Journal ArticleEffects of post oak (Quercus stellata) and smooth brome (Bromus inermis) competition on water uptake and root partitioning of eastern redcedar (Juniperus virginiana)Hamati, Samia; Medeiros, Juliana S.; Ward, DavidGuo, XiaoEastern redcedar Juniperus virginiana is encroaching into new habitats, which will affect native ecosystems as this species competes with other plants for available resources, including water. We designed a greenhouse experiment to investigate changes in soil moisture content and rooting depths of two-year-old J . virginiana saplings growing with or without competition. We had four competition treatments: 1) none, 2) with a native tree ( Quercus stellata ), 3) with an invasive grass ( Bromus inermis ), and 4) with both Q . stellata and B . inermis . We measured soil moisture content over two years as well as root length, total biomass, relative water content, midday water potential, and mortality at the end of the experiment. When J . virginiana and B . inermis grew together, water depletion occurred at both 30–40 cm and 10–20 cm. Combined with root length results, we can infer that J . virginiana most likely took up water from the deeper layers whereas B . inermis used water from the top layers. We found a similar pattern of water depletion and uptake when J . virginiana grew with Q . stellata , indicating that J . virginiana took up water from the deeper layers and Q . stellata used water mostly from the top soil layers. When the three species grew together, we found root overlap between J . virginiana and Q . stellata . Despite the root overlap, our relative water content and water potential indicate that J . virginiana was not water stressed in any of the plant combinations. Regardless, J . virginiana saplings had less total biomass in treatments with B . inermis and we recorded a significantly higher mortality when J . virginiana grew with both competitors. Root overlap and partitioning can affect how J . virginiana perform and adapt to new competitors and can allow their co-existence with grasses and other woody species, which can facilitate J . virginiana encroachment into grasslands and woodlands. Our data also show that competition with both Q . stellata and B . inermis could limit establishment, regardless of water availability.2023-02-0110412175PLOS ONE182e02801001932-6203https://doi.org/10.1371/journal.pone.02801001915908National Science Foundation