The project would meet these goals with a comprehensive program that will achieve the following objectives:

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1 The Proposed Project September 2, 2010 Project Description Kent Island is a naturally formed emergent (dune-capped) flood-shoal tidal delta that is geomorphically unique in California. Kent Island is formed by deposited sand transported through Bolinas Lagoon s inlet by waves and flood currents. Historically, it was subject to partial geomorphic stabilization by resilient native salt marsh and dune vegetation, alternating with complete submergence during seismic subsidence events. The dominant vegetation s dynamic response to wind, wave, and tidal current transport of sand is highly important for the natural hydrological and sediment dynamics within the Lagoon. However, Kent Island has been colonized by non-native vegetation in particular invasive beach grass, acacia, iceplant, French broom, cypress, and pine that stabilizes the island. These invasive plants displace the diverse native plant communities that are well-adapted to dynamic coastal disturbances such as storm surge flooding, sand erosion, accretion and gradual sea level rise. The dominant non-native vegetation on the island also displaces suitable habitat for native plants and wildlife, including specialstatus species. Goals and Objectives As stated in the Estuary Restoration Act grant application, the goals of the Kent Island Restoration at Bolinas Lagoon are to: 1) Improve habitat for rare and special status species of plant and animals, 2) De-anchor the island to allow its natural function as a dynamic flood-shoal island, and 3) Improve hydrologic function and sediment transport in Bolinas Lagoon as a whole. The project would meet these goals with a comprehensive program that will achieve the following objectives: 1) Elimination of dominant non-native invasive plants 2) Restoration of native high salt marsh and beach vegetation 3) Community involvement and long-term community-based stewardship of Bolinas Lagoon resulting from an important restoration project Rationale for the Revised Project We are asking the Estuary Restoration Habitat Council to allow us to modify the proposed project due to a biological constraint (i.e., an active heron rookery). The revised project will achieve all of the goals and objectives outlined above with the 1

2 exception that a grove of trees that supports the heron rookery would be left intact; this grove covers approximately 6 of the island s 23 acres and has a limited expected life span of 5-30 years due to sea level rise (see Appendix 1). The primary grove of trees on the island has been used for the last two years by nesting Great Blue Herons. This year (2010) four herons nested on the island and 5 herons nested across the Bolinas Channel on the mainland (Figure 1); this latter area has been used by nesting herons off and on for several years. Heron rookeries are an important biological resource and an integral part of the ecological community at Bolinas Lagoon a large heron and egret rookery is located at Audubon Canyon Ranch (ACR) on the east side of the lagoon. While egret numbers have remained stable there, nesting great blue herons have declined significantly in recent years. ACR owns a portion of Kent Island (Figure 2), including a substantial portion of the forest albeit not the trees on which the herons are nesting. ACR is strongly opposed to removing mature trees from the island due to the possible adverse impact to the nesting heron colony (John Kelly PhD, Director- Conservation Science and Habitat Protection, ACR; pers. comm.). The No Project Alternative If the revised project is not implemented, none of the ecological or hydrological benefits will be realized. The grove of trees will expand over the short term and canopy shade and heavy deposition of leaf litter and woody debris from woody non-native vegetation will continue to displace and preclude natural regeneration of native high salt marsh and beach vegetation. Iceplant, beachgrass, pines, and cypress will continue to spread into intact adjacent native vegetation by seed dispersal from existing stands. Long-lived seed banks of acacia and French broom will accumulate in the sandy soil. Restoration time requirements, efforts, and costs will likely increase over time as non-native species seed banks accumulate and cover increases. In a report on the 50-year projection of the evolution of the Lagoon, PWA 1 stated that these current impacts from colonization from invasive plants will only continue to increase in severity and impact without intervention: accelerated accumulation of sand along the windward side of Kent Island has created a disturbed regime that is favorable for the establishment of non-native invasive plant species, namely European beach grass, scotch broom, and iceplant. The incursion of these exotic species likely indicates that the area is undergoing rapid change that has resulted in disturbance to native plant populations. European beach grass, in particular, is an aggressive colonizer of beach areas that forms dense mats of grass and rhizomes, unlike any of the native dunemat species. The beachgrass captures sand, decreasing natural sand movement, and causing the dunes to increase in height. Succession ensues toward colonization by other exotic plant species, until the integrity of the ecosystem is threatened. 1 Bolinas Lagoon Ecosystem Restoration Feasibility Project: Projecting the Future of Bolinas Lagoon Marin county Open Space District. Prepared by Philip Williams Associates. 2

