内蒙古半干旱地区空气和土壤加湿对幼龄樟子松生长的影响

Effects of air and soil humidification on the growth of young Pinus sylvestris var.mongolica trees in semi-arid area of Nei Mongol,China

干旱半干旱区约占全球陆地总面积的30%,植物生长对于水分变化的响应在此区域更为敏感。大气干旱和土壤干旱都会对植物生长产生影响,目前关于这两者对植物生长的影响已有不少实验研究,但具体的影响机制尚不清楚。该研究以幼龄樟子松(Pinus sylvestris var.mongolica)为研究对象,通过设计改变空气湿度与土壤湿度的野外控制实验,探究空气加湿与土壤加湿对幼龄樟子松生长特性的影响。结果表明:1)与对照相比,空气加湿使饱和水汽压亏缺(VPD)降低了20.5%,空气加湿和土壤加湿使土壤湿度分别增加了23.4%和21.3%。2)空气加湿显著增加了叶片密度,土壤加湿显著加粗了枝条直径,空气与土壤共同加湿对叶片和枝条的生长均有显著的促进作用。3)结合加湿处理对径向生长的影响及结构方程模型的结果发现,土壤加湿可直接促进树干的径向生长,空气加湿对径向生长的显著促进作用一方面是由于VPD降低的直接影响,另一方面是由于空气加湿显著提高了土壤湿度。该研究揭示了半干旱地区幼龄樟子松生长对大气水分和土壤水分改变的响应差异。

Aims Arid and semi-arid areas account for about 30% of the total global land area.Plant growth in these areas is more susceptible to drought stress.Both atmospheric drought and soil drought can affect plant growth.Although there have been many experimental studies on the effects of atmospheric drought and soil drought on plant growth,the specific mechanism is not clear.Methods In this study,the differential effects of air and soil humidification on the growth characteristics of young Pinus sylvestris var.mongolica trees were investigated by manipulation experiments of altering air humidity and soil water content.Important findings The results showed that:1) Compared with the control,air humidification significantly reduced vapor pressure deficit by 20.5%,and air humidification and soil humidification significantly increased soil moisture by 23.4% and 21.3%,respectively;2) Air humidification significantly increased leaf density,soil humidification significantly increased twig diameter,and air and soil humidification significantly promoted the growth of leaves and twigs;3) Taking into consideration of the effect of humidification treatment on radial growth and the analysis with structural equation model,the results showed that soil humidification directly promoted the stem radial growth,and the significant positive effects of air humidification on radial growth is due to the direct effect of the decrease in vapor pressure deficit,and the indirect effect in the increase of soil moisture caused by air humidification.This study revealed distinct responses of young P.sylvestris var.mongolica tree growth to atmospheric water and soil water changes.