Water status measurement in a banj oak (Quercus leucotrichophora A. Camus.) forest in Kumaun Central Himalayas.

The present study was undertaken in a banj oak (Quercus leucotrichophora) f orest located at 1730 m altitude in Kumaun Central Himalaya between 29 degr ees 80' latitude and 79 degrees 20' longitude. Highly significant correlati on (P<0.01) between soil water potential at 60 cm depth and predawn tree wa ter potential existed. This lends support to the fact that soils at this si te were shallow resulting in roots drawing maximum water from this soil dep th. The ability of Q, leucotrichophora to maintain a daily change of -0.7 M Pa when predawn tree water potential was -1.8 MPa places this species in a class of drought 'tolerator'. The marginal rise in predawn water potential during spring at the time of leaf production could partly be due to thinnin g of canopy (about 25%) as in this species leaf drop and leaf production oc cur simultaneously and the present data and those of Savannah forest lend s upport to this Reich-Borchert hypothesis that leaf flushing is determined b y changes in internal water status of plants.