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HomeMy WebLinkAboutCT 99-08; Spyglass II; Tentative Map (CT) (61)STATUS REPORT PERENNIAL GRASSLAND REVEGETATION PROJECT SPYGLASS DEVELOPMENT MITIGATION CARLSBAD, CALIFORNIA 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 1 June 2004 HECEIVED R. Mitchel Beauchamp, M. Sc., President JUN 0 2 2004 ; AQWit OESiGN GR o STATUS REPORT PERENNIAL GRASSLAND REVEGETATION PROJECT SPYGLASS DEVELOPMENT MITIGATION CARLSBAD, CALIFORNIA 1 June 2004 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 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 visited the site 26 May 2004 for inspection of the 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. The 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 acres have established areas of native grassland vegetation. This is heavily concentrated on the south portion of the site with patches of target vegetation occurring at northeast portions of the site as well. Non-native grasses occur at a high density, with the genus Bromus occupying 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 nigrd) 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 spp.) occur. DISCUSSION The most robust area of native grasses occurs 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 predated on by rabbits, resulting in the complete eradication of the surviving growth. In early 2003, this portion of the site was reseeded a second time, with target vegetation emergent and abundant as of the 26 May 2004 visit. Since the last monitoring report (16 May 2003) Pacific Southwest has attempted to remove the non-native grasses and establish target species in the portion of the site lacking target species. In January 2004 this portion of the site was disked then reseeded with native grass. In late March 2004 the site was weeded. The only weed noted was Black Mustard, which was completely removed from the site. During this time no native grasses were rioted. Currently the area disked in January 2004 lacks Black Mustard, but has an abundance of non-native grasses, with a very minimal amount of native grasses amongst them. These results can be explained in part by the general natural history 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 an established non-native grassland. 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 had a major effect on the low success rate of target grasses. Because there was not a seed bank on-site consisting of native grasses, the success of native grasses on-site can only occur once the grass becomes established. The problem however, is achieving initial establishment. As the site is not irrigated, the critical element in this process is rain. Timing for seeding the site should coincide with rain events. This is an essential timing component as the rain serves two purposes. The first is that rain would provide hydration to the Pacific Southwest Biological Services, Inc. o PSBS #T472D seeds, which will initiate the germination process. The second is that the rain will prevent consumption of the seeds by insects, birds, etc. When the site was seeded most recently (January 2004), it was hoped that a substantial rain would occur within the following week. This did not happen. A slight rain did occur the week after, producing minimal amounts of water to the site. That was the last rain event of the season. The lack of sufficient water to the site is the primary reason why the seeds did not germinate. RECOMMENDATIONS Because 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 on approximately 70% of the site. Before any other reseeding efforts occur, these grasses need to be eliminated. A more aggressive approach needs to occur as past efforts have yielded no new results. Pacific Southwest recommends that this area be intensively disked prior to the start of the rainy season. Once this occurs, monthly site visits will occur to monitor and control the invasive non-native weeds. A second disking would then occur a few weeks after the first rain. This would allow the non-native grass seeds to germinate and then be removed prior to them maturing to a seed producing state. Then, once the next rain event occurs, Pacific Southwest will hand seed the site. Weeding will then occur on a monthly basis, varying in intensity based on the amount of weeds/non-native grass occurring on site. Use of fire would accelerate competition in favor of native grasses but past efforts to convince the fire marshal to support this technique have failed. For the portion of the site that is doing well weeding also needs to occur. As of the May 2004 site visit weeds were noted around the mature native grasses. This weeding needs to occur to prevent these non-native grasses from chocking out the native species and hindering the growth of recently germinated native grasses. Pacific Southwest Biological Services, Inc. Appendix 1.PSBS# T472D Photo #1. View of the non-target grasses dominating the lower slopes of the site. Looking east. Photo #2. Another view of the non-native grasses, which dominate a majority of the site. Looking west. Photos taken on 5-26-04 Pacific Southwest Biological Services, Inc. Appendix 1.PSBS# T472D Photo #3. View of a portion of the site dominated by native grass. Looking north. Photo #4. Another view of the portion of the site dominated by native grass. Looking northeast. Photos taken on 5-26-04 Pacific Southwest Biological Services, Inc. Appendix 1.PSBS# T472D Photo #5. View of area surrounded by native grass, which needs weeding. Photo #6. Looking at a recently germinated native grass, which was surrounded by non-native grasses that were removed for the picture. Photos taken on 5-26-04 Pacific Southwest Biological Services, Inc. o o o o PSBS #T472D " ^^ MOVED TC LOCATION CARLSBAD UNIRED SCHOOL DISTRICT HOLLY SPRINGS, LTD. Figure 1 PS0S #f472D Sp/g/oss Vegetation & Sensitive Resources t V = 136* Legend A Nassella lepida & Nassela pulchra dominated B Bromus dominated area with Nassella sp. present C Area dominated by non-native grass 5-28-04 Pacific Southwest Biological Services, Inc.