The Ecohydrological Characteristics Of Two Typical Forests In The Upper Reaches Of Minjiang River

This study chose two typical forests (Abies faxoniana forest and Quercus aquifolioides forest) in upper reaches of Minjiang River. The experiment studied the eco-hydrological features of the three main layers, such as canopy, litter and soil in the two typical forests by the method of the positioning and semi-positioning observation in the field and indoor simulation.The results showed canopy interception rate of A. faxoniana forest was 49.4 % which was more than that of Q. aquifolioides forest (16.5 %). There both were significant linear relationship between throughfall and gross rainfall in A. faxoniana forest and Q. aquifolioides forest (P<0.01). Canopy interception rate (%) reduced with the increase of rainfall (mm) by hyperbolic in Q. aquifolioides forest. And the results also proved that the revised Gash model could be used to estimate the canopy interception of Q. aquifolioides in the region.The amount of undecomposition, semi-decomposition and decomposition of litter in Q. aquifolioides forest were 4.00, 6.77, 14.43 t/hm2, respectively, and that in A. faxoniana forest were 1.14, 7.40, 11.99 t/hm2, respectively. There existed better logarithmic relationship between water-holding (mm) amount of litter and immersing time (h).The sum of the water storage capacity of the soil in Q. aquifolioides forest and A. faxoniana forest was 69.95 mm, 90.40 mm, respectively. The soil macroporosity size in Q. aquifolioides forest and A. faxoniana forest both were maximal in 60-80 cm. The soil infiltration characteristics of the two typical forests appeared consistent regularity. The water infiltration process of soil in the two typical forests was simulated based on the experienced formula of Kostiakov and Horton. The analysis showed that the relation of the sap flow with air vapor pressure deficit, solar radiation and air temperature was highly significant positive correlation in Q. aquifolioides (p<0.01). And there was a significant negative correlation between the sap flow velocity and the air relative humidity (p<0.01). The 40-60 min time lag of sap flow velocity to solar radiation intensity in Q. aquifolioides was presented. This paper set up the regression model for the sap flow velocity, daily transpiration, and environment factors in different basal diameter of Q. aquifolioides. Stand daily transpiration changes was 0.84-5.54 mm which estimated for scaling-up from sap flow of the single tree trunks on leaf area as a space quantity (2007.7.23-7.31).