Quantifying plant dispersal: New methods from multiple disciplines

Dispersal is a key process in plant ecology, evolution, and conservation (Howe and Smallwood, 1982; Trakhtenbrot et al., 2005; Ronce, 2007; Clobert et al., 2012; Driscoll et al., 2014; Johnson et al., 2019; Beckman and Sullivan, 2023). Dispersal influences fitness (Hamilton and May, 1977; Nakashizuka et al., 1995; Bonte et al., 2014), population dynamics (Neubert and Caswell, 2000; Levin et al., 2003; Jongejans et al., 2008), genetic diversity (Browne et al., 2018; Imwattana et al., 2024), and biodiversity (Levine and Murrell, 2003; Cadotte, 2006) across temporal and spatial scales (Robledo-Arnuncio et al., 2014; Stevens and Emery, 2015; Germain et al., 2017; Oldfather et al., 2021; Peniston et al., 2024). In sessile organisms like plants, diaspore (the pollen, spore, seed, or fruit plus attached structures that disperse as a unit) dispersal is particularly important as it is the main period in an organism's life cycle for significant movement (Harper, 1977; Zobel et al., 2010). Without dispersal, plants cannot move to suitable habitat as conditions change (Corlett and Westcott, 2013), nor can gene flow occur to allow for adaptation to these changes (Kremer et al., 2012). However, dispersal is a complex, multiscale process that is difficult to measure (Bullock et al., 2006; Nathan, 2006), with the majority of diaspore dispersal relying on one or more abiotic and biotic vectors (Vittoz and Engler, 2007; Lorts et al., 2008; Rogers et al., 2021). This complexity requires multiple disciplinary perspectives (e.g., genomics, physiology, animal movement, atmospheric sciences, hydrology, ecology, evolution) to accurately measure the dispersal of diaspores by a diversity of vectors and resulting dispersal patterns (Rogers et al., 2019; Beckman et al., 2020). Under increasing global change, accurate prediction of plant dispersal becomes even more critical, given that diaspore movement is one of the main ways plant populations build resiliency in the face of this change (Török et al., 2020). Global change is altering many aspects of plant dispersal. Land use conversion is causing habitat loss and fragmentation (Theobald et al., 2011; Newbold et al., 2016; Wimberly et al., 2018), making dispersal critical to maintain connectivity (Brudvig et al., 2009; Sullivan et al., 2021). Anthropogenic homogenization of biotic communities is altering the availability of seed dispersers, which in turn can disrupt the dispersal of plants (Fricke and Svenning, 2020; Shaw et al., 2021). Finally, changes to global temperature and wind patterns can have effects on plant movement when diaspores disperse abiotically (Kuparinen et al., 2009; Kling and Ackerly, 2020). These global change effects on plant movement make it increasingly critical to quantify dispersal and changes to species population patterns. However, not nearly enough dispersal data is being collected, nor is it of the quality required to support much of the needed conservation work (Driscoll et al., 2014). Therefore, it is critically important that scientists continue to develop new and better methods for studying dispersal that allow researchers to collect data that facilitates accurate predictions about plant movement into the future. This special issue reviews methods and highlights new approaches for measuring plant dispersal from multiple disciplinary perspectives and across levels of biological organization. The papers are organized by the primary dispersal mechanism, either biotic or abiotic modes; we first review literature within that mode and then introduce new methods for measuring dispersal. Our aim is for these methods to support a detailed and broader understanding of plant dispersal that can increase understanding and movement prediction in the face of global change. Animal-mediated seed dispersal (zoochory) is one of the most widespread and ecologically important dispersal modes, yet it remains challenging to quantify due to its multiphase nature and the diversity of interacting organisms involved. In this special issue, Beckman et al. (2026) provide a comprehensive review of quantitative, empirical, and emerging methodological approaches used to study animal-mediated seed dispersal across all dispersal phases, from predispersal processes through postdispersal fate. The review synthesizes methods for quantifying seed removal, relocation, deposition, and establishment, alongside approaches for measuring disperser behavior and plant traits that influence dispersal outcomes. Importantly, the authors highlight recent technological advances—such as tracking tools, molecular methods, and integrative modeling approaches—that enable researchers to link