Understanding population dynamics is an important issue in population ecology because it can provide insight into factors determining population behavior as well as providing guidelines for population management. Complex population dynamics generally result from the combined influences of both intrinsic and exogenous forces. Therefore suitable analyzing methods are needed. In this presentation, various time series analyses approaches such as autocorrelation, Fourier Transformation, Cross-correlation, synchrony etc. will presented to extract information embedded in the population data observed in agricultural and forest ecosystems.