Total water infiltration (Fig. 5) varied according to the duration of IFMS operation, increasing from the 1-yearold
site to the 10-year-old site, at which point it was similar to that of the virgin forest. This was because, when
water is supplied to an initially dry soil, the suction gradient across the soil surface becomes very high, which results
in a high IR. As the wetting front moves downward, the suction gradient across the soil profile decreases, which
limits the IR of water into the soil surface. After a long time, the IR approaches zero. The decrease in IR may also be
caused by the dispersion of soil aggregates, or slaking, as well as soil compaction and surface sealing or clogging of
the soil pores [29]. Pores in the soil become clogged when the soil pores are saturated with water. Pores in forest
soils are always related to the trees in that particular forest. Depending on the age of the tree, the tree roots create
pores and enlarge the existing pores as they grow. The standing trees in the 10-year-old site were bigger than those
at the other sites. Their larger roots would have created larger pores, leading to rapid water movement. Therefore, it
can be concluded that forest rehabilitation would recover the infiltration capacity of degraded areas. We estimate
that infiltration capacity would recover to the level of a virgin forest in less than 15 years in the line-planted, cleared,
and logged areas but after 20 years in the skidder track area, if allowed to recove