Ecological Indicators (Jun 2021)
Utilization of ecological indicators to quantify distribution and conservation status of Mt. Tamalpais Springs, Marin County, California
Abstract
Spring ecosystems are keystone habitats, providing refugia and supporting high levels of ecological biodiversity and productivity. However, they are often overlooked, overdeveloped, or destroyed altogether. Protocol and inventory methods exist that provide detailed and quantified data collection that enable land managers to monitor and assess their ecological indicators. These methods typically require expertise from many fields, which limits the ability of land managers with lower economic and human resources to implement them on landscape scales. This study presents the Adapted Springs Ecosystem Assessment Protocol (A-SEAP), a simple adaptation of well-established methods as a preliminary, low cost method to evaluate ecological indicators of springs and identify areas of concern. Findings are used to prioritize regions and springs for monitoring and restoration using the rigorous established methods. For this study, a total of 72 springs were evaluated on Mount Tamalpais in Marin County California, a managed wildland surrounded by urban developments. Our assessment showed that spring geomorphology was distributed as follows: hillslope (56) > rheocrene (10) > helocrene (3) ≥ limnocrene (3). Of those, 20 have anthropogenic influences due to roads or trails. Vegetation inventories revealed that springs supported 96% native species, 3% invasive species, and 1% rare and endemic species. Nearly 10% of all native species, as well as 10% of wetland species known in the area of interest were found in only 0.005% of the landscape. Among these springs, slope was negatively correlated to habitat area (r = -0.42, p < 0.001) and was positively related to discharge (r = 0.614, p < 0.001). There was no correlation between discharge and vegetation cover (r = -0.007, p = 0.8). A-SEAP demonstrated that the majority of springs in this region have fair ecohydrologic integrity relative to other spring studies, with a mean value of 3.62 out of 6. A-SEAP indicators identified springs located in Mt. Tamalpais State Park as lower ecohydrologic integrity than springs in the protected Marin Municipal Water District. A-SEAP indicators also successfully identified springs in need of restoration that fit the goals of the local land management agencies. Our results demonstrate that Mount Tamalpais springs are ecologically significant and require further inventory, monitoring, and conservation attention.
