The GEMMA (Geo-EnvironMental multivariate analysis) toolbox: A user-friendly software for multivariate analysis

Abstract

Understanding the complex past and present environmental systems requires methodologies capable of analyzing large multi-parameter datasets. The intricate interrelationships within these heterogeneous data would not be effectively detectable using simply bivariate approaches (single parameters versus time/sequence) data series. The mono- or bivariate approaches often fall short, leading to over/underestimation of processes simultaneously affecting the environment. The Geo-EnvironMental Multivariate Analysis (GEMMA) toolbox addresses these challenges, offering a user-friendly software for multiparametric analyses of large and diverse datasets. In the context of increasing dataset complexity, the GEMMA toolbox employs advanced multivariate statistical methods to transcend traditional univariate analyses. It moves beyond compartmentalizing environmental systems, allowing for the analysis of diverse interrelations by setting an efficiency balance between simplicity and comprehensiveness. The GEMMA toolbox uses the programming language R and features a graphical user interface (GUI) to provide a user-friendly tool without requiring advanced programming skills. It allows to perform collinearity analysis (COA), cluster analysis (CLA), principal component analysis (PCA), detrended correspondence analysis (DCA), redundancy analysis (RDA), and integrates statistical analysis with time series (also from geological stratigraphic succession). At every step, the PCA, the DCA, and the RDA analysis are validated through Monte Carlo permutation tests, and results are automatically exported. Source-code is freely available (https://github.com/NewGeoProjects/GEMMA_Toolbox) to allow advanced R users to custom and further develop the software according to the open-source principles (https://opensource.com/open-source-way). Two case studies illustrate the flexibility and efficiency of this software in investigating datasets that differ greatly in data source and research purpose. The first explores the Miocene-Pliocene transition that occurred ∼5.33 million years ago in the Mediterranean Sea, tracking the environmental change at the end of the Messinian salinity crisis through alkenones molecular fossils record. The second case study investigates landslides induced by intense rainfall in north-western Italy, aiming to explore the impact of morphometric and lithological factors on landslide susceptibility.

The GEMMA toolbox is software designed to perform advanced multivariate statistical analyses on environmental datasets. It integrates data analysis algorithms, statistical validations methods, and dynamic workflow procedures into an easy-to-use GUI, proving GEMMA toolbox as an effective and flexible software solution for research.