Archaeologists working in the vast coniferous uplands of the American Southwest have commonly assumed that the subsistence economies of the prehistoric peoples who dwelt there focused on corn (Zea mays) agriculture, the erratic yields of which were supplemented with the unintensive collection of wild plants. In this paper, we develop an alternative to this orthodox view, in which we posit that human-controlled burning of understory biomass was a vegetation-community and successional-stage management strategy intended to propagate wild plants in bulk quantities. By comparing the relative frequencies and ubiquities of macrobotanical remains recovered from a variety of storage and consumption contexts with pollen frequencies from production and processing contexts, we show that the systematic encouragement of ruderals in pyrogenic resource patches ('niches') was a sustainable practice that overcame natural limitations to biomass productivity and corn cultivation in pinyon-juniper (Pinus edulis and Juniperus sp.) woodlands. Importantly, these analyses indicate that low-intensity burning was a key aspect of fire-reliant subsistence economies that generated anthropogenic ecosystems whose composition and productivity were markedly different from today's.