Long-term monitoring of ground-dwelling arthropods in the McDowell Sonoran Preserve, Scottsdale, Arizona, ongoing since 2012

*Project overview*

Protected lands, such as the McDowell Sonoran Preserve (hereafter
referred to as the Preserve) in Scottsdale, Arizona, provide critical
refuge for native biota and natural, ecological processes within and
near urban environments. At the same time, a key feature that makes
urban, open-space preserves so valuable − their proximity to urban areas
− places strain on the ecological integrity of these systems through
visitation, habitat fragmentation, and the introduction of exotic
species among others. Effective management of these systems requires
detailed knowledge of the biota within the protected area, and
monitoring of ecological indicators through time. Arthropods are well
suited to monitoring ecological health. This diverse group of organisms
typically reflects overall biological diversity of a system, and
includes several trophic levels; their short generation times mean they
will likely respond quickly to change; and they are relatively easy to
sample. As part of a broad effort by the McDowell Sonoran Conservance
Field Institute, an organization that oversees science and research in
Preserve, to establish a baseline inventory of biota in the Preserve,
investigators with the Central Arizona−Phoenix Long-Term Ecological
Research (CAP LTER) program at Arizona State University (ASU) in
collaboration with Field Institute Citizen Scientists are monitoring
ground-dwelling arthropods at select locations that reflect a diversity
of habitat within the Preserve. Investigators employ a sampling design
that is intended to provide insight regarding influence of the
urban-wildland interface on the arthropod community within the protected
area. The simple but effective technique of pitfall trapping is used to
sample ground-dwelling arthropods at select locations spanning a wide
range of habitat with the Preserve. Additional collections of
vegetation-dwelling arthropods have been conducted at the sampling
locations at periodic intervals.

*Project design and sampling*

Pitfall trap transect locations include five groups of paired transects
that span a large range of the north-south and east-west axes of the
Preserve, and include numerous unique vegetation communities. Four
transect pairs are positioned such that one transect is within 100 m of
the Preserve boundary and existing development, and the second transect
at least 0.5 km from the Preserve boundary-development. A fifth paired
transect treated as a control is located in a similar fashion but at a
location where there is not currently development near the Preserve
boundary (Dixie Mine and Prospector sites). Transect locations were
selected specifically to include relatively similar geomorphological
characteristics, including elevation (610-914 m), slope (≤ 20%), and
aspect (0-270°, 315-360°) to minimize extraneous factors. All transects
are positioned within 75 m of existing trails to facilitate access and
limit off-trail travel while keeping traps out of public view. Sampling
is conducted quarterly in keeping with CAP LTER protocols and
concomitant sampling at other Valley location.

项目概况

麦克道尔·索诺兰保护区（McDowell Sonoran Preserve，下称本保护区）位于亚利桑那州斯科茨代尔，这类保护地为城市内部及周边的本土生物群落与自然生态过程提供了关键庇护所。与此同时，城市开放空间保护区之所以价值斐然，核心特质之一便是其紧邻城市区域，但这也带来了诸多压力：游客到访、栖息地破碎化以及外来物种引入等，均会威胁这些生态系统的完整性。

对这类系统开展有效管理，需要详尽掌握保护地内的生物群落信息，并长期监测生态指标。节肢动物（Arthropods）非常适合用于生态健康状况的监测：这一类群生物多样性丰富，能够反映生态系统整体的生物多样性水平，且涵盖多个营养级；其世代周期较短，可快速响应环境变化；同时采样工作相对简便易行。

作为麦克道尔·索诺兰保护地野外研究所（McDowell Sonoran Conservance Field Institute）开展的全面工作的一部分——该机构负责本保护区内的科学研究工作，旨在建立本保护区内的生物群落基线名录——亚利桑那州立大学（Arizona State University, ASU）的中亚利桑那-凤凰城长期生态研究（CAP LTER）项目团队与该研究所的公民科学志愿者合作，在本保护区内具有代表性的多样栖息地点位开展地表栖息节肢动物的监测工作。研究团队采用的采样设计，旨在探究城市-荒野交错带对保护区内节肢动物群落的影响。

研究团队采用简便高效的陷阱诱捕法（pitfall trapping），在本保护区内覆盖多样栖息地的选定点位采集地表栖息节肢动物。此外，项目组还定期在采样点位开展植栖节肢动物的补充采集工作。

项目设计与采样方案

陷阱诱捕样带的布设点位涵盖5组成对样带，覆盖本保护区南北与东西方向的广阔区域，并包含多种独特的植被群落。其中4组成对样带的布设方式为：一条样带位于保护区边界与现有开发区域100米范围内，另一条样带则距离保护区边界-开发区域至少0.5千米。第5组成对样带作为对照样带，布设方式与上述一致，但点位位于保护区边界附近暂无开发活动的区域（迪克西矿区与探矿者点位）。

样带点位的选择均严格控制地貌特征的一致性，包括海拔（610~914米）、坡度（≤20%）以及坡向（0°~270°、315°~360°），以尽可能减少无关因素的干扰。所有样带均布设于现有步道75米范围内，既便于人员通行、限制步道外活动，同时可避免诱捕装置被公众发现。

采样工作按照CAP LTER的规范每季度开展一次，并与其他山谷点位的同步采样工作保持一致。