As argued in other Q&As on this site, the invasive alien maybe the symptom not the cause of a change in species composition. Any opening up of vegetation cover, anthropogenic or otherwise creates opportunities for invaders, alien and indigenous alike. If the invaders are transformers, a return to the historical ex ante composition may be unlikely at a human time scale.

Attached are a few articles that may help but the general trend in the articles is: yes drought like other perturbations can make an ecosystem more susceptible to invasive plants. Hope these help!

It is hard for grasslands to be threatened in this way imo. Many grasses are very drought resistant due to their C4 photosynthetic cycle, which improves photosynthetic ability and minimises water loss in dry environments. So I think new plants would have trouble competing in grasslands :)

Yes, extreme drought events can increase invasion process.

Just like one of the respondents rightly said, drought is in its own way a perturbation and disturbance is a basic prerequisite for plant invasion.

Since these invasive plant species are phenotypically plastic (check the "ideal weed concept" by Baker, 1965), I am of the opinion that extreme drought events can increase plant invasion.

The habitat type is a matter. For example, the roadside habitats (native, ruderal) well resistant to drought, invasives do not get advantage in these habitat types, but in wetland types invasives with drought for longer period can explode and get substantial advantage even change the habitat type.

Very variable. In Namibia, an indigenous invasive woody species (Acacia mellifera) recruits in protracted wet periods, and saplings die fairly easily in drought. An exotic invasive grass, Pennisetum setaceum, also responds favourably to rainfall, but unfavourable to competition with other road verge species such as Heteropogon contortus. In other words, the grass appears to respond to other forms of disturbance thata remove the Heteropogon. road verges in Namibia are relatively benign habitats accumulating a lot more water than normal from the tar roads. I don't have much experience of other exotic invaders. Perhaps Namibia is a case in point where, because it is already dry, the reverse is more applicable. Perennial grasses here are more susceptible to overgrazing than drought, and this can be seen in drought years when the well managed rangelands are nowhere near as negatively affected (in terms of rangeland productivity) than rangeland dominated by pioneer annual species (that can be quite productive in high rainfall years). Thanks for the nice, simple question with not such simple answers!

In Austria we see a continuos spread of following grassland weeds,

with cause of the drivers of

1 - reduced fertilizing by environment protetion programms and

2 - and probably climate warming:

Very poisonous grassland weeds

Wasser-Kreuzkraut - Jacobaea aquatica

Jakobs-Kreuzkraut - Senecio jacobaea

Alpen - Kreuzkraut - Senecio alpinus

Wiesenlabkraut - Galium mollugo

Regulary grassland weeds

Wiesenpippau - Crepis biennis

Flockenblume - Centaurea jacea

Spitzwegerich - Plantago lanceolata

Scharbockskraut - Ficaria verna

Zypressen-Wolfsmilch - Euphorbia cyparissias

Klappertopf - Rhinanthus minor

See more om my webpage:

https://de.slideshare.net/JohannHumer/2015-kreuzkraeuter-ausbreitung-giftiger-kreuzkrautarten-auf-wiesen-weiden-almen

http://futterwiesenexpertehumer.wikispaces.com/Dürre+lückige+Wiesen+ein+attraktiver+Brutplatz+für+Engerlinge+und+Jakobskreuzkraut

http://futterwiesenexpertehumer.wikispaces.com/file/view/BZ%201726_06-07%20Futternot%20Sommerd%C3%BCrre%20HUMER%20edel.pdf/615136311/BZ%201726_06-07%20Futternot%20Sommerd%C3%BCrre%20HUMER%20edel.pdf

http://futterwiesenexpertehumer.wikispaces.com/Ersatzfutter+und+klimatische+Futterumstellung+bei+Futternot+und+Sommerdürre+im+Grünland

http://futterwiesenexpertehumer.wikispaces.com/Jakobskreuzkraut+und+Engerlinge+bedrohen+d%C3%BCrregesch%C3%A4digte+Wiesen

Use easy translation with:

https://www.deepl.com/translator

Yes, drought events bring along with them invasive species. When this occurs, returning to the natural state of the ecosystem is almost impossible naturally. As the term invasive implies, when these set, their growth is literally exponential, suppressing the once general existing vegetation types. Thus the impact of drought is to eliminate existing species, leaving the ground open to invasive species, which thrive in the new environmental condition of drought.

The extreme condition of drought or even with soil becoming non favorable due to other reasons may change species composition resulting establishment of more tolerant species generally weeds or other invasive species.

Opportunistic species start invasion replacing the sensitive species

Sensitive species may fail to adopt to the changing climatic conditions, and as they perish, new opportunistic ones (the so called hyposensitive species) would replace them. This is survival for the fittest.

Hello Mohammed; In the southwestern USA native grasslands are under great pressure and are changing rapidly. The obvious stressors include non-native annual grasses, non-native grazers including cattle and feral equiids and high-frequency fires. All of these factors are associated with human intrusion. Throughout the region native grasses are under threat. In California there are practically no native grassland species left. Best regards, Jim Des Lauriers

Dear Mohammed Abu Sayed Arfin Khan . See the following useful RG links: Article The effects of extreme climate on the invasive plant Gutenbe...

https://www.nature.com/articles/srep15110

Kindly see also the following useful RG link: Article Soil biotic legacy effects of extreme weather events influen...

Also check please the following useful RG link: Article Experimental drought indirectly enhances the individual perf...

The following links are also very useful: https://www.biorxiv.org/content/10.1101/2021.07.26.453896v2.full.pdf

https://hal.archives-ouvertes.fr/hal-00884011/document

https://www.intechopen.com/chapters/41849

https://doi.org/10.1016/j.heliyon.2022.e09172

https://doi.org/10.3390/su13115976

DOI: 10.5772/53833

https://escholarship.org/content/qt4n72m49d/qt4n72m49d_noSplash_b061595100bd144bd4f315d36f05575e.pdf

https://www.nisaw.org/climatechange/

Yes, extreme drought events can increase plant invasion. During droughts, weakened native plants create opportunities for invasive species to thrive. Altered environmental conditions, disturbed habitats, and increased dispersal can further promote their spread. Effective management strategies are crucial to mitigate the impact of drought-induced plant invasion.

Extreme drought events can indeed increase plant invasion in certain cases. Plant invasion refers to the introduction and spread of non-native plant species into an ecosystem, which can have various ecological and environmental impacts.

During extreme drought events, the environmental conditions can change significantly, creating disturbances in the ecosystem. These changes may provide opportunities for invasive plant species to establish and thrive. Here are some reasons why extreme drought events can promote plant invasion:

It's essential to note that the relationship between extreme drought events and plant invasion can vary depending on the specific ecosystem and the characteristics of the invasive species involved. In some cases, drought may suppress invasive plants if they are not well-adapted to water-stressed conditions.

Managing plant invasions in the context of extreme drought events requires a comprehensive understanding of the specific factors influencing invasion dynamics. It involves efforts such as monitoring invasive species, implementing early detection and rapid response strategies, restoring native plant communities, and promoting sustainable land and water management practices to minimize the impact of drought-induced plant invasion.