Department of Ecosystem Science and Management and Program in Ecology, University of Wyoming, 1000 E University Avenue, Laramie, Wyoming, 82070, USA.
USDA-ARS Rangeland Resources and Systems Research Unit, 1701 Centre Avenue, Fort Collins, Colorado, 80526, USA.
Ecology. 2021 Jan;102(1):e03195. doi: 10.1002/ecy.3195. Epub 2020 Oct 28.
Keystone engineers are critical drivers of biodiversity throughout ecosystems worldwide. Within the North American Great Plains, the black-tailed prairie dog is an imperiled ecosystem engineer and keystone species with well-documented impacts on the flora and fauna of rangeland systems. However, because this species affects ecosystem structure and function in myriad ways (i.e., as a consumer, a prey resource, and a disturbance vector), it is unclear which effects are most impactful for any given prairie dog associate. We applied structural equation models (SEM) to disentangle direct and indirect effects of prairie dogs on multiple trophic levels (vegetation, arthropods, and birds) in the Thunder Basin National Grassland. Arthropods did not show any direct response to prairie dog occupation, but multiple bird species and vegetation parameters were directly affected. Surprisingly, the direct impact of prairie dogs on colony-associated avifauna (Horned Lark [Eremophila alpestris] and Mountain Plover [Charadrius montanus]) had greater support than a mediated effect via vegetation structure, indicating that prairie dog disturbance may be greater than the sum of its parts in terms of impacts on localized vegetation structure. Overall, our models point to a combination of direct and indirect impacts of prairie dogs on associated vegetation, arthropods, and avifauna. The variation in these impacts highlights the importance of examining the various impacts of keystone engineers, as well as highlighting the diverse ways that black-tailed prairie dogs are critical for the conservation of associated species.
关键种工程师是全球生态系统中生物多样性的重要驱动因素。在北美大平原，黑尾草原犬鼠是一种受到威胁的生态系统工程师和关键种，其对牧场系统的动植物有大量记录在案的影响。然而，由于该物种以无数种方式影响生态系统结构和功能（即作为消费者、猎物资源和干扰向量），因此不清楚对于任何给定的草原犬鼠伴生物种，哪些影响最为显著。我们应用结构方程模型（SEM）来厘清草原犬鼠对 Thunder Basin 国家草原多个营养级（植被、节肢动物和鸟类）的直接和间接影响。节肢动物对草原犬鼠的占据没有表现出任何直接反应，但多个鸟类物种和植被参数受到直接影响。令人惊讶的是，草原犬鼠对群体相关鸟类（角百灵[Eremophila alpestris]和山地美洲鹤[Charadrius montanus]）的直接影响比通过植被结构的中介效应更有支持，这表明草原犬鼠的干扰可能比其对局部植被结构的影响总和更大。总体而言，我们的模型表明草原犬鼠对相关植被、节肢动物和鸟类有直接和间接的影响。这些影响的变化突出了研究关键种工程师的各种影响的重要性，以及黑尾草原犬鼠对相关物种保护的重要性。
