4.3. Linkages of vegetation, macronutrients and soil erosion
Our findings suggest that the changes in land management and the
associated changes in understory and ground cover can alter soil physical
properties, macronutrient contents, and both short- and long-term
soil erosion rates. The decrease in understory vegetation and ground
cover is believed to be the primary cause of the increase in soil erosion
and decrease in macronutrients (Table 4). Similarly, soil chemical
richness is strongly linked to understory biomass litter biomass, and
possibly the degradation of soil physical properties as exemplified by
bulk density.
The linkages among vegetation, macronutrients and soil erosion also
can be seen in component 2 which indicates vegetation condition and
the short-term soil erosion in ten land-use types (Table 5). In general,
each principal component in PCA is a group of linkable variables with
similarity. In this component the effect of vegetation was quantified
through the high positive loadings of understory biomass, litter
biomass, and total ground cover, and soil pedestal height had an equivalent
negative loading (Fig. 5). The relatively highest loadings were soil
erosion indicator (soil pedestal height), and vegetation (known as
understory biomass, litter and total ground cover), followed by soil
nutrients such as total carbon and macronutrient (SOC and SON)
in component 2, which indicates their tight linkage. Previous
studies have shown that soil vegetation cover alters SOC and SON
(Vanderschaaf et al., 2004). In flatter downslope areas deposition can
enrich SOC and radionuclide inventories (Frye et al., 1982), but all of
our plots were in sloping source areas. An upslope–downslope design
focusing on a few land use types would be necessary to quantify both
the loss and the redistribution of soils and macronutrients, and thereby
apply the present results to larger scales.
4.3. Linkages of vegetation, macronutrients and soil erosionOur findings suggest that the changes in land management and theassociated changes in understory and ground cover can alter soil physicalproperties, macronutrient contents, and both short- and long-termsoil erosion rates. The decrease in understory vegetation and groundcover is believed to be the primary cause of the increase in soil erosionand decrease in macronutrients (Table 4). Similarly, soil chemicalrichness is strongly linked to understory biomass litter biomass, andpossibly the degradation of soil physical properties as exemplified bybulk density.The linkages among vegetation, macronutrients and soil erosion alsocan be seen in component 2 which indicates vegetation condition andthe short-term soil erosion in ten land-use types (Table 5). In general,each principal component in PCA is a group of linkable variables withsimilarity. In this component the effect of vegetation was quantifiedthrough the high positive loadings of understory biomass, litterbiomass, and total ground cover, and soil pedestal height had an equivalentnegative loading (Fig. 5). The relatively highest loadings were soilerosion indicator (soil pedestal height), and vegetation (known asunderstory biomass, litter and total ground cover), followed by soilnutrients such as total carbon and macronutrient (SOC and SON)in component 2, which indicates their tight linkage. Previousstudies have shown that soil vegetation cover alters SOC and SON(Vanderschaaf et al., 2004). In flatter downslope areas deposition canenrich SOC and radionuclide inventories (Frye et al., 1982), but all ofour plots were in sloping source areas. An upslope–downslope designfocusing on a few land use types would be necessary to quantify boththe loss and the redistribution of soils and macronutrients, and therebyapply the present results to larger scales.
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