Accumulation in nutrient acquisition strategies of arbuscular mycorrhizal fungi and plant roots in poor and heterogeneous soils of karst shrub ecosystems

Table 2 Effect of nutrients distribution on the N₂ fixation rate and AM colonisation

Response variable	Linear mixed models	AIC	BIC	T value	Significant Difference
N₂ fixation rate	Null model	401.65	404.64	3.66	a
	Plant species	398.14	402.12	5.93	b
	Nutrients distribution	402.50	406.48	3.02	a
	Plant species * Nutrients distribution	391.40	396.38	14.19	c
AM colonisation	Null model	159.24	162.23	3.26	a
	Plant species	158.75	162.73	3.50	a
	Nutrients distribution	158.81	162.79	1.64	a
	Plant species * Nutrients distribution	153.16	158.14	3.84	b

(1) Null model: ƒi = α + bi × Zgroups + εi; (2) Nutrients distribution or Plant species model: ƒi = α + β × X (Nutrients distribution or Plant species) + bi × Zgroups + εi, (3) Nutrients distribution * Plant species model: ƒi = α + β1 × X Specie + β2 × X Nutrients distribution + bi × Zgroups + εi. Here, ƒi represents response variable, α represents model intercept, bi represents random factor parameter, Z represents random effect, β represents fixed factor parameter, X represents fixed effect, and εi represents the unexplained effect. The minimum AIC (Akaike Information Criterion) and BIC (Bayesian Information Criterion) was defined as the optimal model. The null model was mainly used to estimate the effect of random factor on random factor, and other models were used to the effect of random and mixed factors. If letters in the last column were different, the mixed factors (Plant species or Nutrients distribution) were captured into these models

ISSN: 1471-2229