BACKGROUND
Many early and still fundamental concepts in ecology were developed in small-scale aquatic mesocosms across a limited geographic range. Developing concepts of trophic cascades, limnologists (scientists who study characteristics of fresh water systems) reasoned that the productivity of animals was limited by nutrient resources and that energy inputs into lakes (transferred as carbon), which could be used as ecological currency, was generalized to all ecosystems from early work in aquatic systems. Many researchers have built on these early insights, but the cost of monitoring all interactions is clearly prohibitive.
The National Science Foundation’s (NSF) National Ecological Observatory Network (NEON) is a first-of-a-kind continental-scale observatory with an unprecedented array of publically available atmospheric, terrestrial, and aquatic data products systematically collected at 81 sites following consistent protocols to enable users to develop new understanding of interconnections and response to climate over the 30-year lifetime of the program. As the first continental-scale ecological observatory, NEON provides a unique opportunity to study ecological interactions across the United States (including Alaska, Hawaii, and Puerto Rico).
The NEON aquatic data collections allow us to examine: (1) which ecological relationships can be detected across contrasting eco-climatic space, (2) how the strength of the relationships varies across the US, (3) whether well-established ecological concepts are supported by this new standardized data, and (4) how variance in the strength of ecological relationships can be used as a marker of ecosystem health. These studies open the possibility to improve our ability to deal with environmental challenges like climate change, pollution and the influence of land use change on aquatic systems. For ecosystem management, a major goal is to prevent unintended perturbations, thus perturbations must be well understood. The identification of ecological data interrelationships can lead to understanding the perturbations. In addition, resilience (amount of perturbation required to change states or resistance to change of an ecological state) of the ecosystem must also be studied. Previously unknown interrelationships between various data types are expected, but an essential element in recognizing these interrelationships will be to develop methods to explore and recognize time lag between environmental drivers and ecological response.
APPROACH
This project used a straightforward approach where the starting point was with well-known data interrelationships, and then expanded with analyses to identify and evaluate less well-known or previously unrecognized interrelationships. NEON has aquatic and terrestrial field sites with three collection systems: (1) automated instruments that collect data year round, (2) observational sampling collected by researchers during the growing season, and (3) airborne remote sensing surveys that are scheduled every 3-5 years. There are three types of NEON aquatic sites: (1) wadeable streams, (2) rivers, and (3) lakes. This research focused on the aquatic data collected at wadeable streams via automated instruments and observational sampling. The technical research objective was to determine interrelationships between ecological processes and environmental drivers across the continental US using the NEON aquatic data products. The project included the following four primary technical tasks: (i) Task 1 – Data product selection for interrelationship analysis, (ii) Task 2 – Protocol development for analysis of ecological interrelationships, (iii) Task 3 – Protocol expansion, (iv) Task 4 – Application extension.
ACCOMPLISHMENTS
Our research identified a number of pitfalls and gaps in NEON data products that interfered with efficient data analysis. Despite these challenges, the project developed an analysis protocol to evaluate relationships, which demonstrates that protocols for discovery of interrelationships can be developed and used effectively at any NEON aquatic site and with any NEON aquatic data product. Several specific avenues for future work were identified while conducting this Targeted Research project.