Scientific knowledge is a primary resource that scientists use to shape their activities to make sense of natural phenomena. Support for students' adaptation of scientific knowledge can enhance their ability to make sense of the natural world. This study aims to examine how ecological concepts are used when students plan field-based modeling of ecological phenomena and to identify teachers' support for students' use of ecological concepts. This study adapts the categorization of ecological concepts as natural, functional, and integrative according to how they are used in ecological research. With this foundation, we examine a field-based modeling activity that was implemented in a middle school science club. The goal of this activity was to develop models that make sense of ecological phenomena through processes that involve field investigations. Video recordings and transcriptions of the activities were analyzed as the main data sources. The analysis results reveal how different types of ecological concepts are used in modeling and illustrate how teachers support students' use of different ecological concepts. Based on these findings, we discuss instructional supports to expand the resources that students can use in field-based modeling of ecological phenomena and the importance of domain-specific knowledge in making sense of the natural world.