Research on Habitat and Species Diversity of Spontaneous Plants in the Dujiangyan Canal Corridors

Objective The canal system is a key element in changing the hydrological process in agricultural irrigation areas, and it is also an important ecological network in irrigation areas. The canal corridor habitat is an important habitat for living beings, which is of great significance for the maintenance of biodiversity in irrigation areas. Dujiangyan Essence Irrigation Area is located in the southeast of Dujiangyan county level city in Chengdu, and its canal habitat is an important place to maintain biodiversity and an important part of the regional green space ecological network. The study of the spontaneous plants and their composition and diversity characteristics in different habitats in the canal corridor of Dujiangyan Essence Irrigation Area is conducive to the conservation of biodiversity and the optimization of the landscape of the canal corridor in the irrigation area. Methods In the spring, a comprehensive survey of spontaneous plants was carried out, and a total of 81 sample points and 167 quadrat data were collected, and the habitats were divided into 6 categories: semi-natural revetments, hard revetment, wasteland, artificial green space, hard texture plot and self-use vegetable plot habitats. And the community composition analysis was carried out by two-way indicator species analysis (TWINSPAN), and the diversity of spontaneous plants in different canal corridors and habitat types was compared by Kruskal-Wallis test. Results The results showed that: 1) A total of 257 species of spontaneous plants belonging to 180 genera and 79 families were recorded in the canal corridor of Dujiangyan Essence Irrigation Area. Spontaneous plants species in this research belong to 10 life forms, perennial herbaceous plants accounted for the highest proportion, followed by annual and biennial herbaceous plants. In terms of species origin, native spontaneous plants account for the highest proportion, accounting for 42.02%. The life form of the dominant species were mainly annual and biennial herbaceous plants and perennial herbaceous plants, and the species origin of the dominant species are mostly native and domestic species. 2) There were 15 dominant clusters on the revetment and 24 dominant clusters on the shore, and the dominant clusters without invasive species could provide a reference for plants community construction for specific habitats. Revetment clusters II., III., and X.III. can be used as dominant clusters for hard revetment habitats; shore cluster VII. Can be used as the dominant cluster of artificial green space habitat and hard texture habitat, and cluster X.IX. can be used as dominant clusters of wasteland habitat and self-use vegetable plot habitat. 3) There were significant differences in species composition, life form composition, species source and dominant species composition among the six habitats. The species composition of different habitats was studied, and it was concluded that the habitat type with the largest number of families, genera and species was wasteland habitat, and the lowest habitat was semi-natural revetment habitat. Classification and statistics of species life forms in different habitats were carried out, the results showed that, except for the semi-natural revetment habitat, the life forms with higher rankings were annual and biennial herbaceous plants and perennial herbaceous plants, and the life forms with a high proportion of semi-natural habitats were perennial herbaceous plants and shrubs. The habitats with the highest proportion of annual and biennial herbaceous plants included hard revetments, artificial green spaces, and self-use vegetable plots. The habitats with the highest proportion of perennial herbaceous plants include semi-natural revetments, wasteland and hard textures. There were differences in the composition of dominant species in different habitats, and the proportion of the importance value of dominant species was the highest in hard revetment, and the lowest proportion was in artificial green space. The habitat with more native dominant species was semi-natural revetment, and the habitat with more invasive dominant species was self-use vegetable plot. And there were also significant differences among the diversity indexes, especially among the hard revetment habitat and some habitats, and all the indexes of the hard revetment habitat were the lowest. Conclusion The results showed that there were significant differences in species composition and diversity among different habitats in the canal corridor of Dujiangyan Essence Irrigation Area. In the hard revetment habitat, ferns are not only the dominant species with a high proportion, but also appear as indicator species and dominant species in the dominant clusters, so ferns occupy an important position and play an important role in the revetments, especially in the hard revetments. The frequency of the occurrence of the Papermulberry was relatively high, and it even appeared as an indicator species in the dominant clusters of the habitat in the habitat of wasteland and self-use vegetable plot, indicating that the native plant species had strong growth adaptability and could occupy a place in the multi-habitat, and it should be studied more deeply in the follow-up to explore whether it can be used as a high-quality native tree. At the same time, there were significant differences between the species richness, diversity and evenness of the hard revetment habitat and some other habitats, and its diversity-related indicators were the lowest. In order to maintain irrigation efficiency and reduce water infiltration, the canal system in irrigation areas often uses anti-seepage engineering materials to construct revetment, and the relationship between different revetment materials and construction practices and diversity is worthy of in-depth study, which is conducive to the construction of ecological water conservancy projects in the future. At the meantime, it is necessary to protect the dominant spontaneous plants species and communities in different habitats, and strengthen the dynamic monitoring and timely removal of invasive species in the construction of the future.