| Guizhou plateau, situated on the Southwest Karst ecological fragile region, is a joint center, because of the unreasonable actions by humans, the land has become desertificated and the forest vegetation has disappeared. The advantage of shrub has relatively increased and degenerated into shrub forest, which has the features of calciphilia, drought tolerance and stone features strong. The dominant shrubs in rocky desertification has become the flora that can’t be replaced in rocky desertification ecosystem. The population spatial pattern, which depends on the interaction of its own biological characteristics and habitat, is an important feature and it is an important aspect of self-recovery and steady. Based on the case study on the dominant shrub of P. Angustifolia population and its own corresponding rocky desertification ecosystem, we have carried out the study on the characteristics of P. Angustifolia population and the interaction between P. Angustifolia population spatial pattern and the soil environment.The results show that in below.1.The genus composition of P. Angustifolia community of rocky desertification shrubs indicates that, the P. Angustifolia community is mainly distributed in three typical rocky desertification regions respectively, which is potential rocky desertification, light desertification and moderate rocky desertification.We recorded 66 plant species belonging to 30 genera and 55 families, and with the increase of rocky desertification degree, species richness and life-style composition show a decreasing variation.2.The analysis of P. Angustifolia in shrub layer species composition shows that the shrub layer species under different degree of rocky desertification shows the different composition characteristics, the shrub populations in mild rocky desertification area is the highest, and the lowest of shrub populations is in the moderate rocky desertification region. The artificial disturbance is less in the potential desertification areas, and the shrub populations is mainly dominated by P. Angustifolia and Po Liu; the shrub populations in mild rocky desertification areas is mainly dominated by Pyracantha, wild pepper, Spiraea; the shrub populations in moderate rocky desertification areas is mainly dominated by P. Angustifolia, Rosa cymosa and wild pepper because of the artificial disturbance and patchy soil. The shrub layer species under different slopes shows different characteristics. The artificial disturbance is less in the 15°areas, and the shrub populations is mainly dominated by P. Angustifolia and Coriaria; the shrub populations in the 45°areas is mainly dominated by P. Angustifolia, wild pepper, Spiraea; the shrub populations in 60°areas is mainly dominated by P. Angustifolia, Rosa cymosa and wild pepper because of the artificial disturbance and patchy soil.3.The analysis of species diversity on P. Angustifolia community shows that the species diversity index of P. Angustifolia community shows highest in moderate rocky desertification stage and the 45° areas; the lowest index is in the light rocky desertification and the 60°slope. This suggests the species are more complex in 45°areas, the vegetation restoration ability and anti-interference ability are more stronger and the community was relatively more stable.4.The analysis of distribution pattern intensity on P. angustifolia population shows that the P. angustifolia population presents aggregated distribution pattern in potential rocky desertification, light desertification and moderate rocky desertification, there has the highest level of aggregation in light rocky desertification and the lowest level of aggregation in potential desertification area; the P. angustifolia population presents aggregated distribution in different slope areas, the aggregation is the highest in 45°slope area and the lowest is in the 15°slope area.5.The analysis of P. angustifolia population spatial pattern based on the GS+ shows that P.angustifolia population are mainly aggregated distribution under different rocky desertification degrees, the radius becomes more bigger with the intensification of rocky desertification and the spatial heterogeneity becomes more stronger with the increasing of rocky desertification grade; The spatial distribution pattern of P. angustifolia population under different slope grade exhibits that in the samples of 15°and 45°present aggregate distribution patterns, the radius in low and middle slope become more bigger as the slope raised, but in the sample of 60° presents an random distribution pattern and the spatial heterogeneity becomes more stronger with rising of slope; The difference in all directions becomes more significant with the intensification of rocky desertification and rising of the slope.6.The effect on P.Angustifolia population spatial pattern by environmental factors of rocky desertification habitats and the results show that P. angustifolia population spatial pattern is deeply influenced by soil total nitrogen, total phosphorus and hydrolytic nitrogen and topographic conditions and they make the decisions for the distribution pattern for P.Angustifolia population. |
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