The use of modern technologies, in this case wireless sensor networks, which can be part of the IoT concept (Internet of Things), promotes, simplifies and improves the quality and frequency of measurement or monitoring in all spheres of today, also in forestry. The possibility of continual monitoring, allows getting much more data of the observed parameters than with usual manual measurement methods, which further allows a more detailed analysis of the observed processes and phenomena. "Smart forests" are forests in which data are collected using various sensors, and further transmitted by wireless forms of communication to clouds for storage, processing and preparation for further use. The paper focuses on the possibility of using sensor networks and the IoT concept in forestry, especially in forest management in protected areas and protected area management, which usually requires a special approach. Texas Instrument’s (TI) design for ultra low-power (LP) wireless PIR motion detector TIDA-01398 and AiRiCOM’s STREGA LoRa Motion Detection sensor for motion detection are presented. Based on the informations from these sensors, besides the presence of people or veicles, the environmental conditions (as temperature) and movements in the forests (tree twisting caused by wind or bumps by trunks cused by illegal logging) can also be monitored. Detection of characteristic noises in forests deriving from presence of peolpe, illegal logging or using motor veicles can be monitored by sensor modules based on passive microphones gathered with adequate passive electronics (condenser micropfone, comparator with potentiometer). The selected examples applicable in the field of forest management in protected areas claim that wireless sensor networks gathered with the IoT concept open new opportunities for creating usful services in forest science.