My paleomaps have a legend linking to different images. I wanted to make it clear what vegetation these refers to. The differences between different forests and woods I think is clearest. It is not as clear about grasslands or different types of scrubland. However, their plants are adapted to different temperature intervals. What I call temperate scrubland has colder winters than the hot. The later may entirely lack a winter if it is close to the Equator. Same applies to grassland. In addition there is the tundra-steppe which has even colder winters. Very little of it can still be found today. The photo used as illustration is taken on the Ukok Plateau.
On subtropical latitudes (about 23 – 40 degrees north and south) the distribution of rain over the year matters. Generally the west sides of the continents get most rain in winter. The east sides instead have rainy season at the same time as they have summer. It rarely gets so cold there, it for example gets snowfall. At least not at low altitudes.
Plants are as such more or less adapted to the climate. This also applies to cultivated plants. They can only cope with a certain interval of temperature and moisture. Outside this interval they grow poorly or not at all. Is the time with the right conditions too short the plant dies before it produces what it is cultivated for. Such set boundaries for in which climate they can be grown. Even if the plant survives it may produce too little. Then it is still not worth it.
Moreover there are differences in the characteristics of the soil. It may contain too little nutrients for agriculture to be worth it. In some areas the nutrients are concentrated in the local vegetation. As soon as it ends up in the ground plants absorb it. So it is in most of the world’s tropical rainforest. Exceptions are along sediment transporting rivers which water level varies between different parts of the year. Alternatively the area has to be heavily volcanically active. Recurrent volcanic eruptions then make more plant nutrients form.
Nearly all arable land has formed naturally. Dead plants has decayed and mixed with decayed rock. Dust can be transported by wind from areas with sparse vegetation too. Sediment can be transported by water and accumulate on river plains and deltas. Regardless of which origin it has arable land have to be maintained. Unless rivers flood every year people have to do it themselves. Methods for this are crop rotation, companion planting and using fertiliser. Only using fertiliser requires very large amounts. Growing the same monoculture year after year on the same field appear for this reason as madness to me.
Uploaded on the 26th of February 2025.
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This site was last changed on the 29th of June 2025.