As a habitat type, the vernal pool is something particularly special. A vernal pool is formed when a low area develops a hard, impermeable sub-surface layer that allows water to accumulate during the wet season, which in most of California is the winter. What makes vernal pools so special is that they are transient communities, bursting into life during the brief period of water availability, before dying back when the water dries up. This boom and bust cycle leads to short but spectacular displays of flowers when the pools are filled.
Many of the plants found in vernal pools are found nowhere else, making them exceptionally valuable as havens of biodiversity. However, many of the vernal pools are imperiled, due to human activity. Grazing in vernal pool habitat and development both have a serious, negative effect on the pools, from disruption to outright destruction. As such, it is of the utmost importance that the remaining pools are protected as well as studied to ensure that what is left doesn't vanish without a trace.