Vertebrate-mediated seed dispersal is probably the main long distance dispersal mode. Through endozoochory, large mammals act as mobile links between habitats within and among forest patches. Along with other factors, their feeding regimes do affect their contribution as dispersal vectors. We conducted a cross-species comparative experiment involving two herbivores, red deer and roe deer; and two opportunistic omnivores, wild boar and brown bear, all occurring in the forest and steppe-forest ecotone habitats of the south-eastern Caspian region. We compared their role as endozoochorous seed dispersal agents by monitoring seedling emergence in their dungs under greenhouse and natural conditions. In total, 3078 seedlings, corresponding to 136 plant taxa sprouted from 445 paired dung sub-samples, under greenhouse and natural conditions. Only 336 seedlings, corresponding to 36 plant taxa, emerged under natural conditions, among which five taxa did not appear under greenhouse conditions. Graminoids and forbs composed 91% of the seedlings in the greenhouse whereas shrubs were more abundant under natural conditions, representing 55% of the emerged seedlings. Under greenhouse conditions, first red deer and then wild boar dispersed more species than the other two mammals, while under natural conditions brown bear was the most effective vector. We observed remarkably higher species richness and seedling abundance per dung sub-sample under buffered greenhouse conditions than we did under natural conditions. The four sympatric mammals studied provided different seed dispersal services, both in terms of seedling abundance and species richness and may therefore be regarded as complementary. Our results highlight a positive bias when only considering germination under buffered greenhouse conditions. This must be taken into account when planning management options to benefit plant biodiversity based on the dispersal services concluded from greenhouse experiments.

中文翻译：

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食草动物和杂食动物的内生食虫传播是由发芽条件介导的。

脊椎动物介导的种子传播可能是主要的长距离传播方式。大型哺乳动物通过气管内腔作为森林斑块内部和之间的栖息地之间的活动联系。除其他因素外，它们的摄食方式确实会影响它们作为传播媒介的贡献。我们进行了跨物种比较实验，涉及两种食草动物，即马鹿和ro。还有两个机会性杂食动物，野猪和棕熊，都发生在里海东南部的森林和草原-森林过渡带生境中。我们通过监测温室和自然条件下它们的粪便中的幼苗出苗，比较了它们作为内生食虫种子分散剂的作用。在温室和自然条件下，总共从445个配对的粪便子样本中萌芽了3078株幼苗，相当于136个植物分类单元。在自然条件下仅出现336种幼苗，相当于36种植物分类单元，其中在温室条件下未出现5种分类单元。温室中的幼苗中，类固醇和前叉占91％，而在自然条件下，灌木更为丰富，占出苗的55％。在温室条件下，首先是马鹿，然后是野猪，比其他两种哺乳动物分散了更多的物种，而在自然条件下，棕熊是最有效的媒介。我们观察到，在缓冲温室条件下，每个粪便子样品的物种丰富度和幼苗丰度均比自然条件下高得多。所研究的四种同胞哺乳动物在种子丰度和物种丰富度方面都提供了不同的种子传播服务，因此可以被认为是互补的。当仅考虑在缓冲的温室条件下发芽时，我们的结果突显了一个积极的偏见。在基于温室试验得出的扩散服务来规划使植物生物多样性受益的管理方案时，必须考虑到这一点。