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HomeMy WebLinkAboutCT 99-08; Spyglass II; Tentative Map (CT) (60)DRAFT SPYGLASS DEVELOPMENT MITIGATION CARLSBAD, CALIFORNIA PERENNIAL GRASSLAND REVEGETATION PROJECT STATUS REPORT Donor Site: UTM: 3,670,OOOmN, 470,OOOmE Receptor-Mitigation Site UTM: 3,669,OOOmN, 473,OOOmE Prepared for Concordia Homes of California, LLC 1903 Wright Place, Suite 120 Carlsbad CA 92008 Telephone: 760 804-1576 Facsimile: 760 804-1577 and Ladwig Design Group, Inc. 703 Palomar Airport Road, Suite 300 Carlsbad CA 92009 Prepared by Pacific Southwest Biological Services, Inc. Post Office Box 985 National City CA 91951-0985 Telephone: 619 477 5333 Facsimile: 619 477 5380 E-mail: bio@psbs.com PSBS # T472D 8 August 2003 R. Mitchel Beauchamp, M. Sc., President RECEIVED Allfi 1 1 2083 LADWIG DESIGN GR SPYGLASS DEVELOPMENT MITIGATION CARLSBAD, CALIFORNIA PERENNIAL GRASSLAND REVEGETATION PROJECT STATUS REPORT 8 August 2003 INTRODUCTION The development of a site at the southeast corner of El Camino Real and Carlsbad Village Drive (Elm Street), called Spyglass II (CT 99-08/SDP 99-04.SUP 99-04/ HDP 99-07) impacted a remnant Perennial Grassland by landform alteration of the site. As mitigation for this three-acre impact to native Perennial Grassland, the establishment of a 10.3-acre area of Perennial Grassland was required to fulfill Condition 5 of the Mitigating Measures for the Spyglass II project. The site is a portion of land owned by the State of California and administered by the Departments of Transportation and the Department of Fish and Game as a mitigation bank and natural preserve. Prior to project implementation, weedy, non-native grasses and forbs covered the site. The site lies northwest of another area proposed as a mitigation area, called Holly Springs. The site was considered suitable for restoration to Perennial Grassland by virtue of the Altamont clay soils on the site and the proposed land uses nearby. The site lies between 80 and 200 feet in elevation and is generally a west to northwest facing slope system. The lands to the south are owned by the Carlsbad Unified School District and presumable will be developed as a school site. Having a natural preserve next to an educational facility offers opportunities for educational and monitoring activities. METHODOLOGY The following actions, generally following the plan for the project, dated 13 December 2000, were implemented in the establishment and maintenance of the native, perennial grassland cover for the site that affords watershed protection, reduces fuel loading, retains populations of grassland-associated native plants and provides a prey base of rodents as foraging habitat for native raptors. Pacific Southwest biologist Jason H. Kurnow then visited the site 13 May 2003 for further inspection. Kurnow and PSBS botanist R. M. Beauchamp visited the site on 30 April 2003 to evaluate general success of project area and documentary photography (Appendix 1). The assessment of the project sites consisted of a series of photographs and visual examination of the project areas. Vegetation on-site was mapped using the grid system established in 2002 (Figure 1). This was done by walking transects from north to south along the eastern boundary of each grid. Pacific Southwest Biological Services, Inc. PSBS #T472D RESULTS Approximately 2.9 of the 10.3 acres have established areas of native grassland vegetation. This is heavily concentrated on the south, upper portion of the site with patches of target vegetation occurring at northeast portions of the site as well. A high density of non-native grasses, in the genus Bromus occupy most of the remaining 7.1 acres on-site. Patches barren of any vegetation also occur on-site. Due to an ongoing weeding effort, invasive non-target vegetation such as Black Mustard (Brassica nigra) and Sweet Fennel (Foeniculum vulgare) were absent from the site. However, many non-target species such as Common Sow-thistle (Sonchus oleraceus), Arizona Chess (Bromus arizonicus), Wild Oat (Avenafauta) and other non-native grasses are present in areas where native grasses (Nassella & Anstidapupurea spp.) occur. DISCUSSION The most robust area of native grasses occur where an herbicide was used to eliminate the extensive growth of Field Mustard (Hirschfeldia incand) on 27 February 2002. Where sprayed, all vegetation was killed and the subsequent bare area was reseeded early March 2002. Due to the record setting dry season occurring throughout 2002, a minimal amount of seedlings germinated. Consequently, these newly emerged plants were eaten by rabbits, resulting in the severe eradication of the drought surviving growth. In early 2003, this portion of the site was reseeded a second time, with target vegetation emergent and abundant as of the 13 May 2003 visit. The increase in rainfall through late April of 2003 most likely contributed to the success of this reseeding effort. However, the same favorable