J. For. 112(4):337–345 RESEARCH ARTICLE http://dx.doi.org/10.5849/jof.14-017 Copyright © 2014 Society of American Foresters wildlife management Family Richness and Biomass of Understory Invertebrates in Early and Late Successional Habitats of Northern New Hampshire Matthew K. Wilson, Winsor H. Lowe, and Keith H. Nislow In the northeastern United States, many vertebrate species rely on early successional forest habitats (ESHs). ESHs gional wildlife fauna of 338 species) that are may also support higher invertebrate diversity and abundance than late successional habitats (LSHs). We restricted to ESH and only 32 species (10%) assessed the differences in family-level richness and biomass of understory terrestrial invertebrates during the as not using ESH in combination with other Ͼ summer season in paired ESH (3–7 years since harvest) and LSH ( 50 years since last harvest) stands in the forest size classes. A common explanation northern hardwood forests of northern New Hampshire. Invertebrate family richness was 1.5 times greater in for the frequent use of ESH by vertebrates is ESH, with 35 families found only in ESH compared with 5 families found only in LSH. Invertebrate biomass was higher abundance of invertebrate prey rela- 3.2 times greater in ESH than in LSH. Our sampling methodology and time frame were limited, and taxonomic tive to surrounding forests (e.g., Chandler et resolution was relatively coarse. Nevertheless, our results suggest that including ESH stands in northeastern al. 2012). However, studies evaluating com- managed forest landscapes may help maintain high levels of invertebrate diversity and are consistent with the munity-level differences in invertebrate use of ESH by many insectivorous vertebrates. richness and biomass in ESH and late suc- cessional habitat (LSH) are rare (Loeb and Keywords: biodiversity, early successional forest habitat, forest management, New England, terrestrial O’Keefe 2011). Furthermore, although the invertebrates steady decline of ESH in the northeastern United States over recent decades has led to abitat heterogeneity is important maintained by natural disturbance processes special-status designations of plants and ver- for supporting plant and animal (windstorms, ice storms, fires, drought, and tebrates that rely on this habitat (DeGraaf diversity. In the northeastern insect and disease infestations) (Litvaitis and Yamasaki 2001), the implications of de- H creasing ESH for invertebrate taxa have re- United States, early successional habitat 2003a), but forest management is perhaps (ESH), characterized by abundant short- the most important single process for these ceived little consideration. statured woody vegetation, abundant and habitats (Lorimer 2001). ESH is critical to Several characteristics of ESH vegeta- diverse herbaceous vegetation, and a high many species of vertebrates in northeastern tion in northern hardwood forests suggest that productivity:biomass ratio, results from nat- forests, including birds, bats, and small invertebrate diversity and biomass should be ural and anthropogenic disturbances and mammals (King and Schlossberg 2014). De- greater in ESH than in LSH, including contributes heterogeneity to forested land- Graaf and Yamasaki (2001) listed 40 New higher floral diversity (Elliott et al. 2011), a scapes. ESH in this region is created and England wildlife species (12% of the re- higher productivity:biomass ratio (Horn Received February 7, 2014; accepted May 20, 2014; published online June 12, 2014. Affiliations: Matthew K. Wilson ([email protected]), University of Montana, Missoula, MT. Winsor H. Lowe ([email protected]), University of Montana. Keith H. Nislow ([email protected]), USDA Forest Service. Acknowledgments: We thank Kevin Evans (Dartmouth College) and Scott Rineer (Wagner Forest Management, Ltd.) for access to study sites, Ian Drew (US Fish and Wildlife Service), and Lorraine Turner (Dartmouth College) for hospitality in the study region, Erik Lokensgard and Jeff Ojala for field assistance, and Lisa Eby, Laurie Marczak, Don Bragg, Brice Hanberry, and three anonymous reviewers for helpful comments on this article. This study was funded by a grant from the Northeastern States Research Cooperative. This article uses metric units; the applicable conversion factors are: meters (m), 1 m ϭ 3.3 ft; hectares (ha): 1 ha ϭ 2.47 ac; millimeters (mm): 1 mm ϭ 0.039 in.; milligrams (mg): 1 mg ϭ 0.015 gram. Journal of Forestry • July 2014 337 1974), and higher nutrient content and re- nities, we tested whether these landscape- IDRISI (Taiga 2009). All study sites were duced secondary compounds (Ohgushi level variables were related to invertebrate between 582 and 683 m in elevation (Ta- 1992). This increase in plant diversity, nu- family richness