Trade-off strategy of leaf functional traits of desert halophyte Lycium ruthenicum in the lower reaches of Heihe River, Northwest China: response to soil moisture and salinity
Abstract Abstract Background: Understanding salinity resistance and water utilization on shrub species is a challenge to the management and conservation of desert halophytes. Lycium ruthenicum Murr.with a significant soil and water conservation capacity, is one of the dominant shrubs and halophytes in the lower reaches of the Heihe River, Northwest China. In this paper, the effects of two depths (0-40 and 40-80 cm) of soil salinities and water contents on the leaf functional traits of eight L. ruthenicum communities in different distances from the main channel were studied. Fourteen leaf water physiological and ecological stoichiometric traits were investigated, linking with soil factors to explain desert plant trade-off strategies. Results: Specific leaf volume (SLV), specific leaf area (SLA), leaf thickness (LT), nitrogen (N), C:N, C:P could serve as good indicators of drought and saline resistance. Low N, specific leaf area (SLA) indicated that the plant was located at the slow investment-return axis of the species resource utilization. Low C:N, C:P showed that L. ruthenicum had a defensive life history strategy at drought and salinity areas. The RDA results showed that 0-40 and 40-80 cm soil properties respectively explained 93.45% and 99.96% leaf traits variation. Soil water contents, HCO3- had extremely positive correlation (P<0.01) with leaf functional traits. Shallow soil water contents significantly affects P, and deeper soil water contents significantly responds C and N; shallow soil salinity significantly affected LT, C and N contents, whereas deeper soil salinity significantly affected N and SLV. Conclusions: L. ruthenicum had a foliar resource acquisition and resource conservation trade-off with a defensive life history strategy in the area of drought and salinity. This finding provides baseline information to facilitate the management and restoration of arid-saline desert ecosystem.