It would give her faction's ecosystem more room to take root before the deadly struggle began in earnest.

This was not the first such competition. The Regals had held them for decades as an objective test of the skills of rival factions. It helped the Regals' divide-and-conquer policy, to set the factions against one another.

And in the centuries to come, as Mars grew more hospitable to life, the gardens would surge from their craters and spread across the surface. Mars would become a warring jungle of separate creations. For the Regals the competitions were closely studied simulations of the future.

And the competitions gave the factions motives for their work. With the garden wars to spur them, the ecological sciences had advanced enormously. Already, with the progress of science and taste, many of the oldest craters had become ecoaesthetic embarrassments.

The Ibis Crater had been an early, crude experiment. The faction that had created it was long gone, and its primitive creation was now considered tasteless.

Each gardening faction camped beside its own crater, struggling to bring it to life. But the competitions were a shortcut up the Ladder. The competitors' philosophies and talents, made into flesh, would carry out a proxy struggle for supremacy. The sine-wave curves of growth, the rallies and declines of expansion and extinction, would scroll across the monitors of the Regal judges like stock-market reports. This complex struggle would be weighed in each of its aspects: technological, philosophical, biological, and aesthetic. The winners would abandon their camps to take on Regal wealth and power. They would roam T-K's jeweled corridors and revel in its perquisites: extended life spans, corporate titles, cosmopolitan tolerance, and the interstellar patronage of the Investors.

When red dawn broke over the landscape, the five were poised around the Ibis Crater, awaiting the signal. The day was calm, with only a distant nexus of jet streams marring the sky. Mirasol watched pink-stained sunlight creep down the inside slope of the crater's western wall. In the mangrove thickets birds were beginning to stir.

Mirasol waited tensely. She had taken a position on the upper slopes of the landslide's raw debris. Radar showed her rivals spaced along the interior slopes: to her left, the hourglass crawler and the jewel-headed snake; to her right, a mantislike crawler and the globe on stilts.

The signal came, sudden as lightning: a meteor of ice shot from orbit and left a shock-wave cloud plume of ablated steam. Mirasol charged forward.

The Patternists' strategy was to concentrate on the upper slopes and the landslide's rubble, a marginal niche where they hoped to excel. Their cold crater in Syrtis Major had given them some expertise in alpine species, and they hoped to exploit this strength. The landslide's long slope, far above sea level, was to be their power base. The crawler lurched downslope, blasting out a fine spray of lichenophagous bacteria.

Suddenly the air was full of birds. Across the crater, the globe on stilts had rushed down to the waterline and was laying waste the mangroves. Fine wisps of smoke showed the slicing beam of a heavy laser.

Burst after burst of birds took wing, peeling from their nests to wheel and dip in terror. At first, their frenzied cries came as a high-pitched whisper. Then, as the fear spread, the screeching echoed and reechoed, building to a mindless surf of pain. In the crater's dawn-warmed air, the scarlet motes hung in their millions, swirling and coalescing like drops of blood in free-fall.

Mirasol scattered the seeds of alpine rock crops. The crawler picked its way down the talus, spraying fertilizer into cracks and crevices. She pried up boulders and released a scattering of invertebrates: nematodes, mites, sowbugs, altered millipedes. She splattered the rocks with gelatin to feed them until the mosses and ferns took hold.

The cries of the birds were appalling. Downslope the other factions were thrashing in the muck at sea level, wreaking havoc, destroying the mangroves so that their own creations could take hold. The great snake looped and ducked through the canopy, knotting itself, ripping up swathes of mangroves by the roots. As Mirasol watched, the top of its faceted head burst open and released a cloud of bats.

The mantis crawler was methodically marching along the borders of its sector, its saw-edged arms reducing everything before it into kindling. The hourglass crawler had slashed through its territory, leaving a muddy network of fire zones. Behind it rose a wall of smoke.

It was a daring ploy. Sterilizing the sector by fire might give the new biome a slight advantage. Even a small boost could be crucial as exponential rates of growth took hold. But the Ibis Crater was a closed system. The use of fire required great care. There was only so much air within the bowl.

Mirasol worked grimly. Insects were next. They were often neglected in favor of massive sea beasts or flashy predators, but in terms of biomass, gram by gram, insects could overwhelm. She blasted a carton downslope to the shore, where it melted, releasing aquatic termites. She shoved aside flat shelves of rock, planting egg cases below their sun-warmed surfaces. She released a cloud of leaf-eating midges, their tiny bodies packed with bacteria. Within the crawler's belly, rack after automatic rack was thawed and fired through nozzles, dropped through spiracles or planted in the holes jabbed by picklike feet.

Each faction was releasing a potential world. Near the water's edge, the mantis had released a pair of things like giant black sail planes. They were swooping through the clouds of ibis, opening great sieved mouths. On the islands in the center of the crater's lake, scaled walruses clambered on the rocks, blowing steam. The stilt ball was laying out an orchard in the mangroves' wreckage. The snake had taken to the water, its faceted head leaving a wake of V-waves.

In the hourglass sector, smoke continued to rise. The fires were spreading, and the spider ran frantically along its network of zones. Mirasol watched the movement of the smoke as she released a horde of marmots and rock squirrels.

A mistake had been made. As the smoky air gushed upward in the feeble Martian gravity, a fierce valley wind of cold air from the heights flowed downward to fill the vacuum. The mangroves burned fiercely. Shattered networks of flaming branches were flying into the air.

The spider charged into the flames, smashing and trampling. Mirasol laughed, imagining demerits piling up in the judges' data banks. Her talus slopes were safe from fire. There was nothing to burn.

The ibis flock had formed a great wheeling ring above the shore. Within their scattered ranks flitted the dark shapes of airborne predators. The long plume of steam from the meteor had begun to twist and break. A sullen wind was building up.

Fire had broken out in the snake's sector. The snake was swimming in the sea's muddy waters, surrounded by bales of bright-green kelp. Before its pilot noticed, fire was already roaring through a great piled heap of the wreckage it had left on shore. There were no windbreaks left. Air poured down the denuded slope. The smoke column guttered and twisted, its black clouds alive with sparks.

A flock of ibis plunged into the cloud. Only a handful emerged; some of them were flaming visibly. Mirasol began to know fear. As smoke rose to the crater's rim, it cooled and started to fall outward and downward. A vertical whirlwind was forming, a torus of hot smoke and cold wind.

The crawler scattered seed-packed hay for pygmy mountain goats. Just before her an ibis fell from the sky with a dark squirming shape, all claws and teeth, clinging to its neck. She rushed forward and crushed the predator, then stopped and stared distractedly across the crater.