Red Jungles
Located around volcanic vents, the Red Jungles of Ymir take their name from the red vegetation that dominates the landscape around them. Trees, bushes, even verns and moss, all plants in these areas have adapted to vented gases and the heavy metals in the soil. Some animals species appear to live well as long as they avoid the volcanic vents themselves, though it seems both herbivores and carnivores suffer long-term health complications due to the metals in their diets.
While the flora and fauna have adapted well, the Red Jungles have been labeled as too dangerous for human settlements. First of all, the soil can be unstable, so there is no telling when a new volcanic vent will appear, which is a threat to construction. Second, long-term health consequences on human bodies are not fully studied, but research by the Medical Laboratory suggests a minimum of 15 years of lifespan reduction, and the possibility of serious health complications within two years. As such, Red Jungles and all land within 10km have been banned from claiming by Homesteaders.
Additionally, the existence of Black Lung Moss makes these areas an even greater risk, as they are the source of many an Ursa Major stampede. When an older herbivore starts suffering from Black Lung, they tend to seek out carnivores. While Ursa Majors avoid Red Jungles, when an infected herbivore travels far enough, they may encounter a group of Ursa Majors and become the source of their infection.
Oh I like how the plants have adapted and taken on special colors but the animals have problems with eating them.
As a plant, you can just dump the toxin in your leaves and let it fall off. With animals, it tends to accumulate over time... And heavy metals in the soil is one of the things that can turn leaves red on Earth, so I cheated and just made it the same on Ymir. =)
Too low they build who build beneath the stars - Edward Young