Relative Efficiency of Pitfall Trapping vs. Nocturnal Hand Collecting in Assessing Soil-Dwelling Spider Diversity along A Structural Gradient of Neotropical Habitats

Kaïna Privet,Jérôme Orivel,Julien Pétillon,Claire Fortunel,Quentin Martinez,Axel Cerdan,Vincent Vedel,Christopher Baraloto

doi:10.3390/d12020081

Abstract

Assessing spider diversity remains a great challenge, especially in tropical habitats where dozens of species can locally co-occur. Pitfall trapping is one of the most widely used techniques to collect spiders, but it suffers from several biases, and its accuracy likely varies with habitat complexity. In this study, we compared the efficiency of passive pitfall trapping versus active nocturnal hand collecting (NHC) to capture low understory-dwelling spider taxonomical (morpho-species) and functional (hunting guilds) diversity along a structural gradient of habitats in French Guiana. We focused on four habitats describing a structural gradient: garden to the orchard to the forest edge to the undisturbed forest. Overall, estimated morpho-species richness and composition did not vary consistently between habitats, but abundances of ground-hunting spiders decreased significantly with increasing habitat complexity. We found habitat-dependence differences in taxonomic diversity between sampling strategies: NHC revealed higher diversity in the orchard, whereas pitfalls resulted in higher diversity in the forest. Species turnover resulted in high dissimilarity in species composition between habitats using either method. This study shows how pitfall trapping is influenced by habitat structure, rendering this sampling method incomplete for complex, tropical environments. However, pitfall traps remain a valuable component of inventories because they sample distinct assemblage of spiders.

Highlights

Spiders constitute a mega-diverse taxon, with more than 48,000 species described to date [1]and still many new species found every year
To compare the efficiency low understory‐dwelling spider sampling methods along structural gradient of Neotropical habitats, we focused on four different land‐use types along the orchard after slash and burn, (iii) forest edge, and (iv) undisturbed tropical forest
Similar total numbers of individuals were collected by both methods, 174 by pitfall traps and 181 by Nocturnal Hand Collecting (NHC)

Summary

Introduction

Spiders constitute a mega-diverse taxon, with more than 48,000 species described to date [1]and still many new species found every year. To get reliable estimates of local spider diversity, ecologists and conservationists need a robust sampling protocol, i.e., standardized (repeatable in space and time, without introducing bias), and optimized (with a maximized ratio of sampling effort by collected diversity) for realistic sampling given time and resource constraints [2,3,4]. To achieve such a standardized and optimized sampling protocol, the selection of cost-effective complementary methods is a critical issue [5]. The number of collecting methods should be limited to minimize the complexity of a sampling protocol and to maximize its repeatability

Objectives

Results

Conclusion