The Effect Of Plant Community Composition On Goat Forage Trajectory In The Semi-arid Hilly Loess Plateau

In this study, we recorded the daily goat movement trajectory in the semi-arid hilly Loess Plateau using GPS, and acquired high spatial resolution movement trajectory of individual goat using photography when the goat herd passing the hillside, and we also analyzed the plant community compositions of different hillside aspects in the biomass peak season. Geographical information system was used to analyze (1) the characters of goat movement trajectory (including: speed, angle between trajectory and horizontal plane, turn angle); (2) the using intensity of different hillside aspects in different seasons. We found:(1) The goat movement trajectory was significantly affected by the plant community compositions. With the declining of food resource in winter, the relative foraging time of goats herd increase. There were different plant community compositions in different hillside aspects, which may have affected the movement trajectory, the goats herd preferred semi-shady to shady and sunny hillside, and the foraging time was also longer in semi-shady aspect than in other aspects.(2) There were two movement states:forage and transfer, their movement speeds ranged 0～ 0.25 m/s and 0.25～1 m/s respectively. There were significantly different angle between trajectory and horizontal plane and turn angle in different movement states. In the forage state,51.3% of angle between trajectory and horizontal plane and 47.5% of turn angle ranged 60°-90°. In the transfer state,78.4% of angle between trajectory and horizontal plane and 76.9% of turn angle ranged 0°～30°. The goats turned more frequently when the food resource was abundant and in semi-shady aspect hillside.(3) The proportion that the goats use trail when the forage was at a high value. 90.7% trampling was located on trail, and 86.6% "feeding station" was located on trail. The goats prefer using trail than creating new trail.(4) The intensity of forage area use repeatedly was affected by plant community composition. The ratio of revisiting was more frequency in the winter than in the autumn when food resource was abundant, and in the semi-shady than in the shady and sunny hillside.