Conservation of terrestrial and aquatic species through management of riparian areas within private, working forests

Symposium
ROOM: RSCC, D5
SESSION NUMBER: 8247
 
Private working forests are a dominant land use type in the U.S., encompassing approximately 360 million ha. Throughout these forests are streamside (SMZs) and riparian management zones (RMZs) where forested strips are maintained along waterways such as intermittent and perennial streams. Within private working forests, these management zones act as buffers between areas managed for timber production and sensitive aquatic ecosystems. Although these buffers are designed to protect water quality by filtering and trapping nonpoint source pollutants, including suspended sediments, nutrients, and other chemicals from reaching surface water, SMZs and RMZs also contribute to fish and wildlife habitat, serve as travel corridors, and provide habitat features that may not be present in the surrounding landscape. In this symposium, presenters will provide diverse perspectives on opportunities among private landowners to conserve terrestrial and aquatic species through management of riparian areas within private working forests. We will feature recent research findings on the value, issues, and opportunities of conserving biodiversity within SMZs and RMZs.

1:10PM Form, Function, and Future of Riparian Buffers on Private Forestlands
  Ashley Coble
Retaining forested riparian buffers, often termed streamside management zones or riparian management areas, is one of the most widely implemented forestry best management practices (BMPs). Riparian buffers are strips of forestland adjacent to streams where management practices are modified or restricted to reduce transport of sediment, nutrients, or forest chemicals to surface waters while also providing other ecosystem functions such as shade, corridors, and food sources to a wide diversity of aquatic and terrestrial species. Although guidelines and regulations vary greatly by state, riparian buffers are typically designed to offer a greater degree of protection when fish or at-risk species are present. Despite the intent to protect these biota, state regulatory agencies and private forest landowner effectiveness monitoring remains heavily focused on utilizing water quality and habitat monitoring as a proxy for the protection of biota. Furthermore, forestry certification programs, through their third-party audit process, seek to maintain biodiversity, but research that incorporates effectiveness testing for biodiversity and at-risk species associated with riparian forests is lacking. For example, in private working forests, as riparian forests continue to age and provide structurally complex vegetation, it remains unclear to what degree that riparian corridors may be used by semi-aquatic and terrestrial species as a refuge or terrestrial corridor. It also remains unclear which, if any, management prescriptions might be developed to enhance the quality of riparian forests for conservation. Currently, research programs in the Pacific Northwest and the southeastern U.S. are underway to address this knowledge gap. In this presentation, we review history and development of riparian forest BMPs, current research needs, and discuss the increasing expectation that riparian forests must be managed to meet multiple ecosystem functions.
1:30PM Significant Green Tree Retention in the Southern United States Contributes to Biodiversity
  Steve Demarais
Efficient production of products is primary on private, working pine forests (WPF) of the southern United States, biodiversity conservation is integrated into management plans. In this region, WPF management units are usually harvested commercially by clearcutting with green tree retention. Quantifying green tree retention and the associated bird community improves our understanding of effects on biodiversity. We classified land cover on 1,187 management units (“MUs”; totaling 51245.7 ha), defined as contiguous, forested areas containing one or more WPF patches, harvested and established as a cohort, plus associated green tree retention areas. Green tree retention cover averaged 18.6% (± 14.2%) of land cover and consisted mostly of streamside management zones (SMZs; mean 14.0 % ± 13.1% of land cover) buffering perennial and intermittent streams, and stringers (mean 3.4% ± 4.3% of land cover) buffering ephemeral streams. To understand relationships between retained structures and avian communities, we compared species diversity of breeding bird species and avian guilds in three-year-old regenerating clear cuts (RCCs) and their associated SMZs and stringers on 60 PWF management units. We detected 5617 individuals of 60 species; 8 species were considered common birds in steep decline. SMZs and stringers comprised an average of 17.4% of management unit area, but 27% of species were detected solely in retention cover types. There was an 84% species overlap between SMZs and stringers. Stringers augmented SMZ contributions to site avian diversity by hosting forest specialist guilds. Diversity of early-successional specialists was similar between stringers and RCCs, suggesting stringers enhanced RCC contributions to site bird diversity. Furthermore, we detected several species only within stringers. Green tree retention land cover represented a substantial proportion of the PWF landscape and contributed to avian diversity disproportionately to its area, and in particular, stringer cover appeared to enhance the value to avifaunal species diversity of PWFs.
