Groundwater salinisation intensifies drought impacts in forests and reduces refuge capacity

1. Shallow groundwater aquifers regularly support drought refuges for water-dependent ecosystems. However, many aquifers are impacted by over-extraction and pollution, potentially degrading their ability to support groundwater-fed drought refuges. 2. We investigated the response of groundwater-connected riverine forests to a drought considered equivalent in intensity to those predicted under severe climate change for 2030. The drought's impact was investigated in an area where shallow groundwater resources are heavily exploited and polluted by salinization. 3. We used remotely sensed vegetation productivity (enhanced vegetation index) data from a long-term data set (2000–2011) at 475 riverine forest sites in the Campaspe catchment, south-eastern Australia. Generalized additive mixed models and boosted regression trees were used to model the relationship between groundwater and other environmental covariates with forest change during drought. 4. Models explained up to 44% of the variatio...