Mountain environments comprise a great variety of environments and unique taxa, which are facing significant threats due to Global Change. In this sense, long-term monitoring projects are crucial for capturing biodiversity trends and their temporal variability, as they are the basis for understanding the populations’ dynamics and viability. The citizen science project “Adopt a Plant” was launched in northeast Spain in 2013. Coordinated by scientists from the Pyrenean Institute of Ecology (CSIC), this monitoring network aims to maintain a collaborative system where volunteers and rangers monitor plant populations’ dynamics and possible threats. This project includes ~350 populations of ~200 plant species distributed over a broad range of habitats, from semi-desert to high alpine in Euro-Siberian and Mediterranean regions, and involves 209 participants. Given the success of the project, we are now expanding the network to nearby territories by collaborating with other researchers, in order to enhance interoperability. Citizen science projects are a key tool not only for obtaining huge amounts of data of interest for species conservation and the scientific community but also for boosting environmental education in society. Moreover, the project “Adopt a plant” is part of BIOTREND, a national project also led by the same Institution, which coordinates more than 25 research teams and naturalist societies monitoring plant and animal’s dynamics all over Spain. This kind of collaborative projects allow the integration of society, researchers and managers to the scientific study of the anthropogenic effect on population trends and vulnerability at large spatial and temporal scale.