Robles Hugo, Martin Kathy
Department of Forest and Conservation Sciences, Centre for Applied Conservation Research, University of British Columbia, Vancouver, British Columbia, Canada.
Department of Forest and Conservation Sciences, Centre for Applied Conservation Research, University of British Columbia, Vancouver, British Columbia, Canada ; Pacific Wildlife Research Centre, Environment Canada, Delta, British Columbia, Canada.
PLoS One. 2014 Feb 28;9(2):e90071. doi: 10.1371/journal.pone.0090071. eCollection 2014.
Through physical state changes in biotic or abiotic materials, ecosystem engineers modulate resource availability to other organisms and are major drivers of evolutionary and ecological dynamics. Understanding whether and how ecosystem engineers are interchangeable for resource users in different habitats is a largely neglected topic in ecosystem engineering research that can improve our understanding of the structure of communities. We addressed this issue in a cavity-nest web (1999-2011). In aspen groves, the presence of mountain bluebird (Sialia currucoides) and tree swallow (Tachycineta bicolour) nests was positively related to the density of cavities supplied by northern flickers (Colaptes auratus), which provided the most abundant cavities (1.61 cavities/ha). Flickers in aspen groves provided numerous nesting cavities to bluebirds (66%) and swallows (46%), despite previous research showing that flicker cavities are avoided by swallows. In continuous mixed forests, however, the presence of nesting swallows was mainly related to cavity density of red-naped sapsuckers (Sphyrapicus nuchalis), which provided the most abundant cavities (0.52 cavities/ha), and to cavity density of hairy woodpeckers (Picoides villosus), which provided few (0.14 cavities/ha) but high-quality cavities. Overall, sapsuckers and hairy woodpeckers provided 86% of nesting cavities to swallows in continuous forests. In contrast, the presence of nesting bluebirds in continuous forests was associated with the density of cavities supplied by all the ecosystem engineers. These results suggest that (i) habitat type may mediate the associations between ecosystem engineers and resource users, and (ii) different ecosystem engineers may be interchangeable for resource users depending on the quantity and quality of resources that each engineer supplies in each habitat type. We, therefore, urge the incorporation of the variation in the quantity and quality of resources provided by ecosystem engineers across habitats into models that assess community dynamics to improve our understanding of the importance of ecosystem engineers in shaping ecological communities.
通过生物或非生物材料的物理状态变化，生态系统工程师调节着其他生物可利用的资源，并且是进化和生态动态的主要驱动因素。了解生态系统工程师在不同栖息地对于资源使用者而言是否以及如何具有可替代性，这在生态系统工程研究中是一个很大程度上被忽视的课题，而这一课题能够增进我们对群落结构的理解。我们在一个树洞巢网络（1999 - 2011年）中探讨了这个问题。在白杨树林中，山地蓝知更鸟（Sialia currucoides）和树燕（Tachycineta bicolour）巢穴的存在与北美扑动鴷（Colaptes auratus）提供的树洞密度呈正相关，北美扑动鴷提供的树洞最为丰富（1.61个树洞/公顷）。尽管之前的研究表明树燕会避开北美扑动鴷的树洞，但白杨树林中的北美扑动鴷为蓝知更鸟（66%）和树燕（46%）提供了大量的筑巢树洞。然而，在连续的混交林中，筑巢树燕的存在主要与红颈吸汁啄木鸟（Sphyrapicus nuchalis）的树洞密度相关，红颈吸汁啄木鸟提供的树洞最为丰富（0.52个树洞/公顷），也与毛啄木鸟（Picoides villosus）的树洞密度相关，毛啄木鸟提供的树洞较少（0.14个树洞/公顷）但质量很高。总体而言，在连续森林中，吸汁啄木鸟和毛啄木鸟为树燕提供了86%的筑巢树洞。相比之下，连续森林中筑巢蓝知更鸟的存在与所有生态系统工程师提供的树洞密度相关。这些结果表明：（i）栖息地类型可能会调节生态系统工程师与资源使用者之间的关联；（ii）不同的生态系统工程师对于资源使用者而言可能具有可替代性，这取决于每个工程师在每种栖息地类型中所提供资源的数量和质量。因此，我们敦促将生态系统工程师在不同栖息地所提供资源的数量和质量变化纳入评估群落动态的模型中，以增进我们对生态系统工程师在塑造生态群落中的重要性的理解。
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