Purpose: Information ecology refers to the effect of environment on information elements and reaction among information elements in the context and environment which has been used as reactions of subject categories in this research. Therefore, in identifying information ecology, we studied the reaction of subject categories of Knowledge and Information Science with other subjects such as information and communication technology (ICT) in 2001-2011 different journals of knowledge and information science. Methodology: This was a quantitative content analysis regarding the identification of subject categories of 2510 papers in 9 journals of knowledge and information science indexed in ISC (Islamic Science Citation database). The data collection tool was the schedule of classifying subject categories of KIS confirmed by Delphi Panel in two stages. Findings: The results showed that all subject categories of KIS have reactions with other subject categories and the reaction of subject categories with information and communication technology (ICT) had more share. In contrast, the reaction of other subject categories in different of science have taken less share. The results of comparing reaction of subject categories ICT separated by journals show the reaction of subject categories with ICT in journals of library and information science of Astan Ghods Razavi, the Iranian Journal of Information Processing & Management, Journal of Academic Librarianship and Information Research, and Research on Information Science & Public Libraries and Informology in the second period (2006-2011) was higher than that in the first period (2001-2005).