, although identifications are not free of biases. We close by providing suggestions for enhanced identification quality and continuing steps to enhance equitable credit and trust across the ecosystem of observers, identifiers, and data users.

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