The hydrological functions of litter layer in a bench-terraced rubber monoculture plantation in SW China

Abstract:

Experimental 1-m² field runoff microplots on terrace risers were monitored to evaluate surface runoff and erosion under the presence or absence of litter cover in a bench-terraced rubber monoculture plantation in SW China. The effect of rainfall intensity on litter layer moisture dynamics was tested under various litter masses. Results showed that the maximum water storage capacity of the litter layer was proportional to the litter mass. The litter interception storage capacity increased with increasing litter mass in the range of realistic rainfall conditions, regardless of the rainfall intensity. Litter layer had an immediate effect in reducing both runoff and erosion and this effect progressively became weaker when litter had gradually decomposed (litter coverage decreasing from c. 70% to less than 20%). The cumulative runoff in litter-removed plots was 3.4 times greater than that in litter-covered plots, while soil loss was 3.42 kg m^–2 yr^–1 and 0.73 kg m^–2 yr^–1, respectively. This implies that the thick, intact litter layer is an important soil protection agent, and it was more effective in protecting the soil surface against sediment loss than it was in reducing runoff. Solely from the point of view of erosion control, particular attention in practical soil conservation activities should be given to the capacity of tree litter to maintaining soil cover on risers in a bench-terraced rubber plantation.