Natural resource condition assessment: Lincoln Boyhood National Memorial
Authors: Jones David , Cook Roy , Sovell John , Ley Matt , Shepler Hannah , Weinzimmer David , Linares Carlos 
Published: January 2024

The National Park Service (NPS) Natural Resource Condition Assessment (NRCA) Program administered by the NPS Water Resources Division evaluates current conditions for important natural resources and resource indicators using primarily existing information and data. NRCAs also report on trends in resource condition, when possible, identify critical data gaps, and characterize a general level of confidence for study findings. This NRCA complements previous scientific endeavors, is multi-disciplinary in scope, employs a hierarchical indicator framework, identifies and develops reference conditions/values for comparison against current conditions, and emphasizes spatial evaluation of conditions where possible.

Lincoln Boyhood National Memorial (LIBO) was authorized by an act of Congress on February 19, 1962, (Public Law 87-407) to preserve the site associated with the boyhood and family of President Abraham Lincoln, including a portion of the original Tom Lincoln farm and the nearby gravesite of Nancy Hanks Lincoln. The 200-acre memorial commemorates the pioneer farm where Abraham Lincoln lived from the age of 7 to 21.

The NRCA for LIBO employed a scoping process involving Colorado State University, LIBO and other NPS staffs to establish the NRCA framework, identify important park resources, and gather existing information and data. Indicators and measures for each resource were then identified and evaluated. Data and information were analyzed and synthesized to provide summaries and address condition, trend and confidence using a standardized but flexible framework. A total of nine focal resources were examined: four addressing system and human dimensions, one addressing chemical and physical attributes, and four addressing biological attributes. The quality and currentness of data used for the evaluation varied by resource.

Landscape context ? system and human dimensions included land cover and land use, natural night skies, soundscape, and climate change. Climate change and land cover/land use were not assigned a condition or trend?they provide important context to the memorial and many natural resources and can be stressors. Some of the land cover and land use-related stressors at LIBO and in the larger region are related to the development of rural land and increases in population/housing over time. The trend in land development, coupled with the lack of significantly sized and linked protected areas, presents significant challenges to the conservation of natural resources of LIBO to also include natural night skies, natural sounds and scenery. Climate change is happening and is affecting resources, but is not considered good or bad per se. The information synthesized in that section is useful in examining potential trends in the vulnerability of sensitive resources and broad habitat types such as forests. Night skies and soundscapes, significantly altered by disturbance due to traffic, development and urbanization, warrant significant and moderate concern, respectively, and appear to be in decline.

Air quality was the sole resource supporting chemical and physical environment at the memorial. The condition of air quality can affect human dimensions of the park such as visibility and scenery as well as biological components such as the effect of ozone levels on vegetation health. Air quality warrants significant concern and is largely impacted by historical and current land uses outside the memorial boundary.

The floral biological component was examined by assessing native species composition, Mean Coefficient of Conservation, Floristic Quality Assessment Index, invasive exotic plants, forest pests and disease, and forest vulnerability to climate change. Vegetation resources at LIBO have been influenced by historical land uses that have changed the species composition and age structure of these communities. Although large tracts of forests can be found surrounding the park, the majority of forested areas are fragmented, and few areas within and around LIBO exhibit late-successional or old-growth characteristics. Vegetation communities at LIBO have a long history of being impacted by a variety of stressors and threats including noxious and invasive weeds, diseases and insect pests; compounding effects of climate change, air pollution, acid rain/atmospheric chemistry, and past land uses; and impacts associated with overabundant white-tail deer populations. These stressors and threats have collectively shaped and continue to impact plant community condition and ecological succession. The sole metric in good condition was native species composition, while all other indicators and metrics warranted either moderate or significant concern.

The faunal biological components examined included birds, herptiles, and mammals. Birds (unchanging trend) and herptiles (no trend determined) warrant moderate concern, while mammal populations warrant significant concern (no trend determined). The confidence of both herptiles and mammals was low due to length of time since data were last collected. Current forest structure within and surrounding LIBO generally reflects the historical overstory composition but changes in the hardwood forest at LIBO and the surrounding area have resulted in declines in the avian fauna of the region since the 1970s. The decline in woodland bird populations has been caused by multiple factors including the conversion of hardwood forest to other land cover types, habitat fragmentation, and increasing human population growth.

The identification of data gaps during the course of the assessment is an important NRCA outcome. Resource-specific details are presented in each resource section. In some cases, significant data gaps contributed to the resource not being evaluated or low confidence in the condition or trend being assigned to a resource. Primary data gaps and uncertainties encountered were lack of recent survey data, uncertainties regarding reference conditions, availability of consistent long-term data, and the need for more robust or sensitive sampling designs.

Impacts associated with development outside the park will continue to stress some resources. Regionally, the direct and indirect effects of climate change are likely but specific outcomes are uncertain. Nonetheless, within the past several decades, some progress has been made toward restoring the quality of natural resources within the park, most notably the forested environments. Regional and park-specific mitigation and adaptation strategies are needed to maintain or improve the condition of some resources over time. Success will require acknowledging a ?dynamic change context? that manages widespread and volatile problems while confronting uncertainties, managing natural and cultural resources simultaneously and interdependently, developing disciplinary and interdisciplinary knowledge, and establishing connectivity across broad landscapes beyond park borders.