Spatial extent of invasiveness and invasion stage categorisation of established weeds of Queensland, Australia

Abstract

The risk posed by invasive alien species is determined primarily by two factors: distribution (occupancy) and abundance (density). However, most ecological studies use distribution data for monitoring and assessment programs, but few incorporate abundance data due to financial and logistical constraints. Failure to take into account invaders’ abundance may lead to imprecise pest risk assessments. Since 2003 as part of the Annual Pest Distribution Survey (APDS) exercise in the state of Queensland, Australia, government biosecurity officials have collected data on distribution and abundance of more than 100 established and emerging weeds. This data acquisition was done at spatial grid sizes of 17–50 × 17–50 km and across a very broad and varied geographical land area of ~2 × 106 km2. The datasets provide an opportunity to compare weed dynamics at large-medium spatial scales. Analysis of the APDS datasets indicated that weed distributions were highest in regions along the southern and central, coastal parts of Queensland, and decreased in the less populated inland (i.e. western) and northern parts of the state. Weed abundance showed no discernible landscape or regional trends. Positive distribution–abundance relationships were also detected at multiple spatial scales. Using both traits of weed abundance and distribution, we derived a measure of invasion severity, and constructed, for several (64) weed species, ‘space-for-time’ invasion curves. State-wide and in each of Queensland’s 10 regions, we also categorised the invasion stages of these weeds. At the grassroots of local government area or regional levels, the derived invasion curves and stage categories can provide policy direction for long-term management planning of Queensland’s priority weeds.

Lag times and invasion dynamics of established and emerging weeds: insights from herbarium records of Queensland, Australia

“…lantana [Lantana camara], rat's tail grasses [Sporobolus complex], and water hyacinth [Eichhornia crassipes]), others in the same category are not formally listed (specifically, lippia [Phyla canescens], calotrope [Caltropis procera], thatch grass [Hyparrhenia rufa], and Chinese violet [Asystasia gangetica]). We hope the afore-mentioned, unlisted weeds attract attention for policy and necessary management actions, especially because many are still confined to few regions or local government areas (see Osunkoya et al 2020).…”

“…gov.au/view/pdf/inforce/current/act-2014-007-accessed Jan. 13 2021). As a result, these species are targeted for active management at the State, regional and local government area levels (Osunkoya et al 2019a(Osunkoya et al , b, 2020. Data on the distribution (i.e., presence) of these species from 1850-2010 were extracted from the Australasian Virtual Herbarium (AVH).…”

Biology, Ecology and Management of the Invasive Navua Sedge (Cyperus aromaticus)—A Global Review

“…Seeds can germinate easily from 2–3 weeks after maturity at any time of the year under suitable temperature, photoperiod and humidity conditions [ 2 ]. The rhizome system of Navua sedge is very efficient for vegetative propagation as it starts to grow within 2–3 weeks of seedling emergence [ 26 , 27 ]. New tillers are usually produced by secondary bud formation, whereas the third bud is responsible for branching the rhizome system [ 7 ].…”

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

“…First introduced in the 1970s into Queensland, parthenium weed has since become widespread (Osunkoya et al 2020, Osunkoya et al 2021 and is now documented to be in the final stage of a typical invasion curve in many regions of the state (Osunkoya et al 2020). Parthenium weed reproduces after 4-to 6-week growth, when the structure of the achene complex (hereafter referred to as an achene) becomes distinctive: without a developed pappus, but still adapted to air movement by having floral bracts forming 'air sacs' (Rollins 1950, Auld et al 1982, Navie 2002.…”

“…First introduced in the 1970s into Queensland, parthenium weed has since become widespread (Osunkoya et al . 2020, Osunkoya et al . 2021) and is now documented to be in the final stage of a typical invasion curve in many regions of the state (Osunkoya et al .…”