增温对荒漠草原植物群落组成及物种多样性的影响

Effect of warming on plant community composition and plant species diversity in the desert steppe

以短花针茅荒漠草原为研究对象，通过采用远红外线辐射器模拟增温的方法，探讨了增温对荒漠草原植物群落结构及生物量和物种多样性的影响。结果表明：由于远红外线辐射器的增温作用，在2012年整个生长季内，增温样地10、20、30 cm土壤平均温度与对照样地相比，平均增加了0.39、0.38、0.31℃；各土层土壤含水量较对照平均减少0.76%、0.73%、0.60%。受温度升高及土壤含水量减少的影响，模拟增温6个生长季后，与对照样地相比，群落的高度整体增加，密度、盖度、频度表现为部分物种增加和部分物种减少的趋势，冷蒿（Artemisia frigida）等物种的重要值下降，阿氏旋花（Convolvulus ammanii）等物种的重要值上升，但是增温没有明显改变植物群落的组成。同时，增温处理使荒漠草原禾草的盖度减少，杂类草的盖度增加，半灌木和一两年生植物分盖度未发生明显变化；增温使地上地下生物量出现了不同程度的减少，在0~30 cm土壤深度地下生物量分配中，增温样地0~10 cm分配比例（81.23%）小于对照（86.07%），10~20 cm分配比例（11.55%）大于对照（9.16%）；20~30 cm 分配比例（7.22%）大于对照（4.77%），增温使得地下生物量分配格局向深层转移。增温后，增温样地植物Shnnon-Winener指数降低，Pielou均匀度指数升高，温度升高使荒漠草原植物群落的均匀度增加，但并没有提高草地植物的物种多样性。

The effect of warming on plant community structure and species diversity was studied in the Stipa brevifora desert stppe by using infrared radiation method to simulate global warming. The results showed as follows：Compared with control （CK）, the soil temperatures increased by 0.39, 0.38 and 0.31 ℃ at depths of 10, 20 and 30 cm, respectively, under the warmed plots in the whole plant growing season of 2012, whereas soil water content was decreased 0.76%、0.73%、0.60%in different soil depth, respectively;The change of plant community height, density, frequentness and diversity was found due to the elevated soil temperature and the decreasing soil water content. The structure of plant community has also been changed by warming. The warming significantly decreased the important value of Artemisia frigida, but it significantly increased the important value of Convolvulus ammanii. In addition, warming significant increased the coverage of grasses, whereas it significantly increased the coverage of forbs. No change was detected for semi-shrub and annual-biennial. Warming significantly decreased plant community above- and below-ground biomass allocation pattern transferred to deep soil layers. The below-ground biomass of 0-10 cm soil layers was lower in warming than in control, but below-ground biomass of 10-20 cm was higher in warming （11.55%） than in control （9.16%） and 20-30 cm was higher in warming （7.22%） than in control （4.77%）. Warming led to the transfer of below-ground biomass from upper layer to lower layer. Warming significantly decreased Shnnon-Winener index, but significant increased Pielou index by elevated temperature. Warming significantly increased evenness of desert steppe, whereas no change on plant species diversity.