Vegetal cover estimated by digital photographs related to biomass in a grassland site in northern Mexico

• Published in: Phyton (Buenos Aires) 2015-01, Vol.84 (2), p.312
• Main Authors: Gutiérrez-Guzmán Un, Castellanos-Pérez, E, Uiñones-Vera, Jj Q, Serrato-Corona, Js, Martínez-Ríos, Jj, Orona-Castillo, I, Chairez-Hernández, I
• Format: Article
• Language: eng ; fre ; ger ; ita ; por ; spa
• Subjects: Aerial photography; Autumn; Biomass; Digital imaging; Grasslands; Growing season; Normality; Regression analysis; Regression coefficients; Regression models; Summer; Vegetation; Vegetation cover
• ISSN: 0031-9457; 1851-5657

A regression model was used to determine the relationship between aerial herbaceous biomass and vegetation coverage estimated by digital images. Four samplings (n=36 each date) of vegetation cover and herbaceous biomass were performed during the growing season in 2011 in a grassland dominated by Bouteloua gracilis in La Cieneguilla, Municipality of Villa Hidalgo, Durango. Average production of dry biomass was 37.36 ± 9.66 g/m2, and mean vegetation cover 30.02%. Dry biomass data were tested for normality using the test of Kolmogorov Smirnov, finding a lack of fit. The data were subjected to a logarithmic transformation and the model Ln(y) = 1.637926 + 0.08501X - 0.000586X2 with an adjusted R2 = 0.89 was found. In order to validate this model, another five samplings were carried out in 2013 at the same site during summer and autumn, using the same sampling size for each date as in 2011. Data collected in 2013 were analyzed with the model Ln (y) = β0 + β1X + β2X2. A comparison of regression coefficients was carried out between the 2011 and 2013 models with t (180+144-9-11-2=302, p