Variability of Giant Kelp Forests in Southern California: Remote Assessment of Kelp Biomass and the Drivers of Kelp Forest Dynamics.

摘要

Coastal ecosystems are structured by a complex interplay of forcing processes that operate across a variety of scales. However, it is often difficult to monitor these dynamic systems over large geographic areas and long time periods. Thus, there are significant gaps in our understanding of how the relative roles of important coastal ecosystem forcing processes vary in space and time. Here, I developed novel methods for estimating the biomass of giant kelp from satellite imagery, which allowed me to examine kelp biomass dynamics on spatial scales ranging from meters to 1000s of km and temporal scales ranging from months to decades. I combined this satellite biomass data with diver surveys of kelp biomass to describe the relationship between plot (40 m), forest (∼1 km), and regional (∼60 km) scale changes in kelp biomass along the Santa Barbara mainland coast. I then compared changes in kelp biomass across the entire Santa Barbara Channel with environmental and climatic data and found substantial spatial and temporal heterogeneity in the controls of giant kelp biomass dynamics. Finally, I evaluated the relative roles of spatial metapopulation and local environmental controls on giant kelp extinction/colonization dynamics and resilience. Many coastal ecosystems are well studied at the local scale, but long-term, large-scale studies of these systems provide valuable insight into the spatial and temporal generality of local results.