荒漠化草原土壤种子库的季节动态和垂直分布

Seasonal Dynamics and Vertical Distribution of Soil Seed Bank in Desert Grassland

[目的]掌握荒漠化草原土壤种子库的季节动态和垂直分布。[方法]采用萌发法测定内蒙古高原荒漠化草原不同季节(种子成熟期、生长季初期和生长季中期)、不同土层(0~3、3~6、6~9 cm)土壤种子库的总种子数、种子发芽指数和RGF。[结果]土壤种子库中的总种子数和种子发芽指数均从种子成熟期(9月)—生长季初期(次年5月)—生长季中期(次年7月)呈下降的趋势;RGF的季节动态整体呈现出先上升后下降的单峰趋势;总种子数从浅层到深层(0~3、3~6、6~9 cm)呈现递减趋势;种子成熟期的RGF从浅层到深层呈现增加趋势;生长季初期的RGF从浅层到深层呈现出先下降后上升的趋势;不同土壤深度快速萌发种子占土壤种子库总数比例不同,表现为0~3层(33.48%)>3~6层(11.54%)>6~9层(9.38%);土壤种子库中以一年生、多年生草本为主,未统计到灌木种子。[结论]研究结果为内蒙古高原荒漠化草原的生态恢复提供了理论依据。

[Objective] The aim was to understand the seasonal dynamics and vertical distribution of soil seed bank in desert steppe.[Method]We investigated the total number of soil seed bank,seed germination index and RGF in different seasons（ seed maturity period,early growing season and middle growing season） and in different soil depth（ 0-3,3-6 and 6-9 cm） at desert steppe on Inner Mongolia using the germination method.[Result]The total number of seeds and seed germination index decreased from the seed maturity period at September to the early growing season at May,then to the middle growing season at the following July; the seasonal dynamics of RGF were high at early growing season and low at seed maturity period,showing a curve with single valley. The total number of seeds decreased with the increasing of the soil depth,while the RGF at seed maturity period increased from the surface soil to deep soil. RGF at early growing season increased first then decreased. The ratio of rapidly germinated seeds in different soil depths was different,our results followed the pattern： 0-3 cm（ 33. 48%） 3-6 cm（ 11. 54%） 6-9 cm（ 9. 38%）. The soil seed bank is dominated by annual and perennial herbs and no shrub seeds in soil seed bank.[Conclusion] The results provide theoretical basis for ecological restoration in desertification grassland in Inner Mongolia plateau.