影响科尔沁沙地不同林龄樟子松径向生长的关键气候因子

Key climatic factors affecting the radial growth of Pinus sylvestris var. mongolica of different ages in Horqin Sandy Land

关键词:  樟子松, 生长-气候关系, 关键气候因子, 季节窗口, 林龄差异

Key words:  Pinus sylvestris var. mongolica, growth-climate relationship, key climate factors, seasonal window, stand age variation

摘要:

为了明确影响不同林龄樟子松(Pinus sylvestris var. mongolica)生长的关键温度和降水因子,该研究以辽宁章古台中龄林(33 a)、成熟林(48 a)和过熟林(64 a)樟子松为对象,分析2003—2022年间不同林龄樟子松生长(胸高断面积增量,BAI)变化特征,并使用Climwin模型确定了对不同林龄樟子松生长影响最强的温度和降水季节窗口。结果表明:(1)2003—2022年间,3个林龄樟子松BAI显著升高。(2)当年7—8月平均温度对中龄林生长影响最强,7—8月平均温达到23.7 ℃时,中龄林径向生长与气候关系由正转负; 上一年11月至当年5月的降水量对中龄林和成熟林影响最强,中龄林和成熟林生长与降水的响应由正转负的降水量阈值分别为124 mm和122 mm。(3)温度对成熟林生长无显著影响; 然而,当年7月温度和上一年8月至当年5月的降水量与过熟林生长呈显著线性正相关。(4)降水对各林龄樟子松生长的重要性强于温度,而且降水对生长的重要性随樟子松林龄增大而增加。因此,在未来气候暖干化趋势下,制定随林龄变化的林水平衡营林措施有助于促进樟子松人工林生长。

Abstract:

To identify the key temperature and precipitation factors influencing the growth of Pinus sylvestris var. mongolica at different stand ages, this study focused on middle-aged(33 a), mature(48 a), and overmature(64 a)P. sylvestris var. mongolica stands, and analyzed the growth patterns(basal area increment, BAI)of these stands during the 2003—2022. In addition, the Climwin model was used to determine the temperature and precipitation seasonal windows with the strongest influence on growth at different stand ages. The results were as follows:(1)BAI significantly increased from 2003 to 2022.(2)The July-August mean temperature had the strongest influence on the growth of middle-aged stand. When the July-August mean temperature reached 23.7 ℃, the growth-climate relationship of middle-aged stand turned from positive to negative; precipitation from last November to current May showed the strongest impact on both middle-aged and mature stands. The thresholds of precipitation at which the growth-climate relationship of middle-aged and mature stands shifted from positive to negative were 124 mm and 122 mm, respectively.(3)The temperature had no significant impact on the growth of mature stand; conversely, the temperature in the current July and the precipitation from last August to current May were positively correlated with the growth of overmature stand.(4)Precipitation proved to be more important than temperature across all stand ages, with relative importance increasing as the stands aged. Therefore, in the context of a warming and drying climate trend, developing forest management strategies that consider water balance and vary with stand age will facilitate the growth of P. sylvestris var. mongolica plantations.