气候变化和种子萌发特性对轮叶马先蒿种群扩张的影响

Impacts of climatic changes as well as seed germination characteristics on the population expansion of Pedicularis verticillata

轮叶马先蒿(Pedicularis verticillata)是一种根部半寄生性杂草,在新疆巴音布鲁克草原迅速蔓延,严重危害了当地畜牧业的利用和发展。通过分析巴音布鲁克草原近30年的气候变化并结合轮叶马先蒿种子的萌发特性和传播特点,探讨气候因素对近些年来轮叶马先蒿种群在巴音布鲁克草原迅速扩张的影响。结果显示:1)1980—2010年新疆巴音布鲁克草原轮叶马先蒿生长季内的日平均温,最高温,最低温均表现出增高趋势,且气候倾向率在0.3℃(10 a)左右;此外马先蒿生长季内的有效积温和年积温也有显著的增长,增幅分别为48.755℃(10 a)和61.469℃(10 a);生长季内的平均降雨量和年均降水量也出现了明显的增多,每10年的增幅在20 mm以上;说明巴音布鲁克草原的气候朝着"暖湿化"的方向发展。2)轮叶马先蒿种子具有循环休眠的现象,属条件休眠状态。而这个状态主要受温度条件的变化所影响,萌发率随温度升高而显著提高。室温储藏和赤霉素处理下轮叶马先蒿种子在3/16℃和5/20℃这2个变温条件下萌发率最高,可达50%以上;而湿冷层积处理中种子的萌发率虽然也表现为随温度的升高而提高,但5/20℃时的最大萌发率仅为(44.44±2.94)%。3)巴音布鲁克草原气候的"暖湿化"变化有利于轮叶马先蒿种子的萌发和扩散,这可能是导致轮叶马先蒿在巴音布鲁克草原迅速蔓延的主要原因之一。

Pedicularis verticillata is a kind of root hemiparasite, which has recently been expanding in Bayanbulak Grassland of Xinjiang, and reducing productivity of grassland. Hence, threatening the utilization and development of local animal husbandry industry. In this research, we focused on the patterns of climatic change in past 30 years and the effect of temperature on seed germination. We then analyzed the reasons for population expansion of P.verticillatain along the Bayanbulak Grassland. The results showed：1） during 1980 to 2010, the mean, maximum and minimum temperature was increased with the rate of 0.3 ℃ each 10 years. The rate of effective accumulate temperature in the growing season of P. verticillata increased by about 48.755 ℃ （10 a） and per annual increased at 61.469 ℃ （10 a）. Precipitation was increased significantly during the growth stage of P. verticillata. It indicated that the climate in Bayanbulak Grassland was getting warmer and wetter. 2） Seed of P. verticillata has the phenomena of dormancy cycle, which is an adaptation to the changeful alpine climate. Germination rate was significantly increased with the rise in temperature. Seeds stored in root temperature germinated highest in 3/16 ℃ and 5/20 ℃, and the germination rate was more than 50%. After moist-chilling, seed germination rate of P. verticillata also improved with the increase in temperature, but only up to （44.44±2.94）%in 5/20 ℃. 3） The “warm-wet”trend may facilitate seed germination and dispersal, contributing to the population expansion of P. verticillata.