Weed seeds on clothing: A global review

Abstract

Weeds are a major threat to biodiversity including in areas of high conservation value. Unfortunately, people may be unintentionally introducing and dispersing weed seeds on their clothing when they visit these areas. To inform the management of these areas, we conducted a systematic quantitative literature review to determine the diversity and characteristics of species with seeds that can attach and be dispersed from clothing. Across 21 studies identified from systematic literature searches on this topic, seeds from 449 species have been recorded on clothing, more than double the diversity found in a previous review. Nearly all of them, 391 species, are listed weeds in one or more countries, with 58 classified as internationally-recognised environmental weeds. When our database was compared with weed lists from different countries and continents we found that clothing can carry the seeds of important regional weeds. A total of 287 of the species are listed as aliens in one or more countries in Europe, 156 are invasive species/noxious weeds in North America, 211 are naturalized alien plants in Australia, 97 are alien species in India, 33 are invasive species in China and 5 are declared weeds/invaders in South Africa. Seeds on the clothing of hikers can be carried to an average distance of 13 km, and where people travel in cars, trains, planes and boats, the seeds on their clothing can be carried much further. Factors that affect this type of seed dispersal include the type of clothing, the type of material the clothing is made from, the number and location of the seeds on plants, and seed traits such as adhesive and attachment structures. With increasing use of protected areas by tourists, including in remote regions, popular protected areas may be at great risk of biological invasions by weeds with seeds carried on clothing.

Human-mediated dispersal of aquatic invertebrates with waterproof footwear

“…plants and invertebrates are among the main target groups of research on human-mediated dispersal (e.g., Griffiths et al 1991;Ansong and Pickering 2014). The majority of these studies focused on commercial transport (of goods such as seeds, soil, aquaria, and machinery) and on organisms attached to boats or in ship ballast waters (e.g., Carlton 1999;Reichard and White 2001;Escrivà et al 2012).…”

Diaspore heteromorphism in the invasive Bromus tectorum L. (Poaceae): Sterile florets increase dispersal propensity and distance

“…This is notably likely when sterile florets carry awns, resulting in a dispersal unit with awns pointing in different directions. Awns were shown to play a key role in the dispersal and establishment of several grasses species (Ansong and Pickering, 2014;Cheplick, 1998;Peart, 1981).…”

Modelling seed retention curves for eight weed species on clothing

“…Unintentional humanmediated seed dispersal is possible for many plant types, including many weeds. For example, seeds from 450 species have been collected from clothing including 391 (87%) species that are considered weeds somewhere in the world, of which 58 are considered major environmental weeds (Ansong & Pickering 2014). Other human-related dispersal mechanisms are also important with seeds from 249 species of plants found to germinate from horse dung (Ansong & Pickering 2013a) and seeds from 626 species collected from vehicles (Ansong & Pickering 2013b).…”

“…This includes experiments that quantified seed attachment and retention/detachment for vectors such as: clothing (Pickering et al 2011;Ansong & Pickering 2013c and others cited in the review Ansong & Pickering 2014), footwear (Wichmann et al 2009), vehicles (von der Lippe & Kowarik 2007 and others cited in the review Ansong & Pickering 2013b), planes and ships (Lee & Chown 2009;McNeill et al 2011) and a range of domesticated animals (Shmida & Ellner 1983;Couvreur et al 2004;Tackenberg et al 2006). As it is complicated to estimate the seed dispersal ability for specific species for these vectors, most studies focus on specific aspects of the dispersal process and observe how variation in one, or a few factors, affect seed retention.…”

“…Research has shown that people may unintentionally carry weed seeds on their clothing when they use these areas for a range of recreational activities (Pickering & Mount 2010;Chown et al 2012;Ansong & Pickering 2014).The type of clothing, the combination of clothing worn and behaviour of visitors can affect the amount and type of seeds dispersed (Ansong & Pickering 2014). For example, in previous studies, seed was found to detach earlier from trousers made of 100% drill cotton than from socks made of cotton/nylon blend (Pickering et al 2011;Ansong & Pickering 2013c).…”