Research On The Plant Diversity And Its Conversation In Ningxia Helan Mountain National Nature Reserve

The Ningxia Helan Mountain National Nature Reserve is located in the middle and northern parts of the east slope of Helan Mountain,and the geographical coordinates are 38°19′～39′22′N,105°49′～106°41′E The total area of the reserve is 2062.66 km~2.In this paper,by applying a large number of field surveys,we studied flora,species diversity,vegetation diversity,and evaluated plant priority conservation grade and priority conservation association.1.There is a total of 731 wild vascular plant species(including subspecies),belonging to 317 genera,81 families in the Ningxia Helan Mountain National Nature Reserve.Among them,there are 15 pteridophyte species,belonging to 9 genera,8 families,and they respectively account for 9.88% families,2.84%genera and 2.05%species of the wild vascular plant;Gymnosperm species is scare, there are 8 species,belonging to 5 genera,8 families,and the gymnosperm account for 3.70%families, 1.58%genera and 1.09%species;There are 708 angiosperm species,belonging to 303genera,70 families,and the angiosperm account for 86.4%families,95.6%genera and 97.1%species.2.The results of the wild vascular plant flora in the Ningxia Helan Mountain National Nature Reserve shows that in distribution types of families,Cosmopolitan has 40 families,accounting for 54.79 %of the total families,and Cosmopolitan is absolutely dominant.In genus flora component,temperate component is absolutely dominant,it has 232 genera,accounting for 73.19%.Species distribution types has 15 types and 20 subtypes,and there is no significant dominant,East Asia component accounts for 22.57%of the total species,and it is the largest type;Followed by Temperate Asia component (13.00%),Old Continent Temperate composition(12.18%),Mongolian composition(11.08%),and North Temperate composition(9.17%),and these floristic elements have a considerable impact on this area;In life-form spectrum,Hemicryptophytes has the most species,up to 362 species,accounting for 49.52%of the total species;followed by therophytes,it has 126 species,accounting for 17.24%of the total species;Cryptophytes has 108 species,accounting for 14.77%of the total species;Phanerophytes has 85 species,accounting for 11.63%of the total species;chamaephytes has the least of 50 species, accounting for 11.63%of the total species.In water ecotype,mesophyte has the largest number,457 species accounting for 62.77%of the total species;The second is xerophyte,accounting for 19.78%of the total species,indicating that the overall environment of this reserve is mainly in semi-drought.3.Applying comprehensive quantitative method,it evaluates verge of 718 species on disappearing risk,the result shows that there are 14 very easy disappearing species,29 easy disappearing species,55 might disappearing species,and 620 safety species;According to priority conservation index,which determines conservation grade,the result shows that there are 38 first-class protected plants,90 second-class protected plants,and 590 species of common protective plants.4.Results of plant diversity distribution research show that:a-species diversity,(such as Patrick abundance index,Simpson index,Shannon-Wiener index,pielou evenness index,Brillouin index, Mcintosh index),is highest at elevation 3100m - 3200m,and lowest at 2700m - 2800m;The species diversity of forest community is highest at elevation 1800 m - 2200m,and lowest at 2700m - 2800m; The species diversity of shrub community is highest at elevation 1800m - 2200m,and increasing following the elevation.Inβ-diversity,Wilson index presents 3 peaks from elevation 1200 m to 2400 m, they are 1400m - 1500m,1900m - 2000 m,and 2200m - 2300 m,it shows that alternating speed of species is faster in these three sections,and differences among species are greater;Whittaker index at elevation 1400m - 1600m and 1700m - 1900m is higher than others.The result of comparingα-species diversity at different aspects shows that the species diversity at east aspect is the highest,followed by north aspect and southwest aspect,the species diversity at northeast aspect is the minimum;In different slopes,the species diversity at slope 20°～30°is the highest,the second is noah slope and southeast slope,the species diversity at slope 40°～50°is the minimum,but the difference is very little,it shows that,α-species diversity is not closely related to slope when the slope is small than 50°.Comparison ofα-species diversity in different investigation area,the result shows that the species diversity has two boundaries,south boundary is Yushu Ditch,north boundary is Ruji Ditch,the species diversity at south area from Yushu Ditch and north area from Ruji Ditch is approximately equal,the species diversity at median area is significantly higher than the former both.The result of calculating Jaccard similarity index in different investigation area shows Jaccard similarity index at Suyukou is the highest.5.According to data of 