4Displaces marsh animals. Here: salt marsh harvest mouse water.ca.gov
5Spreads by Rhizomes and Seeds Not only does pepperweed live in a variety of conditions, it has a variety of mechanisms for spreadingSeeds float and can germinate in saline conditionsSpread by rhizomes and vegetative parts seems to be the most common method of spread in wet areas, though.
6Marshes are at high risk for pepperweed invasion Vanderhoof et al. 2009
7Marshes are at high risk for pepperweed invasion Vanderhoof et al. 2009
8Management Needs for LELA Efficient search modelsEradication plan for wetlandsRight now, recommendations for eradicating pepperweed aren’t very practical for marshes.Methods for treatment in uplands, rangelands aren’t appropriate for wetlands- mowing with heavy equipment and grazing isn’t an option.For wetland managers, the best defense is to find new invasions in the early stages. Since no one has unlimited funds or personnel, we focused on figuring out ways to make searching for new invasions as effective as possible.
9San Pablo Bay NWR Sacramento San Pablo Bay Suisun Bay Sacramento Delta Golden GateThis is a reference map of San Francisco Bay that shows where I’m working.For this project, I’m working with the staff of San Pablo Bay National Wildlife refuge to figure out where pepperweed invasions are most likely.The refuge is on the north side of San Pablo Bay and it consists of saline tidal marsh. It’s a unique area for studying pepperweed because most of the research that has been done is in freshwater wetlands and rangelands.San Francisco Bay
10Project Area Ag Land Bay 4 km 10 km This is a closer view of the section of the refuge where pepperweed was mapped. This is actually a bit bigger than the mapping area- the mapping was generally in the dark brown areas near the bay. This shows that the marsh is sandwiched between agricultural land and the bay.Bay10 km
17Map of predicted probability of invasion Ag LandBayDeviance Explained = 27%
18A practical application of modelled probabilities: Maps identifying potential habitatLELA Present in 2005Potential HabitatSearch AreaAg LandBayThis is the practical use of the modelling probabilities. This map shows places where the model predicts pepperweed is likely to establish in green. The yellow spots are places that actually had pepperweed in the 2005 mapping. The patch sizes are exaggerated so the colors show up.I really like this map for a couple of reasons. First, it’s a practical application of the model. This is something that the staff can use to focus their searches. They can see where the patches were, and where new patches are likely to establish. They can also see that there are large sections of the refuge that probably don’t need to be searched as often. Second, it shows why the model doesn’t do well numerically- there are many places that have reasonable habitat for pepperweed that haven’t been invaded yet. These are important areas to check, but they show up as errors in the model.
20Potential habitat that hasn’t been invaded yet shows up as “false positives” in our model True PositivesFalse PositivesSearch AreaFalse NegativesAg LandBay
21New patches mapped in 2010 as a test case for the model New LELA Invasions 2010Potential HabitatSearch AreaAg LandPepperweed was also mapped in 2010 and the model predicted most of the new patches. That’s a pretty exciting thing because it shows that if managers used this map, they would have found most of the new patches in the early stages. That’s going to be important for controlling invasions in the future.Bay
22Focus search and efforts for LELA on levees and channel berms.