Abstract:

In this paper we investigated damage caused by a rare early-snow event at late autumn in 2011 on the Larix principis-rupprechtii plantation of the Liupan Mountains, Ningxia of Northwest China. The relationships between the stand damage rate, site conditions and stand structure were analyzed. It was found that the damage rate was significantly higher in the stands on the sites with high-altitude, wind-exposure and thin soil thickness. The damage rate of high-density stands was apparently higher than that of the low-density stands, which illustrates that the stand density is an important stand structure indicator that affects its ability against snow damage. However, the direct affecting factor should be the higher H/DBH (the ratio of tree height to the diameter at breast height) caused by the high stand density. When H/DBH was 0.7-0.9, the stand might suffer from snow damage, but the increasing range of the damage rate with increasing H/DBH was slight. When H/DBH was higher than 0.9, the stand damage rate increased rapidly with increasing H/DBH. When H/DBH was higher than 1.0, the stand damage rate increased very rapidly with increasing H/DBH. Therefore, reducing the stand density to lower the stand H/DBH to around 0.7 through a timely thinning, and then maintaining it within 0.9 would be a feasible silvicultural measure to improve the forest ability against snow damage.

Key words: snow damage, Larix principis-rupprechtii, the ratio of tree height to DBH, damage rate, Liupan Mountains