Table 2.
Fixed effects plant trait and soil property variables retained within the multiple variable REML models for each of the microbial properties; also presented is the percentage variation in each microbial property explained by the site, the retained fixed effects, the proportion of explanation afforded by the fixed effects due to plant traits and soil parameters, respectively, and the significance (P), Wald statistic and the direction and magnitude of the standardized effect for each of the retained fixed effects
| Response variable | Retained fixed effect | % variation explained by site | % variation explained after site effect was removed |
|||||||
|---|---|---|---|---|---|---|---|---|---|---|
| % variation explained by fixed effect | Proportion of % variation explained by plant traits | Proportion of % variation explained by soil parameters | P | Wald effect | Effect | |||||
| Microbial abundances | Total microbes | Microbial biomass N | pH | 59·5 | 89·8 | 2·9 | 97·1 | <0·0001 | 41·01 | −0·190 |
| Total Soil Carbon | <0·0001 | 69·22 | 0·085 | |||||||
| Specific Leaf Area | 0·0012 | 15·39 | −0·020 | |||||||
| Fungi and bacteria | F/B ratio | Total Soil Carbon | 97·6 | 57·1 | 47·9 | 52·1 | 0·0039 | 10·95 | −0·003 | |
| Soil DON | 0·0375 | 5·04 | 0·017 | |||||||
| Root Diameter | <0·0001 | 15·29 | −0·190 | |||||||
| Nitrifiers | AOA | pH | 63·1 | 78·8 | 14·6 | 85·4 | <0·001 | 30·04 | 0·500 | |
| Soil NO3– | 0·002 | 12·99 | 0·470 | |||||||
| RDMC | 0·0048 | 10·29 | −5·690 | |||||||
| AOB | NH4+ sorption | 17·7 | 74·9 | 28·8 | 71·2 | <0·001 | 18·88 | 0·900 | ||
| RDMC | 0·0265 | 5·95 | −3·350 | |||||||
| RLSM | 0·0325 | 5·43 | −0·530 | |||||||
| AOA/AOB ratio | Soil total Nitrogen | 51·5 | 74·4 | 0·0 | 100·0 | <0·001 | 23·91 | −1·270 | ||
| NH4+ sorption | <0·001 | 37·36 | 0·950 | |||||||
| NO3– sorption | 0·0013 | 17·67 | −0·120 | |||||||
| Soil NH4+ | 0·0164 | 7·88 | 0·880 | |||||||
| NIP | pH | 24·3 | 68·7 | 0·0 | 100·0 | <0·001 | 20·55 | 0·428 | ||
| Soil NH4+/NO3– ratio | <0·001 | 26·63 | −0·600 | |||||||
| NIB | NO3– sorption | 6·9 | 62·1 | 11·4 | 88·6 | 0·023 | 6·57 | 0·400 | ||
| RDMC | 0·042 | 4·92 | −4·930 | |||||||
| NIP/NIB ratio | NH4+ sorption | 42·1 | 58·4 | 24·3 | 75·7 | <0·001 | 19·04 | −1·060 | ||
| Leaf C/N ratio | 0·0248 | 6·22 | 0·036 | |||||||
| Denitrifiers | NRK | NH4+ sorption | 55·1 | 74·4 | 52·7 | 47·3 | 0·0112 | 8·18 | 0·258 | |
| Root C/N ratio | <0·001 | 28·86 | 0·017 | |||||||
| NRS | pH | 41·7 | 56·6 | 0·0 | 100·0 | <0·001 | 25·59 | 0·385 | ||
| NRK/NRS ratio | Root C/N ratio | 31·3 | 79·2 | 100·0 | 0·0 | <0·001 | 47·37 | 94·480 | ||
| Vegetative Height | 0·0074 | 18·93 | 87·410 | |||||||
| Microbial activities | Nitrification | Vmax | pH | 13·3 | 93·3 | 0·0 | 100·0 | <0·001 | 63·28 | 0·300 |
| NO3– sorption | 0·0197 | 6·93 | 0·081 | |||||||
| Soil NH4+/NO3– ratio | <0·001 | 49·75 | −0·457 | |||||||
| Km | pH | 25·1 | 25·0 | 0·0 | 100·0 | 0·0231 | 5·97 | 0·248 | ||
| Denitrification | DEA | Total Soil Carbon | 30·2 | 85·0 | 13·0 | 87·0 | <0·001 | 78·44 | 0·006 | |
| Soil NH4+/NO3– ratio | <0·001 | 26·28 | −0·160 | |||||||
| Leaf Carbon Content | 0·0008 | 15·94 | −0·006 | |||||||
RLSM (root length per gram of dried soil), C/N ratio (carbon/nitrogen content ration), RDMC (root dry matter content), DON (dissolved organic nitrogen), NO3– and NH4+ sorption (in situ nitrate and ammonium absorbed in resin), F/B ratio (fungal to bacterial PLFA ratio), AOA and AOB (ammonia-oxidizing archaea and bacteria, respectively), NIP and NIB for nitrite oxidizers (genera Nitrospira and Nitrobacter, respectively), NRK and NRS (nitrite reductase genes), Vmax and Km (kinetic response variables of potential nitrification), DEA (potential denitrification enzyme activity).