One major way that ecology advances is by comparing the functioning of ecological processes in similar systems that are subject to different starting conditions, drivers, or management approaches. The National Science Foundation and other agencies have made major investments in long-term ecological research networks, including LTER, National Ecological Observatory Network (NEON), Critical Zone Observatories (CZO), Long-Term Agro-Ecosystem Research Network (LTAR), and AmeriFlux.

The International LTER Network was founded on the model of the U.S. LTER Network and operates as a network of country-based networks. Its focus is on long-term, place-based research from an ecosystem perspective. It includes 44 member networks and over 800 sites in almost every biome on Earth. Both developed and developing countries are welcome and dues and meeting fees differ based on a country’s development status. As in the U.S. LTER Network, data preservation, sustainability, and access are priorities.

Broadening Comparisons

Network-to-network collaborations enable U.S. researchers to easily identify international sites that extend the range of environmental conditions and to connect with enthusiastic collaborators who share a common vision of the value of long-term site-based research. The International LTER Network (ILTER) has launched several new research efforts to address global scale dynamics of biodiversity, nitrogen and other topics, and maintains an extensive database of site characteristics, projects, investigators, and data.

In a few specific cases, such as coral reefs, kelp forests, mangrove systems, tropical forests, alpine, and Arctic ecosystems — the U.S. LTER Network has only one site of each type. For those sites, long-term comparative studies require cooperation with international sites. These types of sites have been strongly supportive of the International LTER (ILTER) Network and similar networks with a more thematic focus, such as the Complex Mountain Landscapes Network, Kelp Ecosystem Ecology Network (KEEN), the Smithsonian Forest GEO Network, International Arctic Science Committee (IASC), and the Sustaining Arctic Observing Networks (SAON).

Over the next decades, ecosystems of the United States will experience changing conditions (plant-insect interactions, disease spread, pollinators, temperature and moisture regimes, soil conditions, changes in cultivation practices) many of which we have not previously experienced. Enhanced collaborations with international colleagues provide glimpses into our past and our future. Adaptation in urban and other managed ecosystems is one particularly profound challenge that can only be addressed by broadening the range of environmental and socioeconomic conditions and cultural legacies of research sites.

Training and Culture of Science

International collaborations broaden the horizons of U.S.-based trainees, exposing them to new techniques, approaches, cultures, and practices, as well as connecting them to a global network of advanced researchers. International training courses, such as those developed by the International Nitrogen Training Initiative, rely on network-to-network connections to structure the course material, identify instructors, and recruit the most promising students. These experiences feed back to the success of U.S. scientists in understanding both U.S. and global-scale phenomena.

Distributed Experiments

In the past decade, ecology has seen the rapid growth of a new type of experiment in which a fairly simple protocol is carried out at many, widely-distributed locations. These distributed experiments (DroughtNet, NutNet, Detrital Input Removal and Trenching (DIRT), and the Tea Bag Index) are key bridges between continental scale networks and in-depth site-based studies that reveal principles that are ripe for testing in wider contexts. International networks and connections help identify enthusiastic partners in these large-scale and highly efficient collaborations.