| Taking spontaneous herbs in the main urban area of Zhengzhou as the research object,this paper uses the systematic sampling method to set up 65 sampling grids of 1 km×1 km,investigates the species composition,ornamental characteristics,community characteristics,habitat characteristics and human disturbance degree of spontaneous herbs,analyzes and discusses the species composition and community characteristics of spontaneous herbs under the background of urbanization,and the diversity pattern and influencing factors of spontaneous herbaceous communities under different urban habitats.Through analytic hierarchy,the spontaneous herbaceous plant resources that not only have ornamental value but can adapt to the special habitat of the city are screened and applied for popularization,which has important scientific value and practical significance for guiding and optimizing biodiversity management and conservation in Zhengzhou.The main findings are as follows:(1)Species composition characteristics of spontaneous herbsA total of 291 species of spontaneous herbaceous plants belonging to 167 genera in 46 families were found in this survey,mainly Asteraceae,Poaceae,Fabaceae and Brassicaceae families,including 133 species in 79 genera,accounting for 47.31% of the total genera and 45.70% of the total species.A high proportion of monospecies(108/64.67%)indicated that the species composition in the study area was more complex.From the perspective of geographical composition,46 families can be divided into 4 distribution types and 2 subtypes,167 genera can be divided into 14 distribution types,291 species can be divided into 15 distribution types,the distribution types of the family are dominated by tropical components,while the distribution types of genera and species are mainly temperate components.In terms of lifestyle,annual spontaneous herbs(173/59.45%)were more abundant than perennial spontaneous herbs(118/40.45%).In terms of growth type,the main upright type(75/25.77%)was the main type,followed by short-term rosette type(40/13.75%),branching type(40/13.75%)and clumpy type(39/13.40%).From the perspective of species source,local species are the mainstay,accounting for 72.85% of the total number of species,and alien species cannot be ignored,some of which such as Alternanthera philoxeroides,Symphyotrichum subulatum and Solidago canadensis have malignant invasive nature,which may damage the local ecosystem and need to be managed by humans.(2)Community characteristics of spontaneous herbaceous plants and factors affecting the distribution of dominant species in the communityThe three-level classification method of "life type-growth type-community type" was adopted,and the 1 667 spontaneous herbaceous plant communities surveyed were divided into 3 life types,19 growth type and 115 community types,and the dominant life forms of the community were mainly annual spontaneous herbaceous plants(73/63.48%),and the growth types were mainly erect(29/25.22%),clumpy(20/17.39%)and short-term rosette(19/16.52%).The CCA ranking results showed that the factors that had significant effects on the distribution of dominant species in52 colonies in spring were: soil water content > soil p H > soil compactness in order of importance> while the factors that had significant effects on the distribution of dominant species in 78 populations in summer and autumn were: soil water content>anthropogenic disturbance> soil compactness> depression closure > soil conductivity.In general,the main influencing factors affecting the distribution of dominant species of spontaneous herbaceous plant communities in the main urban area of Zhengzhou City were three limiting factors: human disturbance,soil moisture content and soil compactness.(3)Diversity patterns of spontaneous herbaceous plant communities in different urban habitats and their influencing factorsThe number of spontaneous herbaceous species contained in the six urban habitat types was,in descending order: soil wasteland(176)>garden green space(148)>river corridor(127)>gravel wasteland(108)>roadside gap(78)>tree pond(54).The number of community types was soil wasteland(77)>garden green space(68)>river corridor(59)>gravel wasteland(44)>roadside gap(33)>tree pond(24).From the perspective of the dominant life forms of the dominant species in the community,there was little difference between the dominant life forms of the three habitats of soil wasteland,garden green space and river corridor,and the proportion of summer annual species in the remaining three habitats(gravel wasteland,roadside crevices and tree ponds)was higher than that of winter and perennial.In terms of growth type,the proportion of high-growth dominant species in soil wasteland,gravel wasteland and river corridor was higher than that of dwarf growth type,while the proportion of dwarf growth dominant species in roadside gaps and tree ponds was significantly higher than that of high-growth type,and the proportion of dwarf growth dominant species in park green space was not much different from that of high-growth type.The mean values of Richness index,Shannon-Wiener index and Simpson index of soil wasteland,garden green space and river corridor were relatively large,which were significantly higher than those of the other three urban habitats(P<0.05),but the Pielou index was the largest in the tree pond.The influencing factors affecting the diversity of spontaneous herbaceous plants in the main urban area of Zhengzhou were as follows: human disturbance > Soil water content> soil conductivity> soil compactness.(4)Individual ornamental characteristics of spontaneous herbs and evaluation of garden utilizationFrom the perspective of species height,nearly 60% of the species(including grassy vines)are concentrated in the height of 0~50 cm,and only 17 species are extremely tall(>120 cm),and the overall height of the species is low.From the leaf point of view,the leaf length of most species was concentrated between 0~5 cm,accounting for 59.66% of the total number of species.From the perspective of flower characteristics,the species were mainly small flower diameter(diameter <1 cm),accounting for 54.67% of the flower-watching species.There are 15 kinds of flower colors,mainly 3 kinds of flowers: white,yellow and purple red;The flower types can be divided into 8 types: lip type,butterfly type,head type,spike type,five-petal type,radial type,cross type and funnel type,among which the number of species with five-lobed,radial type and head type is the largest;The flowering period of species is mainly concentrated in summer,followed by spring.From the perspective of fruit characteristics,there were 12 types of fruits,mainly 4 types of lean fruit,capsule fruit,Ying fruit and nut,and only 21 species with more eye-catching fruits,showing 7colors.The analytic hierarchy method was used to construct a comprehensive evaluation model of garden utilization of spontaneous herbaceous plant resources in the main urban area of Zhengzhou City,and 126 selected spontaneous herbaceous plants were evaluated and analyzed,which were divided into four grades according to the comprehensive score.There are 26 species in grade I.,such as Helianthus tuberosus,Dicranostigma leptopodum,Orychophragmus violaceus,Ixeris chinensis,Solanum nigrum,Viola philippica,Erysimum cheiranthoides,etc.have high ornamental value,wide distribution,and can be widely developed and utilized;There are 42 species in Grade II.,which have some weaknesses compared with Grade I species,which can be promoted and applied according to the site conditions,such as Brassica rapa var.oleifera,Crepidiastrum lanceolatum,Vicia cracca,Hypecoum erectum,Nicandra physalodes,Inula japonica and other species.For example,species such as Setaria viridis,Humulus scandens,Digitaria sanguinalis,Phragmites australis,Eleusine indica,Artemisia annua,Chenopodium album and other species that have certain ecological benefits but are not very high ornamental value;There are 30 species in Grade III.,which can be selectively developed and utilized according to the ecological habits of species,such as Commelina communis,Physalis angulata,Astragalus scaberrimus,Gypsophila vaccaria and other species can be applied to garden-specific landscapes.There are 28 species in the IV.grade,due to the high requirements for habitat and the scarcity of resources,development and utilization can be temporarily ignored,but it does not exclude species with certain ornamental value,such as Persicaria orientalis,Erodium stephanianum,etc. |
