Seed dispersal plays an important role in maintaining sand-fixing vegetation and the stability of artificial sand-fixing systems. However, it is unclear how wind speed, underlying surface, and seed morphological traits influence seed movement or stationary behavior, as well as short-distance dispersion, long-distance dispersion, or burial. 

A research team led by Prof. Qu Jianjun from the Northwest Institute of Eco-Environment and Resources of the Chinese Academy of Sciences selected seeds from 11 plant species to study the factors that affect secondary seed dispersal in fixed, semi-fixed, and mobile dunes. 

The study was published in Journal of Arid Land on April 4. 

Researchers quantitatively analyzed the threshold of wind speeds (TWS) and the distribution of secondary seed dispersal, and evaluated the relative significance of diaspore characteristics, underlying surface, and wind speed on both the TWS and the outcomes of secondary seed dispersal. 

It was found that the TWS of different species is different in different habitats. The TWS of Caragana korshinskii seed is the highest among the 11 plant species, while the lowest is for Echinops gmelinii seed. Furthermore, the dispersal-enhancing appendages and the underlying surface are significant factors affecting the TWS.  

The study also indicated that most seeds in the study area did not move, were buried, or dispersed over short distances. Compared to other habitats, mobile dunes pose the greatest challenge for secondary seed dispersal. Buried seeds are most easily detected in semi-fixed sand dunes, while fixed sand dunes provide optimal conditions for long-distance seed dispersion.  

Besides, the study suggested that smaller and rounder seeds disperse further. It can be seen that seed shape is another significant factor affecting seed burial. 

The explanatory power of wind speed, underlying surface, and seed morphological traits for unmoved and short-distance dispersed seeds is much greater than for buried and long-distance dispersed seeds, suggesting that the processes and mechanisms of seed burial and long-distance dispersal may be more complex. 

Contact:    

QU jianjun 

e-mail: qujianj@lzb.ac.cn