Published in the journal Forest Ecology and Management, it is the first study to highlight the importance of factoring in soil conditions when looking at where and how to create the temperate rainforests of the future.
Dr Thomas Murphy, Lecturer in Environmental Sciences at the University of Plymouth, is the study’s lead author. He said: “In recent years, there have been increasing calls to plant more trees as part of the global effort to combat climate change. Restoration and expansion of temperate rainforests, which are a globally rare ecosystem, is seen as one of the potential solutions. But with our previous work also predicting an increase in future rainfall we wanted to know if the woodlands we create will support naturally colonising trees in future. Our results show that higher water levels within soils directly contribute to reduced survival of both acorns and young oak trees. We believe it provides landowners, land managers and policy makers with important information as to which species might work in particular locations to support more resilient future rainforests.”
For the study, researchers planted acorns from English oaks (Quercus robur) in containers with four soil states, from completely flooded to low saturation where the water level was 220mm below the acorn.
The acorns did not survive in the flooded soils, but survival rates improved gradually – 43% at high saturation, 77% at medium saturation, and 83% at low saturation – as the water level dropped.
The surviving seedlings also exhibited reduced root:shoot ratio, leaf photosynthesis, and a lower likelihood of late season shoot growth in soils of higher saturation.
In a concurrent field experiment, juvenile English oak and Sessile oak (Quercus petraea) saplings were planted in a region of Dartmoor that is seasonally waterlogged and frequented by grazing livestock.
In these tests, the English oaks exhibited greater shoot growth and leaf photosynthesis than its close relation in areas where the soil was more saturated.
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