荒漠植物叶片碳同位素组成及其水分利用效率

Stable Carbon Isotope Composition of Desert Plant Leaves and Water-use Efficiency

水分通常是影响荒漠植物生长的主要限制因子 ,然而当前很少有关于荒漠群落中植物水分利用效率的报道。作为指示水分利用效率的可靠指标 ,叶片稳定碳同位素组成 (δ13 C值 )可以用来探讨植物适应干旱环境的强弱程度。对阜康和金塔同种或同属的植物叶片δ13 C的测量结果表明 ,干旱可使植物叶片δ13 C升高 :年降水量每增加 1mm ,叶片δ13 C则降低 0 0 1‰～ 0 0 15‰。阜康荒漠灌木叶片δ13 C值明显高于草本 ,这样的趋势也存在于甘肃金塔主要荒漠植物中 ,与前人的报道也基本一致。说明灌木可能更适应干旱胁迫 ,并且这种现象可能是全球荒漠生态系统的一种共性。对阜康四种荒漠代表植物红砂、梭梭、补血草和骆驼刺的SOD活性的测定结果间接地支持了这一结果。进一步的分析表明 ,藜科、豆科和某些禾本科植物适应干旱环境的能力相对较强。

Water is usually considered to be the key limiting factor for growth of desert plants, yet there is little information available of the water use efficiency of species within a desert community. As a reliable indicator of long-term water use efficiency in C3 plants, leaf carbon isotope ratios were often used to evaluate the adaptive degree of plants to arid environments. So, foliar δ 13 C values were measured on species occurring within two desert communities of Fukang, Xinjiang and Jinta, Gansu. The results showed that dryer condition led to higher foliar δ 13 C values. A decrease of 1 mm in annual precipitation amount would result in an increase of 0\^01‰～0\^015‰ in foliar δ 13 C values. Both in Fukang and in Jinta, foliar δ 13 C values of shrubs were significantly more positive to these of grasses, which were closely similar to those from the previous literature sources, indicating that shrubs have stronger adaptability to arid environments than grasses do. The conclusion was indirectly supported by SOD activities, SOD activities of Reaumuria soongorica and Haloxylon ammodendron were higher 1 time than those of Alhagi spasifolia and Limonium gmelinii. The further analysis showed that plants with stronger adaptability to arid environments came mainly from Chenopodiaceae and Leguminosae families and partly from Gramineae families.