Draft terrestrial resources biological assessment
Natural History and Species Occurrence
Download 486.24 Kb.
|
- Navigate this page:
- 4.1 California / Nevada Vernal Pool Fairy Shrimp
- 4.1.1 Site Specific Biological Requirements and Project Context
- 4.1.2 Critical Habitat within the Action Area
- 4.1.3 Site Specific Limiting Factors for Recovery
4.0 Natural History and Species OccurrenceAs stated previously, there is one faunal species and six floral species reported that potentially occur within the action area. Consultation with USFWS’ Region Biologist confirmed the presence of suitable habitat for four species (VPFS, Cook’s lomatium, large-flowered woolly meadowfoam, and Southern Oregon buttercup) and the actual recorded occurrence of three species (VPFS, Cook’s lomatium and large-flowered woolly meadowfoam) within the project footprint (URS 2010c). Southern Oregon Buttercup is located outside the project footprint a considerable distance. Based upon the preliminary nature of the project design, it is not anticipated to be affected, either directly or indirectly, by project elements, and as such is not included in further discussions within this assessment. An account of species within the project footprint is presented below for review. 4.1 California / Nevada Vernal Pool Fairy ShrimpVernal pool fairy shrimp are listed as threatened under the federal ESA. Vernal pool fairy shrimp habitat is associated with mound-vernal pool wetland complexes, as found within both the action area generally and specifically within the project footprint. Within the action area, approximately 106 vernal pools of varying size have been identified (URS 2011a). As explained under Section 4.1.2, all vernal pool wetlands within the project footprint are considered suitable habitat. For the purposes of this project and other studies for quality and suitability (discussed below), these VPCs were grouped into 12 distinct AUs. These features incorporate the more finite geographic extent of habitat for vernal pool fairy shrimp, including both wetland and upland communities within each VPC. AUs were used as a geographic identifier for specific VPCs in the habitat conservation assessment. They are discussed below for purposes of simplicity. The USFWS has digitally mapped three separate areas of DCH within the action area. Two areas are mapped directly within the project footprint. Refer to section 4.1.2 for a more in-depth discussion regarding DCH within the project footprint. 4.1.1 Site Specific Biological Requirements and Project ContextVPFS life cycles are entirely dependent on the cyclical presence and absence of water in vernal pools. Eggs from the previous year hatch as rain begins to fall and vernal pools fill with water as early as mid-December. Vernal pool fairy shrimp feed on algae, bacteria, protozoa, rotifers and detritus before reproducing and dropping their eggs before the pools dry in early spring. Average age to maturity ranges from 18-41 days. Desiccated eggs rest in the dry bottoms of the vernal pools until rain falls again in the following winter (59 FR 48136). 4.1.2 Critical Habitat within the Action AreaTypically the majority of pools in any VPC are not inhabited by the species at any one time. Different pools within or between complexes may provide habitat for the fairy shrimp in alternative years, as climatic conditions vary. As the USFWS cannot quantify what proportion of each critical habitat unit may actually be occupied by vernal pool fairy shrimp, both unoccupied and occupied areas are considered essential to the conservation of the species and are included in areas designated as critical habitat (USFWS 2011). The Service has identified two PCEs necessary for conservation of the species: “Vernal pools, swales and other ephemeral wetland features of appropriate sizes and depths that typically become inundated during winter rains and hold water for sufficient lengths of time necessary to complete the life cycle”; and, “The geographic, topographic and edaphic features that support systems of hydrologically interconnected features within a matrix of surrounding uplands, when taken together, form hydrologically and ecologically functional units called vernal pool complexes” (USFWS 2011). Two areas within the project study area have been mapped by the USFWS as vernal pool fairy shrimp DCH: Agate Road north of the existing OR 62 intersection and Agate Road centered on Touvelle Road (Figure 5-5 ) (USFWS 2010a). These areas are identified as parts of Unit 3A and 3B. Full descriptions of these units may be found within the Programmatic Biological Opinion issued by the USFWS (USFWS 2011). Analysis of the USFWS digital dataset for DCH indicates slight geospatial errors (i.e.,DCH is displayed on top of existing roadways and other currently disturbed areas). The extent of the geospatial errors appears to include both areas within the project footprint. Portions of these critical habitat units within the project footprint have all been disturbed to some extent, either through existing direct development (i.e., road shoulders, other paved or graveled areas) or indirectly through active grazing or untreated stormwater discharge. Based on supplemental field investigations, these mapped areas lack the characteristic vernal pools required for critical habitat identified by the USFWS. As such, it is apparent that designated vernal pool critical habitat does not exist within the project footprint in these specific locations, but does exist within the action area. An assessment of vernal pool habitat was conducted in 2010 to document and evaluate the functions and values of VPCs adjacent to or within the project footprint to assist with determining the ODFW habitat mitigation classification as described in Oregon Administrative Rule (OAR) 635-415-0025. For the purposes of this project and other studies for quality and suitability, the VPCs were grouped into distinct Assessment Units (AUs) based on geographic