关键词: 松嫩平原, 中分辨率影像, 景观指数, 传统大豆, 时空演变

Abstract: Different developmental stages of tadpoles of Mongolian toads, Pseudepidalea raddei were identified by Gosner staging tables (Gosner, 1960). 20 μL solution of three concentrations of phytohemagglutinin-P (PHA-P) (1, 2.5 and 5 mg·mL^-1) or equivalent salt was injected in one side or opposite one of lower legs of Gosner 46 tadpoles. The tissue thickness of injected sites was measured prior to injection (0 h), and 3, 6, 9, and 12 h after injection, and an optimal PHA-P concentration was selected. Under the condition of optimal PHAP concentration, the intensity and latency of PHAP response were compared among Gosner 37, 42, 44 and 46 stages of tadpoles. The results showed that Gosner 46 tadpoles did not show significant differences after injection of the three levels of PHA-P, but the peak of PHA-P response appeared at earlier or later time, and 2.5 mg·mL^-1 was considered as the optimal injection dose. The PHA-P response of Gosner 42 tadpoles peaked at 3 h after the injection. The PHA-P response of Gosner 37, 44 and 46 tadpoles peaked at 3-6, 3-9, and 3-12 h after the injection, respectively. The maximal PHA-P response of Gosner 37 tadpoles was higher than that of Gosner 46 tadpoles, but there were no significant differences among Gosner 37, 42 and 44 tadpoles. The patterns of PHA-P response changed with different developmental stages of tadpoles in Mongolian toads. The single peak of PHA-P response was rapid and short in Gosner 42 tadpoles. The peak was delayed in the other aquatic developmental stages, and the intensity of the peak of the PHA-P response declined with prolonged duration in terrestrial tadpoles, which may be related to various environmental conditions on land.

Key words: landscape index, traditional soybean, Songnen Plain, medium resolution image, spatiotemporal evolution