| In order to understand the C4 plants in karst area habitat adaptability and its resources characteristic and landscape application of C4 plants in Guizhou karst area as the research object,use the method of consulting literature materials,combined with the community on the spot investigation and checking the specimens of forestry college of Guizhou university library,and determine the list of C4 plant resources in Guizhou karst area,and using the method of carbon isotope ratio method to research the adaptability to environment of the typical C4 plants.Based on SBE method et al,the application value of C4 plant landscape in Guizhou karst region was evaluated.The purpose is to provide a theoretical basis for the application of C4 plants in vegetation restoration and landscape in karst areas.The research results are as follows:?1?141 species of C4 plants belonging to 74 genera and 15 families were founded in the Karst regions of Guizhou,which are composed mainly of Gramineae and Cyperaceae;the species of C4 plants in the area are either annual plants or perennial plants,and the species number of perennial plant are slightly more than the annual plant;the overall water ecotype is dry;The C4 plant resources in Guizhou karst regions have the essential characteristics of abundant resources,wide application,long-term utilization,strong competitiveness and large-area distribution,C4 plants can adapt well to karst habitats.Under natural conditions,most of them are restoring early species,which is conducive to ecological restoration in karst regions.C4 plants have good ecological adaptability under the harsh ecological environment of Karst regions in Guizhou,and present relatively high value for medicinal,edible,feeding,landscape and other purposes.The exploitation of C4 plants is of great significance for the ecological restoration in Guizhou and the economic and social development of Guizhou area.?2?By investigating 12 typical C4 plant communities,it was found that in the natural state,C4 plants mostly formed natural communities with poaceae and composite plants,and most of the plant life types were herbaceous plants.Among them,the diversity index of miscanthus community and cauliflower community was higher,and the diversity index of upturned matang community was lower,and the dominant species status was prominent.Soil total nitrogen and total phosphorus in the habitat of C4 plant community were lower than the national average level of surface soil,and generally showed a trend of decreasing layer by layer,soil pH value first decreased and then increased,and the change rule of total potassium and soil moisture in different soil layers was not obvious.In all communities,the content of total nitrogen and total phosphorus in the soil was the lowest,but the content of total potassium was higher.Between different C4 plant communities in the soil total content of calcium,magnesium,the gap is bigger,the overall green bristlegrass community,digitaria community,eleusine indica,heteropogon contortus community and purple sativa community habitat in soil calcium and magnesium content is higher,but its advantage in the cultivation objects,the activity of calcium and magnesium content was low,calcium and magnesium elements enrichment coefficient is low.Based on the contents of calcium and magnesium in the soil and their enrichment coefficients,the C4 herbaceous plants in the karst region can be divided into three types:calciophilic type,calcium-anaerobic type and random type.C4 plants leaf malondialdehyde content in different habitat difference was not significant,overall the karst habitat under shrub leaf content is lower,heteropogon contortus community habitat in the shallow soil layer,the most serious environmental stresses,hispid arthraxon environmental stresses,green bristlegrass suffered a lighter;The C4 plants in the karst area have the characteristics of large range of?13C and high water use efficiency,but there is no significant difference between different water ecotypes.?3?The 12 C4 plants communities had great difference in the beauty degree,and the dominant plant plant type and plant coverage in the community had great influence on the beauty degree of the C4 plants community.There was no significant correlation between C4 plants community beauty value and community diversity index,but it was positively correlated with shannon-wiener index and weakly negatively correlated with ecological dominance index.According to different C4plant community surveys and community characteristics,twelve types C4 plant communities allocation modes were summarized,which could provide reasonable herbaceous community allocation modes for vegetation restoration in karst rocky desertification areas.?4?In the application value evaluation system of C4 plant resource landscape in guizhou karst region,the weight of ecological adaptability is the largest in the criterion layer,and the weight of three factors in the factor layer,including field adaptability,flower observation and life type,is large.The plants with a score of more than 12 in the fuzzy comprehensive evaluation include 7 plants such as Pennisetum alopecuroides,Calamagrostis epigeios and Miscanthus sinensis,and the plants with a score of 10 to 12 include 15 plants such as Heteropogon contortus,Imperata cylindrica and Eragrostis nigra.The threshold value of C4 plant resource landscape application in Guizhou karst region is 5.4758,and 8 species of aquatic or hygrophytic C4 plants,such as Cyperus compressus,Cyperus orthostachyus and Cyperus microiria,are lower than the threshold value,so it is not suitable to be used in Guizhou karst region landscape.C4 plants are of great significance in green Spaces with poor habitats such as highway slope,road green space or roof green space.The full development of the value of C4 plant resources and the rational allocation of C4 plants in the green space system are conducive to enhancing the carbon sink function of green space. |
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