|Alternative Title||The effect of plant community composition on goat forage trajectory in the semi-arid hilly Loess Plateau
|Place of Conferral||兰州
|Abstract||本研究以半干旱黄土高原丘陵区为研究区域，使用GPS记录了羊群日运动轨迹，采取远距离拍照的方法获得了单只山羊在山坡的高精度运动轨迹，同时采用传统样方法在生物量最大季节测量了不同坡向植物群落构成。继而利用地理信息系统和遥感图像处理方法，分析了不同季节（1）放牧过程中羊群日运动轨迹特征（包括：速度、与水平面夹角、转角）；（2）羊群对不同坡向利用强度差异。得到以下结论：（1）羊群运动轨迹受植物群落结构的显著影响。在冬季随着食物资源的减少，羊群相对采食时间增加。不同坡向植物群落结构的差异影响羊群对不同坡向的使用比例。相对于阴坡和阳坡，山羊偏向于使用半阴坡，并且在半阴坡采食时间长于阴坡和阳坡。（2）山羊存在两种基本运动状态：采食和转移，这两种运动状态对应的速度分别为0～0.25 m/s和0.25～1 m/s。采食和转移状态下的运动路径与水平面夹角和转角显著不同。在采食状态下运动路径与水平面夹角和转角分别有51.3%和47.5%分布于60°～90°，而在转移状态下分别有78.4%和76.9%分布于0°～30°。食物资源丰富时，山羊主要是在群落内对个体植物或植物群体选择；食物资源匮乏时，山羊主要是在群落间对植物群落进行选择。在半阴坡，适口性植物丰度较高，转角频率较高；山羊对个体植物的选择时间比例较阴坡、阳坡高。（3）牧道对山羊运动路径的选择有限制作用。山羊对牧道具有高利用率，其运动过程中90.7%的踩踏发生在牧道上，并且86.6%的 “采食站”也位于牧道。山羊在采食和转移过程中，倾向于使用已经存在的牧道网络，而不是创造新的牧道。（4）羊群对采食区域的重复利用强度受植物群落结构的影响。在食物资源匮乏的冬季，羊群对采食区域的重访比例显著高于食物资源丰富的秋季。在冬季和秋季羊群对半阴坡的重访比例均显著高于阴坡和阳坡。|
|Other Abstract||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.|
罗凯. 半干旱黄土高原丘陵区植物群落构成对山羊放牧路径的影响[D]. 兰州. 兰州大学,2015.
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