Logs and stumps in clearcuts support similar saproxylic beetle diversity: implications for bioenergy harvest

Abstract

Stumps from clear cuts are increasingly used for bioenergy. Extracting this wood will reduce the habitat available for saproxylic (wood-living) organisms. As little is known about the species assemblages that will be affected, we investigated the diversity of saproxylic beetles in stumps on clear-felled sites and as a reference, we compared it with the diversity in downed logs. Stumps and logs of aspen (Populus tremula L.), birch (Betula pubescens Ehrh. and B. verrucosa Ehrh.[syn. B. pendula Roth]), spruce (Picea abies (L.) Karst.) and pine (Pinus sylvestris L.) were examined in clear cuts of two different ages: one summer old and 4-5 years old. The beetles were sampled by sieving bark (0.25 m 2 ) peeled from the wood. The samples were taken in pairs of one log and one stump situated close together and of the same tree species, age since death and diameter. In total 3348 saproxylic beetles belonging to 124 species were found in 176 samples. The stumps had a similar number of species to the logs both as measured per sample and as an accumulated number. Exceptions were 4-5 years old wood of birch and pine where the number was significantly higher in the stumps. The number of red-listed species was also similar between stumps and logs. Species composition was more different between the stumps and logs of conifers than of deciduous trees. We conclude that clear-felled stumps have a diverse saproxylic insect fauna. This has to be taken into account if large scale extraction of logging stumps is implemented.

Proportions of saproxylic beetle populations that utilise clear-cut stumps in a boreal landscape – Biodiversity implications for stump harvest

“…There are several other examples of species that live on 'trivial' deadwood substrates that are confined to certain deadwood-rich sites in spite of there being suitable types of deadwood in almost every forest (Jonsell and Nordlander, 2002;Rubene et al, 2014). Moreover, species that are presently red-listed do occur in clear-cut stumps (Hjältén et al, 2010;Jonsell and Hansson, 2011). Some of these are also favoured by sun-exposure (Lindhe and Lindelöw, 2004), and as such they are highly likely to be sensitive to stump extraction.…”

“…http://dx.doi.org/10.1016/j.foreco.2014.08.042 0378-1127/Ó 2014 Elsevier B.V. All rights reserved. stems of dead trees (Hjältén et al, 2010;Jonsell and Hansson, 2011). The potential effect of stump harvest on population sizes will therefore depend on the proportion of populations that are recruited from stumps compared to all other kinds of CWD in the landscape.…”

Effect of stump size and timing of stump harvesting on ground disturbance and root breakage diameter

“…A long delay in stump harvest would also mean that the stumps have been colonised by insects and fungi before they are harvested, thus acting as traps for some species. One summer old stumps have, on average, been colonised by 3.1 different insect species (Jonsell and Hansson 2011). It therefore seems that the only way to improve these aspects is to change/develop the technology used for stump harvesting.…”

Are stumps important for the conservation of saproxylic beetles in managed forests? – Insights from a comparison of assemblages on logs and stumps in oak‐dominated forests and pine plantations

“…logs, standing dead trees) and most of those concern Norway spruce (Abrahamsson & Lindbladh, 2006; Hedgren, 2007; Hjältén et al. , 2010) except Jonsell and Hansson (2011) who compared logs and stumps of pine, spruce, birch and aspen.…”