Investigation Of Grassland Resources In Hainan Province

The status of grassland forage resources is one of the basis for decision-making of biodiversity and plant resource protection,However,the current survey of grassland forage resources in Hainan Province is limited to the inspection of patches and lines,Moreover,the existing data is too old and unsystematic,and the management and communication methods are relatively backward,resulting in a serious lack of data,and it is urgent to update the content,At the same time,new technologies and methods are used for investigation,sorting,and summarization,and electronic,digital,informational,and networked to promote the systematic planning,hierarchical protection,and efficient use of grassland resources in Hainan.This study takes grassland forage resources in Hainan Province as the survey object,Combining resource data with domestic and foreign literature,Combining background research with systematic research,Combining physical resources and information resources,Use modern investigative techniques,And the combination of"3S"remote sensing survey and traditional survey,Understand the spatial distribution of natural grasslands and artificial pastures in Hainan Province,Types of natural grassland,composition and spatial distribution of vegetation communities,Area and yield of natural and artificial pasture,To promote the rational development and utilization of grasslands in Hainan Province,Provide supporting basis for the healthy development of grassland industry.The main contents of this study are as follows:1.Determination of supervised classification method:Take Lingao County,Hainan Province as an example,using sentinel data,Use the method of supervised classification on ENVI,Supervise and classify grassland conditions in Lingao County,and visually interpret and verify the classification results.The results show that in the extraction of grassland information,the random forest method is the best,the neural network method is the second,and the maximum likelihood method is the worst.Among the precisions that affect the results of supervised classification,cultivated land has the greatest impact,According to the characteristics of cultivated land showing bare land after cutting,the existing images are superimposed on multiple bands in time series,and then the random forest method is used for supervised classification.The results show that the classification according to the time series can improve the classification accuracy,and greatly eliminate the impact of cultivated land on the extraction of grassland information.2.Through the data of field investigation,combined with the results of the supervision and classification of natural grassland in Hainan Province,the current status of the existing natural grassland resources in Hainan Province is determined.The results are as follows:the existing natural grassland resource area in Hainan is about 98×10~4mu,The grassland is fragmented and the spatial distribution is discontinuous,mostly distributed around Wenchang and the lower reaches of Changjiang.Can be divided into three types:lowland meadows,thermal grasses and thermal shrubs,mainly thermal grasses.This time,218 species of natural forages were found,the most of which were Gramineae,reaching 62 species,accounting for 28.7%of the total;26 species of Compositae,accounting for 11.9%;25 species of Legumes,accounting for 11.4%;and 24 species of Cyperaceae,Accounting for 11.0%;the remaining few families with a total of 81 species,accounting for 37.3%.The average yield of fresh grass from high to low is thermal shrubs:1549.0g/m~2;thermalgrasses:1265.4g/m~2andlowland meadows:1140.8g/m~2.The average hay yield in these three types of grasslands from high to low are thermal shrubs:590.4g/m~2;thermal grasses:501.8g/m~2and lowland meadows:411.5g/m~2.3.Through the report of the data of artificial forage planting by cities and counties,combined with the survey results of field visits,the current status of artificial forage planting and forage industry development in Hainan is obtained.The results are as follows:The area of artificially planted grassland in Hainan Province is26961 mu.The cultivation of artificial forage is mainly based on king grass,The planting of artificial forages is dominated by Reyan No.4 king grass.The average yield of freshly planted fresh grass according to the forage species is from high to low:Reyan No.4 king grass:2504g/m~2;Taiwan sweet grass:2351.8g/m~2;Reyan No.11Black Seed Paspalum:1868.6g/m~2;Purple Elephantgrass:1763.3g/m~2and Stylosanthes:1687.9g/m~2.The average yield of hay from high to low is Reyan No.4King Grass:575.9g/m~2;Taiwan Sweet Grass:516.2g/m~2;Purple Elephant Grass:493.7g/m~2;Stylosanthes:469.3g/m~2and Reyan 11 No.black seed paspalum:442.9g/m~2.