  In the present paper, we introduce and investigate the notion of a semi
concurrent vector field on a Finsler manifold. We show that some special
Finsler manifolds admitting such vector fields turn out to be Riemannian. We
prove that Tachibana's characterization of Finsler manifolds admitting a
concurrent vector field leads to Riemannain metrics. We give an answer to the
question raised in \cite{DWF}: "Is any n-dimensional Finsler manifold $(M,F)$,
admitting a non-constant smooth function $f$ on $M$ such that $\frac{\partial
f}{\partial x^i}\frac{\partial g^{ij}}{\partial y^k}=0$, a Riemannian
manifold?". Various examples for conic Finsler and Riemannian spaces that admit
semi-concurrent vector field are presented. Finally, we conjectured that there
is no regular Finsler non-Riemannian metric that admits a semi-concurrent
vector field. In other words, a Finsler metric admitting a semi-concurrent
vector field is necessarily either Riemannian or conic Finslerian.
