In recent years, social and natural scientists have gained interest in understanding reciprocal relations between human populations and the environment. Research methods have been developed for investigating the secrets of interations of human and environment. This paper describes the flora data collection methods used in a longitudinal research project "Reciprocal Relation Between Population and the Environment" and highlights how the research sites were selected, how the research plots were designed in each site and how the qualitative and quantitative data of flora found in each research plot were recorded. This paper also discusses how the flora data can be linked with sociodemographic data and how the data can be used to unfold the effect of human activities on flora diversity and/or the effect of flora on the life of the human population in the study area.