A Summary Notes on the concept of system and on the System Theory (by Alessandro Ingegnoli) is presented. Then a synthesis on Complex Systems will be exposed, defining hierarchical, dynamic, and dissipative systems, arriving at the general behavior of non-equilibrium systems, metastability, and disturbances, with important upgrading in the interpretation of landscape transformation and the role and importance of disturbances within it. Complexity can be understood as an attribute of a system containing information that is difficult to understand. In the case of complex systems made up of complex subsystems, we can also talk about levels of complexity and hyper-complexity. After reviewing the main concepts related to the System Theory, we can pass to an upgrading of traditional ecology through the new ecological discipline of Landscape Bionomics. The levels of biological organization cannot be limited to cells, organisms, populations, and communities. They must also include the more strictly speaking ecological systems: landscape, ecoregion, and the Earth as a living system (Gaia). Note that traditional general ecology does not integrate the four criteria of study (space configuration, biotic, functional, and cultural-economic). In contrast, it is their integration that allows us to recognize them as complex adaptive systems as they are. A comparison between traditional ecology (TE) and landscape bionomics (LB) can be seen in Table 2.2. The differences are numerous (only the first 30 have been listed here) and often substantial: for example, the concepts of community and ecosystem, which occupy the same vast range of scales, while they contrasts with the principle of emergent properties. The landscape is a complex system of ecocoenotopes. This observation is less easy to understand than one might think because, in traditional ecology, the reference unit is the ecosystem, which, as we have underlined in the previous chapter, is an ambiguous concept.