Materials and methods:
The sampling sites were shifting agriculture ‘jhum ’ fields of Tacchip village in Aizawl district of the state of Mizoram in North-east India (elevation: 810 meters; 21˚ 35.46ʹ N; 92˚43.07ʹE; mean annual precipitation: 2095 mm). This site had adjacent jhum fallows, which were abandoned after two years of cropping 5-, 8- and 20- years prior to this study. The vegetation composition and biomass of these fallows were different as the extent of re-growth differed depending upon the duration of the fallow. During March 2015, the vegetation in these fallows was cut, allowed to dry naturally for 25 days and burned by the farmers, and then cultivated with a mixed crop of rice (Oryza sativa ), maize (Zea mays ), arahar/pigeon pea (Cajanus cajan ).