Invasive rockrose threatens cork oaks in Portugal

Cork oaks among rockroses in Portugal. Credit: Simon Haberstroh

What strategies and adaptation measures does the cork oak (Quercus suber) use in the savanna-like ecosystems of southeastern Portugal to meet its water needs in summer and winter? And how does it behave when this tree competes for water with the invasive gum rockrose (Cistus ladanifer)? A team led by Dr Simon Haberstroh and Professor Dr Christiane Werner from the Institute of Earth and Environmental Sciences at the University of Friborg describe their findings on these research questions in the journal Functional ecology.

Cork oaks are changing their water use strategy

According to the scientists, neither cork oaks nor rockroses have much control over their water flows in winter or spring. However, this changes during summer drought, when cork oaks limit their water loss to withstand drought conditions. On the other hand, the cistus, an invasive shrub, uses the available water resources of the soil.

“This competitive strategy of shrubs has led to a change in the hydraulic behavior of cork oaks. Previously, we did not know that competition for water between plants could lead to such a change in water use strategy, explains Haberstroh. “As a result, the cork oaks absorbed less carbon, which translated into restricted water flow to the trees, reduced leaf area and stem growth. With continued water stress and recurring, this behavior will most likely have long-term negative effects and could contribute to the already observed decline of cork oaks.”

The team studied the plants between October 2017 and March 2020 in Portugal. In the field, the researchers documented data on weather, groundwater content, leaf area, and sap flow, among others.

Plant competition in the face of climate change

More information:
Simon Haberstroh et al, Plant invasion alters the isohydricity of Mediterranean tree species, Functional ecology (2022). DOI: 10.1111/1365-2435.14126

Provided by the University of Friborg

Quote: Invasive gum rockrose threatens cork oaks in Portugal (2022, July 18) Retrieved July 18, 2022 from

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