1:50PM Small Mammal Species Richness within Riparian Associated Retention Patches
  Sean Sultaire
Green tree retention is used to improve the conservation value of production forests in the Pacific Northwest, USA. Retention requirements for harvest units are often met by aggregating retention trees adjacent to riparian buffers. Although this practice is operationally efficient, leaving all retention along riparian buffers may not increase conservation benefits beyond those provided by riparian areas themselves. We tested the effects of retention tree pattern and location on small mammal species richness in western Oregon and southwest Washington. Our experimental design consisted of five retention treatments, each replicated in 10 blocks. Treatments ranged from completely aggregated and connected to riparian buffers, to dispersed in smaller upland patches. Three of the five retention treatments contained riparian retention, and two contained both upland and riparian associated retention. We placed Sherman and Tomahawk live-traps within and adjacent to retention patches for two summers and estimated small mammal species richness for each location and year. Using linear mixed effects models with the riparian aggregated treatment as the control, we found that small mammal species richness was highest in the control retention treatment, but only for the first year of sampling. We found a significant year by treatment interaction, driven by losses in riparian aggregated species richness and more consistent species richness in the other treatments between years. Aggregating treatments into whether they contained riparian associated retention or not likewise indicated increased species richness in riparian retention. Patterns of community dissimilarity indicated low species turnover between stands of different treatment types in both years. Our results suggest that riparian associated retention supports increased mammal species richness compared to upland retention, aggregated riparian supports the highest richness, and upland patches do not support unique species. However, the increased species richness observed in riparian retention may be short term and not persist into the next rotation.
2:10PM Response of Stream-Associated Salamanders to Timber Harvest with Alternative Riparian Buffer Configurations
  Andrew J. Kroll
Headwater streams comprise the vast majority of stream miles in forests of the Pacific Northwest and provide important habitat for many stream-associated amphibian species. A substantial proportion of those headwater streams are owned and managed by private timber companies, who retain riparian buffers to protect amphibians and other important ecosystem functions during clearcut harvest. We monitored the density of stream-breeding amphibians in a replicated Before-After Control-Impact (BACI) experiment with alternative riparian buffer configurations (continuous buffers, patchy distribution of buffers, and clearcut throughout the riparian area) and unharvested reference basins. We estimated amphibian density using count data adjusted for variation in detection, and estimated the relative change in density for each buffer configuration between the pre- and post-harvest period, after controlling for temporal changes in the reference. In the eight years following harvest, we observed a consistent and substantial decline in larval coastal tailed frog (Ascaphus truei) density in all buffer configurations, regardless of the amount or arrangement of leave trees remaining in the riparian area. The greatest change in mean tailed frog density was -93% (95% credible interval (CI): ‑98%, ‑73%) in basins with a patchy distribution of buffers. However, there was no discernable difference in the change in mean larval density among buffer configurations. In basins with continuous and patchy distribution of buffers, we observed a -71% (CI: -82%, -52%) and -97% (CI: ‑99%, ‑86%) change in post-metamorphic tailed frog densities, respectively. We observed a -64% (CI: -86%, -10%) change in torrent salamander (Rhyacotriton spp.) density in basins with a patchy distribution of buffers. Finally, we did not observe a difference in the change in giant salamander (Dicamptodon spp.) density among basins. Continued monitoring is needed to validate whether our findings reflect longer-term trends.
2:30PM The Role of Thermal Refugia in the Persistence of Terrestrial Salamanders in Intensively Managed Forests
  Tiffany Garcia
Intensive forest management produces substantial amounts of wood biomass from harvesting, but little information is available on how large woody debris may provide thermal refugia for dispersal-limited organisms. We conducted a Before-After Control-Impact experiment over six years to evaluate responses of Oregon slender and Ensatina salamanders to stand-replacing forest harvest. We estimated changes in occupancy and abundance to a single operational treatment (clear-felling, replanting, herbicide application) and control units. We assessed the potential of downed wood as thermal refugia, predicting warmer ambient temperatures in harvested units but not internal downed wood temperatures. We predicted that Oregon slender salamanders, a species endemic to the Cascades in Oregon, USA, would respond negatively to forest harvest while Ensatina, a widespread species that occurs in a broad range of cover types, would not be associated with forest harvest. For Oregon slender salamanders, mean occupancy (90% CRI) was reduced an estimated 20% (0.80; 0.42-1.6) and mean abundance reduced 23% post-harvest (0.77; 0.46-1.3). For Ensatina, mean occupancy was reduced an estimated 83% (0.17; 0.07- 0.42) and mean abundance reduced 68% (0.32; 0.18-0.62) post-harvest. We have strong evidence of positive responses by both species to downed wood density, suggesting a refuge response. Ambient air temperatures were higher in harvest vs. control units, and while internal downed wood temperatures were also warmer in harvested units, relatively larger structures may provide sufficient thermal refugia. The association of both species with downed wood density highlights the importance of maintaining habitat complexity in intensive forest management. Further, comparing upland and riparian debris loads and management strategies across these habitat types will allow us to create a holistic picture of intensively managed forests.
