Ex situ experiments with Rhizophora mangle: what is the ideal sample and plot size?

Sample and plot size are two pertinent questions in experiments with Rhizophora mangle L. propagules that this study aimed to address. Our analysis was performed with 1,724 propagules collected in six different years in the same mangrove. Individual fresh mass (g), length (cm) and apical, median, and basal diameter (mm) were recorded for each propagule. After descriptive statistics, associated with linear correlation analyses and normality tests, sample and sizing methodologies were defined. For non-experimental designs with R. mangle propagules, we used interval bootstrapping to determine the required propagule amount, providing an abacus and equations for decision-makers to dimension their samples according to errors tolerated around means, for example employing a random collection sample with coefficient of variation of 25% and selection of 10% error, 25 propagules are needed. In designed experiments, plot size was defined as the number of propagules per experimental unit based on the objective. The Hatheway method was used to determine the appropriate number per plot for both fully randomized and randomized block designs. Our results provide a clear ideal range: for a common experimental setup (e.g., 5 treatments, 5 replications and 15% precision), the suitable plot size is 29 propagules per plot for a fully randomized and 30 for a randomized design. The study provides practical guidance for experimental planning in restoration and ecology studies. The developed methodology underscores the importance of a rigorous statistical approach in ensuring replicability and validity of ex situ studies with R. mangle propagules. This study establishes sample and plot sizes for Rhizophora mangle ex situ experiments, highlighting statistical precision, morphological variability, and climate influences to improve experimental planning and ensure reliable, replicable ecological research outcomes.