高寒草甸冷季牧场不同休牧期对土壤种子库的影响

为明晰青藏高原高寒草甸冷季牧场的适宜休牧期，在东祁连山天祝高寒草甸设置了土壤解冻临界期—牧草枯黄期(RP1)、土壤解冻后期—牧草枯黄期(RP2)、牧草返青初期—牧草枯黄期(RP3)、牧草返青后期—牧草枯黄期(RP4)和当地传统休牧(优势牧草高5 cm—牧草枯黄期)(RP5)5个休牧期，研究了土壤种子库的物种组成、密度、多样性及其与地上植被的关系。结果表明：供试土壤种子库中共萌发27种植物，分属12科23属；5个休牧期土壤种子库密度表现为RP1(2 136.67粒·m^-2)>RP2(1 983.33粒·m^-2)>RP3(1 576.67粒·m^-2)>RP4(1 220粒·m^-2)>RP5(863.33粒·m^-2)；香农-威纳指数和辛普森多样性指数在RP1休牧土壤种子库中较高，Pielou均匀度指数在RP5中最高；5个休牧期土壤种子库与地上植被的Sorensen相似性指数在0.38～0.49，其中RP1休牧与地上植被的相似性最高。综上，土壤解冻临界期—牧草枯黄期休牧更有利于土壤储备植物种子，增加草地的抗干扰能力。

Effects of Different Rest Grazing Periods on Soil Seed Bank in Cold Season Pasture of Alpine Meadow

To clarify the suitable rest grazing period for cold season pastures of alpine meadows in the Qinghai-Tibet Plateau,five rest grazing periods were set up in Tianzhu alpine meadow of east Qilian Mountain,including the critical period of soil thawing-forage withering period (RP1),the late period of soil thawing-forage withering period (RP2),the initial period of forage regreening-forage withering period (RP3),the late period of forage regreening-forage withering period (RP4) and the local traditional rest grazing (when the dominant forage height was 5 cm-forage withering period) (RP5). The species composition,density,diversity of soil seed bank,and its relationship with aboveground vegetation were studied. The results showed that a total of 27 plants germinated in the tested soil seed bank,belonging to 23 genera and 12 families. The density of the soil seed bank showed that RP1 (2 136.67 seeds·m^-2)>RP2 (1 983.33 seeds·m^-2)>RP3 (1 576.67 seeds·m^-2)>RP4 (1 220 seeds·m^-2)>RP5 (863.33 seeds·m^-2). The Shannon-Weiner index and Simpson diversity index were the highest in the RP1 rest grazing,the Pielou evenness index was the highest in the RP5 rest grazing. The sorensen similarity index between the soil seed bank and the aboveground vegetation in the five rest grazing periods ranged from 0.38 to 0.49,among which the similarity was the highest in the RP1. In conclusion,RP1 rest grazing is more conducive to soil storage of plant seeds and increases the anti-interference ability of grassland.