Studies On Seedling Root Dynamics Of Larix Principis-rupprechtii Mayr. And Its Effecting Factors

Larix principis-rupprechtii Mayr. was one kind of trees to form frigid conifruticeta in mountains of the North China. It had become an important cultivated timber tree because of its rapidly growing and high timber yielding. In this paper, different levels of luminance, fertilizing, weed competition and gradation were given. Through cultivating trials under controlled conditions, root order and biomass characters, correlations between above and under ground of seedlings of Larix principis-rupprechtii Mayr. were studied. The influences on its root order of luminance, nitrogen form, weed competition and gradation were also researched. The laws and growing seasonal dynamics of each root order were grasped. Effecting factors and its mechanism of these causes and interrelations were clarified. It could provide theory basis for the forest cultivating. The results were as follows:The average biomass range of each root order was as follows: the first order was 0.0Q43~0.0867g, the second was 0.0223~0.1081g, the third was 0.1145-0.1544g, the fourth was 0.2183~0.3477g, 1X was 0.0052~0.0404g. The percentage of each order was different. They were 8%, 15%, 25%, 50%, 2%. The range of RSL was as follows: 2000-3800cm/g, 1000~2000cm/g, 450~900cm/g, 150~400cm/g.Luminance had significant influence on above, under ground and total biomass of seedlings. The growing of roots crisscrossed the above parts.Adding different form nitrogen had marked bad effects on root growing. The effects were limit by luminance.Weeds competition and arid coercion had effects on above biomass and root growing. The effects kept close links with luminance. Providing good luminance, the growing of root could be improved by arid coercion.The speed of root growing was different according to luminance. But the large root varied slightly and the fine root varied greatly.The above and under growing were related enormously. The better luminance, the bigger matrix, the more contributions of root growing to above. Poor luminance would break the normal laws of seedling growing.