A Canopy Transpiration Model Based on Scaling Up Stomatal Conductance and Radiation Interception as Affected by Leaf Area Index

Estimating transpiration as an individual component of canopy evapotranspiration using a theoretical approach is extremely useful it eliminates the complexity involved in partitioning evapotranspiration. A model to predict based on radiation intercepted at various levels leaf area index (LAI) was developed controlled environment pasture species, tall fescue (Festuca arundinacea var. Demeter). The assumed be composite two indistinct layers defined sunlit and shaded; proportion which calculated by utilizing weighted (W model). energy utilized each layer from PAR top fraction absorbed photosynthetically active (fAPAR) corresponding LAI shaded layers. relationship between fAPAR also established for this specific aid calculation interception. Canopy conductance estimated scaling up stomatal measured level. Other environmental factors that drive were monitored accordingly layer. Penman–Monteith Jarvis models used basis construct modified suitable conditions. Specially, constructed self-watering tubs measure actual validate output. provided good agreement (actual = 0.96 × transpiration, R2 0.98; p < 0.001) with predicted values. This particularly so lower LAIs. Probable reasons discrepancy higher are explained. Both experimental varied 0.21 0.56 mm h−1 range available physical exceeded near 3.0, however, contribution total remains throughout entire growing season.