From buckets to the biosphere: Linking environment, biodiversity, and ecosystem processes across scales via the Zostera Experimental Network
Ecology is the most difficult science: nature is complex, and understanding it is uniquely challenged by the paradox of reconciling detailed knowledge of individual systems with identifying cross-cutting, unifying principles. This paradox is one reason for the stubborn persistence of some of ecology’s central problems: how important is bottom-up vs top-down control? Is biodiversity central or trivial to ecosystem functioning? And so on. These arguments derive largely from different personal experiences of researchers among places and systems. Collaborative research networks offer promise toward bridging these divides by connecting standardized, purposeful research across environmental gradients, and engaging diverse brains in the process. Such coordination promotes empirical analyses powerful enough to replace foundations based on authority of strong personalities and meta-analyses of data that are sometimes ill-suited for the purpose. Key to their power is the integration of large-scale comparisons with detailed place-based knowledge. As an example, we summarize our experience organizing, implementing, and evolving the Zostera Experimental Network (ZEN), a collaboration among >20 partner institutions across the northern hemisphere. ZEN works to quantify the interactive contributions of abiotic environment and biodiversity to ecosystem functioning using the widespread species eelgrass (Zostera marina) as a foundation.
Seagrass systems illustrate the long debate about importance of bottom-up vs. top-down forcing. Although rigorous experiments and observational studies have been conducted in many seagrass systems wide variation among them precludes generalizations. ZEN tackled this problem by conducting factorial fertilization and grazer reduction at 15 sites across the range, and integrating analyses with global gradients in biodiversity and environmental forcing. Experiments indicated generally stronger control of algae by grazers than by nutrients. But more interestingly, grazer and algal biomass were better predicted by cross-site variation in grazer and eelgrass diversity than by large-scale abiotic gradients. Moreover, these large-scale patterns corresponded strikingly with small-scale experiments, linking global and local evidence for the importance of biodiversity and of grazing in eelgrass ecosystems. ZEN has made progress in answering big questions, fostering collaborations, and spinning up new projects. But network ecology has its own challenges, which provide fertile opportunities for a new generation of ecologists. The central one now for ZEN and others is sustainability as they transition from pioneers to maturation as open but stable, partner-driven “bottom-up” collaborations. We review what we’ve learned along the way about how to accomplish this.