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Recent decline in biological diversity has stimulated the research on the effects of resource conservation on biodiversity and vice versa. We examined soil water and nutrients influenced by rainwater harvesting (RWH) in hillslope and its effects on herbage diversity and productivity at up (USP), middle (MSP) and lower position (LSP) in 75 plots, each of 700-m2 area laid in<10%, 10%–20% and>20% slopes, respectively. The five RWH treatments were Contour trench (CT), Gradonie (G), Box trench (BT), V-ditch (VD) and control. Soil water content (SWC), species number, population, diversity and herbage yield increased (P<0.05) downward suggesting positive relations between soil resource and diversity/productivity. The highest species number, population, richness and diversity in 10%–20% slope were associated with soil water usage and NO3-N and NH4-N concentrations. SWC was 5.0%–19.0% greater in RWH areas than in control influencing herbage species, population, growth and yields. The increase in diversity and yields was the highest (P<0.05) in V-ditch reinforced by soil fertility. The positive effect of diversity on yield increased with resources, and the effect was compositional rather than that of species richness. Conclusively, slope gradient and soil texture influenced herbage regeneration, diversity and productivity, which were positively affected by existing soil fertility and applied RWH and mobilizing soil water and nutrients. The effect of V-ditch was the highest on composition and yield. Thus, RWH enhanced herbaceous vegetation and restoration of degraded forest/rangelands. But long-term effects of diversity in restoring ecosystem productivity could be established through long-term data collections on optimum water/nutrient usage, diversity and productivity. |
