Soil moisture data from grass treatment and control sites in a cloud-affected restoration site at Nakula, Maui, 2016-2019

Fog has been demonstrated to support plant growth, survival and ecosystem maintenance spanning rainfall and elevation gradients across the world. Persistent fog and strong winds on high mountain slopes in Hawaiʻi create a unique ecological environment. To better understand the effect of fog and rainfall on soil moisture responses, we installed six soil moisture sensors across three sites at a depth of 5 cm. We condensed soil moisture data into mean daily responses (increase/decrease) and compared these to days classified by precipitation type (clear, fog, rain, or rain + fog). To explicitly test whether non-native grass removal affected responsiveness of surface soils to precipitation events, we then identified days when soil moisture increased or decreased, grouping observations from grass treatment/grass control plots and compared these to days classified by precipitation type, described above.