and biomass in focal ESH ble 1). trient content, and palatability should ben- patches. By focusing at the family level, we The entire Dead Diamond drainage ex- efit invertebrate growth and reproduction sacrifice resolution of patterns of diversity at perienced heavy timber harvest in the late and improve invertebrate resistance to para- finer taxonomic levels (e.g., genus and spe- 1800s and early 1900s, and its headwater sites and disease. Because of the high floral cies). However, family-level data are often drainages have experienced various degrees abundance in ESH and the patchy nature of used to assess taxonomic diversity for use in of clearcut and selective harvest since the this habitat across the landscape, we expect management decisions (e.g., Adkins and 1930s (Kevin Evans, Dartmouth College that invertebrates that rely on this habitat Rieske 2013, Bennett and Gratton 2013), Woodlands Office, pers. comm., Apr. 17, will be winged and have greater dispersal and recent studies showed that such higher 2010). Within these watersheds, stand ages ability than invertebrates that rely on LSH levels of taxonomic resolution are often ranged from 0 to approximately 70 years (Brown 1984). However, to date, most stud- strongly correlated with species-level pat- old. LSH (Ͼ50 years old) was composed of ies comparing invertebrate richness and bio- terns (Kallimanis et al. 2012, Timms et al. mixed conifer and deciduous vegetation mass in ESH and LSH limit sampling to one 2013). Nevertheless, the taxonomic resolu- with a distinct overstory; ESH (3–7 years order or family (for review, see Lewinsohn et tion of this study, as well as its temporal and old) was composed of shrubs and short-stat- al. 2005). We are aware of no study compar- geographic constraints, may limit our scope ured deciduous trees. Tree species in the ing broader, community-level responses of of inference. LSH included red maple (Acer rubrum), invertebrates to ESH and LSH of the north- sugar maple (Acer saccharum), speckled alder eastern United States. Furthermore, com- Methods (Alnus rugosa), balsam fir (Abies balsamea), munity-level responses to ESH of inverte- paper birch (Betula papyrifera), yellow birch brates appear to vary by region, highlighting Study Area and Watershed (Betula alleghaniensis), spruce (Picea spp.), the importance of collecting region-specific Characteristics data (Lewinsohn et al. 2005). Understand- Study sites were located in 12 first- and and green ash (Fraxinus pennsylvanica). ESH ing broader invertebrate responses to ESH second-order watersheds of the Dead Dia- was dominated by wild raspberry (Rubus in northeastern forests is especially impor- mond River drainage of New Hampshire, spp.) and mapleleaf viburnum (Viburnum tant, given the declining trajectory of ESH USA. (Figure 1). ESH and LSH focal acerifolium). cover in the northeastern United States patches were paired within eight of these wa- Invertebrate Sampling (Trani et al. 2001). tersheds. The four remaining watersheds did We sampled invertebrates from ESH Our goal was to measure how inverte- not have patches of both ESH and LSH and LSH focal patches in the 12 study wa- brate family richness, community composi- large enough to meet the invertebrate sam- tersheds in July and August 2010. In water- tion, biomass, and abundance differ be- pling criteria. However, these watersheds sheds with both patch types, ESH and LSH tween ESH and LSH understories in the had sufficiently large patches of one habitat northern hardwood forests of northern New type (ESH in two watersheds and LSH in patches were separated from each other by a England. To meet this goal, we used colored two watersheds), so the sampling design re- minimum distance of 100 m. In each patch, pan traps to sample invertebrates in ESH mained balanced at the stand level. Water- five replicate arrays of three colored pan and LSH focal patches in 12 small water- sheds differed in their total percent coverage traps (white, yellow, and blue) were set out sheds in northern New Hampshire, USA, of ESH and focal patches of ESH differed at a height of 0.5 m aboveground (Leather during July and August 2010. We defined in size (Table 1). We measured both of these 2005). To minimize the influence of edge ESH as clearcut patches ranging from 3 to 7 characteristics from aerial photographs in effects on terrestrial invertebrate samples, all years old and LSH as intact northern hard- wood forest Ͼ50 years old. These categories are relative and are based on the predomi- Management and Policy Implications nant range of forest stages in managed land- Foresters are under increasing pressure to demonstrate, document, and communicate the broader scapes of northern New England, including the study area in northern New Hampshire ecological