[in Dutch with English abstract: ] This article concerns Solleveld, a small dune area south of The Hague. Solleveld includes a quite narrow stretch of calcareous dunes near the sea and, on the inland side, a larger stretch of non-calcareous dune grasslands, heath vegetation and dune forests. The grasslands and heath vegetation have a well-developed lichen soil vegetation including many species of Cladonia. The article compares two lichen inventories, the first executed in the year 2012, the second in the year 2020. The reason for the first inventory was the construction of a large sandbank, shaped as a peninsula and known as the Sand Motor, on the coast near Solleveld in 2011. This sandbank is meant to act as a sand supply for coastal reinforcement. It is expected that ocean streams, wind and waves will gradually spread the sand along the coast. The first inventory was intended as a baseline measurement for monitoring the possible effect of the Sand Motor on the lichen flora of Solleveld. The results of the second inventory are studied and compared with the results of the first one. The differences are analysed, and an attempt is made to correlate the results with changes in the sand-spray (lime fragments) and salt-spray on Solleveld due to the Sand Motor. Other causes of changes in Solleveld’s abiotic factors are studied as well, such as the effect of a high nitrogen load. The effect of the nitrogen load is studied using two index values, one that calculates an index concerning acidophilic lichens on tree trunks (AIW) and another that calculates an index concerning nitrophilous lichens on tree trunks (NIW). The possible effect of the Sand Motor is also studied using two index values, one that computes a covering factor for calcicole soil lichens (KHI) and another that computes a covering factor for calcifuge soil lichens (KAI). The mean calculated value of the AIW showed a decrease of 12% when comparing the results of the two inventories and the NIW showed an increase of 76%. These differences are very likely caused by the high nitrogen load. The mean calculated value of the KHI showed an increase of 40% and the KAI showed am decrease of 26%. The changes in KHI and KAI values are probably due to a combination of abiotic factors. In my opinion the main contribution to the differences is caused by the spray of lime fragments from the Sand Motor.