Research On The Determination Of Seagrass Coverage Ratio Of The Dongjiao Coconut Forest By UAV Aerial Survey Technology

Seagrass coverage ratio is an important indicator of the ecological status of seagrass beds.Through aerial photography scheme design and flight condition experiments,high-resolution seagrass image maps of the Dongjiao Coconut Forest were obtained with UAV,and the color characteristics of seagrass were extracted and vectorized by image classification tools and 3D tools of ArcGIS software,the distribution of seagrass in the seagrass was inverted,and a new method for seagrass coverage ratio calculation was studied,and the ecological characteristics of seagrass in the Dongjiao Coconut Forest seagrass were studied as an example,and the seagrass coverage ratio in the area of(300×500)m~2was calculated.Seagrass in the sea area of the Dongjiao Coconut Forest of Wenchang City was mainly distributed on coral reefs within 300 m offshore,with patch-like and spaced distribution,and 860 patches in the survey area were obtained by the maximum likelihood method of ArcGIS software tools,and the concentrated distribution area of seagrass was 23 443 m~2,with the ratio of 17.96%.Field investigations found Five species of seagrass including Cymodocea rotunda,Halodule uninervis,Enhalus acoroides,Thalassia hemprichii and Halophila ovalis,with the dominant species being Thalassia hemprichii.Monovein diherb and Ovalea salina are distributed in the low-tide zone with silt in the intertidal area;It is distributed in the upper part of the low tide zone to the subtidal zone,at the junction of the seafloor accumulation and erosion zone;Thalassia hemprichii is distributed in different water depths,and the distribution area is the largest.The seagrass coverage area with The unsupervised classification of ISO clustering yielded is 16 423 m~2 and the average of seagrass coverage ratio is 12.58%.In the southeast area of the survey area is the dense distribution area of sargassum,sargassum mainly grows on the reef with a water depth of 0.5-2 m,sporadic distribution,the color is yellow-brown,the average plant height is about 30 cm,cylindrical floating growth calculated that there are about 2879 sargassum plants,an area of about 755.6 m~2,accounting for 0.5%,the survey found three species of sargassum including Sargass umeuryphyllum,Sargassum polycystum and Sargassum duplicatum.In this paper,the method for calculating seagrass coverage ratio based on unmanned aerial survey technology combined with ArcGIS tools can be applied to seagrass coverage ratio survey and ecological monitoring.