黄土高原油松人工林干旱风险评价

为了揭示黄土高原油松人工林径向生长与干旱之间的关系,以吴旗县、志丹县和延川县30个样地的油松为研究对象,获取黄土高原及周边72个气象站点1961-2012年地面气象逐日降水观测资料,以连续无有效降雨日数作为干旱指标,分析不同干旱类型与不同径级油松人工林相关性,进而对黄土高原油松人工林干旱进行风险评价。结果表明:(1)当年春季轻度干旱和前一年夏季轻度干旱均抑制油松径向生长,且前一年夏季轻度干旱对油松径向生长的影响更大。(2)黄土高原油松人工林干旱风险最大的地区靠近研究区西北边界处,其油松人工林受到干旱胁迫最严重,因此最不稳定。沙区南缘黄土区与沙区的过渡地区,干旱风险评价指数次之。其它大部分地区干旱风险评价指数较小,油松人工林稳定性较高。

The assessment on drought risk of Pinus tabuliformis plantations in the Loess Plateau

In order to reveal the relationship between the radial growth of Pinus tabuliformis plantations and the drought in the Loess Plateau, we took 30 sample plots of Pinus tabuliformis in Wuqi, Zhidan, and Yanchuan counties as the research object, and obtained the ground meteorological observation data of daily precipitation from 1961 to 2012 from 72 weather stations in and around Loess Plateau. We took the number of consecutive days without effective precipitation as a drought index, analyzed the correlation between drought types and different diameter classes of Pinus tabuliformis plantation, and thus assessed the drought risk of Pinus tabuliformis plantations in the Loess Plateau. Results showed that: (1) The mild drought in the spring and mild drought in the previous summer could inhibit the radial growth of Pinus tabuliformis, and the latter had more influence on the radial growth of Pinus tabuliformis. (2) The greatest drought risk of Pinus tabuliformis plantations in Loess Plateau was near the northwest border of the study area, where the plantations were under the most severe drought stress and therefore was the most unstable. The transition area between the sand area and the loess area to its south had the second highest drought risk assessment index. Most of the other areas had a relatively low drought risk assessment index and relatively stable Pinus tabuliformis plantations.