朱溪流域水土流失治理序列芒萁叶片叶绿素的变化分析

芒萁是南方红壤区水土流失治理的先锋植物,但其叶片叶绿素含量的作用尚未明晰。以南方红壤区典型流域朱溪流域为研究区,选择4个不同水土流失治理年限样地和2个对照样地以形成水土流失治理序列。通过调查、测定芒萁生长环境和叶片叶绿素含量,分析叶片叶绿素含量在水土流失不同治理年限的变化,揭示其在芒萁抵抗环境胁迫时的表现方式。结果表明:沿治理序列,土壤全碳、全氮和全磷含量均趋于增加且总体上未治理对照地最低,植被郁闭度增加且总体上治理36年样地和风水林对照地相对较高,而芒萁叶片叶绿素a含量、叶绿素b含量、叶绿素a/b和总叶绿素含量均呈上升趋势,总体上上述数值在未治理对照地与治理6年样地和治理12年样地均无显著差异,治理36年样地和风水林对照地相对较高。综上,水土流失治理初期土壤养分未对芒萁产生严重胁迫,提高叶绿素含量和改善叶绿素比例结构是芒萁抵御水土流失治理后期遮阴胁迫的重要方式之一。

Analysis on the Change of Leaf Chlorophyll Content of Dicranopteris dichotoma Across the Soil and Water Conservation Chronosequence in the Zhuxi Watershed

Dicranopteris dichotoma is the pioneer plant used in soil and water conservation in the red soil region of southern China,but it was not clear the function of leaf chlorophyll content of Dicranopteris dichotoma.Taken the Zhuxi Watershed as the study area,4 plots with different years of soil and water conservation and 2 control plots were selected for the forming of the soil and water conservation chronosequence.Through the investigation and determination of the growth environment and leaf chlorophyll content of Dicranopteris dichotoma,it was analyzed the changes of leaf chlorophyll content with different soil conservation years,revealling the expression way of Dicranopteris dichotoma in the stress resistance.The results show that across the soil and water conservation chronosequence,contents of total C,N and P in soil appear the tendency of increase and the content in the uncontrolled plot is the lowest.The canopy density increase,of which,the controlled plot for 36 years and Fengshui forest enjoy the comparatively higher density.The contents of leaf chlorophyll a,b,the chlorophyll a/b and total chlorophyll content of Dicranopteris dichotoma appear the tendency of increase,of which,the above values have no significanct difference among the uncontrolled land,plot controlled for 6 years and plot controlled for 12 years,while the values at the plot controlled for 36 years and the Fengshui forest are comparatively higher than the others.Thus,soil nutrients are not the main stress factors to Dicranopteris dichotoma in the initial stage of the soil and water conservation chronosequence,while the improvement of leaf chlorophyll content and its scale are the key ways for Dicranopteris dichotoma to resist shading stress in the later stage of the soil and water conservation chronosequence.