On an upper bound for the spreading speed

<p style='text-indent:20px;'>In this paper, we use the exponential transform to give a unified formal upper bound for asymptotic rate of spread population propagating in one dimensional habitat. We show through examples how can be obtained directly discrete and continuous time models. This has form <inline-formula><tex-math id="M1">\begin{document}$ \min_{s>0} \ln (\rho(s))/s $\end{document}</tex-math></inline-formula> coincides with speeds several models found literature.</p>