Figure 2 A visualization of a Pearson correlation matrix of ecosystem
functions, and the effects of different trophic diversity on 15
ecosystem functions through linear models. Line thickness is plotted and
the value is labeled as Adjusted R 2 from the
linear model. The pink lines indicate positive effects and the blue
lines indicate negative effects. A single asterisk (*) and a double
asterisk (**) indicate significant relationships via the Pearson test atP < 0.05 and P < 0.001, respectively.
Abbreviations: TN, total nitrogen (g·kg−1); OC,
organic carbon (g·kg−1); TP, total phosphorus
(g·kg−1); AHN, alkali hydrolyzed nitrogen
(mg·kg−1); AP, available phosphorous
(mg·kg−1); AMN, ammonium nitrogen
(mg·kg−1); NN, nitrate nitrogen
(mg·kg−1); MC, moisture content (%); C:N, ratio of
organic carbon to total nitrogen; C:P, ratio of organic carbon to total
phosphorus; N:P, ratio of total nitrogen to total phosphorus; C:N:P,
ratio of organic carbon to total nitrogen to total phosphorus; AGB,
plant aboveground biomass (g·m−2); BGB, plant
belowground biomass (g·m−2); A:B, ratio of plant
aboveground biomass to belowground biomass.
3.3 Predictors of major ecosystem functions and multifunctionality
We further grouped these 15 individual ecosystem functions into four
major functions and ecosystem multifunctionality (water conservation,
soil fertility, nutrition cycling and transformation, and community
productivity, figure 3). A Random Forest analysis showed that altitude,
plant, and rodent diversity indices as predictors could better explain
the four major functions and ecosystem multifunctionality (Figure S11).
Moreover, the significant predictors of ecosystem functions and
multifunctionality were different (Figure 4 and Table S4). A
function-dependent pattern was found among these relationships. For
example, plant diversity had positive relationships with water
conservation, nutrition cycling and transformation, and community
productivity (Figures 4a, c, and d), and rodent diversity had positive
relationships with soil fertility, community productivity, and ecosystem
multifunctionality (Figures 4b, d, and e). Among these predictors,
multitrophic diversity as a critical one to explain the relationships
with functions except for community productivity (Figures 4a, b, c, and
e). Notably, it was interesting to observe that multitrophic diversity
had a more pronounced positive impact on ecosystem multifunctionality
when compared to species diversity within any individual group, which
could improve ecosystem multifunctionality (Figure 4e). Overall,
ecosystem multifunctionality was better predicted by multitrophic
diversity than by other types of diversity.