At high school he worked with Paul Opdam (born 1949) to search in the Utrechtse Heuvelrug moraine for the few remaining nests of the goshawk.

Oak, hazel, cattle and horse"), on the appearance of the vegetation in the lowlands of Central and Western Europe after the end of the last ice age, early in the current Holocene epoch.

He has argued that as a result European primeval forests were not closed-canopy, i.e. with dense growth of trees in which the top branches and leaves form a ceiling, or canopy, so that light can barely penetrate to reach the forest floor, resulting in reduced vegetation growing under and between the mature trees, leaving the ground mostly free of brush.

Vera argues that, if the ancient natural forest were to consist only of closed-canopy conditions, then the light demanding tree species would not be as well represented in the fossil record as they are.

He proposes a semi-open landscape for the lowlands of Central and Western Europe of c.7,000 years ago, and that large herbivores produced a shifting mosaic of vegetation.

Poorter, biologist at the R.IJ.P., wrote about the Oostvaardersplassen in De Lepelaar ("The Spoonbill"), the journal of the Vogelbescherming Nederland (the Netherlands Society for the Protection of Birds).

He wrote an article for the magazine Natuur en Milieu ("Nature and Environment") to draw attention to the fact that the area did not have any protected status.

[24][25] The experiment is considered scientifically controversial due to the lack of predators and other native megafauna such as wolves, bears, lynx, elk, boar, and wisent.

[27] Although his theory about large grazers in the original European landscape, and the operation of the Oostvaardersplassen Nature Reserve, remains controversial,[28] he has had great influence.

His key work is the 1997 thesis Metaforen voor de Wildernis ("Metaphors for the Wilderness"), of which an adapted English version was published in 2000 entitled Grazing Ecology and Forest History.

The greatest impact of Vera's hypothesis is that some ecologists now believe the key principle of "rewilding" should be to change conservation away from preservation and towards the restoration of natural processes, by letting the landscape with its plants and animals run wild.