In the areas of road safety, fruit growing and forestry, there is an increased need for assessing the vitality of standing trees. Various dendro-acoustic emissions (DAEs) potentially allow conclusions to be drawn about the vitality of the trees and various diseases and pest infestations. All types of DAE events produce structure-borne sound inside the tree and can be automatically measured and evaluated by a piezoelectric sensor node attached to the tree trunk. The events are characterized by short, broadband cracking signals. Depending on the type of event, these differ in their number, strength and acoustic center frequency and can be separated from various types of background noise such as traffic, wind, rain, etc. In the frame of a German collaborative research project (TreeMon), an autonomous sensor prototype for long- and short-term monitoring using LoRaWAN technology was developed and successfully tested in the field. We present selected results of various test and field measurements at different trees, including several hardwood species like beech, birch and fruit trees. We compare temporal DAE profiles of single trees with simultaneously recorded weather, dendrometer and sap flow data and demonstrate first interesting correlations between them.