Event Title

Estimating Species Loss Caused by Reductions in Coarse Woody Debris in Eastern Boreal Mixedwood Stands

Event Website

http://www.nafew2009.org/

Start Date

25-6-2009 10:50 AM

End Date

25-6-2009 11:11 AM

Description

In eastern boreal forests and elsewhere, use of residual forest biomass for bioenergy has been proposed and in some cases mandated. While advocated as ‘green’ energy, the long-term consequences of biomass harvesting on forest productivity and biodiversity are the subject of intensive research. One likely consequence of biomass harvesting is the reduction of residual coarse woody material (CWM) throughout forest stands. Saproxylic organisms, which require deadwood as either a habitat or resource, will likely be affected by these reductions. In this context, it is necessary to have a means to estimate the overall effect of reductions in CWM on species richness in order to develop ecologically relevant standards for biomass harvesting and to assess the feasibility of biomass harvesting in perspectives of sustainable forest management. Here we demonstrate an approach to estimating species loss as a function of reduced volumes using incidence based rarefaction. We used saproxylic diptera (flies) collected from in situ emergence cages placed on aspen and spruce CWM from a variety of decompositional stages in eastern boreal mixedwood forests as an example of this approach. We extrapolated incidence-based rarefaction curves based on 216 species and morph-species to observed CWM volumes in our study sites. These curves are then used to estimate species loss under different levels of biomass harvest. Two factors, species turnover among individual downed logs (inter-log variability) and the variability of species along the length of downed logs (intra-log variability) emerged as important factors in our approach. Intra-log variability was estimated empirically from subsequent sampling of log sections taken along the length of downed aspen and spruce logs. This approach can be easily adapted to other biodiversity studies and regions. It also provides a means to rapidly evaluate impacts of biomass harvesting that can be used in conjunction with empirical studies that manipulate CWM.

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Jun 25th, 10:50 AM Jun 25th, 11:11 AM

Estimating Species Loss Caused by Reductions in Coarse Woody Debris in Eastern Boreal Mixedwood Stands

In eastern boreal forests and elsewhere, use of residual forest biomass for bioenergy has been proposed and in some cases mandated. While advocated as ‘green’ energy, the long-term consequences of biomass harvesting on forest productivity and biodiversity are the subject of intensive research. One likely consequence of biomass harvesting is the reduction of residual coarse woody material (CWM) throughout forest stands. Saproxylic organisms, which require deadwood as either a habitat or resource, will likely be affected by these reductions. In this context, it is necessary to have a means to estimate the overall effect of reductions in CWM on species richness in order to develop ecologically relevant standards for biomass harvesting and to assess the feasibility of biomass harvesting in perspectives of sustainable forest management. Here we demonstrate an approach to estimating species loss as a function of reduced volumes using incidence based rarefaction. We used saproxylic diptera (flies) collected from in situ emergence cages placed on aspen and spruce CWM from a variety of decompositional stages in eastern boreal mixedwood forests as an example of this approach. We extrapolated incidence-based rarefaction curves based on 216 species and morph-species to observed CWM volumes in our study sites. These curves are then used to estimate species loss under different levels of biomass harvest. Two factors, species turnover among individual downed logs (inter-log variability) and the variability of species along the length of downed logs (intra-log variability) emerged as important factors in our approach. Intra-log variability was estimated empirically from subsequent sampling of log sections taken along the length of downed aspen and spruce logs. This approach can be easily adapted to other biodiversity studies and regions. It also provides a means to rapidly evaluate impacts of biomass harvesting that can be used in conjunction with empirical studies that manipulate CWM.

http://digitalcommons.usu.edu/nafecology/sessions/forest_detritus/3