Measuring saproxylic beetle diversity in small and medium diameter dead wood: The "grab-and-go" method

Abstract

Abstract. Saproxylic organisms play a key role in a variety of forest ecosystem functions, which result in an increase in overall fo rest productivity and biodiversity. At present, dead wood is frequently removed from exploited forests. Estimating the effect of current forest management on biodiversity, and what gain in biodiversity would result from implementing restoration programs, requires the use of standardized sampling protocols. These protocols need to be suitable for use in different sampling areas and cost effective. In this paper, we developed, tested, and optimized a method for sampling saproxylic insects during a single visit to a sample site (i.e., the "grab-and-go" method). In the spring of 2011, we collected samples of downed decaying small and medium diameter wood debris in two Italian beech forests: Sega di Ala (Alps) and Vallombrosa (Apennines). We used ex situ emergence traps in the laboratory to collect the beetles emerging from the wood sampled. At both sites, the minimum number of wood samples that resulted in a satisfactory description of the saproxylic beetle assemblage was 20. Wood moisture, mean diameter, and geographical location were significantly associated with the beetle assemblages. We discuss the implications of using the "grab-and-go" method in large-scale forest monitoring programs. In this context, we recommend collecting at each site twenty 50 cm-long samples of wood lying on top of the litter, with a diameter of 12 ± 2 cm, cortex cover < 50%, and at Hunter's stage of decay class 2.

Heritage Trees as an Important Sanctuary for Saproxylic Beetles in the Central European Landscape: A Case Study from Litovelské Pomoraví, Czech Republic

“…This is consistent with the findings of [25], who confirmed that bulky standing oaks are more valuable than thinner trees or even lying trunks. Some studies have also confirmed that the number of species increases with the dimensions of deadwood [73,74], and large specimens also host large species of beetles [75]. As the trunk diameter increases, the tree can offer a more diverse mosaic of microhabitats, such as large cavities or various stages of wood decomposition.…”

Italian account for Stephanopachys linearis (Kugelann, 1792), a species listed in Annex II of the Habitats Directive (Coleoptera: Bostrichidae)

“…All of these factors combined have probably allowed the local survival of the species, but this needs to be confirmed by an adequate field survey using the methods (direct collecting, light traps, intercept traps, ex situ emergence traps) usually adopted in the monitoring of the closely related S. substriatus and other saproxylic Bostrichidae (cf. Mairhuber & Paill 2005;Paill 2005;Brustel et al 2013;Trizzino et al 2013;Redolfi De Zan et al 2014;Macagno et al 2015;Mifsud & Nardi 2016;Nardi et al 2016). …”

Saproxylic insects and fungi in deciduous forests along a rural–urban gradient

“…Macagno et al. (2015) showed that the size of a bundle can influence the colonization rate of saproxylic species. We therefore determined the volume of each bundle by measuring the diameter and length of the six branches.…”