Silurian-Devonian Terrestrial Revolution
[8] Herbivory, granivory and detritivory subsequently evolved independently among terrestrial arthropods (especially hexapods such as insects, as well as myriapods), molluscs (land snails and slugs) and tetrapod vertebrates, causing plants to in turn develop defenses against foraging by animals.
The nutrient-distributing glomeromycotan mycorrhizal networks of nematophytes were very likely to have acted as facilitators for the expansion of plants into terrestrial environments, which followed the colonising fungi.
[13] The earliest radiations of the first land plants, also known as embryophytes, were bryophytes, which began to transform terrestrial environments and the global climate in the Ordovician.
[18] The end of the Homerian glaciation, a glacial phase of the Early Palaeozoic Ice Age, and the corresponding period of global warming marked the first major diversification of plants that produced trilete spores.
The later glaciation during the middle Ludfordian, corresponding to the Lau event, led to a major marine regression, creating significant areas of new dry land habitat that were colonised by plants, along with cyanobacterial mats.
Basal members of Euphyllophytina, the clade that includes trimerophytes, ferns, progymnosperms, and seed plants, are known from Early Devonian fossils.
[13] Early Devonian plant communities were generally similar regardless of what landmass they inhabited,[29] although zosterophyllopsids displayed high levels of endemism.
[9] Seed ferns and true leaf-bearing plants such as progymnosperms also appeared at this time and became dominant in many habitats, particularly archeopteridaleans, which were likely related to conifers.
[36] Archeopteridaleans had likely developed extensive root systems, making them resistant to drought, and meaning they had a more significant impact on Devonian soil environments than pseudosporochnaleans.
Expansion of terrestrial Devonian flora modified soil properties, increasing silicate weathering by way of rhizosphere development as evidenced by pedogenic carbonates.
[48][49] This caused atmospheric CO2 levels to fall from around 6300 to 2100 ppmv, although it also drastically reduced the albedo of much of Earth's land surface, retarding the cooling effects of this greenhouse gas drawdown.
[50] The biological sequestration of so much carbon dioxide resulted in the beginning of the Late Palaeozoic Ice Age at the terminus of the Devonian,[51][52][53] together with the tectonic uplift of the continent Gondwana.
[55] Some palaeoclimatic simulations have found that depending on the circumstances, the spread of plants could temporarily increase pCO2 by promoting regolith growth that would hinder the ability of water containing dissolved carbon dioxide to percolate into bedrock.
[61] The rise of trees and forests caused greater amounts of fine sediment particles to be retained on alluvial plains, increasing the complexity of meandering and braided fluvial systems.
The expansion of trees in the Late Devonian drastically increased biological weathering rates and the consequent riverine input of nutrients into the ocean.
[63][64][65] The altering of soil composition created anoxic sedimentation (or black shales), oceanic acidification, and global climate changes.
