State of the Park Report, De Soto National Memorial, Florida

National Park Service U.S. Department of the Interior State of the Park Report De Soto National Memorial Florida 2016 National Park Service. 2016. State of the Park Report for De Soto National Memorial. State of the Park Series No. 29. National Park Service, Washington, DC. On the cover: Photos of De Soto NM clockwise from top left: kayakers; De Soto Trail marker; Reenactor on horse; Reenactors on beach; gumbo limbo tree; musicians; Ranger with visitors Disclaimer. This State of the Park report summarizes the current condition of park resources, visitor experience, and park infrastructure as assessed by a combination of available factual information and the expert opinion and professional judgment of park staff and subject matter experts. The internet version of this report provides the associated workshop summary report and additional details and sources of information about the findings summarized in the report, including references, accounts on the origin and quality of the data, and the methods and analytic approaches used in data collection and assessments of condition. This report provides evaluations of status and trends based on interpretation by NPS scientists and managers of both quantitative and non- quantitative assessments and observations. Future condition ratings may differ from findings in this report as new data and knowledge become available. The park superintendent approved the publication of this report. Executive Summary The mission of the National Park Service is to preserve unimpaired the natural and cultural resources and values of national parks for the enjoyment, education, and inspiration of this and future generations. NPS Management Policies (2006) state that “The Service will also strive to ensure that park resources and values are passed on to future generations in a condition that is as good as, or better than, the conditions that exist today.” As part of the stewardship of national parks for the American people, the NPS has begun to develop State of the Park reports to assess the overall status and trends of each park’s resources. The NPS will use this information to improve park priority setting and to synthesize and communicate complex park condition information to the public in a clear and simple way. The purpose of this State of the Park report is to: • Provide to visitors and the American public a snapshot of the status and trend in the condition of a park’s priority resources and values; • Summarize and communicate complex scientific, scholarly, and park operations factual information and expert opinion using non-technical language and a visual format; • Highlight park stewardship activities and accomplishments to maintain or improve the State of the Park; • Identify key issues and challenges facing the park to help inform park management planning. De Soto National Memorial (DESO) was authorized by Congress on March 11, 1948 commemorating De Soto’s landing in Florida in 1539 and the first large-scale European exploration of what is now the southeastern portion of the United States and its overwhelming impact on the course of North American history. De Soto National Memorial comprises approximately 26 acres in Manatee County on the west coast of central Florida. Situated on a spit of land at the mouth of the Manatee River at its confluence with Tampa Bay, the park has more than 3,000 feet of shoreline. Roughly 80% of the park is mangrove estuary. Live oaks and gumbo limbo trees command much of the landscape of the memorial. Significance statements express why the park unit’s resources and values are important enough to warrant national park unit designation. DESO is significant because: • De Soto’s 1539 expedition was the first large-scale organized European exploration, which traversed 4,000 miles during its four-year quest. • The contact between De Soto’s expedition and American Indians caused social and cultural instability among indigenous peoples. Within 200 years of the expedition, American Indian populations were drastically reduced as a result of warfare, the introduction of pigs, disease, and the capture and displacement of leaders. • Written accounts by members of the De Soto expedition were the first widely published and translated documents of their kind, which encouraged and accelerated European powers to explore and colonize North America. The summary table, below, and the supporting information that follows, provide an overall assessment of the condition of priority resources and values at DESO based on scientific and scholarly studies and expert opinion. The internet version of this report, available at http://www.nps.gov/stateoftheparks/deso/, provides additional detail and sources of information about the resources summarized in this report, including references, accounts on the origin and quality of the data, and the methods and analytical approaches used in the assessments. Reference conditions that represent “healthy” ecosystem parameters, and regulatory standards (such as those related to air or water quality) provide the rationale to describe current resource status. In coming years, rapidly evolving information regarding climate change and associated effects will inform our goals for managing park resources, and may alter how we measure the trend in condition of park resources. Thus, reference conditions, regulatory standards, and/or our judgment about resource status or trend may evolve as the rate of climate change accelerates and we respond to novel conditions. In this context, the status and trends documented here provide a useful point-in-time baseline to inform our understanding of emerging change, as well as a synthesis to share as we build broader climate change response strategies with partners. The Status and Trend symbols used in the summary table below and throughout this report are summarized in the following key. The background color represents the current condition status, the direction of the arrow summarizes the trend in condition, and the thickness of the outside line represents the degree of confidence in the assessment. In some cases, the arrow is omitted because data are not sufficient for calculating a trend (e.g., data from a one-time inventory or insufficient sample size). State of the Park Report iii De Soto National Memorial Confidence in Condition Status Trend in Condition Assessment Warrants Condition is Improving High Significant Concern Warrants Condition is Unchanging Medium Moderate Concern Resource is in Good Condition is Deteriorating Low Condition State of the Park Summary Table Condition Priority Resource or Value Rationale Status/Trend Natural Resources web Air pollution may be causing damage to monuments and other cultural resources at DESO. River vistas are often obscured by pollution-caused haze but are improving. Ozone sometimes reaches levels that can make breathing difficult for sensitive groups but is improving. Some vegetation communities and surface Air Quality water in the park may be susceptible to acidification and nutrient enrichment effects of excess sulfur and nitrogen deposition. Airborne toxics, including mercury, can deposit with rain and accumulate in birds, mammals, amphibians, and fish. Erosion of the park’s shoreline is an ongoing concern. Riprap and other erosion Geologic Processes control methods have been used for protection of the shoreline, but more is needed. The park supports a rich and thriving Mangrove Forest. Ongoing management of invasive species is successful. Unique Gumbo Limbo trees in the park are being Plants and Animals treated, but continue to suffer symptoms of disease. Despite the park’s richness, there is little-to-no active biological monitoring by the NPS network. A photic environment is described as the physical amount and character of light at a particular location, irrespective of human perception. The NPS Night Sky Program characterizes a park’s photic environment by measuring both anthropogenic and natural light. Anthropogenic Light Ratio (ALR) is a measure of light pollution calculated as the ratio of median Anthropogenic Sky Glow to Dark Night Sky average Natural Sky Luminance. ALR for De Soto National Memorial is 9.60, which is considered a moderate condition for urban parks. Population growth for the Tampa-St. Petersburg and Bradenton-Sarasota metropolitan areas have been moderate (>5%) over the last five years, resulting in a negative trend (U.S. Census Bureau 2015). State of the Park Report iv De Soto National Memorial Condition Priority Resource or Value Rationale Status/Trend All sound resources, whether audible or not, are referred to as the acoustic environment of a park. The quality of the acoustic environment affects park resources including wildlife, cultural resources, the visitor experience, and landscapes. The condition of the acoustic environment is assessed by determining how much man-made noise sources contribute to the acoustic Acoustic Environment environment through the use of a national noise pollution model. This measure is referred to as the mean acoustic impact level. Impact is measured in A-weighted decibels (dBA). The mean acoustic impact level at the park is 8.6 dBA, meaning that the condition of the acoustic environment warrants moderate concern. Overall, long-term projected increases in ground-based and aircraft traffic indicate a deteriorating trend in the quality of acoustic resources at this location. Cultural Resources web The park’s known archeological resources are in good condition, except for the Tabby House Ruins. The overall level

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