2:50PM Refreshment Break
3:20PM Differential Responses of Amphibian and Reptile Assemblages to Size of Riparian Buffers within Managed Forest
  Jacquelyn Guzy
Streamside management zones (i.e., riparian buffers; SMZs) are commonly implemented within managed forests to protect water quality, but may also provide habitat for riparian-associated wildlife. Yet, little research has rigorously addressed the value of SMZs for wildlife, particularly cryptic species such as amphibians and reptiles. However, recent statistical advances have improved our ability to analyze large multi-species presence-absence datasets, accounting for low detection rates typical for some herpetofaunal species. Our study represents an extensive landscape-scale examination of herpetofaunal communities within SMZs using a multi-species occupancy approach. We conducted four replicate surveys at 102 headwater streams, spanning a gradient of SMZ widths and adjacent forest stand ages, within the Ouachita Mountains, Arkansas, USA. We used a hierarchical Bayesian community occupancy model to estimate species richness and species-specific occupancy responses to SMZ and overstory characteristics. We documented high richness (37 species) within SMZs. Across the herpetofaunal community, occupancy and species richness were consistently positively associated with SMZ width, with maximum predicted richness of 30 species occurring at sites with buffers extending 51 m on either side of the stream. However, we documented considerable variation among groups and among species within groups, underscoring the potential for different responses to forest management among taxa. Reptile predicted richness increased more rapidly up to SMZs of ~35 m, whereas maximum salamander predicted richness was not seen until a SMZ width of 55 m. Estimated salamander richness was highest within SMZs embedded in mature managed pine stands and was higher in SMZs comprised of a deciduous or mixed overstory versus a pine. Compared to salamanders, more anuran species showed high mean estimated occupancy (>75%) at narrower SMZs (<30 m). Collectively, our results indicate that SMZs surrounding small first-order streams in intensively managed forests not only protect water quality, but also can support diverse amphibian and reptile communities.
3:40PM Conservation of a Crayfish Species of Concern on a Managed Forest Landscape in Mississippi
  Darren A. Miller
In the eastern United States, voluntary forestry Best Management Practices (BMPs) are used to protect water quality during and after forest management activities such as site preparation, road building and maintenance, and forest harvest operations. Although voluntary, BMP implementation rates by private forest landowners often exceeds 90%, and BMPs are required by participants in forest certification programs. A critical component of BMPs are streamside management zones (SMZs), vegetated buffers along streams that are maintained on these privately-owned forest landscapes in perpetuity. Although past research has clearly demonstrated effectiveness of BMPs, and SMZs specifically, to protect water quality, the linkages between water quality and conservation of aquatic species within managed forest landscapes is not as clear. Therefore, we examined ecology of the Yalobusha rivulet crayfish (Hobbseus yalobushensis), a species of conservation concern known from only 6 localities in 3 northcentral Mississippi counties, where it occurs in intermittent streams within a landscape dominated by short rotation loblolly pine (Pinus taeda) stands. We sampled 56 sites within 24 reaches of 16 streams in Calhoun County, MS, during 2011-2013. We documented H. yalobushensis in 8 streams additional to previously known localities. We captured 2,225 individuals representing at least 3 age classes, with 81% of those being juveniles. We found that H. yalobushensis was negatively correlated with presence of predatory fish species and 3 other crayfish species. H. yalobushenis has persisted in a network of intermittent streams imbedded in an intensively managed forest landscape. This provides evidence that, in this location, BMPs are effective at maintaining conditions in intermittent streams for H. yalobushensis. Research is needed to further understand the role of BMPs in conserving other at-risk aquatic species within managed forest landscapes. This information is essential to understanding conservation value of such landscapes for conservation of aquatic species and systems.