dispersal phases and address persistent data gaps. By emphasizing the need for standardized protocols and the simultaneous development of theory and quantitative models, this review provides a unifying framework for improving mechanistic understanding, comparability across systems, and predictive capacity in zoochory research, with direct implications for ecology, evolution, and conservation. Fruit traits mediate the dispersal of fleshy fruits by animals and have a long history of study (e.g., Wallace, 1877; Ridley, 1930, p. 19; Van Der Pijl, 1982). Nguyen et al. (2026) provide a comprehensive overview of methods and their nuances to quantify functional traits of fleshy fruits, including methodology to sample fruit; quantify fruit morphology, color, and chemistry; and analyze processes and patterns underlying functional traits (e.g., DNA, RNA, fruit microbiomes). Despite the growing availability and accessibility of trait data, several challenges remain in the study of fruit traits. Nguyen et al. (2026) present opportunities to overcome these challenges to advance our understanding of fruit–frugivore interactions and seed dispersal by providing a review of the classical and recent innovative methods to study fruit traits from which researchers can clarify and align their research objectives and methods and collect data on traits that are currently absent or understudied in available trait databases. This comprehensive review on methods to study fruit traits is essential reading for any researcher interested in the ecology and evolution of seed dispersal by animals and fruit–frugivore interactions. Seeds dependent on avian consumption and dispersal (endozoochory) are common in many systems, but are difficult to track, as significant time and labor expenses are required to conduct observations and morphologically identify defecated seeds. For some taxa, identification to species based on seed morphology alone is extremely difficult, if not impossible, due to morphological similarity. Furthermore, seed consumption may significantly alter the appearance of the seed, causing additional identification complications. The use of DNA metabarcoding has grown in recent years to study cryptic diversity and plant–animal interactions (Kuzmina et al., 2018; Nitta and Chambers, 2022; Benkendorf et al., 2025; Waters et al., 2025). Motta et al. (2026) build on this work and discuss the complementary application of DNA metabarcoding and seed morphology to identify seeds from bird feces in the highly diverse Neotropics. By using this complementary approach, Neotropical birds were shown to consume a greater diversity of seeds than the morphological and observation-based approaches were able to identify. Using DNA metabarcoding may help resolve questions regarding bird fruit consumption and dispersal in dense and diverse regions and across seasonal variation. Anemochory, or wind-mediated dispersal, can be complicated to study in the field due to difficulties in diaspore tracking in heterogeneous environments, especially when working with small diaspores or in diverse, densely structured environments. Starting in the mid-1900s, and expanding in the 1980s, researchers began using wind tunnels to study diaspore dispersal distances, terminal velocity, and trajectory in a controlled environment (Kohlermann, 1950; Woodall, 1982; Maddox and Carlquist, 1985; Niklas, 1985). More recent work has focused on improving these initial wind tunnel structures to include factors that better mimic a natural, heterogeneous habitat. In this special issue, Tian et al. (2026) provide a review on wind tunnel structures and factors to consider when designing these experiments. Features such as airflow parameters, location and size, seed arrangement and morphology, dispersal environment, and wind field setup are discussed in detail. This review provides a roadmap for individuals interested in conducting wind tunnel research and clearly discusses factors that should be considered when using wind tunnels to examine dispersal patterns. Fern spores disperse primarily by wind (Brock, 2025) and have the potential to disperse farther than angiosperm seeds and pollen (Després et al., 2012). Interest in fern spore dispersal dates back to the mid-1800s, when both Darwin and Wallace collected fern spores in air samples during their early voyages (Darwin, 1846; Wallace, 1880). Despite long-standing historical interest, the aerobiology of fern spores is extremely understudied. To address this shortfall, Gómez-Noguez et al. (2026) first provide a review of the methods for measuring fern spore dispersal by wind, and then describe a method for measuring spore dispersal via a release and recapture experiment. They find that spores