Wind dispersal of seeds of Parthenium hysterophorus L. (Asteraceae) contributes to its steady invasion and spread

Abstract

Wind dispersal is considered to be a potentially important mode of spread for parthenium weed (Parthenium hysterophorus L.), an invasive Asteraceae herb of worldwide significance. However, empirical evidence of the role of wind dispersal on the seeds (achenes) of parthenium weed in natural landscapes is lacking. The results of a simulation study undertaken at a wind tunnel facility, Australia, indicated that the dispersal distance of parthenium weed achenes is largely determined by wind velocity (109-131% increase in distance where wind velocity is doubled) and plant release height (75-80% increase when release height is doubled). Glasshouse harvested achenes released from 1 m in height could travel up to 2 m under a 2 m s −1 wind velocity, with the majority of achenes reaching more than 1 m. Smaller-sized achenes travelled 5% further than larger-sized achenes. The terminal velocity was calculated to be 1.256 AE 0.006 m s −1 , indicating a moderate wind dispersal ability for the weed. A complementary field study in Southeast Queensland, Australia, indicated that the cumulative wind velocity and wind direction, instead of the mean wind velocity, determined the direction of dispersal of the achenes. Further post-dispersal surveys suggested the number of achenes outside of a standing population declined rapidly as distance from the population increased. Most achenes were dispersed less than 2 m from their parent plant, while the maximum distance achieved was less than 5 m under natural conditions in North Queensland. In conclusion, the natural wind dispersal of parthenium weed consists of small, but measurable increments each year, thus contributing to the weed proliferation and spread at the landscape scale level.

Functional consequences of temporal reversal of height dimorphism for pollen and seed dispersal in a dioecious plant

“…A variety of morphological, demographic, and atmospheric factors influence seed dispersal by wind; however, seed‐release height has been shown both theoretically and empirically to be one of the most important determinants governing dispersal distance (Sheldon & Burrows, 1973; van Dorp et al, 1996; Travis et al, 2010; Skarpaas et al, 2011; Thomson et al, 2011; Zhu et al, 2016; Bullock et al, 2017; DiTommaso et al, 2018; Schupp et al, 2019; Mao et al, 2022). Our experimental results were generally consistent with these findings (Fig.…”

Herbaceous Diversity in the <i>Gumuk</i> Ecosystem in Ledokombo District-Jember Regency with Varied Land Use Type

“…Asteraceae dominance was also reported on herbaceous dynamics in urban areas in India (Khan 2020), also became the family with the highest IVI value in the Savannas in Padar and Komodo Islands (Sutomo 2020). This weed dispersal strategy is strongly influenced by geographical conditions (Dematteis et al 2019), natural seed dispersal by wind also contributes to the breeding and spread of this weed at the landscape level (Mao et al 2022).…”

Role of dispersal in the altitudinal migration of Pinus hartwegii and Abies religiosa in mountain systems

“…For example, low mass:area ratios may enhanced the aerodynamic transport of diaspores by increasing drag and hence the travel time through the air (Nathan et al, 2011). Similarly, wind carries Parthenium hysterophorus diaspores further when the achene:pappus size ratio decreases (Mao et al, 2022); and in a wind-tunnel study that included 14 anemochoric species with winged seeds suggested that the larger ratio mass:wing area was the best predictor of secondary dispersal capacity through lift-off from the ground (Liang et al, 2020). In our study, the ratios of wing area:diaspore area and of wing area:mass were the traits in which the two species differed most.…”