4:00PM Using Existing Datasets to Investigate the Effects of BMP Compliance on the Presence or Persistence of at-Risk Aquatics
  Duncan Elkins
The southeastern United States is a global hotspot for temperate aquatic biodiversity, yet this biodiversity is significantly imperiled in many areas. The US Fish and Wildlife Service currently tracks almost 300 “at-risk” species of fish, amphibians, and freshwater invertebrates in the Southeast, a category that includes species that are not yet listed under the Endangered Species Act but that have been petitioned, are candidates, or have been proposed for ESA listing. This imperilment is due, in part, to extensive land cover changes in the region since European settlement. Land clearing began in the 1600s, continued with widespread deforestation, wetland drainage, and intensive land use for row crops such as cotton by 1920. The last century has been a period of forest regrowth, intensive agriculture, urban expansion, and landscape fragmentation. Freshwater systems seem to have been resilient to much of this disturbance, though some legacy effects are evident. Since the passage of the Clean Water Act in 1972, forestry Best Management Practices (BMPs) have been developed and implemented to reduce non-point source pollution effects resulting from forest management activities. In recent decades, BMP compliance has increased and approaches 100% in many areas. Researchers in the Georgia Cooperative Fish and Wildlife Unit and the University of Georgia River Basin Center have recently embarked on a spatial analysis and modelling effort to assess the effects of forestry BMP implementation on the presence and persistence of at-risk aquatic species in the Southeast. Staring with the state of Georgia, this project is using extensive datasets of species occurrence, assembled from sources such as museums and natural resource agencies, to develop models at several scales to estimate the effects of land cover, geography, and BMP implementation/compliance.
4:20PM Delimiting the Upper Fish Distribution Boundary in Forested Streams with Electrofishing and Environmental DNA
  Brooke Penaluna
Delimitation of geographic distribution of species have fundamental implications for biodiversity, species conservation, and decision–making. The distribution boundary at the upper extent of fish across North America receives extra attention because stream reaches with fish have more protections and wider riparian buffers than fishless reaches. We provide a description and analysis of the upper distribution of fish in forested streams in the Pacific Northwest with two management-relevant approaches of eDNA and electrofishing. Both approaches have the ability to identify the presence and absence of fish separating them from other approaches that can only identify presence. We compare and discuss approaches for identifying the upper extent of fish by comparing eDNA of Coastal Cutthroat Trout Oncorhynchus clarkii clarkii and sculpins to standard electrofishing data. Coastal Cutthroat Trout are the fish generally found the highest in their stream network across their native range in North America. However, there are some streams, especially coastal–origin streams, where sculpins Cottus spp. are the last fish. All sampling was conducted during springtime to coincide with the recognized sampling window for evaluating the end–of–fish boundary under Forest Practices Rules in each state. We predicted that eDNA would detect fish better than electrofishing across the study area because of its acknowledged strength for identifying the presence and absence of species in low abundance, as is the case for fishes near their upper distribution boundary. Some streams showed agreement between electrofishing and eDNA while others showed eDNA detecting fish further upstream than electrofishing. From this work, we will understand more about the end–of–fish boundary and operational limitations of eDNA to determine last fish.
4:40PM Temporal Variability in the Upper Extent of Fish Distributions in Headwater Streams in Southwest Washington
  Jason Walter
Washington forest practice rules require different protective measures on fish (Type-F) streams than non-fish (Type-N) streams during the application of forest management activities. Weyerhaeuser utilizes Protocol Electrofishing Surveys as a tool to assess the upstream extent of fish distribution and to identify water type breaks separating fish and non-fish stream segments. To address the potential for temporal variability in fish distribution surveys incorporate the extent of “habitat likely to be used by fish” when delineating the water type break. This determination of ‘potential fish habitat’ can be done more accurately with a better understanding of the temporal variability that exists in the location of the uppermost fish. From the population of sites where Weyerhaeuser conducted Protocol Electrofishing Surveys in 2015, 2016 and 2017, approximately 65 were resurveyed annually to assess temporal variability in the upstream extent of fish distribution. Where the location of the uppermost detected fish changed relative to the original survey, we measured the distance to the previous last fish point and recorded stream habitat characteristics associated with the new uppermost fish point. This study is ongoing, but preliminary results indicate minimal temporal variability in the upstream extent of fish distribution. For instance, results from the 69 streams resurveyed in 2016 show no change in the location of the uppermost fish in 33 of the 35 streams with a ‘lateral’ F/N break, and in 12 of the 34 streams with a ‘terminal’ F/N break. While temporal variability in the location of the uppermost fish was more common in ‘terminal’ than ‘lateral’ sites, changes in the location of the uppermost fish were within 100 feet of the original point in 70% of cases. Where variability did exist, movement was almost always incorporated into the extent of habitat likely to be used by fish identified in the original protocol survey.

 
Organizers: Daniel Greene, Darren Miller, Jessica Homyack, Ashley Coble, AJ Kroll, Duncan Elkins, Jake Verschuyl, Angie Larsen, Jennifer Bakke
 
Supported by: TWS Biological Diversity Working Group

Symposium
Location: Reno-Sparks CC Date: September 30, 2019 Time: 1:10 pm - 5:00 pm