关键词: 农业洪涝, 指标构建, 洪涝指数, 灰色关联, 西南地区

Abstract: It is not clear how fire, an important factor maintaining ecosystem stability, affects spore banks of Sphagnum, the dominant plants in peatlands. In this study, mature spores of three Sphagnum species and peat soil collected from peatlands in the Changbai Mountains were used as experimental materials. We simulated a process of fire in laboratory and measured soil temperature at different depths. Four temperature levels (20, 40, 60 and 100 ℃) and five time levels (0.5, 1, 2, 4 and 10 min) were set to simulate a heat shock experiment to treat Sphagnumspores. The effects of temperature and time of heat shock on spore germination percentage were assessed with germination test. During the process of fire, temperature decreased with soil depth. Surface peat reached an extreme high temperature of 300 ℃, while it was only 70 ℃ at the layer 1 cm below the surface, reflecting the good thermal buffering property of peat soil. Compared to the treatment at 20 ℃, 40 ℃ heat shock increased  20% of spore germination percentage of S. fuscum and 50% of S. magellanicum,while 60 ℃ heat shock could double the spore germination percentage of S. capillifolium. In contrast, 100 ℃ treatment strongly decreased spore germinability. Our results indicate that the efficient thermal insulation of peat soil may keep Sphagnum spores away from lethal high temperature and that moderate heat shock may facilitate spore germination of Sphagnum.These may be of great significance for the establishment of Sphagnumspores in peat and population persistence in response to fire disturbance.

Key words: agricultural flood, indicator construction, flood index, gray correlation, southwestern China.