PlotDEM: An Open and Reproducible Relocation Workflow for Quasi-Permanent Vegetation Plots in Mountain Areas

Aims: In this study, we present a novel workflow for the relocation of quasi-­ permanent vegetation plots during resurveys in topographically complex environments, such as mountain regions. Location: Western Italian Alps, Gran Paradiso National Park. Methods: This standardized workflow integrates historical plot site data and descriptions, digital elevation models (DEMs), and in-­ field expert knowledge to identify the most suitable sites for plot relocation, even when precise geographical coordinates are unavailable. The resulting methodology is fully reproducible, thanks to the application of an entirely open-­ source workflow. The performance of the relocation method was evaluated in terms of both precision and reproducibility among operators during the pre-­ fieldwork steps by means of generalized and linear mixed-­ effects models. In addition, by performing an ecological case study, the applicability of the workflow was demonstrated by quantifying pseudoturnover through comparison among four independ- ent plot replicas and with historical data from alpine grasslands. Results: The proposed workflow proved to be effective in supporting plot relocation, showing good reproducibility among op- erators. Moreover, it resulted in lower levels of pseudoturnover compared to those reported as acceptable in previous resurvey studies while substantially reducing the effort required for plot relocation in the field. Conclusions: This method has the potential to facilitate the execution of large resurvey campaigns by enabling the sampling of single plot replicas rather than multiple ones, as previously recommended. Nevertheless, we recommend identifying a subset of plots for conducting replicate surveys within the identified suitable area, in order to empirically estimate spatial pseudoturnover and further enhance the robustness of resurvey-­ based studies.