Data and code from: Breakdown in seasonal dynamics of subtropical ant communities with land-cover change

Concerns about widespread human-induced declines in insect populations are mounting, yet little is known about how land-use change modifies the dynamics of insect communities, particularly in understudied regions. Here, we examine how the seasonal activity patterns of ants—key drivers of terrestrial ecosystem functioning—vary with anthropogenic land-cover change on a subtropical island landscape, and whether differences in temperature or species composition can explain observed patterns. Using trap captures sampled biweekly over two years from a biodiversity monitoring network covering Okinawa Island, Japan, we processed 1.2 million individuals and reconstructed activity patterns within and across habitat types. Forest communities exhibited greater temporal variability of activity than those in more developed areas. Using time-series decomposition to deconstruct this pattern, we found that sites with greater human development exhibited ant communities with diminished seasonality, reduced synchrony, and higher stochasticity compared to sites with greater forest cover. Our results cannot be explained by variation in regional or site temperature patterns, or by differences in species richness or composition among sites. Our study raises the possibility that disruptions to natural seasonal patterns of functionally key insect communities may comprise an important and underappreciated consequence of global environmental change that must be better understood across Earth’s biomes.

Methods
The ant activity data used in the analysis was collected with Sea, Land, and Air Malaise (SLAM) traps on Okinawa Island in Japan from 2016-2018, and was processed using the code provided in the Zenodo archive (see README for links and the paper for references). Other datasets come from the Japan Meterological Agency (JMA), in situ climate variables for sampling stations measured on-site, and land-cover data for Okinawa developed by our team. The data used in the analysis is included in the data upload (with JMA and land-cover data files in a Zenodo supplemental information under the CC-By 4 license), and all the analysis code is included in the R package provided in a separate Zenodo software archive.

NOTE: All datasets (from Dryad and Zenodo) must be put into a single folder called `/data` within the main directory of the R analysis package before running any code. Please consult the README for further details on the data and code.

当前，学界对人类活动普遍导致昆虫种群衰退的担忧与日俱增，但我们对土地利用变化如何改变昆虫群落动态的认知仍十分有限，在研究不足的区域更是如此。本研究以亚热带岛屿景观为研究对象，探讨作为陆地生态系统功能关键调控者的蚂蚁，其季节性活动模式如何随人类活动主导的土地覆盖变化发生改变，并验证温度差异或物种组成差异能否解释观测到的活动模式。本研究依托覆盖日本冲绳岛的生物多样性监测网络，通过两年间每两周一次的诱捕采样，共处理了120万头个体，并重建了不同生境内部及生境间的蚂蚁活动模式。相较于开发程度更高的区域，森林生境中的蚂蚁群落活动的时间变异性更强。通过时间序列分解拆解该模式后，我们发现，与森林覆盖度更高的样地相比，人类开发程度更高的样地内，蚂蚁群落的季节性减弱、同步性降低且随机性更高。本研究结果无法通过区域或样地的温度格局差异，或是样地间物种丰富度与组成的差异来解释。本研究表明，具有关键生态功能的昆虫群落的自然季节性活动模式遭到破坏，可能是全球环境变化带来的一项重要却未被充分重视的后果，该现象亟需在全球各生物群区中得到更深入的研究。

## 研究方法
本分析所用的蚂蚁活动数据，于2016-2018年间在日本冲绳岛利用海陆空马尔塞（Sea, Land, and Air Malaise, SLAM）诱捕器采集，并通过Zenodo存档中提供的代码进行处理（数据链接与参考文献详见README文件与论文）。其余数据集分别来自日本气象厅（Japan Meteorological Agency, JMA）、采样站点的原位实测气候变量数据，以及本团队开发的冲绳岛土地覆盖数据。本分析所用的数据集已随上传数据一并提供（其中日本气象厅与土地覆盖数据文件以CC-By 4许可协议发布于Zenodo补充材料中），所有分析代码则收录于单独存档于Zenodo的R软件包内。

## 注意事项
所有数据集（来自Dryad与Zenodo）需在运行任何代码前，放置于R分析包主目录下名为`/data`的单一文件夹中。有关数据与代码的更多细节，请参阅README文件。