location. Per the Agate Desert Methodology, a VPC is delineated by drawing a boundary around a group of vernal pools within a common patterned ground landscape area. VPC/AU boundaries are generally defined by impervious roads or changes in soil type (e.g. discontinued patterned ground). Within the project footprint, twelve AUs were identified. Eight of the 12 AUs were evaluated by URS. Four AUs (AU-9, 10, 11, and 12), located north of Vilas Road, were previously evaluated during the development of the functions assessment methodology (URS 2010). AUs observed within the Project study area have been severely impacted by soil and water flow disturbance due to encroachment by development, grazing, farming, illegal trash dumping, and invasion of exotic plants. In general, most of the AUs evaluated within the Project study area received low to moderate ratings for hydrologic and water quality functions. Most of the complexes contain only a few scattered shallow pools that are not likely to retain large volumes of precipitation. Additionally, most of the pools have been moderately to severely degraded to various degrees by hydrologic and soil disturbance associated with agriculture, which affects the capacity to provide hydrologic and water quality functions. AUs generally received moderate to high ratings for native plant and native wildlife support functions. All the AUs lack a dominance of native plant species; however, five have documented populations of rare or ESA-listed plants and one was previously determined to contain cysts belonging to federally protected VPFS (URS 2010f). The primary variables used to determine the habitat conservation value of each AU include: naturalness of surrounding land cover, level of land use development, number of other wetlands within the drainage, degree of hydrologic alterations within the complex, and dominance of native plants. “Values” as defined by the habitat conservation assessment, are defined as “the social, economic, and ecological expression of a wetland’s opportunity to provide functions that are valued by humans and of the significance to humans of those functions”. At the landscape level, all AUs are similar in disturbance, level of urban development, and position in the watershed, so while individual value scores may vary somewhat from complex to complex, the cumulative scores indicate that all AUs evaluated are similarly valued. The following table 4-1 summarizes relative conservation values that were determined for 12 Assessment Units that are either within or immediately adjacent to the project footprint:
A more detailed discussion is available in the Final Wetlands Resources Technical Report, Highway 62 Corridor Solutions Project, prepared for ODOT (URS 2011a). 4.1.3 Site Specific Limiting Factors for RecoveryThe total number of VPFS have declined primarily because of destruction or degradation of vernal pools through development of urban, suburban, and agricultural projects (USFWS 2005). In addition to direct habitat loss, VPFS populations have declined from of a variety of activities that degrade existing vernal pools by altering pool hydrology (water regime). Vernal pool hydrology can be altered by a variety of activities, including the construction of roads, trails, ditches, or canals that can block the flow of water into, or drain water away from, the vernal pool complex (URS 2010). Farming practices, grazing, introduction of non-native plant species, development and trash dumping have all impacted vernal pool quality within the action area. Disruption of vernal pool water flow and/or changes in seasonal inundation can significantly alter vernal pool species composition (USFWS 2011). For example, vernal pools that prematurely dry up may prevent certain plants, insects or amphibians from reproducing, which could result in diminished populations of certain plant or animal species. Surface water and groundwater flow can be impacted by fill and excavation activities during road construction which dam or truncate surface swale systems or break through subsurface, impermeable hardpans that currently support perched aquifers. Other roadway-related excavation activities such as the construction of stormwater management facilities and utility trenches can have the same effect. In addition, the introduction of subsurface roadbed substrates (e.g., roadbed aggregate) could potentially result in hydrological damming of the near-surface aquifer. The damming effect and/or draw down effect caused by these physical barriers or construction activities could potentially result in either longer or shorter periods of inundation within the affected wetlands. Since many of the wetlands in the action area rely on surface water input as a substantial means of their water budget, these actions could change the existing character of the remaining wetlands. Redirecting flows may inadvertently eliminate supporting water inputs resulting in permanent drying or draining of wetlands. Additional water inputs could increase nutrient and sediment loadings beyond the capacity of these wetlands to absorb such inputs. Additional flows may also increase the duration and depth of surface ponding, resulting in permanent changes of vegetative structure and alterations of the existing habitat for vernal pool fairy shrimp. In general, there is the possibility that the reduction or addition of hydrology inputs could continue to further degrade these wetland habitats if not appropriately mitigated (URS 2010). A comprehensive recovery plan has been drafted by the USFWS for VPFS (USFWS 2005) and has been referenced in the Programmatic Biological Opinion issued for projects that may affect VPCs within Jackson County, Oregon (USFWS 2011). Directory: HWY62 -> Terrestrial BA Terrestrial BA -> Draft Terrestrial Resources Biological Assessment oregon highway 62 corridor solutions project Download 486.24 Kb. Share with your friends:
| |||||||||||||||||||||||||||||||||||||||||||||