Recursion to food plants by free-ranging Bornean elephant.
Recursion to food plants by free-ranging Bornean elephant.
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作者：
English M;Gillespie G;Goossens B;Ismail S;Ancrenaz M;Linklater W
草食后的植物恢复率被认为是促使草食动物回归到地点和植物以优化资源利用的关键因素，但尚未被研究作为大型草食动物回归的原因。我们调查了沙巴州下基纳巴坦干野生动物保护区的植物恢复与大象(Eephas Max Bornesis)回归的关系。我们确定了来自30个物种的182种最近食用的植物，沿着14×50米的横断面，并测量了它们在9个月内每月的恢复生长，或者直到它们被大象重新觅食。每种植物的叶片和枝条或枝条长度的月生长量被用来计算每个物种恢复到其被吃掉前的长度所需的时间(月)。大象带着10种被吃掉的植物回到了除了两个横断面之外的所有地方，另有26种植物死亡，剩下146种可以重新食用。58%的植物和30种植物中的12种发生了回归。被重新吃掉的植物中有77%是草。根据物种的不同，所有植物的恢复时间从2个月到20个月不等。对所有草的回归与植物的恢复相一致，而对大多数被浏览的植物的回归发生在它们恢复到以前的长度之前的4到12个月。许多被浏览的植物的样本量很小，而且植物物种在横断面上的分布不均匀，这限制了我们对大多数被浏览物种的概括能力，但在植物规模的递归中确实出现了一个显著的模式。植物恢复时间是回归时间的一个很好的预测指标，但随着生长形式(草、生姜、棕榈、藤本植物和木本)和地点之间的差异而变化。种植递归的时间与大象喜欢的食物--草，或许还有生姜--的植物恢复时间不谋而合，但其他被觅食的物种却没有。大象是大宗捕食者，因此很可能在数量恢复到足以满足它们的摄入量时，它们会选择在数量恢复到足以满足它们的摄入量时大量捕食这些草种。对栖息地和大象管理的影响进行了讨论。
Plant recovery rates after herbivory are thought to be a key factor driving recursion by herbivores to sites and plants to optimise resource-use but have not been investigated as an explanation for recursion in large herbivores. We investigated the relationship between plant recovery and recursion by elephants (Elephas maximus borneensis) in the Lower Kinabatangan Wildlife Sanctuary, Sabah. We identified 182 recently eaten food plants, from 30 species, along 14 × 50 m transects and measured their recovery growth each month over nine months or until they were re-browsed by elephants. The monthly growth in leaf and branch or shoot length for each plant was used to calculate the time required (months) for each species to recover to its pre-eaten length. Elephant returned to all but two transects with 10 eaten plants, a further 26 plants died leaving 146 plants that could be re-eaten. Recursion occurred to 58% of all plants and 12 of the 30 species. Seventy-seven percent of the re-eaten plants were grasses. Recovery times to all plants varied from two to twenty months depending on the species. Recursion to all grasses coincided with plant recovery whereas recursion to most browsed plants occurred four to twelve months before they had recovered to their previous length. The small sample size of many browsed plants that received recursion and uneven plant species distribution across transects limits our ability to generalise for most browsed species but a prominent pattern in plant-scale recursion did emerge. Plant recovery time was a good predictor of time to recursion but varied as a function of growth form (grass, ginger, palm, liana and woody) and differences between sites. Time to plant recursion coincided with plant recovery time for the elephant’s preferred food, grasses, and perhaps also gingers, but not the other browsed species. Elephants are bulk feeders so it is likely that they time their returns to bulk feed on these grass species when quantities have recovered sufficiently to meet their intake requirements. The implications for habitat and elephant management are discussed.