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Background: Plant–pollinator community diversity has been found to decrease under conditions of drought stress; however, research into the temporal dimensions of this phenomenon remains limited. In this study, we investigated the effect of seasonal drought on the temporal niche dynamics of entomophilous flowering plants in a water‐limited ecosystem. We hypothesized that closely related native and exotic plants would tend to share similar life history and that peak flowering events would therefore coincide with phylogenetic clustering in plant communities based on expected phenological responses of plant functional types to limitations in soil moisture availability. Location: Galiano Island, British Columbia, Canada. Methods: Combining methods from pollinator research and phylogenetic community ecology, we tested the influence of environmental filtering over plant community phenology across gradients of landscape disturbance and soil moisture. Floral resource availability and community structure were quantified by counts of flowering shoots. We constructed a robust phylogeny to analyze spatial and temporal variation in phylogenetic patterns across the landscape, testing the significance of the observed patterns against a randomly generated community phylogeny. Phylogenetic metrics were then regressed against factors of disturbance and soil moisture availability. Results: Critical seasonal fluctuations in floral resources coincided with significant phylogenetic clustering in plant communities, with decreasing plant diversity observed under conditions of increasing drought stress. Exotic plant species in the Asteraceae became increasingly pervasive across the landscape, occupying a late season temporal niche in drought‐stressed environments. Main conclusion: Results suggest that environmental filtering is the dominant assembly process structuring the temporal niche of plant communities in this water‐limited ecosystem. Based on these results, and trends seen elsewhere, the overall diversity of plant–pollinator communities may be expected to decline with the increasing drought stress predicted under future climate scenarios. [ABSTRACT FROM AUTHOR]

An amendment to this paper has been published and can be accessed via a link at the top of the paper. [ABSTRACT FROM AUTHOR]

Highlights • We examined the relationship between wet and dry biomass of 12 common macroalgae and seagrass from the Northeast Pacific Ocean. • Ten species displayed a strong and predictable relationship between wet and dry conditions. • Researchers from this region can apply these results to their own research, reducing the need to perform dry mass determinations for each new study. • With continued research, species-specific wet-to-dry biomass ratios could be established with greater precision and for more species. Abstract Macroalgae and seagrasses form the base of productive ecosystems in the Northeastern Pacific Ocean. Often, ecological research on macroalgae, seagrasses, and sea wrack requires the conversion of biomass from wet to dry to create consistency across investigations. This process, however, can be destructive, impractical, time consuming, and labour intensive. We collected samples of twelve common Northeastern Pacific Ocean seaweed species (Alaria marginata , Codium fragile , Egregia menziesii , Fucus distichus , Macrocystis pyrifera , Mazzaella spp., Nereocystis luetkeana , Pterygophora californica , Pyropia spp., Ulva spp., and the seagrasses Zostera marina and Phyllospadix spp.) in two states: wet and fresh, or aged and partially desiccated. We weighed, dried, and compared samples, finding that many species displayed a strong (R 2 > 0.8) and predictable linear relationship between wet and dried conditions. In contrast, half the aged samples did not have a significant relationship between partially desiccated and dried conditions. Our results provide practical wet weight to dry weight ratios for many species, and with further research, a reliable set of species-specific wet to dry weight ratios for all species could be established. Wet to dry weight ratios are useful for macroalgae, seagrass, and sea wrack research or commercial applications and would reduce the need to conduct extensive wet-dry calibrations in each study. [ABSTRACT FROM AUTHOR]