Objective Weed control has always been a difficult problem for urban green space managers around the world. Weeds grow rapidly, which not only compete with flowers for nutrients, water and other resources, but also serve as the intermediate host of a variety of pests and diseases. Therefore, the poor control of weeds will surely affect the growth of flowers and plants. The current weed control methods mainly include manual weed removal, mulch cultivation and use, chemical weed control, etc., some of which are time-consuming and laborious or prone to cause environmental pollution, thus failing to achieve efficient and ecological weed control. However, the biological control method is seldom used in garden green space, for which the main reason is that the survival mechanism between different species (such as adaptive relationship with the habitat, community structure, community composition, external interference, etc.) has not been transformed into operable rules and methods. The key to biological control is to improve the invasion resistance of plant community, which is also a key way to radically reduce the cost of weed control. Relevant research on the mechanism of invasion resistance, the core content of invasion ecology research, has revealed a large number of underlying rules. However, such research has neither systematically sorted out the influence mechanism on community invasion resistance nor designed the application and transformation of the aforesaid rules, making it difficult to really realize the value of guidance of invasion resistance for community design.
Methods Through literature analysis, this research sorts out the influence mechanism of community invasion resistance, and puts forward relevant strategies for improving community invasion resistance from the perspective of landscape architecture. This research systematically analyzes the ecological factors affecting the invasion resistance of herbaceous plant community and their relationship with community invasion resistance in ecological research, and transforms them into the design strategies for improving community invasion resistance from the perspective of landscape architecture.
Results The invasion resistance of herbaceous plant community is influenced by a combination of factors such as habitat, community structure, community composition and disturbance, with community composition is the main influencing factor. Different factors have different impacts on the invasion resistance of herbaceous plant community, and communities composed of different species vary greatly in invasion resistance. 1) In terms of habitat, shady habitats perform best in invasion resistance, seconded by semi-aerobic habitats, while positive habitats perform worst; invasion is likely to occur in areas and years with relatively abundant rainfall; invasion is generally more likely to occur in fertile soils with relatively high carbon, nitrogen, and phosphorus contents. 2) In terms of community structure, increasing the number of community layers can help enhance the invasion resistance; when an invaded site has native species overlapping with the ecological niches of exotic species, it will be difficult for the exotic species to invade. 3) In terms of community composition, some special species in a plant community can increase the community’s invasion resistance; in general, the invasion resistance of a community is positively correlated with the number of species in the community; the higher the diversity of functional groups in a community, the stronger the community’s invasion resistance; theoretically, the edge area of a community is less resistant to disturbance, where the interface is prone to mutation, indicating that the edge area is less resistant to invasion. 4) In terms of disturbance, mowing can significantly reduce interspecific competition in a community, thus increasing the community’s invasion resistance; fire can reduce the seeds and propagules of weeds and inhibit the invasive disturbance of weed seeds on the community; gravel mulching can effectively reduce the germination of light-dependent weed seeds in the soil; and the fewer the species in the seed bank and the seed rain, the lower the possibility of community invasion.
Conclusion Therefore, the mechanism of community invasion resistance can be transformed into specific design strategies for invasion resistance enhancement such as habitat creation, community design, pathway establishment, and management and maintenance through the association of ecological and design variables. By creating herbaceous plant community from the four aspects of site habitat, community structure, community composition and disturbance relationship, the invasion resistance of a community can be effectively improved, so that the community can inhibit or influence the growth of surrounding weeds through its own “immune” system, without introducing chemicals that are difficult to degrade into the system or causing environmental problems related to chemical pesticides, while reducing the production cost, which can help promote the sustainable development of urban herbaceous plant community. Further, this research confirms that the basic theories of ecology can be converted into design-guided methods, and the key lies in the association between ecological variables and design variables, which is one of the “bridges” to realize the intersection of ecology and landscape architecture. However, this research decomposes the complex community system into single factors and simply considers the single-factor effect on species, which makes the research limited to a certain extent. In the future, it is supposed to take into account more composite factor variables to elucidate the mechanism of species coexistence and community invasion resistance, so as to better solve the problem of weeds in urban gardens.
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