Aims: The soil ecosystem includes a lot of animals with representatives from almost all major taxa of terrestrial animals and may stand for one quarter of all currently described biodiversity. Nevertheless, biodiversity loss of soil animals has become a serious problem for agricultural ecosystems globally, especially in China. Though many solutions have been proposed, this problem has not been effectively tackled. Constructing permanent plots and monitoring them long-term has been regarded as an important and effective method for solving the challenge of soil animal biodiversity loss. However, we still know little about the implementation protocol of scientific investigation and monitoring of a permanent plot of agricultural soil animals, until now.
Methods: We propose the implementation protocol for scientific investigation and monitoring of permanent plots of agricultural soil animals in this study. The plot establishment and field investigation design are conducted according to the field protocol of the 50-ha Forest Dynamics Plot on Barro Colorado Island (BCI), Panama. The field investigation and long-term monitoring are carried out according to prior research of forest and farmland utilizing large permanent plots of soil animal in China.
Results: First, we must confirm which scientific questions need to be solved and decide the basic principles to be observed for scientific investigation and monitoring in permanent plots of agricultural soil animals. Eighteen scientific questions have been proposed from a basic theory and practical application standpoint, and four basic principles have been proposed: integrating the needs and ideas of scientific research and agricultural practice, scientific setting and selecting monitoring indices, concerning spatio-temporal heterogeneity and detection probability of monitoring indices, and emphasizing the effects of agricultural productions and human activities. Second, we need to standardize the terminology for long-term investigation and monitoring, such as site, plot, square, sample and specimen. Sites and plots should be selected according to research objectives and study area, and priority should be given to sites that are representative of typical agricultural activities and regional climatic characteristics. Then, the large permanent plot of agricultural soil animal can be established in terms of BCI 50-ha field protocols. Third, focusing on soil animal biodiversity and its effects on agricultural ecosystem health and function, we need to carry out long-term monitoring for four-class and twenty-seven-item scientific indices. Moreover, the field investigation and laboratory experiment should be performed based on a unified and standardized workflow. For field investigation, the working processes include drawing detailed sampling point map, training all investigators, looking for and locating the permanent plot of agricultural soil animals in the field using GPS or other instruments, labeling the sampling points in the permanent plot, and collecting samples. For laboratory experiment, different extracting methods for soil animals should be used according to different taxa characteristics and research objectives. Finally, we need to identify, describe, and preserve specimens scientifically. Researching and developing database and management information system that encompass the characteristics of soil animal are recommended. This process will help with data invoking, checking, analyzing, and mining later.
Conclusion: This study systematically puts forward the implementation protocol of scientific investigation and long-term monitoring of permanent plots of agricultural soil animals. The implementation protocol can be widely applied to almost agricultural ecosystems in China and can be used effectively to investigate and monitor all taxa of soil animals. The results of this study will promote standardized plot construction and network monitoring in China, and globally, as well as provide reliable long-term scientific data support for the assessment and protection of agricultural soil animals in China.