Spatial Distribution Characteristics Of Plant Communities In Desert Hinterland Oasis

Dariyaboyi Oasis is located in the lower reaches of the Kerry River in Xinjiang and the natural oasis oasis.It is a rare oasis of scale in the rare desert hinterland of the world,and the ecosystem is extremely fragile.The spatial distribution heterogeneity of this oasis plant community is significant.This study takes the typical plant community of the natural oasis of Dariyaboyi Oasis as the research object.Based on the field vegetation survey combined with the aerial data of low-altitude drones,the suitable scales of field vegetation sample survey were discussed by statistical methods.The spatial variation of the coverage of typical plant communities in desert hinterland oasis was discussed by using high-precision low-altitude remote sensing data.The main conclusions are as follows:(1)According to the composition characteristics and important values of the community,the Dariyaboyi Oasis Oasis vegetation is divided into five typical community types.Reed community,Tamarix chinensis community,Populus euphratica community,Camelina sinensis community and Glycyrrhiza uralensis community.According to the investigation of the vegetation survey of the Dali Yabo Oasis,from the survey,the Populus euphratica is distributed on both rivers and ancient rivers.The community can be cross-distributed along the river in the oasis,forming a large-scale network of riverbanks;The community is widely distributed,mostly found in floodplains,riverbank terraces and sand dune margins;reed communities are widely distributed in riverside marshes,groundwater levels,higher meadow soils and various salinized meadow soils,which are also suitable for flow.The lowland area of the dunes;the camel thorn community is mainly distributed on the paleo-channel or the saline soil in the low-lying groundwater level;the licorice-growing community is distributed on both sides of the river bank,the groundwater level is high,and the soil is mostly salinized grass.The soil of the soil or meadow is distributed in a small area and is mostly mixed with reeds.In the survey sample,Populus euphratica,Tamarix chinensis and Phragmites australis were established species,and licorice,big leaf white hemp and bitter bean were associated species.(2)According to the field vegetation survey data,the population structure of Populus euphratica is inverted cone-shaped,the number of seedlings is small,and the number of mature individuals is large,which belongs to the declining population.The proportion of grade I seedlings was 5.79%,the proportion of young forests of grade II was 7.89%,the proportion of middle-age forests of grade III-IV was 31.6%,the mature forests of grade V accounted for 22.1% of the total,and the over-ripe forests with breast diameter greater than 50 accounted for The ratio is as high as 32.63%.The structure analysis of Tamarix chinensis population showed that the spatial distribution of Tamarix chinensis was clustered.The health of the willow is poor,9.3% of the willows are in a state of sudden death,the number of willows is as high as half,accounting for 52.4% of the total,moderately healthy willow is about 29%,and the good state of the willow is only 6.3%.Only 3%.(3)With the support of low-altitude remote sensing data,26 samples of traditional ground samples were sampled and spliced into color remote sensing images larger than the image range of 100m*100m.The 20m×20 m square is simulated and randomly sampled on the remote sensing image.It is found that the sample with a relatively uniform vegetation area of 20m×20 m has certain stability,and the sample of 20m×20 m in the sparse desert area has a large The random volatility does not represent the characteristics of the plant community in the survey area.The vegetation index threshold method was used to quickly calculate the coverage of the sample vegetation at different scales.According to the statistical analysis,in the 100×100 m sample,when the vegetation distribution is more uniform,the 40×40 m sample and the 50×50 m sample are both Close to the 100×100 m square vegetation coverage,it is representative;while in the random distribution area of the plant,only 50×50 m square is closer to the 100×100 m square vegetation coverage,which is relatively more representative.This part of the work also shows that in the desert arid area,the difference of plant community distribution is significant,the traditional 20 m × 20 m sample can not represent the plant community characteristics of the survey area.However,if the ground survey sample is too large,it will bring the exponential trend workload to the survey work.Therefore,the combination of low-altitude high-precision remote sensing data and ground survey may be an important way to investigate deserted sparse vegetation.(4)Using the high spatial resolution data of drones,the vegetation coverage FVC of 100×100 m squares was quickly extracted.It was found that the vegetation coverage in the southern and central oasis was good,and the vegetation coverage in the north and east showed a downward trend;According to the data of vegetation survey,the decline of oasis vegetation coverage is mainly due to the reduction of surface water in the eastern and northern parts,and the shortage of water resources,which leads to the gradual decline of Populus euphratica and Tamarix chinensis populations,and indicates that the plant communities in the eastern and northern oasis are gradually degraded.This paper explores the suitable scales of desert plant community survey with significant spatial heterogeneity,finds a method for rapid extraction of vegetation coverage from low-altitude remote sensing data,and analyzes the spatial distribution characteristics of oasis plant communities in desert hinterland,providing ideas for this study method.