Species and populations are probably the two most commonly used ecology terms, but they are often difficult concepts to grasp. Throughout this chapter, they will be discussed in detail, expanding on the definitions from previous chapters and explaining why there are no universally acceptable definitions.
Jefferson County, Arkansas is a county located in the U.S. state of Arkansas in the area known as the Arkansas Delta, that extends west of the Mississippi River. As of the 2010 census, the population was 77,435. Its county seat and largest city is Pine Bluff. Jefferson County is Arkansas's 21st county, formed on November 2, 1829, from portions of Arkansas and Pulaski counties, and named for Thomas Jefferson, third President of the United States.
Van Buren County, AR has a population of 17,002 people with a median age of 47.1 and a median household income of $32,312. Between 2014 and 2015 the population of Van Buren County, AR declined from 17,090 to 17,002, a -0.51% decrease and its median household income grew from $31,030 to $32,312, a 4.13% increase.