283 sample,vegetation of the Helan Mountain Natural Nature Reserve is classified into 9 vegetation types,35 formations and 79 associations.The result ofα-species diversity in formations shows that the diversity of Spiraea mongolica shrub is the highest,the second is Ulmus glaucescens,Artemisia dubia veld,and the diversity of Sabina vulgaris is the lowest.The result of the diversity in forest community,the diversity of Picea crassifolia forest is the lowest at either the whole community or hierarchical diversity.The result of the diversity in shrub community,the diversity of Potentilla parvifolia shrub,Salix cupularis var.lasiogyne shrub,Caragana jubatashrub,Syringa oblate shrub,Lonicera microphylla shrub,Spiraea mongolica shrub is significantly higher than others.The diversity of Sabina vulgaris and Ephedra rhytidosperma shrub is the lowest.The result of the similarity of 33 communities shows that the similarity of the most community is 0～0.6,the similarity between Salix cupularis shrub,Caragana jubata shrub and 5 desert community is 0;The similarity between Salix cupularis shrub and Caragana jubata shrub is the highest,it is 0.59.6.Vegetation vertical distribution rules are as follows:desert grassland vegetation of Stipa breviflora-Ptilagrostis pelliotii,Ajania fruticulosa- Stipa gobica,desert vegetation of Reaumuria soongorica,Salsola laricifolia distribute under elevation 1500 m.Ulmus glaucescens forest,various teperature resistance shrub,and Ulmus glaucescens veld distribute at elevation 1600m～2000m, Coniferous forest,and Sabina vulgaris shrub,Salix cupularis var.lasiogyne shrub and Caragana jubata shrub at elevation 2000m.According to aspect,there are the most vegetation types at half-sunny slope, the next is at half-shaded slope and shaded slope,the least is at sunny slope.There are almost all the vegetation types distribution at half-sunny slope and half-shaded slope,coniferous forest and shrub mainly distributes at shaded slope,shrub and veld mainly distributes at sunny slope.The frequency of Ephedra rhytidosperma shrub,Caragana jubata shrub,and Ammopiptanthus mongolicus desert distribution at sunny slope is more than 50%,it shows that these communities are suitable to grow at sunny slope;The frequency of Picea crassifolia forest,Syringa oblata shrub,Salsola laricifolia shrub distribution at shaded slope is more than 50%,they are the most suitable to grow at shaded slope.There are the most abundant at slope 20°～30°,the next is at slope 10°～20°,the least is at slope 40°～50°. There are 14 vegetation types at slope 0°～10°,among them,the frequency of Tetraena mongolica shrub distribution is 100%,the frequency of Salsola passerina desert distribution is 50%,the peak of the frequency of Ajania fruticulosa,Stipa breviflora grassland distribution is at slope 0°～10°.There are 25 vegetation types at slope 10°～20°,among them,the peak of the frequency of Juniperus rigida forest and Ulmus glaucescens- Bothriochloa ischaemum veld,Stipa breviflora grassland,and Ajania fruticulosa,Ptilagrostis pelliotii grassland distribution is at slope 0°～10°.The peak of the frequency of Ulmus glaucescens forest,Potentilla parvifolia shrub,Lonicera microphylla shrub,Syringa oblata shrub,Spiraea mongolica shrub,Caragana stenophylia shrub,Salsola laricifolia desert,Ptilagrostis pelliotii grassland and Ulmus glaucescens- Artemisia gmelinii veld distribution is at slope 20°～30°. The frequency of Picea crassifolia forest,Salix cupularis var.lasiogyne shrub,Caragana jubata shrub and Ulmus glaucescens-Ajania fruticulosaveld distribution at slope 30°～40°is more than 50%,the peak of the frequency of Leptodermis ordosica shrub and several veld distribution is at slope 30°～40°. There are only 11 vegetation types at slope 40°～50°,the peak of the frequency of Ulmus glaucescens-Synotis atractylidifolius - Stipa breviflora veld and Ulmus glaucescens- Artemisia dubia eld distribution is at slope 40°～50°.7.The result of the similarity at every investigation area shows that the similarity between 11 investigation sites at from Qingyang Ditch to Chaqi Ditch is the highest.The similarity between two ends of south,north and others is lower,it illustrates that these investigation area has little vegetation types,especially the similarity between Liutiao Ditch at the northeast and others is the lowest.8.The results of association priority conservation grades shows that there are 8 first-class protective associations,they are Assoc.Ulmus glaucescens - Syringa oblate-Carex lanceolata,Assoc. Juniperus rigida - Cotoneaster acutifolius var.villosulus - Artemisia gmelinii - Roegneria kanashiroi, Assoc.Pinus tabulaeformis - Cotoneaster acutifolius - Carex lanceolata,Assoc.Picea crassifolia - Salix cupularis var.lasiogyne- Polygonum viviparum,Assoc.Ulmus glaucescens- Spiraea mongolica -Carex lanceolata,the accumulative fidelity is all more than 0.03;There are 15 second-class protective associations,the accumulative fidelity is between 0.02 and 0.03,the common protective associations are 56.