conditions that caused the emergence of target vegetation also caused an emergence of non-target species in this area. These non-target species were removed to reduce competition between both target and non-target species. Herbicide was used only at locations where mustard species were most excessive. Areas where herbicide was not used now have a dense cover of non-native grasses. Non-native grasses are invasive in their nature and can tolerate harsh environmental conditions. These species are generally more adaptable, aggressive and opportunistic than native grasses, and like all grasses, store seeds in a seed bank. A seed bank consists of seeds dropped by parent plants that stay in the soil until conditions are favorable for germination. The site prior to disking in 2000 consisted of established non-native grassland. Disking was used to clear this vegetation and the soil was additionally solarized in an attempt to exterminate these non-native grasses along with other non- native species in preparation for the seeding of native grasses. The site was then seeded, but the success of target species was low. This was due to many abiotic factors, with the lack of rain contributing as a major factor. Germination of non-native plants in the seed bank also had a major effect on the low success rate of target grasses. The characteristics associated with the non-target grasses mentioned above then caused a decline in the success of the now emergent native grasses. The net result is a majority of the site dominated by non-native grasses. RECOMMENDATIONS As the establishment of native perennial grassland is the focus of the project, the removal of non-native grasses on site is critical. These grasses have established a strong foothold Pacific Southwest Biological Services, Inc. PSBS #T472D on approximately 70% of the site. Before any other reseeding efforts occur these grasses need to be eliminated. This can be accomplished using a few different methodologies, such as: 1. A control burn of the site focusing on areas dominated by non-native grasses. 2. Use herbicide on areas that are dominated by non-native grasses 3. Establish nucleus locations for native grasses by cutting and sucking numerous patches of non-native grasses throughout the site. These methodologies are arranged from highest success probability to lowest. Thus, burning is most favorable with the establishment of nucleus locations the least favorable. Each of these recommendations has plusses and minuses associated with them, which are: Recommendation #1 This is the most cost effective and efficient procedure. The intensity of heat will envelope all vegetation, also destroying much of the seed bank. This action needs to be approved by the California Department of Fish and Game (CDFG) before implementation. However, this idea was suggested to CDFG in the past, who ultimately denied approval for this action. Recommendation #2 The results of this action would be similar to that of the previous area sprayed with herbicide. Non-target vegetation would most likely emerge in low densities. These areas would then need constant weeding to prevent a takeover by these non-native species. Recommendation #3 This would allow for a variety of manageable areas throughout the site. The idea being that first the native grasses would become established in these areas. Then, they would continue to invade into adjacent areas eventually taking over the entire site. However, it is more probable there would be a patchwork of native and non-native grasses on site. Irrigation of the site has been approved, and this tool should be used with care to expedite the germination process, as well as increase the success rate of target vegetation. Too much irrigation will favor non-natives. Pacific Southwest Biological Services, Inc. PSBS #T472D CARLSBAD UNIFIED SCHOOL DISTRICT PSBS #T472D Spyglass Vegetation & Sensitive Resources N 1" = 136' Legend A Nassella, Convolvulus and Bare Ground B Dead Bromus patch C to/rum patch D Lolium and Bromus arlzonicus patch E Disturbed Bromus patch F Calochortus splendens and Bloomeria patch G Nassella patch H Bromus arlzonicus and Convolvulus patch I Existing Native Nassella stand (off-site) to west J Silybum marianum patch Appendix 1.PSBS# T472D Photo #1. View of the western portion of the site. Looking northwest. Photo #2. View of Bromus dominated area with mustard in the foreground and area previously sprayed with herbicide in the background, to the right. Looking southeast, Photos taken on 4-30-03 Pacific Southwest Biological Services, Inc. Appendix 1.PSBS# T472D Photo #3. View of dead Bromus patch and area previously sprayed with herbicide. Looking northwest. Photo #4. View of area previously sprayed with herbicide. Looking east. Photos taken on 4-30-03 Pacific Southwest Biological Services, Inc. Appendix 1 PSBS# T472D Photo #5. View of Bromus dominated area. Looking west. Photos taken on 4-30-03 Pacific Southwest Biological Services, Inc.