Plants

Permian

2nd Wave Palaeosols Wood Rot Animals

Early Conifers

This period began with the Carboniferous flora still flourishing, but the swamp-loving lycopod trees were progressively replaced in the continental interior by the more advanced seed ferns and early conifers. They reproduce using cones rather than flowers and fruit. There are nearly 600 known species, many of which radiated in this period, including the ancestors of many present-day families. The plants of this period did not rely on or interact with creatures for their existence. Ginkgo also evolved in this era before flowering plants, when ferns, cycads, and cycadeoids dominated disturbed streamside environments, forming low, open, shrubby canopies. This would be ideal conditions and place for making more soil.

Conifers

Conifers can withstand cold and dry conditions. Their roots are dense and go down about a metre, but can get deeper in drier conditions. They spread vertically and horizontally and have surprisingly strong roots and in search of water, following cracks, will create damage - as many people in new housing estates know to their cost. They can cover an area 3X the tree cover, making them very resistant to storms, although the tap root plays its part.

Present day conifers have mycorrhizal relations, so we can presume the relation goes back to this period, as their endomycorrhiza have been around for a hundred million years. A higher rhizosphere SOC quality of conifers was found in the mixed conifer plantation compared to the pure plantation. The microbial necromass efficacy (dead fungal contribution of to SOC) in the rhizosphere of two root functional modules (i.e. absorptive roots and transport roots) in the bulk soil in an alpine coniferous forest found the roots absorbing water and nutrients contributed more than the roots just transporting them (Li et al., 2022)

What does this tell us about soils then? The horizontal branching roots look capable of following cracks to break rocks thereby adding lumps of them to the soil mix. The tap roots do not seem as strong but instead grow where the soil structure allows, that now seems to be deeper offering further support for the tall trees. Soils could now be a couple of metres deep in places, with boulders going in the mix.

Tap roots

Some coniferous trees produce tap roots, especially when growing in deep soils. Several pine (Pinus spp.) trees develop taproots – a single root growing straight down, under certain growing conditions. The longleaf pine (P. palustris) grows to 100 feet tall with a 12-foot-long taproot. This tree lives for up to 300 years. Other firs can grow over 200 feet, live for hundreds of years and have taproots in deep soil. Similarly, Giant Sequoias can also live in hardy conditions for hundreds of years and also have a taproot in deep soil. The taproot of the longleaf pine may reach 8 to 12 feet at maturity. Tap roots also provide another important function. They tap water deep down, which means they can withstand dry conditions better than those with only superficial roots. Many desert plants can send roots down more than 25 metres allowing them to find water, even in dry climates or conditions. Taproots can also serve to store food reserves, making them even more self-sufficient and resilient. This would have been crucial to those conifers growing into the arid hinterland. It also means they are capable of withstanding the mixture of dry/wet and cold/warm conditions, which seem to be a property of this period.

Glossopterids

The rapid appearance, expansion, and relatively quick extinction of this group, as well as the large number of species, has made the group very important for understanding paleobiogeography, specifically in the recognition of areas that were once connected together.

Species of Glossopteris were the dominant trees of the middle to high-latitude lowland vegetation across the super southern continent Gondwana during the Permian Period.

They are called Glossopterids because of their tongue-like leaves

Rich forests were present in many areas, with a diverse mix of plant groups. Oxygen levels were probably high there. The ginkgos and cycads also appeared during this period.

Glossopterids (dark green)
Gondwana now S.America Africa & Australia

Keystone species

“The primary producers were dominantly tree-sized glossopterid gymnosperms(fossil conifers) together with a significant proportion of Cordaitales (we saw earlier) of similar stature. Less abundant understorey elements of the flora included ferns and herbaceous lycophytes.

Fungi and fungi-like organisms appear to have played key roles in nutrient cycling through saprotrophy, and possibly via mycorrhizal interactions with the plants encouraging soil animals

The Glossopteris trees themselves appear to have been the keystone species within the ecosystem, since many groups of arthropods and fungal saprotrophs fed directly or indirectly on both the living and decaying tissues of the Glossopteris plants,… the energy flux and consumer activity in this ecosystem likely varied greatly on a seasonal basis”. (Slater, Mcloughlin, and Hilton, 2015)

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