The evolution of trees

How long have trees existed in the world?

First plants

It all began when the first living things stirred three billion years ago, then tiny green plants developed in the primordial oceans. These algae remained the only form of vegetation there until some left the seas at an unknown time and settled on the mainland. Helpers in this colonization may have been fungi, as symbiotic partners within lichens. Lichens consist of at least three or also several partners, whereby always fungi are involved and also algae and/or special bacteria (cyanobacteria, green algae). 400 million years ago these land plants developed vascular systems – conduit cells for the transport of water and nutrients. Over the next 50 million years, these first plants (lycopods, horsetails, ferns, …) grew larger and larger, forming roots, shoots, and leaves. Some developed a hard, woody tissue that reinforced the main shoot: about 350 million years ago, there were the first trees similar plants and forests.

Small forms of the horsetail still exist today. Here is the largest species found in our area, the giant horsetail. These specimens are about 1.5 m high.

First trees – fern, horsetail & co.

These early trees similars needed a moist environment to reproduce (like ferns still do today). One example is the Gilboa tree (named after the place where it was found in New York State/USA). It originated about 385 million years ago and resembled today’s tree ferns. It grew up to 8 m high, had a simple root system and operated a primitive kind of photosynthesis. According to scientific definition, however, these were not yet trees, just as palms are not included in this group.

Today’s fern trees in South Africa. (Photo: Hans Schuster)

Gymnosperms – needles and cones

The next stage of development were the gymnosperms (gymnosperms). They were no longer dependent on water for reproduction. Their seeds had protective coverings and nutrients for the seedling and could therefore survive long periods of drought unharmed.

Most species of gymnosperms still found today are NEEDLE TREES or conifers. (Conifer means „cone-bearer,“ from Latin conus „cone, cone“ and ferre „to bear.“) They have needles and their seeds are usually in cones. These plants usually depend on the wind for pollination.

Neither deciduous trees nor conifers include the GINGKOS, they form a separate group more closely related to conifers (!). 150 million years ago, the Gingko tree flourished all over the world. The Gingko biloba (you can find a specimen in the Museum´s Park), native to China, planted all over the world, is the only living representative of the Ginkogoales of an otherwise extinct group of seed plants. It is therefore also known as a „living fossil“.

 

The fanleaf tree, native to China, is the last survivor of the tree genus Gingko. Here, the ginkgo in the museum´s park in bright golden-yellow autumn colors.

 

flowering trees – flowering dreams

The most recent evolution was flowering plants or angiosperms (angiosperms, here the seeds are enclosed in a ovary e.g. in an apple). Flowering plants are the result of co-evolution: they need insects (or birds, bats and lizards) for pollination, and the insects need the pollen and nectar from these plants to survive. Forests with flowering trees were already widespread 120 million years ago.

Tree age  in Central Europe

The development of the angiosperms (angiosperms, flowering plants) was the last big step of development in the realm of plants and therefore trees. A never again reached abundance of vegetation determined this period. Many deposits of fossil energy (anthracite, brown and hard coal, crude oil) originate from this time.

About 60 million years ago, oak, maple, walnut and fig trees began to establish themselves. There was an extremely favorable climate for our trees.

The big frost – ice age

Then, about 1.8 million years ago, at the end of the Tertiary, things got uncomfortable: at least 4 major and many minor ice ages froze all trees. Some species „fled“ to the south of Europe, some became extinct in Europe altogether and have recently been re-imported and planted by people from other continents, such as the magnolia, the amber tree or the tulip tree.

Pioneers and the hazel and beech period

After the end of the last ice age, about 12 000 years ago, pioneer tree species around the Alps managed to return from their „hiding place“ in warm southern Europe. The first to return were the pioneer tree species, pine and birch, around 8,000 BC. They were then joined by the hazelnut, so that around 6 000 BC we can speak of a „hazel age“.

In the Neolithic Age (~ 6 000 – 3 000 B.C.) a climatic optimum had been reached, in which a mixed oak forest with lime, elm, maple and ash had spread.

In the Bronze Age (~ 2 000 BC – 0) it became cooler again. Beech trees coped particularly well with this. Since about 800 B.C. until today the predominant tree species in our country (of course not in the high mountains) is the beech. Massive plantations by man changed this forest pattern in favor of pine and spruce. Currently, global warming seems to be bringing an end to the beech age.

 

Sources : Jake Page u. A. „Der Planet Erde. Wälder“, Time Life Books, 1984.
Doris Laudert „Mythos Baum“, BLV, 2003.