Response of Montia howellii (Howell's montia) to road management in California coastal timberlands
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Howell's montia (Montia howellii S. Watson), a tiny annual plant with a California Rare Plant Rank of 2.2 (rare in California but more common elsewhere), is found throughout its range in seasonally wet, natural and disturbed habitats. On Humboldt Redwood Company timberlands it occurs on native surface or lightly rocked roads and turnouts, and in wet meadows used by cattle. We examined the spatial and temporal extent of Howell's montia on 10 road complexes over 6 years by counting the plants in consecutive fixed 10 meter segments of road. Using GIS event routing, we documented the changes in plant numbers in each segment, the movement of plants into new segments, and their decline and disappearance from segments over time. We found that opening and using seasonal, native surface roads was related to increases in plant numbers and spatial spread. After road use ceased, plants declined in both numbers and spatial extent. On rocked roads with heavy use and annual maintenance, populations were not well sustained even with a nearby seed source. We conclude that where Howell's montia occurs on roads, periodic seasonal use and road maintenance appears to maintain the local population.