云南南部和中部地区公路旁紫茎泽兰土壤种子库分布格局

公路边缘生境促进外来植物的入侵,土壤种子库作为植被天然更新的物质基础对未来植被的构成至关重要。研究路旁生境中紫茎泽兰土壤种子库的分布格局,对揭示路旁紫茎泽兰种群的补充和更新、探讨公路与入侵植物之间的关系以及科学制定紫茎泽兰防除对策具有重要意义。本文在紫茎泽兰入侵的云南南部和中部地区选择三种不同级别的9条公路的23个取样地点,沿垂直于公路方向设置55条样线,采得374个10 cm?10 cm?10 cm土样。采用温室萌发法,研究了紫茎泽兰土壤种子库从公路沿线到邻近景观的储量、影响因子以及分布格局。结果表明：9条公路旁的土壤中贮藏着丰富的紫茎泽兰种子,其种子库密度变动于3 152～25 225 粒?m-2,占所有有效种子密度的平均比例为48.7%。公路级别、路旁景观类型和海拔对路旁紫茎泽兰种子库密度有显著影响,密度随公路级别的提高而增加;不同路旁景观类型中的种子库密度排序为：稀树林>稀树灌木林>撂荒地和荒坡>森林;海拔1 700～1 900 m范围内的种子库密度最大。不同样线的种子库密度值随垂直于公路的距离变化格局略有不同,平均密度值和平均种子数量占样线总数的比例值都呈单峰变化,在距离公路最近端已经有很高密度,大多数样线的高峰值出现在9 m以内。公路旁已经分布有一个紫茎泽兰种子带,因而提高路旁本地植物的盖度及郁闭度有利于控制紫茎泽兰通过种子更新进一步扩散。

The soil seed bank of Eupatorium adenophorum along roadsides in the south and middle area of Yunnan, China

Acuumulated evidence has indicated that roads are contributing to the spread of invasive exotic plants in numerous ecosystems by providing corridors for invasion and suitable habitat. However, little has been known about the effect of roads on the exotic plant soil seed banks (SSBs) which are important components of population dynamics, affecting the ecosystem resilience. Herein, we examined the effect of different roadside habitats and distance from roads on SSB of Eupatorium adenophorum (EA) towards revealing the regeneration and recruitment of its population. Importantly, our study will be remarkably helpful to realize the relationship between roads and exotic plant invasion and propose measurements for weed regulation. We performed the study at 23 sits along 9 roads of three different grades in southern and middle part of Yunnan where was invaded by EA. 10 cm×10 cm× 10 cm soil samples were taken along transects leading awy from the edges of roads at each sit. Totally, 55 transects were established and 374 soil samples were collected. Greenhouse germination method was applied to determine SSB storage and density. The results showed that there were abundant EA seeds stored in SSBs as well as the 9 roads with densities ranged from 3 152 to 25 225 ind/m². Averagely, the proportion of EA seeds reached 48.7% of the total SSBs. The grade of roads, landscape along roadsides and elevation showed significant effects on EA seed bank density: it increased with road grade; density of different roadside landscape together with the order of Open forest> Open shrubs>Abandoned land and slope>Forest; it reached its maximum within 1 700-1 900 m above sea level. The curve of both seed bank density and the proportion of the total number of transects seeds have only a single peak. Density of EA seeds at the nearest point of the roads was already very high, however, the highest density in any transects was usually found within 9 m distance to the roadside. Taken together, we can conclude that there exists a seed storage belt along with roadsides, and management of roadside habitats should be considered as a key to prevent and controll exotic plant invasion, and the maintenance of a dense canopy of native vegetation would benefit the regulation of EA.