In the Hautil massif
The Hautil is home to the densest forest in the area. There are many oaks, but the most widespread species is the chestnut tree. The springs, and various wetlands, have allowed different varieties to spread there: polysticks with bristles or prickles, humped duckweed, dark green epilobium or field buttercup, hogweed.
At the edge of the fields, which extend as far as the eye can see as soon as you enter the Vexin plateau, the so-called "field flowers" color the surroundings, the ditches, the immediate edges of small roads: papaver rhoeas, orchis mascula, trofolium repens, potentilla reptans and other colorful grasses.
There are many urban parks: Parc des Larris, Jardin des Cinq Sens or Lavandières in Pontoise, coulée verte in Saint-Ouen l'Aumône, Bois de Cergy, Square de la Vénus aux Loups or Parc François Mitterrand in Cergy are all places where flora, in different forms, can flourish in the city.
A nod to the distant past, the vine is still - somewhat - cultivated here: if, at the end of the 18th century, the territory was the most important place of wine production in France, some perpetuate this tradition. The vines find here a ground always favourable to their development, like in Jouy-le-Moutier, where 500 are cultivated by an associative structure.
Wildlife: from the Hautil to the fields via the Oise
Because of its geographical configuration (numerous ponds, dense forest, relative isolation from the city due, in particular, to its low altitude), the Hautil massif is home to several species: the agile frog, the great crested newt, the pearly blue argus, the grey cuckoo, the common buzzard, the common linnet, the wall lizard and even the harmless garter snake! For several years, the public authorities have carried out numerous works to allow aquatic species to remain close to wetlands, which had a tendency to dwindle: dredging, reprofiling of banks and other small developments have allowed the maintenance, and the development, of these species.
Other natural areas of interest: the fields and their surroundings. These are a real wildlife reserve: small birds, such as the Colchis pheasant, and many mosquitoes, so useful for the regulation of the natural space, live there. The birds, logically, are also very numerous. The lapwing and the northern chaffinch live or pass through here. The latter regularly stops here on its long journey from Scandinavia to North Africa.
On the aquatic side, the Oise is obviously the most fishy river (the various streams only have a few tadpoles) with numerous species: the roach, of course, the bleak with a shiny body, the bream, the gudgeon, the perch, the pike-perch, the carp and especially the pike. The fishermen are not mistaken, and are numerous on the banks of the river. The abundance of the aquatic flora and the respect of the spaces allow the persistence of an intense life.
Still in the aquatic part, not only is the leisure island a place of outstanding entertainment, but it is also a place of blossoming for many animal species. For example, swans and ducks are plentiful here, and beehives have even been installed. Children can also learn about the local fauna during group walks, with quizzes for the youngest.
It borders the Cergy-Pontoise agglomeration, and extends northward: the French Vexin Regional Nature Park, created in 1973, is mostly located in the Val-d'Oise - the rest being in the Yvelines - and has undergone various evolutions, with several communes joining it over the years. Its main vocation, to promote the natural and landscape heritage, provides many preserved natural areas, which can be the setting for nice walks and other moments of discovery. The park house, located in a splendid castle in Théméricourt, a few kilometers from Cergy-Pontoise, highlights the actions of the park