were recovered at the highest heights of recapture traps, indicating fern spores travel much farther than previously assumed. Bolecochory, or the censer seed dispersal mechanism, is a mode of anemochory in which diaspores remain on the plant after ripening and physical forces derived from the wind shake the plant back and forth, thereby catapulting diaspores off the plant (Vittoz and Engler, 2007). This mechanism is relatively understudied and likely occurs in many species as an additional dispersal mode that has not been quantified as it may not be an evolutionary adaptation to dispersal (Willson et al., 1990). For this special issue, Motter et al. (2026) provide a simple method for measuring whether a species is dispersed by the censer mechanism and quantifying how far seeds move by this process. This method connects individual plant stems to a string that is pulled to the beat of a metronome, and the rhythmic motion provides the horizontal force needed to replicate wind movement that could shake stems and catapult seeds. The authors develop metrics to calculate the proportion of seeds that disperse via the censer mechanism and the proportion that disperse via traditional passive means (i.e., those diaspores that do not fall off from active shaking). Seed arrival is a critical process for increasing species diversity in plant communities (Myers and Harms, 2009). One of the most common ways to study seed arrival is to measure seed rain, or the number and identity of seeds that fall to the ground in a given area (Rabinowitz and Rapp, 1980; Cottrell, 2004; Arruda et al., 2020). Seed rain measurements are common in forest systems (e.g., Peart, 1979; Loiselle et al., 1996; Clark et al., 2001; Cubiña and Aide, 2001; Grombone-Guaratini and Rodrigues, 2002; Huanca Nuñez et al., 2021) but are much less so in grassland systems (Arruda et al., 2018; Wynne et al., 2024). In order to understand seed rain in grasslands more broadly, a method is needed that can accurately recover seeds across different grassland environments. For this special issue, Sullivan et al. (2026) compare the seed recovery rate of two common types of grassland seed rain traps, artificial grass traps and sticky traps, across two grassland ecosystems. They find that sticky traps tend to retain more seeds and are better for estimating primary dispersal, whereas artificial grass traps lose seeds to the environment and granivores and are thus better for estimating effective dispersal. The articles in this special issue highlight the diversity and innovation of approaches to quantify diaspore dispersal of plants and include papers serving as methodological reviews along with those that discuss novel methods. Such methods range from field-based experiments, molecular approaches, computational modeling, and manipulative studies. Collectively, these papers draw attention to the difficulties often encountered when studying diaspore dispersal patterns, offering readers methods to consider when designing experiments, but also the opportunities to advance our mechanistic understanding of how diaspores move across landscapes, interact with biotic and abiotic vectors, and contribute to population connectivity and ecosystem dynamics. Additionally, a variety of habitat types and taxa are discussed in these papers, providing practical approaches for researchers in a variety of botanical specializations and offering guidance for study design, data collection, and interpretation across ecological contexts. These papers also illustrate that no single method can capture all aspects of dispersal. Thus, integrative and multidisciplinary approaches are essential for generating comprehensive, comparable, and predictive data. Ultimately, these methodological advances can facilitate more accurate predictions of plant movement in the face of global change and guide future research bridging theory, experimentation, and conservation practice. L.L.S. and N.G.B. initiated this special issue, and S.M.C. and I.C.S. contributed to its development. All authors contributed to editorial duties for the manuscripts included in this special issue. All authors contributed text for the manuscript, and L.L.S. combined those contributions and led the writing and editing. All authors approved the final version of the manuscript. We thank the Applications in Plant Sciences Editor-in-Chief Dr. Briana L. Gross and Managing Editor Beth Parada for their guidance and support throughout the editorial process and for their feedback on this manuscript. L.L.S. was supported by the National Science Foundation (NSF; grant #2441141). N.G.B. acknowledges funding from NSF (grants DEB 2231761 and IOS 1953934). This is Kellogg Biological Station Contribution no. 2431.