Journal cover Journal topic
Web Ecology An open-access peer-reviewed journal
Web Ecol., 7, 94-105, 2007
© Author(s) 2007. This work is distributed under
the Creative Commons Attribution 3.0 License.
14 Nov 2007
Effects of a nurse shrub on seed deposition and seedling recruitment of the annual Agriophyllum squarrosum
F.-R. Li1, G. Li2, L.-F. Kang1, Z.-G. Huang1, Q. Wang1, and J.-L. Liu1 1Chinese Ecosystem Network Res. Naiman Desertfication Res. Station, Cold and Arid Regions Environ and Engineering Res. Inst., Chinese Acad. of Sciences, 260 Donggang West Road, Lanzhou, 730000, China
2E. H. Graham Centre for Agricultural Innovation, Wagga Wagga Agricultural Inst., PMB, Wagga Wagga, 2650, Australia
Abstract. The shrub Artemisia halodendron and the annual herb Agriophyllum squarrosum, which typically co-occur in a mobile sandy habitat in eastern inner Mongolia, China, were used to determine whether the presence of A. halodendron influences seed deposition and seedling recruitment of A. squarrosum under and around the shrub canopy in relation to wind direction, sampling position (windward vs. leeward sides) and distance from the shrub. The numbers of seeds deposited, seedlings emerged, and individuals recruited of A. squarrosum around adult shrubs were sampled along four transects aligned to the four main wind directions at 0.5, 1, 2, 3, 4.5 and 6 m from the shrub base on both windward and leeward sides of each transect. Spatial pattern of seed deposition was strongly altered by the presence of shrubs, but effects varied with wind direction, sampling position and distance from shrubs. Significantly more seeds tended to deposit on the leeward than on the windward sides in all four transects, with the exception of transects along the least prevailing wind direction. The presence of shrubs as nursing plants caused a marked variation in seed deposition across sampling locations, but this effect was detected only in the most, secondary and third most prevailing wind directions, but not in the least prevailing wind direction. In general, the shrub’s influence was within a 2 m radius from the shrub, despite some differences among transects. Although seed bank density had no direct effect on A. squarrosum recruitment patterns, it contributed to the observed variation in recruitment indirectly through density-dependent emergence of seedlings. Our findings provide further evidence of shrubs as a source of spatial heterogeneity in seed availability and thereby a common factor determining population dynamics of understorey herbaceous species.

Citation: Li, F.-R., Li, G., Kang, L.-F., Huang, Z.-G., Wang, Q., and Liu, J.-L.: Effects of a nurse shrub on seed deposition and seedling recruitment of the annual Agriophyllum squarrosum, Web Ecol., 7, 94-105,, 2007.
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