Abstract: Ecology explores the fundamental principles and dynamics of macro living-systems and provides the scientific foundation of ecological civilization. China has separated the ecology as an independent subject from the biology subject to better promote its development. This transition calls for a broader conceptual framework for the subject of ecology. In this article, we define “ecology” as “the science that studies the structures, functions and dynamics of macro living-systems”, which provides a theoretical guidance and practical solutions for maintaining sustainable biosphere. Current ecology encompasses multiple living-system levels from molecules to the biosphere, with its core focus on five key levels: individual, population, community, ecosystem, and landscape. The sub-subject system of ecology comprises seven core disciplines: Plant Ecology, Animal Ecology, Microbial Ecology, Ecosystem Ecology, Landscape Ecology, Restoration Ecology, and Sustainable Ecology. Over nearly 160 years, ecology has generated seminal concepts and landmark theories that have profoundly influenced natural science advancement and human civilization. Current ecology is characterized with four distinctive features: (1) expansion of research scope to both macro- and micro-scales; (2) broad adoption of methodologies from other fields such as molecular biology or information science; (3) increased attention to field-based experiments and observational networks, with plat-forms now established at regional and global scales; and (4) enhanced emphasis on applied ecology to address ecological challenges of human society. Serving as both a natural philosophy for comprehending the living world and a praxeology for conserving and utilizing nature, ecology can be framed through five core perspectives: (1) hierarchical perspective (recognizing the multiple structural levels of living systems), (2) holistic perspective (approaching ecological phenomena from an integrative viewpoint), (3) systematic perspective (viewing the living world as interconnected networks), (4) evolutionary perspective (understanding life systems as dynamic and evolving), and (5) practical perspective (developing solutions for sustainable stewardship of nature). Methodo-logically, ecological research relies on four principal approaches: field investigations, laboratory and in-situ con-trolled experiments, model simulations, and meta-analyses. Although ecology and its branches possess robust theoretical frameworks, they lack their own technological systems. Consequently, the development of core eco-logical technologies is essential to promote continued vitality and progression of the ecology discipline.

Key words: Definition of ecology, Ecological principles, Ecological methodology, Ecological theories, Ecological hierarchy, Branches of ecology, Trends in ecology, Ecology civilization