温度变化对兴安落叶松径向生长的抑制性研究

发布时间：2018-03-15 22:28

  本文选题：兴安落叶松　切入点：年轮宽度　出处：《沈阳农业大学》2017年硕士论文　论文类型：学位论文

【摘要】：大兴安岭是我国气候变暖的敏感地区。为了探究气候变暖背景下温度变化对不同区域兴安落叶松(Larix gmelinii)径向生长的抑制性,利用树木年代学方法在大兴安岭主脉南段、中段和北段的15个地区进行树木年轮取样,建立了各点年轮宽度年表,根据取样点地理位置、年表的主成分载荷系数、年表间相关分析对年表进行分类并合成南部、中部和北部各气候分区的兴安落叶松年轮指数。用相关函数剖析了兴安落叶松径向生长与温度的关系,连系滑动响应分析和多元线性回归模型探讨温度抑制兴安落叶松径向生长的根本原因,并展望未来气候变暖背景下,兴安落叶松林生态系统的分布变革。结果主要有:1.近百年来研究区温度变化在20世纪20-30年代和70-80年代有两个明显的分界点,之后研究区进入了显著的升温期。自1960年以来,研究区气候条件为半湿润气候,且自1984年以来,区域干湿状况具有半湿润转化为半干旱的趋势,暖干化趋势呈中部南部北部。研究区自1901-2001年冻土类型均为不连续多年冻土,冻土退化在1925-1955年和1969-1999年最为严重,尤其南部地区在1988年后无多年冻土分布。区域干旱指数、冰冻指数下降趋势在时间上与区域温度升高趋势相对应,因此,气候变暖导致了研究区环境条件的明显变动。2.胸高断面积增量(BAI)指示的树木生长量同期呈中部南部北部的趋势,升温过程中,南部、中部落叶松BAI趋势下降,其中,中部落叶松的BAI在第二次升温中下降趋势最显著。这种趋势变化在时间上与区域温度升高、环境条件变动一致,表明温度升高对兴安落叶松径向生长具有抑制性,且抑制程度具有局地差异性。3.落叶松径向生长对温度的响应具备南北差别(中部北部南部):南部落叶松生长与上年11月-当年4月平均温度显著负相关(p0.05),中部落叶松生长与上年生长季、上年冬季、当年秋季平均温度显著负相关(p0.05),北部落叶松生长与当年4-5月(生长季前)平均温度极显著正相关(p0.01)。气候变暖背景下,高温引起的区域暖干化使土壤水分成为限制落叶松生长的主要因子,土壤干旱加剧使落叶松生长对温度变化的响应增强。BAI指示的落叶松生产力经历了从响应低温胁迫到响应高温引起的水分胁迫的转变。将来几十年,若温度持续升高,大兴安岭区域落叶松径向生长量将呈南部和中部降低、北部升高的趋势。然而,北部区域对落叶松径向生长的天然保护作用并不稳定,年轮指数与温度的正响应系数的降低,预示了兴安落叶松适宜分布区的北移,未来气候变暖可能破坏兴安落叶松林生态系统的平衡,并导致其被其它森林生态系统所取代。
[Abstract]:The Daxing'an Mountains is a sensitive region for climate warming in China. In order to study the inhibition of temperature change on the radial growth of Larix gmelinii in different regions under the background of climate warming, the tree chronology method was used in the southern segment of the main vein of the Daxing'an Mountains. Tree ring sampling was carried out in 15 areas in the middle and north segments, and the chronology of the width of each point ring was established. The chronological table was classified and synthesized according to the geographical location of the sampling point, the principal component load coefficient of the chronological table, and the correlation analysis between the chronological tables. The relationship between radial growth and temperature of Larix gmelinii in central and northern climatic regions was analyzed by correlation function. Coupled sliding response analysis and multivariate linear regression model were used to study the root causes of temperature inhibition on radial growth of Larix gmelini, and to look forward to the future climate warming. The main results are as follows: 1. In the last hundred years, the temperature variation of the study area has two distinct boundary points in 20th century, 20-30 's and 70-80 's, and then the research area has entered a significant warming period. Since 1960, the study area has entered a significant warming period. The climatic conditions in the study area are semi-humid, and since 1984, the dry and wet conditions in the study area have the tendency of converting from semi-humid to semi-arid, and the trend of warm drying is northern and central. The permafrost types in the study area from 1901-2001 are all discontinuous permafrost. The degradation of permafrost was most serious in 1925-1955 and 1969-1999, especially in the southern region, where there was no distribution of frozen soil for many years after 1988. The decreasing trend of regional drought index and freezing index corresponds to the increasing trend of regional temperature in time. Climate warming resulted in obvious changes of environmental conditions in the study area. 2. The tree growth indicated by the increment of sternal height and sectional area was the same as that of the northern part of the central part. During the heating process, the BAI trend of the south and central larch decreased, among which, The BAI of Larix gmelinii decreased most significantly in the second temperature rise, which was consistent with the regional temperature and environmental conditions, indicating that the radial growth of Larix gmelinii was inhibited by the rise of temperature. The response of radial growth of Larix gmelinii to temperature was significantly different from north to south (central and northern: southern larch growth was negatively correlated with the average temperature from November to April of last year), and the response of larch radial growth to temperature was significantly negatively correlated with that of middle tribe. The growth of Pinus tabulaeformis and the growth season of last year. In winter of last year, the average temperature in autumn was significantly negatively correlated with that of P0.05, and the growth of Larix gmelini was positively correlated with the average temperature of April / April (pre-season) of that year. Regional warming and drying caused by high temperature make soil moisture the main factor limiting the growth of larch. When soil drought intensifies, the response of larch growth to temperature changes is enhanced. The productivity of larch indicated by Bai has undergone a transition from response to low temperature stress to water stress caused by high temperature. The radial growth of Larix gmelinii in the Daxing'anling region will decrease in the south and the middle of the region, and increase in the north. However, the natural protective effect of the northern region on the radial growth of the larch is not stable, and the positive response coefficient of annual ring index and temperature is decreased. It indicates that the suitable distribution area of Larix gmelinii is moving northward, and the future climate warming may destroy the balance of forest ecosystem of Larix gmelini forest and lead to its replacement by other forest ecosystems.
【学位授予单位】：沈阳农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S791.222
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本文编号：1617131