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樟子松是沙地主要针叶造林树种,沙地樟子松林天然分布于内蒙古自治区呼伦贝尔市红花尔基;红花尔基地区的气候特点为高纬度、低海拔、寒冷半湿润、短无霜期。沙地樟子松于20 世纪50 年代在科尔沁沙地引种成功,但一直不能天然更新,并于 20 世纪 90 年代初出现了生长衰退、枯梢直至死亡的现象,而天然沙地樟子松林无论在更新还是生长上却一直处于健康状态。为了认识天然沙地樟子松林天然林的更新特征,于 2004 年 7-8 月对红花尔基天然沙地樟子松林的20 块样地、3 种林窗(2 圆形、5 窄长方形、3 宽长方形)樟子松天然更新指数进行了调查。结果表明,林龄大的林分(大于 50 年)总平均更新指数高于林龄小的林分(小于 50 年),最大更新指数达29株m-2。更新的苗龄绝大多数小于10年生。回归分析表明,林龄是决定天然更新的主要因子;虽然樟子松是阳性树种,但林冠的郁闭度似乎对天然更新没有直接影响。林窗更新调查结果表明,林窗内更新指数都较高;对于圆形林窗更新高峰出现在林窗南缘和东缘,而对于窄长方形林窗,更新高峰则出现于东缘;而且更新苗龄相对较大(最大达 38 年)。上述结果表明樟子松更新苗具有一定的耐阴性,但如果没有较大林窗或较大的其它干扰,如火、风雪害或皆伐等,更新苗木将很难进行入主林冠层。
Pinus sylvestris var.mongolica is the dominant coniferous tree species in sandy land. The Pinus sylvestris var. Mongolica is naturally distributed in Honghuaerji, Hulunbeir, Inner Mongolia Autonomous Region. The climate characteristics of Honghuaerji are high latitude, low altitude, cold and semi-humid, short frost- . Pinus sylvestris var. Mongolica was introduced successfully in the Horqin Sandy Land in the 1950s but has not been able to be renewed naturally. In the early 1990s, the Pinus sylvestris var. Mongolica forest had a decline in growth and death till its death. However, In the update or growth has been in a healthy state. In order to understand the renewal characteristics of natural forests of Pinus sylvestris var. Mongolica on natural sandy land, 20 plots of Pinus sylvestris var. Mongolica on natural sandy land of Honghuaerji, three kinds of forest windows (2 circles, 5 narrow rectangles , 3 wide rectangles) Pinus sylvestris natural renewal index was investigated. The results showed that the total average update index (greater than 50 years) of the older stands was higher than that of the younger stand (less than 50 years), and the maximum renewal index reached 29 m-2. The vast majority of younger seedlings younger than 10 years old. Regression analysis showed that stand age was the major factor determining natural regeneration; although Pinus sylvestris was a positive tree species, canopy density seemed to have no direct effect on natural regeneration. The findings of the Gap Update show that the in-shelter update index is high, the peak of the Rupiah-Gap appears at the southern and eastern margins of the Gap and the peak of the Rye appears at the eastern edge of the Gap; Miao age is relatively large (up to 38 years). The above results indicate that the seedlings of Pinus sylvestris var. Mongolica have a certain negative tolerance, but the regeneration of seedlings will be very difficult to enter the canopy if there are no larger gaps or other large disturbances such as fire, snow damage or clear cutting.