Stream Buffers in Managed Forests
Rapidly expanding human populations and conversion of forest to agriculture and urban development has increased importance of managed forests as wildlife habitat and providers of ecosystem services. As such, it is becoming more and more important to understand how timber production can be balanced with maintenance of local and regional biodiversity and ecosystem integrity. Streamside management zones (SMZs), buffers of mature forest maintained along streams, are a primary tool for enhancing biodiversity in managed forest landscapes. Although SMZs were designed primarily to protect water quality and stream microhabitat, they also provide critical upland habitat for stream-associated species and may serve as refugia for terrestrial species during intensive forestry operations in the surrounding landscape.
Amphibians are gaining recognition as important contributors to biodiversity of temperate and tropical forests and important components of many food webs. Despite their prevalence and diversity in forest ecosystems, amphibians are highly sensitive to a variety of anthropogenic activities and are considered excellent indicators of overall ecosystem health. Although a number of recent studies have evaluated responses of fully terrestrial or pond-breeding amphibians to forest management, fewer studies have focused on stream-associated species or evaluated how characteristics of SMZs (i.e., buffer width) or the surrounding landscape (e.g., stand composition, age, etc.) influence their effectiveness for conserving these amphibian populations. Moreover, it has become clear that amphibian species respond differently to forest management and that impacts can vary regionally and with the specifics of forestry techniques being applied. Even less is known about use of SMZs by semi-aquatic and terrestrial reptiles or how forestry best management practices influence reptile biodiversity in general.
We are conducting local- and landscape-scale field studies to assess responses of stream-associated amphibians and reptiles to SMZ, local, and landscape variables within managed forests in the Ouachita Mountains ecoregion of Arkansas. This biodiversity hotspot is home to a diverse array of species, including several endemic salamanders. At the landscape scale, we are conducting repeated low-intensity surveys across >100 headwater stream sites and using multispecies occupancy and binomial mixture modeling approaches to assess relationships between SMZ, surrounding stand, local habitat, and landscape variables and occupancy, species richness, and abundance of stream salamanders. At the local scale, we are using intensive capture-mark-recapture (CMR) of Ouachita Dusky Salamanders (Desmognathus brimleyorum) under a before-after-control-impact (BACI) design at a small number of focal streams to assess demographic responses of salamanders to timber harvest and infer mechanisms potentially driving shifts in abundance and occupancy. Our results will help guide development of forestry best management practices that improve conservation of amphibians and reptiles in managed forests.
5,000th Dusky Salamander Capture
Assess relationships between SMZ, surrounding forest stand, local and landscape characteristics on salamander occupancy and abundance
Assess relationships between SMZ, surrounding forest stand, local and landscape characteristics on herpetofaunal species richness and examine differential responses among guilds (i.e., salamanders, anurans, reptiles).
Use intensive CMR to evaluate demographic responses (survival, growth, movement) of D. brimleyoreum to timber harvesting and better understand population biology of stream salamanders in managed forests.
Guzy†, J.C., K.H. Halloran†, J. Homyack, J. Thornton-Frost, and J.D. Willson. In press. Differential responses of amphibian and reptile assemblages to size of riparian buffers within managed forests. Ecological Applications.
Guzy†, J., K. Halloran†, J. Homyack, and J.D. Willson. 2019. Influence of riparian buffers and habitat characteristics on salamander assemblages in headwater streams within managed forests. Forest Ecology and Management 432: 868-883.
Jackie Guzy, Kelly Halloran
Partners & Funding Sources:
National Council for Air and Stream Improvement (NCASI)
Arkansas Science and Technology Authority
University of Arkansas