Appendix B. Soil characteristics of gaps and landslides, statistical analyses of experimental results, composition of arbuscular mycorrhizal fungal (AMF) communities in the field, and AMF colonization in experiment 2.
TABLE B1. Mean nutrient concentrations (mg g-1 dry mass) (± 1 SE) of soils collected from four landslide and four gap sites within the BCNM.
|Nutrient||Landslide soil||Gap soil||t ratio|
|NO3 1,2||2.65 (2.54)||2.35 (0.65)||-0.08|
|NH4 1,2||34.59 (9.10)||48.06 (11.45)||0.92|
|Mineralized N 3||72.61 (36.02)||134.15 (24.4)||1.41|
|Al||59.66 (14.79)||67.19 (1.20)||0.51|
|Ca||60.10 (20.19)||52.51 (21.26)||- 0.25|
|Fe||2.96 (0.61)||6.05 (1.32)||2.12|
|K||6.84 (1.82)||3.27 (1.46)||- 1.53|
|Mg||56.57 (14.01)||22.78 (6.30)||-2.20|
|P||1.24 (0.16)||0.49 (0.13)||-3.57*|
Nutrients were extracted from fresh soil using 1:10 mv-1 2 M KCl for nitrogen (N) and 1:10 mv-1 Mehlich III solution for P and exchangeable cations (Tran and Simard 1993). Ammonium and nitrate concentrations were determined using a continuous flow autoanalyzer (Latchet Quickchem 8000, Milwaukee, WI). P, Al, Ca, Cu, Fe, Mg, Na, and Zn were determined using Inductively Coupled Plasma (ICP) spectroscopy (Perkin Elmer, Shelto, CT).
TABLE B2. Effects of species, AMF, and nutrients on relative growth rates of the two Trema species, separately for landslide and gap soil (Experiment 2).
|Landslide soil||Gap soil|
|“P addition”||1||0.42||0.768||38.98||< 0.001|
|Species × AMF||1||0.18||0.673||2.04||0.157|
|Species × nutrient||2||0.48||0.618||1.63||0.202|
|AMF × nutrient||2||4.96||0.009||14.85||< 0.001|
|“AMF × N addition”||1||1.37||0.432||3.51||0.124|
|“AMF × P addition”||1||3.79||0.107||12.22||0.002|
|Species × AMF × nutrient||2||1.02||0.364||1.57||0.214|
Note: The nutrient main effect was decomposed into two a priori contrasts, separately per soil type. The first contrast (“N addition”) compared relative growth rates of seedlings (average across species and AMF) when grown without nutrient addition versus those grown with N. The second contrast (“P addition”) compared relative growth rates of seedlings (averaged across species and AMF) when grown without nutrient addition versus those grown with P. The contrasts within the AMF × nutrient interaction examined whether the effects of N and P addition on relative growth rates (averaged across species) were consistent across seedlings grown without AMF and those grown with AMF. Significance levels of contrasts were adjusted for multiple comparisons using Dunn-Sidak correction.
TABLE B3. Effects of species, whole-soil inoculum source and soil type on both relative growth rates (RGR) and log10 root/shoot ratios of the two species of Trema (Experiment 3).
|Inoculum||1||23.34||< 0.001||13.97||< 0.001|
|Species × inoculum||1||5.67||0.021||0.98||0.328|
|Species × soil||1||1.41||0.240||1.34||0.253|
|Inoculum × soil||1||17.71||< 0.001||20.33||< 0.001|
|Species × inoculum × soil||1||1.91||0.174||0.52||0.475|
|“Species × habitat condition”||1||6.16||0.017||0.01||0.920|
Note: The inoculum × soil interaction was decomposed into an a priori contrast (“habitat condition”) that compared relative growth rates and root-to-shoot ratios of seedlings (averaged across species) when grown with only the two inoculum and soil combinations that occur naturally. Specifically, this contrast compared relative growth rates and root-to-shoot ratios of seedlings when grown in landslide soil with landslide inoculum (i.e., landslide condition) and with those seedlings grown in gap soil with gap inoculum (i.e., gap condition). The contrast within the three-way interaction examined whether effects of the two naturally occurring inoculum-soil combinations on relative growth rates and root-to-shoot ratios were consistent across the two species.
TABLE B4. The effects of habitat type and species on concentrations of each foliar nutrient of Trema seedlings planted either on landslides or in gaps (field experiment). LS means of foliar concentrations (averaged across species) are presented per habitat type. Standard errors are in parentheses. Numerator and dominator degrees of freedom for all effects are 1 and 11, respectively.
|Mean foliar concentrations||ANOVA (F values)|
|Nitrogen||0.74 (0.28)||3.96 (0.30)||61.44**||0.43||0.27|
|Phosphorus||0.15 (0.01)||0.13 (0.01)||5.87*||2.94||3.55|
|Calcium||2.25 (0.15)||2.38 (0.16)||0.39||2.53*||2.53|
|Magnesium||0.56 (0.06)||0.49 (0.06)||0.80||1.23||0.59|
|Potassium||1.55 (0.12)||1.51 (0.13)||0.04||0.49||0.10|
*P < 0.05, ** P < 0.01
|FIG. B1. Non-metric multidimensional scaling from ANOSIM analysis illustrating AMF-community similarity among five sites located on landslides (L) and five sites located in treefall gaps (G) of the BCNM.|
|FIG. B2. Percent root colonization of arbuscular mycorrhizal fungi (AMF) in Trema seedlings (averaged across species) grown in either gap or landslide soil with the addition of either nitrogen or phosphorus. The control treatment received no additional nutrients (Experiment 2).|
Tran, T. S., and R. R. Simard. 1993. Mehlich III-extractable elements. Pages 43–40 in W. R. Carter, editors. Soil sampling and methods of analyses. Canadian Society of Soil Science, Lewis Publishers, Boca Raton, Florida, USA.