Indicators of land use by cattle: associations among methods and role of environmental factors

ABSTRACT. The objectives of this study were to investigate the associations among direct and indirect indicators of land use by cattle and to understand the role of some environmental factors on the definition of these indicators. The study was carried out in two areas, Nature Reserve (63.6 ha) and Private Area (30.4 ha), with 53 Hereford animals in each area. Daytime observations of animals’ location were used as direct indicator of land use; while cattle track and dung pat distributions throughout the areas were used as indirect indicators. Environmental characteristics recorded were: terrain slope, prevalence of woody vegetation cover (forests, isolated tress and open grasslands), as well as the position of fences, water sources and salt blocks. Spatial correlations among the three indicators of land use were low (r < 0.30). The environmental factors had lower predictive power of animals’ sightings distribution, followed by cattle tracks, and the highest predictive power occurred for dung pat distribution. We concluded that each one of the methods evaluated in this study addresses a different aspect of land use by cattle. The environmental factors assessed were useful to predict the dung pat distribution, but less valuable to predict the cattle tracks and animals’ sightings distributions.

摘要。本研究旨在探究牛群土地利用的直接与间接指标间的关联，并厘清部分环境因素对这些指标界定的作用。本研究在两个区域开展：自然保护区（63.6公顷）与私有区域（30.4公顷），每个区域各饲养53头赫里福德牛（Hereford）。以日间观测动物位置作为土地利用的直接指标，以牛足迹与粪便斑块在研究区域内的分布作为间接指标。记录的环境特征包括：地形坡度、木本植被覆盖占比（涵盖森林、孤立树木与开阔草原），以及围栏、水源与盐块的位置。三个土地利用指标的空间相关性较低（r<0.30）。环境因素对动物目击分布的预测能力较弱，其次为牛足迹分布，而对粪便斑块分布的预测能力最高。本研究得出结论：本研究评估的每种方法均对应牛群土地利用的不同维度。所评估的环境因素可有效预测粪便斑块分布，但对预测牛足迹与动物目击分布的价值较低。