Abstract: Berberis diaphana is one of the main subalpine shrubs in Qilian Mountains,Northwest China which has adapted the high-cold climate and evolved in a long period. In mountain habitat condition,the shrub density expresses a large difference between different slope positions and different altitudes,then,the allocation characteristics of rainfall in forest stand have no universality for other forestlands. While research the allocation characteristics of rainfall on individual shrub scale has a positive significance for quantitatively recognize and accurately evaluate the eco-hydrologic processes of this type shrub. In this paper,the individual Berberis diaphana shrub was made as the observed object,the area partition,radial distribution characteristic of throughfall under the canopy as well as its influence factors were measured and analyzed under four single representative Berberis diaphana shrubs. The results show as follows:(1) there were 39 meaningful rainfall events occurred in the research period,of which the mean throughfall rate of Berberis diaphana shrubs was 40.44%,therein,the throughfall rate was 19.98% and 50.57% in canopy center area and canopy radial area,respectively;(2) there were linear relationships between throughfall and rainfall both in canopy center area and canopy radial area:the throughfall increased with the increasing rainfall,but the increase rate in canopy central area was far smaller than that in canopy radial area;when the rainfall was no more than 0.7 mm,there was no throughfall appeared under the canopy central area;(3) along with the increase of rainfall,throughfall rates in canopy radial area firstly increased and then tended to stable,a power function relationship was expressed between them;while in the canopy central area, the throughfall rates expressed discrete distribution;(4) in canopy radial area,the throughfall rates had obvious spatial heterogeneity which increased from 16.19% at distance 10 cm to 69.92% at distance 90 cm,the main increase region was 30-70 cm;the spatial variable coefficients along the radial direction of throughfall rate increased with the increasing rainfall;(5) amount of branch and leaf influenced the throughfall rate,the throughfall rate in stable phase of leaf amount was 11.82% lower than that in leaf extension stage,and the influence of leaf amount was more obvious in smaller rainfall events.

Key words: Qilian Mountains, Berberis diaphana shrub, throughfall, distribution characteristics