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The common reed (Phragmites australis australis) is a highly invasive grass species in 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 sign of human modification of the landscape. For these reasons, stemming the spread of Phragmites is a priority for wetland managers.

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 random forest models I generated were highly accurate - over 90% for each year - and produced high resolution maps of Phragmites extent. 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. Phragmites patches in Suisun Marsh expanded outward at a rate of 1.32 m/yr, which is greater than similar ecosystems in other parts of the country. I also found that Phragmites expansion in one property can cause expansion in its neighbors - highlighting the need for collaborative management. My findings are now being used by landowners in Suisun Marsh to target specific areas for treatment, and to design a long-term management plan to eradicate this invasive species for good. 

This video shows the expansion of the common reed in Suisun Marsh from 1144 acres in 2003 to as much as 3823 acres in 2018

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