Measurements in two different mature forests have been performed, considering a pine forest and a eucalyptus forest. The peer-to-peer scenario used responds to the current needing of radio data for network planning: there exist much information about propagation in vegetation in base station to mobile terminal (master-slave) configurations, but there is a lack in peer-to-peer configurations. The current trends in wireless networking in open environments, with growing interest to sensor networks, support the performing of such research work. The attenuation with distance between transmitter and receiver within the forests resulted to follows an exponent n=3.3 in the case of pine forest and n=3.6 in the case of eucalyptus one. This data is different than expected by ITU-R recommendation P.833-4, which uses lower frequencies in its input data, other type of trees, and different configurations.