Optimal Inventorying and Monitoring of Taxon, Phylogenetic and Functional Diversity

Abstract

Abstract1. Inventorying requires comprehensive sampling, while monitoring should build on it and focus on as few components as possible to detect changes in time or space. To sample or acquire information for both purposes can therefore be viewed as different processes, herewith called α-sampling and β-sampling. Biodiversity covers species, their genetic diversity and the way they interact in communities and ecosystems. Quantifying these aspects leads to the need to study taxon (TD), phylogenetic (PD) and functional diversity (FD). Here we propose and test a method for the optimization of sampling protocols to inventorying and monitoring TD, PD and FD for a wide range of taxa.2. We used spiders as a case-study, although the same optimization procedure could be applied to any taxon requiring a combination of sampling methods. Spiders were sampled in multiple sites in the Iberian Peninsula. PD and FD were measured as the sum of the length of branches on a phylogenetic or functional tree. To reach the optimal combination of methods for inventory, we followed an iterative procedure optimizing the accumulation curve of diversity values. Optimal monitoring in space or time required minimizing the difference between sampled and true β-diversity. We used a framework that disentangles species replacement and richness differences contributions to overall β-diversity.3. For α-diversity, the optimal combination of 24 samples for TD, PD and FD allowed sampling more than 50% of real diversity. For β-diversity, the optimal combination of six samples for all measures allowed reaching a bias (difference between sampled and true diversity) below 0.08.4. The widespread use of similar sampling protocols worldwide and regular repetition in time can have a major impact on the scope and usefulness of global monitoring projects. In addition, the comparable sampling of biodiversity in space and/or time allows reusing of data collected for specific purposes, potentiating a synergistic effect among different projects. This makes data useful much beyond their initial plan. We strongly advocate the optimization, standardization and widespread adoption of sampling protocols for all taxa at a global level, for both inventory and monitoring of all levels of biodiversity: taxon, phylogenetic and functional.