When do people take action? The importance of people's observation that nature is changing for pro-environmental behavior within the field of impersonal, environmental risk.
Prior experience has shown to be a highly influencing factor for risk perceptions and behavioral patterns. Yet, often prior experience is connected to a personal threat and damage. We assume that people's mere perception of nature changes, even if it is an impersonal risk and therefore not threatening humans but rather nature, is crucial for explaining effects in environmental and risk communication. A joint survey of biologists and communication scientists was conducted within a field experiment in two waves (N1=479; N2=295) in 12 German districts. Those regions differ in observable nature changes, evoked by the invasive moth Cameraria ohridella, which creates early leaf foliage on white flowering horse chestnut trees. Results show that the biological method, of deciding on sampling region, helps to define a sample of participants, who show different extents in nature change and risk perception. Further we could show that over a longitudinal design, nature change and risk perception increased, having slightly higher change scores in low infested areas, and that changed scores correlate with each other. Mediation analysis reveals that the overall effect of nature change perception on communicative and another active pro-environmental behavior is almost completely mediated by risk perception. Implementations of these results will be discussed.