The Studies On Species Diversity And Morphology And Anatomy Of The Rare Endangered Plants Of Gymnocarpos Przewalskii Maxim

Gymnocarpos przewalskii Maxim. is rare and endangered plantsin arid desert region. This thesis studied species diversity, analyzedreasons for its endangering and proposed the protectionmeasures. Anatomical structure of stem and leaf were alsoobserved with light microscope and scanning electrical microscope(SEM), so as to probe mechanism of adapting to drought habitats.In the study, G. przewalskii Maxim. Was surveyed in most areasof its distribution. It included Gansu, Xinjiang and western areas ofInner Mongolia. These areas belong to arid desert ecosystem. In thecommunity of G. przewalskii Maxim. , Sympegma ragelii,Sarcozygium kaschgaricum, A. centraliasiat-icus and Artemisiagmelinii were mainly distributed in Dunghuang. G. przewalskiiMaxim. , Sarcozygium kaschgaricum, Halogeton glomeratus Mey. ,Reaumuria soongorica Maxim. , Haloxylon ammodendron Bunge.,Ephedra przewalskii Stapf., Alhagi sparsifolia Shap., Reaumuriasoongorica Maxim., Salsola arbuscula Pall. were mainly scattered inXinjiang. In the study, 46 quadrats were investigated with a totalof 14 plant species. They belong to the families Paronychiaceae,Zygophyllaceae, Chenopodiaceae, Tamaricaceae, Ephedraceae,Solanaceae, and Leguminosae. Researching plants were classifiedinto 10 community types: (1) G. przewalskii Maxim. community; (2) A. centraliasiat-icus community; (3) Sympegma ragelii community; (4)Ephedra przewalskii community; (5) Reaumuria soongorica Maxim.community; (6)Salsola arbuscula Pall. community; (7) Sarcozygiumkaschgaricum community; (8) Halogeton glomeratus Mey.communities; (9) Haloxylon ammodendron Bunge. community; (10)Calligonum mongolicum community.This paper systematically studied the characteristic of speciesdiversity of G. przewalskii Maxim. Community. The results showthat the range of Shannon-Wiener species diversity index was0.6876~1.5837, which was lower than 1.8604~3.4142 of desertprairie, was higher than 0.0290~0.6960 of sandy land. Comparedwith other temperate vegetation types, Species diversity of G.przewalskii Maxim. community was lower. It was probably ascribedto local arid ecological geographical environment.Analyze the relationship of elevation between with G.przewalskii Maxim. community distribution, G. przewalskii Maxim.were widely scattered in different altitudes. It was between1229~2540m above sea level. With the elevation changing,Shannon-Wiener diversity index, Simpson diversity index, Pielouevenness index and the Berger-Parker dominance index changedaccordingly, but the undulations were different. In Gansu, G.przewalskii Maxim. were mainly distributed in the altitude of1470~2540 m, where was gravel Gobi, alluvial fan plain, alluvial fanand dry riverbed areas. G. przewalskii Maxim. were mainly locatedat an altitude of 1219~1610 m, where was gravel Gobi alluvial plainnear Sandaoling Hami Xinjiang. The distribution was drought andthe vegetation was sparse. The study also found that the number of G. przewalskii Maxim. was relatively large at an altitude of 2200 ~2540 m.Analyze the relation between species diversity and soil index bylinear regression, revealed that McIntosh evenness index had asignificant correlation with soil moisture(R=0.383, P=0.001), totalN(R=-0.625, P=0.002), total P(R=-0.491, P=0.02), total K(R=-0.557,P=0.007). McIntosh diversity index is significantly associated withsoil moisture(R=-0.37, P=0.011), available N(R=-0.583, P=0.011),total P(R=0.55, P=0.008), available K(R=-0.478, P=0.024). Simpsondiversity index was significantly related to total P(R=0.426,P=0.048). Shannon-Wiener diversity index and Simpson dominanceindex were significantly correlated with available K(R=0.455,P=0.033) and total P(R=-0.487, P=0.022). But soil organic and pH hadno significant effect on species diversity.Morphological and anatomical studies of G. przewalskii Maxim.Show that leaf epidermal cells were closely arranged with a largeamount of inclusions, and the cell wall was thickened. Palisadetissue was developed and contained droplets substances. A largenumber of trichomes and stomata were on the surface. The averagestoma density was 7709.5/mm2. Stem epidermis cells were smalland tightly packed. The cell wall had thick cuticle. The xylem instem conducting tissue contained a large number of catheters andtracheids. Catheter had small caliber, with high lignification. It wasthe tough outer vascular bundles and had the emergence ofmedullary cavity. It was found that a large number of calciumcarbonate crystals were stored in the medullary cavity by EDS(Energy Dispersive Spectrometer) analysis. This was the result of adaption with arid environments.Reasons of G. przewalskii Maxim. endangering involved itsintrinsic factors and external harsh environment surroundings.Therefore, in the work of protecting G. przewalskii Maxim.,protection of its living environments was as important as protectionof its own. For these reasons, it was recommended that protectionmeasures: the establishment of nature reserves, in situconservation and ex-situ conservation.