Pocketwoods (Telmatodendron) are a genus of derived hybrid trees that support Apterra's most diverse temperate ecosystem so far. They are the most massive and longest-lived woodlouse-grasses, though they don't reach the heights of some of their faster-growing cousins. The life cycle of a pocketwood tree begins typically for a palm-grass, with secondary growth commencing after its second or third winter. Over the coming years, fungal activity on the plant's surface accelerates, and the width of the lowest internodes can exceed a meter before the tree reaches its tenth birthday. In any other hybrid tree, this would soon lead to the death of the plant, which would be prone to breaking at their brittle nodes under the stresses of wind, rain, and foraging megafauna. But the pocketwood presses on, with its ever-growing smooth sections forming into "lips" that gradually engulf the nodes, eventually meeting in the middle and fusing together to form a continuous, sturdy exterior. Once fully formed, this structure can easily support the full weight of the tree. The pocketwood can then continue growing outward, but it never completely fills in the space between the nodes and the outer shell of secondary growth. The "lips" also leave two small unsealed gaps, one facing upward and one downward, allowing water to flow in and out of these chambers. This reduces the risk of rot and infection, and it also creates a home for smaller organisms. Over the course of a single tree's 200-plus-year lifespan, each of its pockets may see dozens of species of vertebrate inhabitants come and go, along with an even greater assortment of invertebrates and microbes.
A pocketwood tree sprouts from a small grain that came to rest on the shady forest floor last fall. This particular patch of woods is located in the foothills of the mid-Abelian mountains, where pocketwoods are most numerous, but the genus can be found worldwide. Its seed leaf soon reaches about five centimeters above the soil, soaking in the energy the plant will need to grow its stem and foliage. By the end of spring, a half-meter trunk supports an initial whorl of pointy, sharp-edged blades. This funnel traps up to 250 milliliters of water, a trait shared by most large-leaved Apterran trees. This immediately supports colonies of unicellular organisms like amoebae and Paramecium, followed shortly thereafter by rotifers, copepods, and water fleas. Summer rainfall keeps the tank full for months, and algae soon coats the submerged leaf surfaces. Now mosquito larvae have a reliable food source, and they grow quickly in their protected home, choking the phytotelma with their squirming bodies before pupating and flying off. It's now late summer, and the sapling is ready to grow once again, pushing another meter upward into the understory just a few weeks ahead of the first frost. The new leaves do not unfurl; they'll remain in a tightly-packed bud until springtime. The older ones will keep photosynthesizing into autumn, only falling off once snow begins to blanket the ground.
In the meantime, the funnel, still barren from overgrazing, is discovered by a large songbug. The insect, a male Stridulark (Melodiopteryx sequiens), chirps to alert his partner that he's discovered a suitable location to raise their young. Amphibiinsects, with their food-fetching behaviors, are the only mosquitoes capable of raising a clutch here this late in the season. In the case of the stridularks, this food primarily consists of seeds less than two millimeters in diameter, though smaller arthropods are also on the menu. The female deposits four large eggs, each of which hatches into a larva already upwards of a centimeter long. In optimal conditions, fed from the fall crop of seeds and cold-intolerant bugs that die during the first cold nights, the young could leave the water in as little as two days. Unfortunately, the growing flies are never destined to leave the tree. Instead, they will fall victim to another amphibiinsect that lives and grows alongside them.
The Cuculex (Cuculex absconditus) is a more basal member of the subfamily, with ancestors possessing less-developed parental care. While most non-songbug amphibiinsects have been outcompeted by their singing relatives, this genus has clung on by becoming brood parasites. Several weeks before the stridularks arrived, a mother cuculex traveled across the forest, depositing one of her eggs in every pocketwood funnel she could find. The embryo developed but did not hatch, remaining dormant until it detected the scent of another amphibiinsect nesting in its home. Initially much smaller than the stridulark larvae, it had no choice but to attack one, using its deadly serrated mouthparts to devour its body when the adults were away. This meal allowed it to grow fourfold in a single night, after which it could pose as the deceased songbug. By now, the stridulark parents have accepted the intruder as their own, feeding it a rich diet and keeping it safe from predators. As its appetite increases, it eventually consumes its other adoptive siblings. Finally, it pupates and emerges as a subadult cuculex, setting out in search of a place to wait out the coming winter. But before it can even take off, it's snagged by a flying hunter that swoops down from the larger trees above. The assailant is a Culikestrel (Circumspector desuprus), a diminutive falconfly that represents the adult form of the larvae that inhabited the pocketwood before the amphibiinsects.
