Traits or functional traits are measurable properties that can reflect long-term adaptations to the environment,driving the evolution of organisms (plants, animals, and microbes). There are many remarkable achievements on studies of the traits of plants, animals, and microbes; however, studies of plants focus on either leaves or roots, with few integrating the two, paticularly at the ecosystem and regional levels. Interdisciplinary, systematic, and integrated investigations are needed to reveal the characteristics of complex natural ecosystems (including various traits of plants, animals, microbes, and their interactions) more clearly. With the support of the National Natural Science Foundation of China, comprehensive research on the traits of forest ecosystems (plants, microbes, and soil) along the North-South Transect of Eastern China (NSTEC) have been investigated from 2013 to 2017. This approach aimed to establish a new survey mode (interdisciplinary, systematic, and integrative), facilitating the analysis of new concepts to promote the development of related studies. For the current study, we selected nine typical forest ecosystems along the NSTEC (3700 km), extending from the tropical rainforest to cold temperate coniferous forests. After investigating the community structure, researchers measured various plant traits systematically, including multiple elements of the leaf, branch, trunk, and root, and leaf morphological traits, stomatal traits, anatomical traits, chlorophyll contents, and the contents of multiple elements, non structural carbohydrate content, fine root morphology and anatomy. Furthermore, soil microbial community structure, enzyme activity, the structure and composition of soil organic matter, and the rate and temperature sensitivity of soil carbon and nitrogen mineralization were measured and calculated. Based on the systematic data, the latitudinal patterns and influencing factors of a series of traits for plants, microbes, and the soil were evaluated, in parallel to resolving the major challenge of how to scale the traits from the organ level to the community level objectively. This study was the first to elucidate the quantitative relationships between traits and ecosystem functions in natural forest ecosystems with respect to certain components. Based on the integration of data, we tentatively put forward two new concepts:"Trait network" and "Ecosystem traits". We anticipate that this type of systematic data, combined with new concepts, will help to reveal the mechanisms of complex forest ecosystems. Furthermore, the acquisition of similar systematic data are important for developing and verifying ecological theories in the future. Using systematic data, data collected at the organ level may be scaled up to the community or ecosystem level easily, making it is possible to bridge trait research using rapid-development macro-observation technologies, such as remote sensing, flux observation, and ecological models. The integration of such approach could help us to resolve environmental problems at regional or global scales in future.