Publication describes responses of reptiles and amphibians to harvests of logging residues

With increased interest in using wood for energy, questions have arisen about the long-term sustainability of woody biomass harvests. Responses by reptiles and amphibians to harvests of logging residues are of particular interest because many of these species use downed wood to help regulate body temperature, to stay moist, and as a location for nesting and feeding.

Because of concerns about sustainability, states and environmental groups have developed biomass harvesting guidelines. However, the body of scientific information addressing how much woody biomass is retained on harvested sites and biological community responses is limited.

A recent paper in Ecological Applications presents results from a study that investigated reptile and amphibian community responses to harvest of logging residues in intensively managed, loblolly pine forests. The paper was authored by Sarah Fritts, Christopher Moorman, Steven Grodsky, and Dennis Hazel of North Carolina State University; Jessica Homyack of Weyerhaeuser; and Chris Farrell and Steven Castleberry of the University of Georgia. NCASI and several of its member companies also collaborated in the study.

The authors report few consistent community or population responses to woody biomass harvest in intensively managed loblolly pine forests in the southeastern Coastal Plain. The abstract for the paper follows.

“Forests are a major supplier of renewable energy; however, gleaning logging residues for use as woody biomass feedstock could negatively alter habitat for species dependent on downed wood. Biomass Harvesting Guidelines (BHGs) recommend retaining a portion of woody biomass on the forest floor following harvest. Despite BHGs being developed to help ensure ecological sustainability, their contribution to biodiversity has not been evaluated experimentally at operational scales. We compared herpetofauanal evenness, diversity, and richness and abundance of Anaxyrus terrestris and Gastrophryne carolinensis among six treatments that varied in volume and spatial arrangement of woody biomass retained after clearcutting loblolly pine (Pinus taeda) plantations in North Carolina, USA (n = 4), 2011–2014 and Georgia (n = 4), USA 2011–2013. Treatments were: (1) biomass harvest with no BHGs, (2) 15% retention with biomass clustered, (3) 15% retention with biomass dispersed, (4) 30% retention with biomass clustered, (5) 30% retention with biomass dispersed, and (6) no biomass harvest. We captured individuals with drift fence arrays and compared evenness, diversity, and richness metrics among treatments with repeated-measure, linear mixed-effects models. We determined predictors of A. terrestris and G. carolinensis abundances using a priori candidate N-mixture models with woody biomass volume, vegetation structure, and groundcover composition as covariates. We had 206 captures of 25 reptile species and 8710 captures of 17 amphibian species during 53 690 trap nights. Herpetofauna diversity, evenness, and richness were similar among treatments. A. terrestris abundance was negatively related to volume of retained woody biomass in treatment units in North Carolina in 2013. G. carolinensis abundance was positively related with volume of retained woody debris in treatment units in Georgia in 2012. Other relationships between A. terrestris and G. carolinensis abundances and habitat metrics were weak or absent. The lack of consistent community or population responses suggests the addition of a woody biomass harvest to a clearcut in pine plantations does not impact herpetofauna use of Coastal Plain loblolly plantations in the southeastern United States. We recommend additional research to examine relationships between woody biomass harvesting and rarer species or amphibians with high desiccation risk, particularly in other regions and harvesting systems.”

  

Reference 

Fritts, S., C. Moorman, S. Grodsky, D. Hazel, J. Homyack, C. Farrell, and S. Castleberry. 2016. Do biomass harvesting guidelines influence herpetofauna following harvests of logging residues for renewable energy? Ecological Applications 26: 926–939. http://dx.doi.org/10.1890/14-2078