The Jomon environment was roughly like that of modern Japan today. Hokkaido was covered in large numbers of conifers in the cold temperate forest of the far north. The northern parts of the Japanese mainland was covered in a temperate forest of mixed broadleaf deciduous trees.
Nut-bearing trees like oaks and beeches could be seen everywhere walnuts and chestnuts were common.Walnuts grew in the northern zones. In the west from the Kanto Plain around Tokyo to Kyushu, was a belt of subtropical forest of broadleaf evergreen trees. And the evergreen forested southern parts were more plentiful in the nut-and-fruit-bearing trees. Acorns could be found on the east coast, in the Chubu region, and toward the southwest.
Various nuts available as food to Jomon people (Kawasaki City Museum)
The Siberian mountain lion, the last of the great cats, was present at the beginning of the Jomon period, but disappeared along the way as the climate grew warmer. Deer and wild boar thrived better in the deciduous forested areas of the north.
During the Early Jomon period, the sea invaded much of the coastal lowlands (extending far up the Ara River north of Tokyo, almost to the present city of Kumagaya). The tidal flats that were the result of the flooding, were rich in molluscs and shellfish.
During the Middle Jomon era, the warming climate caused animal wildlife to avoid the hot and humid coastal areas and to migrate to cooler places in the mountains, so that people quickly followed making their homes there too.
Shell midden remains (Kawasaki City Museum)
The Pacific Ocean waters off the coast of northeastern Japan were extremely rich in fish. Salmon were abundant in the rivers in much of northern Japan. The waters in much of the north, especially Hokkaido were inhabited by large numbers of sea mammals.
Like modern-day Japan, the Jomon world saw many natural disasters such as volcanic eruptions, typhoons and floods. The Jomon period witnessed the eruptions of Hakone volcanoes, Aira Caldera underwater volcanoes in Kyushu as well as Mt Sanbe (three times). The activity of Mt Aso in north Kyushu during the Middle Jomon era was so violent that no one could live in the area.