闲置地由于人为干扰程度较低，自然演替和生态过程得以发生，形成了以自生植物为主导的荒野景观，该过程增强了城市生态功能的稳定性。因此，探究城市闲置地自生植物的生长规律与群落特征，有助于为此类特殊生境的生态修复提供科学依据并指导城市荒野景观的营造与更新。

以北京西玉河村闲置地为例，对该区域2009—2022年的卫星影像进行解译，分析拆建前后植被覆盖率的变化趋势。于2023年3—5月对39个样方内的自生植物进行了全面调查，计算其相对频度、相对盖度、相对多度、相对优势度和重要值5个评价指标。

1）拆建前（2009—2017年），场地植被覆盖率整体变化不显著；在建筑拆除后的第1年内（2017—2018年），乔木植被覆盖率未发生显著变化；拆建后（2018—2022年）植被覆盖率显著上升，年均增幅约8.0%。2）场地内共记录到植物24科、41属、44种，其中自生植物39种，以菊科为主，占自生植物种类总数的28.95%；草本植物种类占自生植物种类总数的69.23%。3）传播型为风传播的自生植物占比为43.59%；优势种包括藜（Chenopodium album ）、黄花蒿（Artemisia annua）和尖裂假还阳参（Crepidiastrum sonchifolium）等，共形成11种优势植物群落。4）自生草本植物多在3月集中萌发，4月开花，部分花期延续至5月，个体观赏性强的植物有地黄（Rehmannia glutinosa）、蒲公英（Taraxacum mongolicum）、翅果菊（Lactuca indica）等，整体观赏性由群落质感决定。5）葎草（Humulus scandens）、藜和尖裂假还阳参表现出明显的种间竞争。

科学地保留和利用自生植物为在闲置地营造荒野景观提供了新途径，未来应进一步探究降低人为干扰、维持生态平衡的景观营造方法以及植被恢复初期的管理措施等内容。

The relatively low level of human interference in most of the vacant lands allows natural succession and ecological processes to take place to a certain extent, thus forming wilderness landscapes dominated by spontaneous plants and enhancing the stability of urban ecological functions. Therefore, revealing the community characteristics and growth pattern of spontaneous plants in such special habitats can provide some support for ecological restoration of vacant land and guide the construction and renewal of wilderness landscape.

Taking the Xiyuhe Village construction and demolition site in Beijing as an example, this research comprehensively adopts the satellite image analysis method and the field survey method to visually interpret and statistically analyze the trend of vegetation coverage and the change of vegetation growth distribution before and after the construction and demolition as shown in eight historical satellite images spanning the period from 2009 to 2022. Using the grid distribution sampling method, the research area is divided into native forest area, primitive river area, and construction and demolition area. During the period from March to May in 2023, the investigation of spontaneous plants was repeated 10 times targeting the 39 quadrats selected, and the evaluation indexes such as relative frequency, relative cover, relative density, relative dominance, and importance value were calculated using SPSS 26.0.

1) In terms of vegetation coverage, before construction and demolition and within one year of demolition (2009–2018), the vegetation coverage did not change significantly, with coverage change mainly concentrated in the vacant open space at the forest edge on the west side of the research site and in the area of building demolition on the south side, and newborn plants mainly appearing in the vicinity of the primary vegetation. While after construction and demolition (2018–2022), the vegetation coverage increased significantly, with an average annual increase of about 8%. It is clearly observed that during this period, a large number of plants began to grow at the gaps left by hard paving, in which woody plants grew and spread rapidly, most of the secondary trees grew in the area with more fertile soil and no hard concrete block residues near the primary trees, and the growth range of herbaceous plants was enlarged. 2) In terms of spontaneous plant species, a total of 44 species of plants classified into 24 families under 41 genera are recorded at the research site, including 39 species of spontaneous plants, of which herbaceous plant species are the most numerous, accounting for 69.23%, mainly dominated by Asteraceae (11 species in total), accounting for 28.95% of the total number of spontaneous plants. In addition to the Asteraceae family, the rest families mostly comprise 1 – 2 species each, such as Zygophyllaceae, Gramineae, Labiatae, Cheloniaceae, Coriandrum, Ledebouriaceae, Cruciferae, and Syzygium. 3) In terms of the propagation type of spontaneous plants, wind propagation serves as the dominant propagation type, accounting for 43.59%, which can achieve long-distance propagation of plant seeds by the action of wind, making plant seeds more widely distributed. In addition, animal propagation accounts for 17.95%, autochthonous propagation accounts for 5.13%, the combination of animal propagation and wind propagation accounts for 10.26%, and the combination of wind propagation and autochthonous propagation accounts for 17.59%. In terms of dominant species of spontaneous plants, the dominant species include Chenopodium album, Artemisia annua, Crepidiastrum sonchifolium, Setaria viridis, Humulus scandens, Ulmus pumila, Lactuca indica, etc. The distribution of spontaneous plants in different regions varies locally, with a total of eleven dominant plant communities being formed, such as Ixeris chinensis, Lactuca indica, Humulus scandens, Ulmus pumila, Broussonetia papyrifera, Salix matsudana, Chenopodium album, Salix matsudana, Broussonetia papyrifera, Crepidiastrum sonchifolium, and Artemisia annua. 4) In terms of the ornamentality of spontaneous plants, the herbaceous spontaneous plants typically sprout in March, and bloom in April, with the blooming period of some plants extending to May. Of these spontaneous plants, those with more obvious ornamentality include Rehmannia glutinosa, Taraxacum mongolicum, Lactuca indica, etc. For spontaneous herbaceous plants with unremarkable ornamentality, such as Ixeris chinensis, Crepidiastrum sonchifolium, and Viola philippica, they often also have ornamental flower organs, but due to the small flower volume and sparse inflorescences, it is difficult for them to form an outstanding ornamental effect. Generally, such herbaceous spontaneous plants have strong ornamentality when arranged together, which may compensate for their poor individual ornamentality, and they also play a more important role in autochthonous plant community landscapes. 5) In terms of competition among spontaneous plant species, Humulus scandens, Chenopodium album and Crepidiastrum sonchifolium acuminata show obvious competition. Humulus scandens grows rapidly from March to April, with their number of leaf blades, plant height, and fluffy diameter growing to the maximum extent then, while Chenopodium album and Crepidiastrum sonchifolium still maintain rapid growth from April to May, with Chenopodium album performing best.

The scientific retention and use of spontaneous plants may provide a new idea for creating wilderness landscapes in unused land. In the future, we still need to carry out in-depth research on the reduction of human interference, the ecological balance of wilderness landscapes, and the management measures in the early stage of vegetation restoration.