Using cover measurements to estimate aboveground understorey biomass in Maritime pine stands

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Table III

Models and parameters to estimate understorey biomass per species group (t MS/ ha) as a function of their phytovolume (m³). Indexes 5 and 11 refer to the estimation of phytovolume using the Braun-Blanquet cover measurements and the 11 class cover measurements, respectively.

Species group	Model	RMS	a1	a2
Mosses^*	a1. Vol	0.351	2.210^E-6 (1.825^E-7)	/
Mosses	a1. Vol	0.398	2.086^E-6 (1.845^E-7)	/
Herbaceous sp.^*	a1. Vol	0.013	1.697^E-8 (1.028^E-9)	/
Herbaceous sp.	a1. Vol	0.023	1.966^E-8 (1.619^E-9)	/
Bracken^*	a1. Vol + a2. Vol₅	0.012	4.511^E-9 (1.132^E-9)	3.897^E-5 (1.584^E-5)
Bracken^*	a1. Vol + a2. Vol₁₁	0.017	2.494^E-9 (1.082^E-9)	6.061^E-5 (1.624^E-5)
Woody sp.^*	a1. Vol₁₁	0.445	1.716^E-4 (2.244^E-5)	/
Woody sp.	a1. Vol₅	0.518	1.567^E-4 (2.080^E-5)	/

Indicates the best fitting for each species group, according to residual mean squares values (RMS) and analysis of modelled versus measured plots and residual plots. Values in parenthesis are asymptotic standard deviation on estimated values.