Accuracy Analysis of Soybean Vegetation Coverage Measurement by Photo Line Transect Method

doi:10.11924/j.issn.1000-6850.casb2021-1111

Abstract

Abstract:

Vegetation coverage is the percentage of the total ground area covered by the vertical projected area of vegetation. It is an important parameter in ecology and an important agronomic index of crops such as soybean. The ideal coverage measurement is less time consuming, requires simple tools, provides accurate results, and is less influenced by human factors. In this study, 24 soybean varieties, such as ‘Qiandou 3’, ‘Chuandou 16’ and ‘Daheidou’, were used for assessment. Different methods, including visual estimation, field line transect method and photo line transect method, were used to estimate soybean vegetation coverage and identify one with the maximum accuracy and applicability, using the measured values of the photography method as the reference. The results showed that visual estimation produced the largest error in vegetation coverage measurement, with an average of 7.8%. The error increased first and then decreased with the increase of plant height. The field line transect method displayed higher accuracy, the error was less than 3% (2.8%), but it took the longest time of 6.2 min for a 1 m × 1 m quadrat. The error of the photo line transect method was less than 3%, and it consumed less time for field sampling; processing the photos of each quadrat took only 3 min. Compared with visual estimation, the photo line transect method showed higher measurement accuracy. Besides, it saved the sampling time and improved work efficiency compared with the field line transect method. Therefore, the present study proposed the photo line transect method as the ideal method for vegetation coverage measurement of soybean and similar plant species. Two line-transects (the total length of the line transect was 2.8 m) via this method could meet the accuracy requirements, with an error of less than 5%. However, the applicability of the photo line transect method in measuring the coverage of other crops should be further explored.

Key words: photo line transect method, vegetation coverage, accuracy analysis, soybean, plant height

CLC Number:

S566.1

WANG Huanhuan, YANG Qin, PU Hongmei, HE Jin, CHENG Hua, HAN Min, ZHAO Xuechun, WANG Zhiwei, JIN Baocheng. Accuracy Analysis of Soybean Vegetation Coverage Measurement by Photo Line Transect Method[J]. Chinese Agricultural Science Bulletin, 2022, 38(32): 111-118.

Figures/Tables 8

References 30

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方法	误差/%	耗时/min
目估法	7.8±10.7↓^*	—
实地样线法	2.8±14.4↑^*	6.2
照片样线法(两条样线)	3.7±12.7↓^*	1.9
照片样线法(四条样线)	2.1±13.4↓^*	3.0

方法	误差/%	耗时/min
目估法	7.8±10.7↓^*	—
实地样线法	2.8±14.4↑^*	6.2
照片样线法(两条样线)	3.7±12.7↓^*	1.9
照片样线法(四条样线)	2.1±13.4↓^*	3.0

株高	株高
株高	0~20 cm	20~40 cm	40~60 cm	60~80 cm
20~40 cm	R²=0.26 ^* +	—	—	—
40~60 cm	R²=0.0002 +	R² = 0.09 ^* +	—	—
60~80 cm	R²=0.05 -	R² = 0.21 ^* -	R² = 0.21 ^* +	—
80~100 cm	R²=0.09 -	R² = 0.35 ^* -	R² = 0.09 +	R² = 0.20 +

株高	株高
株高	0~20 cm	20~40 cm	40~60 cm	60~80 cm
20~40 cm	R²=0.26 ^* +	—	—	—
40~60 cm	R²=0.0002 +	R² = 0.09 ^* +	—	—
60~80 cm	R²=0.05 -	R² = 0.21 ^* -	R² = 0.21 ^* +	—
80~100 cm	R²=0.09 -	R² = 0.35 ^* -	R² = 0.09 +	R² = 0.20 +