Ecological Archives E087-166-A2

Eric J. Baack, Nancy C. Emery, and Maureen L. Stanton. 2006. Ecological factors limiting the distribution of Gilia tricolor in a California grassland mosaic. Ecology 87:2736–2745.

Appendix B. Changes in soil attributes across the boundary of the central G. tricolor population.

The table presents least-squared means and standard errors for soil variables measured within core, edge, and peripheral zones from a mixed model analyses that included boundary type (oak canopy vs. valley bottom), transect nested within boundary type, and the interaction between population zone and boundary type, in addition to the main effect of population zone. P values indicated in bold are significant after application of the sequential Bonferroni correction for eight tests. For each soil attribute showing significant variation among population zones, values not sharing the same letter are significantly different from each other. (N = 30)

Soil attribute

Core population sites

Edge population sites

Peripheral population sites

P

         

Ca:Mg ratio

0.88 ± 0.27a

0.90 ± 0.26a

1.55 ± 0.26b

0.0060

% Organic matter

4.48 + 0.77a

6.12 + 0.67a

10.55 + 0.77b

< 0.0001

Cation exchange capacity (meq /100 g dry soil)

18.92 ± 1.00a

21.78 ± 0.92b

22.18 ± 0.965b

0.0074

pH

6.66 ± 0.05a

6.89 ± 0.04b

6.94 ± 0.05b

0.0015

Nitrate (NO3, ppm)

20.42 ± 0.54a

7.89 ± 0.49b

9.17 ± 0.52b

0.0017

Phosphorous (P, ppm)

3.33 ± 1.19

5.82 ± 1.06

6.51 ± 1.15

0.0976

Potassium (K, ppm)

269.27 ± 30.27

276.85 ± 26.34

341.1 ± 29.30

0.1441

% Clay

20.42 + 1.20

21.32 ± 1.05

21.85 ± 1.16

0.6388



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