After the boom-bust-boom of the fifties and sixties, the borough went into a third and more severe decline again in the mid-1970s along with much of the Rust Belt so that population was just 2,804 at the 2000 census. Now in the 2011 Brownsville still has a handful of buildings condemened or just borded up.
Threats to Biodiversity. The primary threats to the savanna biome are humans (for example, poachers are killing elephants for their ivory tusks and hunting animals to the brink of extinction) and global climate change.
Savannas, characterized by a grassy prairie-type ground cover underneath an open tree canopy, were common in northeastern Illinois. Scattered out on the prairie were patches of rich forests completely surrounded by prairie; these forests are called prairie groves.Prairies developed and were maintained under the influence of three major non-biological stresses: climate, grazing, and fire.Occurring in the central part of North America, prairies are subject to extreme ranges of temperatures, with hot summers and cold winters.rairies developed and were maintained under the influence of three major non-biological stresses: climate, grazing, and fire. Occurring in the central part of North America, prairies are subject to extreme ranges of temperatures, with hot summers and cold winters.