Trade-off analyses of plant biomass and soil moisture relations on the Loess Plateau

Plant biomass is a crucial parameter for terrestrial ecosystem carbon cycling. Water plays a crucial role in biomass production, especially in arid and semi-arid regions. However, the trade-off relationships between the plant biomass and soil moisture have not been well investigated on the Loess Plateau. In our study, we synthesized 615 pairs of data to evaluate the trade-off between the plant biomass and soil moisture in different precipitation areas and vegetation restoration ages on the Loess Plateau using the quantitative trade-off method. The results showed that precipitation had the strongest effect on soil moisture content (SMC), and aboveground biomass (AGB) was controlled more by vegetation restoration type and elevation, whereas belowground biomass (BGB) was controlled more by vegetation restoration age and elevation. SMC had a higher relative benefit than AGB and BGB in most precipitation areas. In addition, vegetation restoration age is another critical variable to determine the trade-offs between AGB and SMC and between BGB and SMC. For forest, the minimum trade-off of restoration years was > 10 years, but it was < 10 years for shrubland and grassland. Because the trade-offs between AGB and SMC and between BGB and SMC revealed a large spatial change on the whole Loess Plateau, the vegetation in different precipitation areas should identify suitable management strategy to maintain benefits. Understanding the relationship between the plant biomass and soil moisture will improve our ability to sustainably manage vegetation construction and water resources.