Mid-succession Fertilization Study
Fertilization treatments in the mid-succession site also supported significantly different mixtures of Frankia clades (Table 3) (LR P < 0.0001, pseudo-R2 = 0.13) and subclades (Table 4) (LR P < 0.0001, pseudo-R2 = 0.14). Control soils yielded a relatively even mixture of sequences belonging to the AT clade and sub-clades unique to soil. Proportional representation of AT clade sequences was significantly higher in soils fertilized for 12 years with N (84% of clones, P < 0.0001) or five years with P (51% of clones, P = 0.0026) than in unfertilized control soils (23% of clones). N-fertilized soil also contained notably lower diversity than the other two treatments, yielding less than half of the sub-clade richness as control soils, while P-fertilized soil yielded representatives of every sub-clade present in control soils, albeit at different relative proportions (Figure 2, Table 3, Table 4) due primarily to the dominance of AT clade sequences in P-fertilized soil.