Accurate representation of leaf and canopy stomatal response is important for developing realistic water vapor exchanges between land and the atmosphere, because plant stomatal resistance controls the transpiration rate. Transpiration is one of the most efficient means of uptaking soil moisture from vegetation root zones and hence canopy resistance is a critical parameter in land surface models. In this investigation, we will evaluate the impacts of canopy resistance formulation on the seasonal evolution of plant transpiration and soil moisture storage. The Noah land surface model is extended to include a photosynthesis scheme, based on the photosynthesis Gas-Exchange evaporation Model (GEM). This modified Noah LSM is executed in the framework of NCAR high-resolution land data assimilation system (HRLDAS) for the period of 1st January 2001 to 30th June 2002. The results produced by HRLDAS using the current simple Jarvis canopy resistance scheme in Noah are compared to the results using GEM. Long-term soil moisture data from the Oklahoma Mesonet and surface sensible heat flux and evaporation data obtained from 10 sites, located at different climate regimes and land-use covers, during the International H2O project (IHOP-02) field experiment are used validate these results.