They all seem to be artificial constructions made in wild areas towards the purpose of making it more suitable for people. Igloos are “huts” made of snow, traditionally used by natives in the north, although not so common anymore I think. Maize is corn, an agricultural product common in north America and the result of the last three. The last 3 are all systems of agricultural productions, which would have effected the environment. Slash-and-burn, as the name suggests, involved slashing and burning heavily forested area to make into suitable farm land. Chinampa is a system of making square suitable areas in marshland. Irrigation is a system of changing the land to bring water from its original place to a more suitable location for farming. All three have dramatic effects on the land, turning forests and marshes into plains and dry land into something more like a marsh or wetland. All of which of course effects the local wildlife.