资源环境科技发展态势分析平台

In salt-affected soils, salt stress causes a drastic reduction of plant transpiration. The extent of this reduction is a function of vegetation salt tolerance and can result in highly species-specific controls on soil water budget and salinization levels. Despite their crucial role in regulating the hydrology of saline soils, the effects of salt tolerance on transpiration remain mostly unexplored. Here we propose a minimalist stochastic model of primary salinization which reproduces the hitherto overlooked feedback of salinity on the soil water balance and the active role of plant salt tolerance in modulating such an effect. We show that vegetation can exert significant control on leaching occurrence and soil salinization, thus imposing a species-specific upper limit, C-max to the concentration of soluble salts in the soil. Since C-max increases with plant salt tolerance, salt-resilient species have the potential to sustain more saline conditions in the soil, eventually creating a favorable environment for their ecological success.

Plain Language Summary In arid regions, thousands of hectares of arable land are lost daily to soil salinization as a result of both natural processes and human-induced modifications of the local hydrological regime. Salt-tolerant species (halophytes) have been proposed as an economically viable alternative to traditional salt-sensitive crops (glycophytes) to reclaim saline soils and even contrast dryland degradation. Under saline conditions, however, halophytes use water more efficiently-and transpire comparatively more-than conventional crops, raising the question of whether their ability to tolerate salinity can have an impact on the long-term soil water balance and future salinization trends. To better understand the relation between vegetation, salinity, and soil water dynamics, we propose here a simple parameterization of the effects of salt tolerance on evapotranspiration in salt-affected ecosystems. Using a minimalist stochastic model of natural salinization, we then show that different levels of plant salt tolerance correspond to distinct transpiration, soil moisture, and salinization trajectories. Halophytes, in particular, tend to maintain higher levels of salinity in the soil compared with glycophytes, eventually re-engineering the habitat in their favor. These results suggest that the long-term effects of plant salt tolerance on salinization should be carefully considered in planning large-scale transitions to halophytic agriculture.