Fluctuations that are synchronized through time across multiple locations have long interested ecologists. Spatial synchrony in a species’ populations can increase the risk of extinction, whereas spatial factors that disrupt spatial synchrony may enhance species persistence. Similarly, synchrony among species can reduce ecosystem stability, whereas asynchrony among species may stabilize aggregate ecosystem properties such as primary production. We investigated fine-scale geographic variation in spatial synchrony, focusing on the roles of dispersal, disturbance, and interactions between plant species in driving spatiotemporal plant cover dynamics, using 33 years of data from an annual serpentine plant community at the Jasper Ridge Biological Preserve in San Mateo, California. We focused on the six most-dominant species (Plantago erecta, Bromus hordeaceus, Lasthenia californica, Microseris douglasii, Vulpia microstachys, and Calycadenia multiglandulosa). We used wavelet statistics to characterize spatial synchrony and evaluate evidence for climate, gopher disturbance, and species interactions as drivers of spatial synchrony for each species. Second, we use matrix regression and network analysis to evaluate spatial patterns of synchrony. Our use of wavelet statistics also allowed us to separate synchrony into short (<6 years) and long (>6 years) timescales.
Results/Conclusions
Mean spatial synchrony, quantified as wavelet coherence among plots (n = 36), varied by species and timescale, ranging 0.39 to 0.80. While shared environmental conditions are the likely cause of spatial synchrony, we could not identify a climatic driver for any species. Spatial variation in synchrony of 4 of 6 plant species was related, however, to gopher disturbance, indicating that gophers mediate synchrony patterns. At long timescales, the dynamics of three plant species pairs were spatially coherent: Plantago × Bromus (p = 0.027), Plantago × Microseris (p = 0.023), and Vulpia × Calycadenia (p = 0.006). All significant relationships were at antiphase, indicating that species asynchrony may stabilize aggregate ecosystem properties. Synchrony exhibited distance-decay and more complex spatial structures, including “modules,” i.e., sets of locations showing high within-set but low between-set synchrony. The number and composition of modules varied by species and timescale. At short timescales, spatial structure in synchrony was explained mainly by spatial proximity and synchrony in gopher disturbance, with relationships between plant species also playing a role. The spatial structure of synchrony can yield insights into population and community dynamics, and may provide a lens for understanding community stability.