Factors influencing the natural regeneration of the pioneering shrub Calligonum mongolicum in sand dune stabilization plantations in arid deserts of northwest China

Abstract

Calligonum mongolicum is a successful pioneer shrub to combat desertification, which is widely used for vegetation restoration in the desert regions of northwest China. In order to reveal the limitations to natural regeneration of C. mongolicum by asexual and sexual reproduction, following the process of sand dune stabilization, we assessed clonal shoots, seedling emergence, soil seed bank density, and soil physical characteristics in mobile and stabilized sand dunes. Controlled field and pot experiments were also conducted to assess germination and seedling emergence in different dune soil types and seed burial depths. The population density of mature C. mongolicum was significantly different after sand dune stabilization. Juvenile density of C. mongolicm was much lower in stabilized sand dunes than mobile sand dune. There was no significant difference in soil seed bank density at three soil depths between mobile and stabilized sand dunes, while the emergence of seedlings in stabilized dunes was much lower than emergence in mobile dunes. There was no clonal propagation found in stabilized dunes, and very few C. mongolicum seedlings were established on stabilized sand dunes. Soil clay and silt content, air‐filled porosity, and soil surface compaction were significantly changed from mobile sand dune to stabilized dunes. Seedling emergence of C. mongolicm was highly dependent on soil physical condition. These results indicated that changes in soil physical condition limited clonal propagation and seedling emergence of C. mongolicum in stabilized sand dunes. Seed bank density was not a limiting factor; however, poor seedling establishment limited C. mongolicum's further natural regeneration in stabilized sand dunes. Therefore, clonal propagation may be the most important mode for population expansion in mobile sand dunes. As a pioneer species C. mongolicum is well adapted to propagate in mobile sand dune conditions, it appears unlikely to survive naturally in stabilized sand dune plantations.

Soil reconstruction after mining fails to restore soil function in an Australian arid woodland

“…Higher sand content in upper soil layers in arid zones is also linked to more stable soil‐moisture dynamics (Zhang & Shao ). Remnant soils had higher surface compaction than expected, which may increase evaporative water loss from the compacted soil surface and inhibit seedling establishment (Fan et al ). Higher surface compaction in remnant soils may represent degradation from drought, the trampling effects from wildlife or, conversely, natural hydrological processes of surface soils to enhance water run‐off toward vegetated patches (Tongway & Ludwig ).…”

Relationship between seed morphological traits and wind dispersal trajectory

“…arborescens and C. rubicundum (Feng et al 2008;Fan et al 2018), which could be related to the aforementioned traits.…”

The Bet-Hedging Strategies for Seedling Emergence of Calligonum mongolicum to Adapt to the Extreme Desert Environments in Northwestern China

“…Calligonum mongolicum shrubs are simultaneously and quite often exposed to wind erosion and sand burial, but serve well as a pioneer species in the Minqin deserts ( Fan et al, 2018 ). In this study, we investigated the effects of burial depth, seed age, and light intensity on the seedling emergence of C. mongolicum , and found that the species in seedling emergence stage are well adapted to sand, and have a procreation bet-hedging strategy to adapt to the extreme environment stresses in the desert.…”

“…Thus, it remains unknown which strategy was adopted by pioneer shrubs to inhabit mobile sand dunes and to adapt to unpredictable sand movement and extreme drought. Calligonum mongolicum (Polygonaceae) is a dominant native perennial shrub in active sand dunes in arid deserts of northern China, and is widely used for vegetation restoration in desert region ( Fan et al, 2018 ). In these sandy habitats, each mature shrub produces numerous quantities of fruit and seeds are dispersed considerable distances by prevailing winds.…”