4.2. Soil erosion by land-use type
Soil pedestal heights indicated that short-term soil erosion was
greatest in the four land use types with the least understory biomass
(Fig. 4). The correlation analysis showed that pedestal height was
most strongly related to percent ground cover, as the four land uses
with the highest pedestal heights did not have more than 63% ground
cover (Tables 1, 2), while none of the land uses with more than 76%
cover had any soil pedestals. Other studies also have shown soil erosion
under a forest canopy with sparse understory vegetation and ground
cover (Miyata et al., 2009). Taken together, these results indicate that
both understory biomass and ground cover are important for reducing
rainfall kinetic energy and rainsplash, but ground cover is more important.
This result is supported by both modeling and field studies that
show a strong, nonlinear relationship between percent surface cover
and erosion (e.g., Larsen et al., 2009; Miller et al., 2011). The main difference
between these other studies and our data set in Fig. 4b is that the
threshold for no erosion is at least 76% ground cover. This relatively