3 The report further identified non-native beach grass as the primary factor in capturing beach sand and changing the dynamics of the flood shoal island: One biological feedback that may stabilize the flood tide island is future expansion of European beach grass. This species acts to stabilize beach and dune habitats by trapping windblown sand. The Revised Project The revised project would be exactly the same in removal of non-native beach grass, ice plant, acacia and other invasive plants with the exception of a six acre grove of mature trees. All tree seedlings within the primary grove and elsewhere on the island would be removed on a continuing basis as will all other invasive plants hence, the entire island will be subject to invasive plant removal under the revised project. A critical factor is that the pines and cypress trees are highly intolerant of elevated soil salinity pulses, in contrast with beachgrass, ice plant, and native beach and high salt marsh plants. The woody non-native vegetation is highly prone to eventual failure due to (natural) saline storm surge flooding. The non-native tree and shrub cover, and temporary, artificial outof-place habitat it provides is inherently unstable on the flood tidal delta island location. Given current projections for sea level rise and for increased high wave/storm surge events 2, it is expected that the trees will be killed from salt water exposure from brief, intense episodes of storm surge flooding (El Niño high tide storm events) within 5-30 years (Peter Baye PhD, pers. comm.). The depositional processes that will raise the island naturally in pace with sea level will be lethal to the trees but not to other invasive plants such as non-native dune grass. Removing other invasive plants may accelerate this process in which high wave storm surge will overtop the island resulting in salt water contamination of the fresh water lens that supports the trees 3. In fact, this is one of the main ecological justifications for shifting Kent Island back to resilient native vegetation that can tolerate surges, submergence, and depositional processes. Because the entire island will be subject to invasive plant removal, there is no significant difference between the approved project and the revised project in terms acres treated, functional response, or overall cost. As noted above, the mature pines and cypress have a very short projected life expectancy and all seedlings will be removed on a continuing basis. It will take slightly longer to achieve full benefits because the trees will not be killed immediately. Under the approved project, our approach would have been to either ring the trees are drown them in salt water pumped from the lagoon. Our rationale was that disturbance from immediate harvest/removal of trees may be more disruptive to existing wildlife, more costly, and less energy/carbon efficient than phased girdling (or salt water drowning) and a transition through decay-classes of dying and dead trees. And once the canopy is dead and litter is no longer shed, standing snags would not significantly impair revegetation of the ground layer, and it may actually provide some shelter that facilitates survivorship of transplants during droughts. In addition, retention 2 See Appendix A 3 See Appendix B 3

4 of snags (standing dead trees) and downed large woody debris (fallen logs) would provide ecological benefits. The pre-european Bolinas Lagoon watershed was forested and likely discharged large woody debris (LWD) into the Lagoon during extreme flood events. Large woody debris also came from SF Bay-Sac Delta and adjacent North Coast forested watersheds. These LWD sources are permanently eliminated by flood control, agricultural conversion and residential development. LWD dominates many of the transition zones (drift-lines/terrestrial ecotone) of tidal and nontidal lagoons of the North coast and Pacific Northwest forested watersheds where it plays an important structural habitat role. 4

5 Figure 1. Nesting locations of great blue herons on Kent Island (on right) and the adjacent mainland across Bolinas Channel (on left). April

6 Figure 2. Kent Island showing property boundary of Audubon Canyon Ranch. 6

7 Appendix A. Recent projections of sea level rise and frequency and severity of storm events along the California coast indicate that extreme high water levels will occur with increasing frequency a 30 cm (12 in) increase in SLR would shift the 100-year storm surge-induced flood event to once every 10 years. The frequency of high sea level extremes may be further increased if storms become more frequent or severe as a result of climate change. The increasing duration of high storm-forced sea levels increases the likelihood that they will occur during high tides. The combination of severe winter storms with SLR and high tides that would result in extreme sea levels could expose the coast to severe flooding and erosion, damage to coastal structures and real estate, and salinity intrusion into delta areas and coastal aquifers the numbers of sea level events during the period exceeding the historical percentile for the San Francisco tide gage increase from about 25 events/30 years to about 150, to about 1400, to about 7000, to about 20,000 events/30 years as the sea level change increases from zero to 20 cm, 40 cm, 60 cm, and 80 cm (8 in, 16 in, 23 in, and 31 in). [The latter value is currently the most widely accepted value for projected se level rise] from: Climate change projections of sea level extremes along the California coast D. R. Cayan, P. D. Bromirski, K. Hayhoe, M. Tyree and M. D. Dettinger & R. E. Flick. Climatic Change (2008) 87 (Suppl 1):S57 S73 Appendix B. On Kent Island, as on other islands in marine environments, the trees are dependent on a freshwater lens. This underground pool of freshwater that takes the shape of a lens is a critical water source. The freshwater lens is suspended by salt water. If sea level increases salt water from the sea can intrude or overtopping during storms can inundate the lense making the water toxic to trees. The size of the lens is directly related to the size of the island: larger islands have lenses that are less vulnerable to tidal mixing. Smaller island freshwater lenses shrink during prolonged periods of low rainfall, and water quality is easily impaired by mixing with salt water. Freshwater lenses can be as shallow as 3-8 inches are as deep as 65 feet. Storm surge events have resulted in mortality and loss of pine and other coniferous trees-- - most of these examples are from the east coast of the U.S. as Ghost forests of standing dead trees killed by saltwater intrusion are becoming increasingly common in southern New Jersey, Maryland, Virginia, Louisiana and North Carolina. (p. 60) 7

8 Sea-level rise, changing intensities of tropical storms, and changing rainfall patterns are all components of global change that are predicted to affect coastal systems these factors may interact in shaping coastal ecosystems. The occurrence of a violent storm and a historic drought during an 8-year study of sea-level rise effects on coastal forest in west central Florida presented an opportunity to study these interactions. The system studied was a marshy coastline, on a technically stable, karstic limestone platform, where coastal hydric hammock (a wetland hardwood forest) abutted salt marsh. Both the storm and the drought that occurred during the study were associated with pulses of tree mortality that selectively removed Juniperus virginiana var. silicicola (southern red cedar) from stands. Stable isotope data suggested that these trees used less fresh ground water and more sea water as these stands declined in the face of rising sea level. Drought-associated tree death only occurred in a stand in very late stages of sea-level-induced decline, where ground water became hypersaline during the drought. A storm that occurred in 1993 also selectively removed Juniperus from stands, damaging stands primarily in areas where tree reproduction had already ceased or declined due to sea-level rise. Thus, although these episodic events (drought and storm) caused notable tree death, the projected inability of forest stands to recover from these events was due to prior effects of sea-level rise. Interactions of Storm, Drought, and Sea-Level Rise on Coastal Forest: A Case Study K. Williams, M. MacDonald and L. da Silveira Lobo Sternberg. Journal of Coastal Research, Vol. 19, No. 4 pp