Co-evolution is the problem. Native flora evolved with native fauna and native geography. It anchors the soil in certain ways, feeds species that developed to eat their specific nutrient profile and morphology, and has some sense of balance where one plant species doesn't crowd out another. Introduce an invasive species and the whole ecosystem has to adapt to it. It might out-grow other plants, its root profile might be shallower, it might be shit as food and habitat for wildlife who expect to find a tree that flowers in October and can only find ones that flower in June. We change the course of rivers for irrigation and turn forests into timber farms.

In a sense that's colonialism. That's not an issue of monoculture agriculture though so much as it is human development in general. Suburbs use the same inputs and the same philosophy, equally alienating those species from their needs and forcing them into unnatural states subservient to the invasive populations. A squirrel that has to dodge traffic to find a tulip bulb because nobody plants nut trees is just as much a victim as a bird that has to fly over ten acres of green desert to find an insect that's poisoned by glyphosate.

The answer to it isn't anarchoprimitivism either, ecosystems aren't static and humans will influence them at any level of social organisation, but biocentric re-development that heals the big naturalistic contradictions like the metabolic rift and separation of town and country. Those natural instruments of production need legal protection for their needs, like the non-human human classification we give to other intelligent animals, and the development focus needs to be restoring as much of that landscape as possible because it underlies our ability to live on top of it.

edit: Locally we have three good examples of this.

1. Emerald ash-borer beetles evolved in lower-density forests and were constrained by that. Introduced here with dense conifer forests and no native predators, they've quickly killed most of the forests. This provides a lot of dead wood for historic wildfires. The wildfires destroy the flora that hold the soil in place and cause massive landslides. Entire towns risk being destroyed because of one invasive species.

2. Urban development along the base of the mountains forced deer into the narrow habitable zone of the foothills, someplace they'd seasonally migrate to but that's inhospitable for half the year. Hunters only select the best specimens so the concentrated population is left with the weakest members. Chronic wasting disease developed in them, spread through bodily fluids/soil, and they were concentrated into the same areas as other herds/mammals drinking from the same seasonal streams. Now that risks transmission to humans and the only way we can control the population is through hunting, with the state conservation bureau dependent on tag fees to fund itself.

3. The Great Plains evolved with seasonally migrating big herbivores like buffalo. They'd suppress especially prolific plant species, fertilise and compact the soil, and move on before that interaction became counterproductive. We depopulated them as a genocide project against plains tribal nations while simultaneously introducing cattle and wild horses. Both have different grazing patterns and preferences, neither migrates to the extent of the buffalo or in such large numbers, neither has natural predators. The result is giant ranches with terrible soil and massive runoff, herds of starving horses that have to be culled with the only market that eats them being across an ocean. The cattle ranches further deny land to natural animals and the horses forage what would otherwise go to rabbits without being prey for eagles or coyotes.