The role of sexual versus asexual recruitment of Artemisia wudanica in transition

Artemisia wudanica is an endemic, perennial, pioneering psammophyte 24 species in the sand dune ecosystems of western Horqin Sand Land in northern China. 25 1 Solid Earth Discuss., doi:10.5194/se-2016-29, 2016 Manuscript under review for journal Solid Earth Published: 16 February 2016 c © Author(s) 2016. CC-BY 3.0 License.

. This is where pioneer species establishment is the initiation 88 of community succession (Allen and Nowak, 2008). Therefore, it is essential to 89 elucidate how pioneer species respond to transition zone habitats at different growth 90 stages. This will allow to gain decision-making guidelines which contribute to plant 91 recovery after disturbance, and control of wind erosion.

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Because of their ecotone nature, transition zones ecosystems contain gradients in 93 environmental conditions that span a wide range of variation. They frequently 94 intensify or concentrate the flow and processing of materials; nutrient retention may 95 also be related to their spatial pattern of variation (Traut, 2005 species to persist at those zones, and how differences in these processes affect species 104 responses to changes in environmental conditions (Peters, 2000(Peters, , 2002b.

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We hypothesized that density coming from asexual reproduction of A. wudanica is 149 different from that coming from sexual reproduction in transition zone habitats of

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In early April 2011, we randomly selected three dune slacks in mobile dunes. Their 177 size was either 2.06 ha or 1.62 ha or 1.10 ha. Height of sand dunes was approximately 178 equal around these study areas. At each of the three transition zones (see Fig. 1) with 179 a vegetation cover of less than 5%, we randomly set up nine 1m×1m quadrats.

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Environmental parameters 236 From early April to late May, WE reached 4.67 cm (Table 2). In late May, soil 237 moisture content was 13% greater at 20-30 than 0-10 cm soil depth (Table 2). At this 238 time, pH was 2.9% greater at 10-20 than 0-10 cm soil depth (Table 2). Despite WE 239 showed a negative correlation with SM, OM, and PH, these correlations were 240 non-significant (p>0.05; Table 3). Soil moisture content showed positive correlations 241 with OM and pH1 but none of these correlations was significant (p>0.05). Soil 242 organic matter at 10-20 cm and 0-20 cm soil depth was positively correlated (p<0.05) 243 with pH at 10-20 cm soil depth (Table 3).

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Sexual and asexual reproduction 246 We found 34 and 18 individuals coming from sexual and asexual reproduction, 247 respectively, in all 27 plots. The mean density coming from sexual reproduction was 248 51% higher (p<0.05) than that coming from asexual, vegetative reproduction (Fig. 2).

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Frequency was approximately 11% greater for surviving ramets coming from asexual  The first axis explained 73.6% of the variation between ramet density and the study 273 environmental factors (Fig. 4). However, it was more strongly correlated with these 274 biotic and abiotic factors than it was the first axis for sexual reproduction. The second   (Figs. 3 and 4). Therefore, our hypothesis that density 305 coming from asexual reproduction of A. wudanica is different from that coming from 306 sexual reproduction in transition zone habitats was supported.

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The results that more sexual than asexual reproduction was found in all 27 study 308 plots (Fig. 2) suggest that seeds play an important role in A. wudanica preservation in 10-20 cm layer was slightly higher than that in the 0-10 cm layer (pH2>pH1) ( Table   355 2). It might be that calcareous groundwater and surface water could re-enter most on the density of both reproduction types (Fig. 3, 4); however, the negative effect on 360 the density of ramets was so weak that it could be considered negligible (Fig. 4). This      p=0.0100). Abbreviations for the study variables are given in Table 1.  Table 1.