The expansion of the invasive common reed

Read the scientific article here

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The common reed, familiarly known as Phragmites, is a non-native grass species invading many wetlands in California. Once established, the reed will outcompete native species - conquering large swaths of land and forming dense monocultures in which nothing else will grow. These monocultures offer little in the way of wildlife habitat or food, and are generally a result of human modification of the landscape. For these reasons, stemming the spread of Phragmites is a priority for wetland managers.​

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Understanding Phragmites spread - where it occurs, and the magnitude - can help mitigate its expansion. Using remotely-sensed aerial imagery, I created a model to identify the spatial distribution of Phragmites in Suisun Marsh at nine iterations over two decades (2003 to 2022). The machine learning models I generated were highly accurate - over 90% for each year - and produced high resolution maps of the extent of Phragmites. I found that once covering just 1100 acres of the Marsh in 2003, the common reed expanded to as much as almost 4000 acres in 2018. Even more troublesome, the annual rate of Phragmites expansion in Suisun Marsh was greater than similar ecosystems in other parts of the country. Importantly, my models indicated that Phragmites expansion in one property can cause expansion in its neighbors - underscoring the need for collaborative management. My findings are now being used by both private landowners and wetland scientists in Suisun Marsh to target specific areas for treatment, and to design a long-term management plan to stem the spread of this invasive species for good. ​