CHALLAKERE, India — When laborers began excavating pastureland in India’s southern Karnataka state early in 2012, members of the nomadic Lambani tribe were startled. For centuries, the scarlet-robed herbalists and herders had freely crisscrossed the undulating meadows there, known askavals, and this uprooting of their landscape came without warning or explanation. By autumn, Puttaranga Setty, a wiry groundnut farmer from the village of Kallalli, encountered a barbed-wire fence blocking off a well-used trail. His neighbor, a herder, discovered that the road from this city to a nearby village had been diverted elsewhere. They rang Doddaullarti Karianna, a weaver who sits on one of the village councils that funnel India’s sprawling democracy of 1.25 billion down to the grassroots.