Over the next few months, activity in the forest dies down as most organisms either die or enter a dormant state. The tree exhibits no growth until the days begin to lengthen again, when it finally opens its whorl, getting a head start on photosynthesis over other plants that must first grow new foliage. The next several years will see a similar growth pattern and similar inhabitants. Its first self-contained trunk cavity won't be finished forming until its seventh spring. This immediately invites a new host of animals looking to take advantage of the shelter. The first to arrive are omnivorous Abelitherian rats of the species Notoabelitherium communalis. These Communal Abelitheres build extensive but short-lived colonies in mid-stage pocketwoods, usually starting when a young couple arrives at a tree before any other vertebrate discovers it. They reproduce quickly, and their descendants soon fill the hollow, with numbers reaching as high as 70 before they exhaust all food in the vicinity. No new members are allowed into the colony, so individuals mate with their own close relatives. Like all rats, the genome of communal abelitheres is resistant to inbreeding depression, but genetic diversity is still beneficial. Thus, when food runs out, all colony members disperse, wandering the forest until they find a new unrelated mate to settle down with and start the whole process over, though the majority are doomed to starve before finding a suitable home.
Once the rats have vacated the tree, species with slower reproductive rates can take over in their absence. The lowermost chamber may change ownership many times over the coming years, as both arboreal and ground-dwelling species take refuge for days, weeks, or months. Newly-independent chicks of large bird species are especially common, using it as their first safe place away from the protection of their parents. However, its place in such a high-competition location makes this pocket unsuitable for longer-term habitation, even for birds and mammals small enough to fit inside it as adults. But after just a few more years, other chambers have been enclosed higher up the trunk, and these are much more appealing to creatures looking for a permanent residence. Cavity-nesting downlings are the most common occupants, followed by arboreal Loxoditheres and the occasional large castlebug. All the species that have lived in or on this tree so far have either been commensalists or unintentional mutualists, but now a new arrival poses a serious risk. It's a species of non-downling pillbird called the Burglarbird (Dolosapteryx intrusor). Like many of its cousins, it builds nests of twigs and leaves within the safety of pocketwood cavities. It typically takes the highest available real estate on a still-growing pocketwood, ensuring the nest will be situated roughly halfway up the tree when it matures. This bird does not simply use the pocketwood as a refuge; it is a parasite, robbing the tree of its vital isopod-based immune system. The arboreal isopods first arrived during the tree's second year and, until now, had faced no real threats. Many species have moved in; pocketwoods have such varied microhabitats that dozens of different Scansoriarthriform colonies can share it without competing. All now find themselves at the mercy of the burglarbird, whose scent is nearly indistinguishable from its non-problematic relatives. Similarly, neither the tree itself nor its growth-inducing fungus have any specific defense mechanisms against this intruder.
However, the three-way mutualism has a more generalized defense mechanism that might just be enough to save it. Nectar begins to build up on the trunk, as few woodlice remain to eat it. This triggers an overgrowth of Dendrifex hyphae on the surface, which in turn release large spore clouds. These spores are a signal to arboreal woodlice in neighboring trees, which understand their distinctive scent as a sign that newly-open real estate is available. Swarms begin to amass, and they aren't picky about what species they kill. They kill or drive away every animal in the pocketwood, leaving it barren of any life aside from themselves. This instinct to become hyper-aggressive upon entering new territory was likely selected for by the fact that any tree of significant size without established isopod colonies is almost certainly facing some threat. Thus, newcomers that engage in indiscriminate violence end up preserving their new home more effectively than those that remain as cautious as they would be in their established territories. For its part, the burglarbird moves on; it's small and quick enough to escape with relative ease once it finds itself outmatched. But in the few months it occupied the pocketwood, it successfully hatched three chicks, though only one was able to grow quickly enough to flee with its mother.
The pocketwood reaches its full height of twelve meters in as many years, hidden beneath the canopy of other trees and pseudotrees. Its main stem, containing a dozen spacious chambers, is now called home by a wide variety of birds and mammals, most of which leave the tree daily to forage in the surrounding forest. When they return, their waste fertilizes the tree, allowing its crown to expand quickly. From the top of its trunk emerge seven long branches that grow horizontally, allowing the tree to gather light from a much wider area. Each of these lives only three or four years before being overshadowed by a newer branch, after which the old limb falls off and rots on the ground around the tree. Over many years, this builds a mound of fertile soil around the pocketwood, providing nourishment to decomposers and other shade-tolerant plants. The lowermost chamber is slowly buried, becoming a home to fossorial animals like groundgeese. When the tree finally dies after at least another century, all the resources it had amassed from the droppings of its inhabitants will slowly make their way back into the wider ecosystem, feeding yet another generation of life in the pocketwoodland.