While most people consider Terre Haute as a whole entity, the property encompasses several distinct and different ecosystems - lowland marshes, high ridgelines and slopes, vernal pools and mature hardwood forest all interconnect and thrive from the diverse species of plants and animals that comprise them. Each individual ecosystem is dependent on the others for its continued survival. How vibrant is this ecosystem? In a 24 hour "BioBlitz" survey conducted in Spring 2001, the adjacent (and very similar) Tarrywile Park set a record for the most species of plants and wildlife ever recorded in a non-rural setting. Preserving this biodiversity is a key goal of PATH.

Vernal pools are perhaps the most rare and sensitive of these ecosystems. The pools appear in wet seasons– after rainfalls and snowmelts when the water table is at its highest. The pools are only a few inches deep, but are the home and breeding grounds for a variety of insects and amphibians - that in turn are a major food source for birds and mammals. Rapid overdevelopment of much of the east coast has removed many former vernal pools, reducing species populations over a relatively short period of time. Development of this land could easily disrupt the water table, endangering the pools and the life they support.