Biome: the Loop-Grassland

It is 2.8 million Post-Abandonment, and all of Apterra's old prairie ecosystems are dead or dying. Woodlouse-grasslands cling to life in Ailuropia, sustaining only a tiny fraction of their former diversity. Rat-grasslands have fared even worse, persisting only in far-flung Choeropica where local sappybaras prevent their complete extinction. The surviving kiwizelles and derived Rattaloxen have established themselves in the taiga, though even it has been scattered into many pieces by the glaciers and tundra that continue pushing south. Gone is the Great Northern Taiga, but a similar ecology persists in southern Abeli and Sub-Abeli. This Great Southern Taiga is now Apterra's largest unified land biome. Ice sheets cover a quarter of the land, including nearly all of Unciolis and the Northern Isles. With all the world's shallow continental shelves already above the waterline following the Great Decarbonisation, few new territories have been exposed. Combined, this means that habitable land is at a premium. There is also great opportunity, though; whatever plant can recolonize the old rat- and woodlouse-grasslands will inherit an empty ecosystem with little competition. As it turns out, the genus most capable of exploiting this niche is the loop-grass.

The ancestors of the Wandering Loop-grass (Megadolius subdendrotorqueus) lived in the shadows for almost two million years. The loop-grass group evolved in the Middle Muricene from giant barrel-grasses that adapted to live in pseudoforest understories. Their meandering rhizomes created long chains of foliage, weaving their way into patches of light that peeked through the canopy. Many loop-grasses still employ this technique, finding success in both temperate and boreal hybrid forests. Until now, they failed to compete on the prairie due to their somewhat fragile foliage, which was unable to withstand direct sunlight. With the loss of Apterra's grasslands, though, individual loop-grasses with greater tolerance against ultraviolet radiation have spread far and wide.

There are two loop-grasslands: one Abeli and Loxodia, and a much smaller one in western Ailuropia. Each arose from a separate instance of a point mutation that allowed them to survive on the open plains. So successful were these two initial mutants that they were able to grow to immense sizes, reproducing vegetatively and quickly engulfing all the former rat-grassland and woodlouse-grassland regions. To this day, loop-grasslands are still composed of just a single individual, for their species only flowers when temperatures exceed 35 degrees, which has not occurred on Apterra for over 150,000 years at this point. The Abelian-Loxodian loop-grassland, though divided by mountain ranges, remains tenuously interconnected by a few narrow corridors, such as Abeli's northern coast and a variety of tiny mountain passes. 

Little lives on the loop-grassland aside from its namesake. M. subdendrotorqueus composes more than 99% of plant biomass, with only a small number of smokestalks, sodstalks, and sweetstalks filling in the gaps. Animal life is similarly scarce, with few rat-grassland and woodlouse-grassland species remaining. Castlebugs are frequently found here, as are dermestimimids and the Plague. Pestilarthrid isopods are especially common, regularly forming hordes that cut swathes of loop-grasses down to their roots. With few large skystalks and no palm-grasses left alive in the area, they've abandoned their bridgeworm companions, though such symbiosis does still occur in forested environments. 

A few populations of dustflies still survive here, though in very small numbers due to the scarcity of their preferred food source. Pansanguinophagous mosquitoes are present as well, feeding on the occasional kiwi or rat that passes by. The most common, though, are the descendants of Middle Muricene reapers. These Flagelloculicids once allied themselves with the Plague, but this mutualistic relationship broke apart when the climate began to change at the beginning of the Late Muricene. With jaws well-adapted to cut apart plant matter and little else, they had great difficulty securing food without the aid of Plague woodlice. Unable to hunt effectively, one group was forced to seek alternative forms of sustenance, turning to loop-grasses as an easily available (if nearly indigestible) option. When loop-grasslands exploded onto the scene about 30,000 years ago, the newly herbivorous reapers came along for the ride, becoming the loop-grassland's second-most-numerous herbivores. Though their feeding apparatus is crude and they can barely gain sustenance from their newfound diet, they are able to persist because of how few competitors exist here. Though this will certainly change as more clades expand into the loop-grassland, by that time the grazing reapers themselves will have evolved to become more efficient at processing plant matter, so they stand a decent chance of lasting beyond the Ice Age. 

The only vertebrates that play a major role in this ecosystem are basketbucks and beakbucks. The former, a basal Muridiungulate, once ate prairie basket-grasses and barrel-grasses on the rat-grassland. After surviving the Great Decarbonisation due to their small size, they eked out a living in the shadows of rattaloxen until the loop-grassland emerged, granting them the opportunity to become the largest rats in their habitat - though even now, none grow to more than ten kilos. Beakbucks, a massive species of kiwizelle, had already established themselves in other Ice Age biomes 100,000 years ago. Today, three lineages exist: the Woodlouse-Grassland Beakbuck (C. l. latirostris), being the nominate subspecies, lives a lifestyle similar to earlier beakbucks of the Late Muricene, while the Taiga Beakbuck (C. l. rhizophila) has changed little from their root-eating ancestors outlined previously. Loop-Grassland Beakbucks (C. l. fortis) are the largest of their species, reaching over 300 kilograms. They eat all parts of the loop-grass, including its leaves, roots, and inflorescences that never mature. As a result, no other grazers larger than ten kilograms can exist here. Small rodentian and avian predators can be found on occasion, and if the giant grassland terror kiwis still existed, they'd likely find it hospitable, but none of their surviving forest-dwelling cousins have yet recolonized the open plains.

Loop-Grasslands, despite their extensive size, will not last long. Like so many biomes that have risen and fallen on Apterra, they are doomed to collapse in a relatively short time. In this case, their fate has not been sealed by a changing climate, the rise of new animal clades, or any natural distaster, but rather by their own genes. With each passing year, deleterious mutations slowly build up within these superorganisms. Without sexual reproduction, this genetic damage will eventually result in the grass senescing. Old age and disease will wipe out the loop-grass, and all the other plants and animals that rely on the loop-grassland will either adapt to what comes next or find themselves becoming the next casualties of the Ice Age.