| Intensive forestry in Sweden significantly affect ecosystems and water quality. In particular Norway spruce stands are known for their strong contribution to water brownification - an increase in dissolved organic carbon (DOC) and other contaminants in the soil. In contrast, broadleaved species are believed to filter out more nutrients and contaminants and release less DOC from their root systems. Forest management strategies such as continuous cover forestry (CCF) and sustainable use of riparian buffer zones may help address the issue of deteriorating water quality. However, the exact mechanisms behind tree root exudation affecting water quality, the differences between species, and the effects of drought on these processes remain poorly understood.
This project aims to investigate how different tree species and drought conditions affect forest runoff water quality by examining the physiological and biochemical drivers that influence root exudation and DOC production in the soil.
This research project addresses a critical gap in our understanding of how tree species and climate-induced droughts influence root exudation and soil water quality. While most root exudate research has focused on annual crops, this project shifts attention to trees—particularly those relevant for Swedish production forests and riparian buffer zones. Through a combination of controlled greenhouse experiments and mature forest field studies, the project will assess species-specific physiological responses to drought, exudation rates and compositions, and resulting impacts on soil water quality, including DOC and nutrient levels.
The interactions between tree species and climate-induced drought will be studied from a root-to-soil water perspective. First, in a controlled greenhouse setting, the physiological mechanisms behind drought-induced root exudation will be studied across a wide range of species - from widely used conifers to promising future production species and riparian buffer zone trees. The effects of species identity and drought will be assessed based on their influence on soil water quality, particularly brownification and the concentration and composition of the root exudates released into the soil. Second, species-specific differences will be investigated in mature forest stands, where soil properties and root exudation profiles will be measured in plots dominated by different tree species.
The project will lead to a better understanding of how specific species influence soil water quality, with respect to carbon compounds and contaminant concentrations. The alarming decline in drinking water quality in southern Sweden, evidenced by increased brownification, highlights the relevance and urgency of studying forestry’s role in water conservation. The project will be carried out by a promising young researcher with expertise in fast-growing broadleaved species and their interactions with the soil, mentored by a leading researcher in the field of tree ecophysiology. Ultimately, this research will support more informed decisions on species selection in production stands and riparian buffer zones. This knowledge is essential for securing a safe and affordable supply of drinking water for millions of people in southern Sweden.
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