Abstract: Typhoon, as one of the most common natural disasters in coastal areas, can cause severe threats to the growth of psammophytes by wind erosion, sand burial and sand abrasion. Variations of leaf water potential of the psammophyte Spinifex littoreus under the threats of wind erosion, sand burial and sand abrasion were investigated and corresponding soil water potential, meteorological elements were measured simultaneously after occurrence of typhoon on Pingtan Island, Fujian Province. The results showed that S. littoreus suffered an earlier and more intense water stress after the wind erosion, and its leaf water potential significantly decreased compared with plants without suffering wind erosion (P<0.05), and there was no obvious correlation between leaf water potential and atmospheric water potential (P>0.05). However, the leaf water potential of plants without suffering wind erosion was positively correlated with the atmospheric water potential and relative humidity (P<0.01), while negatively correlated with the temperature (P<0.01). The leaf water potential of S. littoreus that suffered sand burial was higher than that of the ones without sand burial from 10:00 to 16:00, with small amplitude of variations, and lagging response to the meteorological factors. Besides, the leaf water potential of S. littoreus was mainly affected by soil water potential when soil moisture was insufficient, whereas the meteorological factors would become its major influencing factors if soil moisture was sufficient. The leaf water potential of the plants without sand burial was positively correlated with atmospheric water potential and relative humidity (P<0.05), but negatively with the air temperature (P<0.05). With the increasing depth of sand burial, the leaf water potential increase firstly and then decreased, indicating that moderate sand burial would help the plants maintain higher water potential for their adaptation to environmental stresses. Furthermore, the leaf water potential of the abrasive leaves was higher than that of the undamaged ones during most of time, correlating with the atmospheric water potential to an insignificant extent (P>0.05). Nevertheless, the correlations between the leaf water potential of undamaged leaves and atmospheric water potential, relative humidity and temperature were consistent with those of the plants without sand burial.

Key words: carbon density, Henan grassland, carbon distribution, climatic zone.