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Ecological Responses Of Foliar Anatomical Structure & Physiological Charavteristics Of Dominant Plants At Different Site Conditions In North Shaanxi Loss Plateau

Posted on:2011-10-08Degree:MasterType:Thesis
Country:ChinaCandidate:H D DuFull Text:PDF
GTID:2120360305974425Subject:Botany
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In order to reveal characteristics of ecological adaptabilities of dominant plants (including Bothriochloa ischcemum , Stipa bungeana , Artemisia scoparia , Artemisia giraldii, Artemisia sacrorum, Lespedeza dauric) and find out the ecological adaptive mechanism of those plants in the north shaanxi loess plateau, the foliar structures and physiological index of six dominant plants were observed. Foliar superficial structure, stomatal plasticity, mesophyll cells morphology, composition of conducting tissue, xeromorphic anomalous structure which presented in different site conditions (Intergully, Gully, Forestland) were respectively studied through paraffin section. At same time, physiological index of six dominant plants were also studied by correlation method. Addationally, the relationship between leaf structures variations, physiological index and drought-resistance were analysis by grey correlation degree analysis. Using fuzzy membership function comprehensively evaluated drought resistance of six plants. The results provide theoretical basis for natural vegetation recovery and reconstruction at loess hilly-gully region. Morever it reveal internal causes of community succession laws in this region. The main findings are as follows:(1) The tested plant's stomatal density, stomatal index, area and perimeter of stomata, epidermal hair density reduced with the increase of site water, epidermal cell density and length of epidermal hair take opposite; the stomatal plasticity of Lespedeza daurica, Artemisia giraldii are relatively larger, so they show the strong drought-resistant ability; Artemisia scoparia take on minimum stomatal plasticity, display the characteristic that C3 plants tend to CAM plants.(2) There are some special characteristics for each plants to resist the drought and strong light stress in each plants, such as special bulliform cells and kranz structure of Bothriochloa ischcemum; multilayer sclerenchyma under epidermis and stomatal pit of Stipa bungeana; water storage parenchyma and ring palisade type mesophyll of Artemisia scoparia; palisade tissue of Artemisia sacrorum; secretory cavity and total palisade type mesophyll of Artemisia giraldii; mucilage cell of Lespedeza daurica.(3) At the arid and strong light intergully and the worst water condition of locust forestland, upper epidermis cuticular layer thickness, leaf thickness, palisade tissue thickness, water storage parenchyma thickness getting thickness;upper epidermis cells size, phloem transect area makes largen; in contrary for xylem transect area, xylem transect area/phloem transect area became decreased; above index take opposite in gully. All tested plant show minimum leaf thickness at locust forest.(4) At the arid and strong light intergully and the soil desiccation locust forestland, the content of soluble sugar, starch, proline increased. Specific leaf area decreased at gully. Chlorophyll-a, chlorophyll-b and total content of chlorophyll increased in locust forestland and gully.(5) Grey correlation degree analysis indicate that quantitative indicators of leaf anatomical characters and plant's drought-resistant ability have a higher correlation coefficient except xylem, this feature superadd anatomical characters integrative coefficient of variance can evaluate the potential ability of acclimatization of plants; the physiological index grey correlation degree analysis indicate specific leaf area, soluble sugar, starch, proline, malondialdehyde and total content of chlorophyll all can evaluate the potential ability of acclimatization of plants.(6) Using fuzzy membership function comprehensively evaluated drought resistance of six plants. The result show that the order of drought resistance from strong to weak were Lespedeza daurica,Aemisia scoparia,Artemisia sacrorum,Artemisiagiraldii,Bothriochloa ischcemum,Stipa bungeana.(7) Six plants have a different ecological adaptability. Bothriochloa ischcemum can survival at the arid and strong light site. Stipa bungeana grow demands better site conditions, but its ability of acclimatization remains to be further study. Artemisia scoparia have the largest coefficient of variation, those ability make Artemisia scoparia to one of the pioneer plants for vegetation recovering in the north Shaanxi loess plateau. Lespedeza daurica have higher adaptability concering stomatal characteristics and physiological index, those ability make it can adapt to diversified sites and become eurytopic plants at loess hilly-gully region. Artemisia sacrorum adapt to environment on structures and physiological features, it can adjust to the condition of soil desiccation. In spite of the highest adaptability concering point of photosynthesis, Artemisia giraldii have lowest integrative adaptability in mugwort plants in the view of average subordinative values.
Keywords/Search Tags:Loess Plateau, Foliar structures, Ecological adaptability, Xerophyte, Stress-resistance physiology
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