Moe Stein R, Eldegard Katrine, Rannestad Ole Tobias, Okullo Paul, Lindtjørn Ommund, Støen Ole Gunnar, Dale Svein
Faculty of Environmental Sciences and Natural Resource Management Norwegian University of Life Sciences P.O. Box 5003, NO-1432 Ås Norway.
Nabuin Zonal Agricultural Research and Development Institute National Agricultural Research Organisation Moroto Uganda.
Ecol Evol. 2017 Oct 23;7(23):10079-10088. doi: 10.1002/ece3.3513. eCollection 2017 Dec.
Vast areas of the African savanna landscapes are characterized by tree-covered termite mounds embedded within a relatively open savanna matrix. In concert with termites, large herbivores are important determinants of savanna woody vegetation cover. The relative cover of woody species has considerable effects on savanna function. Despite the potentially important ecological relationships between termite mounds, woody plants, large herbivores, and birds, these associations have previously received surprisingly little attention. We experimentally studied the effects of termites and large herbivores on the avian community in Lake Mburo National Park, Uganda, where woody vegetation is essentially limited to termite mounds. Our experiment comprised of four treatments in nine replicates; unfenced termite mounds, fenced mounds (excluding large mammals), unfenced adjacent savanna, and fenced savanna. We recorded species identity, abundance, and behavior of all birds observed on these plots over a two-month period, from late dry until wet season. Birds used termite mounds almost exclusively, with only 3.5% of observations occurring in the treeless intermound savanna matrix. Mean abundance and species richness of birds doubled on fenced (large herbivores excluded) compared to unfenced mounds. Feeding behavior increased when large mammals were excluded from mounds, both in absolute number of observed individuals, and relative to other behaviors. This study documents the fundamental positive impact of termites on bird abundance and diversity in an African savanna. Birds play crucial functional roles in savanna ecosystems, for example, by dispersing fruits or regulating herbivorous insect populations. Thus, the role of birds in savanna dynamics depends on the distribution and abundance of termite mounds.
非洲稀树草原景观的大片区域的特点是，在相对开阔的稀树草原基质中分布着树木覆盖的白蚁丘。与白蚁一样，大型食草动物也是稀树草原木本植被覆盖的重要决定因素。木本物种的相对覆盖度对稀树草原功能有相当大的影响。尽管白蚁丘、木本植物、大型食草动物和鸟类之间可能存在重要的生态关系，但这些关联此前却惊人地很少受到关注。我们通过实验研究了白蚁和大型食草动物对乌干达姆布罗湖国家公园鸟类群落的影响，该公园的木本植被基本上仅限于白蚁丘。我们的实验包括四种处理方式，每种处理方式重复九次；未围栏的白蚁丘、围栏的白蚁丘（排除大型哺乳动物）、未围栏的相邻稀树草原和围栏的稀树草原。在从旱季末期到雨季的两个月时间里，我们记录了在这些样地上观察到的所有鸟类的物种身份、数量和行为。鸟类几乎只利用白蚁丘，在无树的蚁丘间稀树草原基质中的观察记录仅占3.5%。与未围栏的蚁丘相比，围栏（排除大型食草动物）的蚁丘上鸟类的平均数量和物种丰富度增加了一倍。当大型哺乳动物被排除在蚁丘之外时，无论是观察到的个体绝对数量，还是相对于其他行为而言，取食行为都有所增加。这项研究记录了白蚁对非洲稀树草原鸟类数量和多样性的基本积极影响。鸟类在稀树草原生态系统中发挥着关键的功能作用，例如通过传播果实或调节食草昆虫种群数量。因此，鸟类在稀树草原动态中的作用取决于白蚁丘的分布和数量。
