Quantifying Ecological Integrity of Terrestrial Systems to Inform Management of Multiple-Use Public Lands in the United States

Abstract

The concept of ecological integrity has been applied widely to management of aquatic systems, but still is considered by many to be too vague and difficult to quantify to be useful for managing terrestrial systems, particularly across broad areas. Extensive public lands in the western United States are managed for diverse uses such as timber harvest, livestock grazing, energy development, and wildlife conservation, some of which may degrade ecological integrity. We propose a method for assessing ecological integrity on multiple-use lands that identifies the components of integrity and levels in the ecological hierarchy where the assessment will focus, and considers existing policies and management objectives. Both natural reference and societally desired environmental conditions are relevant comparison points. We applied the method to evaluate the ecological integrity of shrublands in Nevada, yielding an assessment based on six indicators of ecosystem structure, function, and composition, including resource- and stressor-based indicators measured at multiple scales. Results varied spatially and among indicators. Invasive plant cover and surface development were highest in shrublands in northwest and southeast Nevada. Departure from reference conditions of shrubland area, composition, patch size, and connectivity was highest in central and northern Nevada. Results may inform efforts to control invasive species and restore shrublands on federal lands in Nevada. We suggest that ecological integrity assessments for multiple-use lands be grounded in existing policies and monitoring programs, incorporate resource- and stressor-based metrics, rely on publicly available data collected at multiple spatial scales, and quantify both natural reference and societally desired resource conditions.

Bridging the research-management gap: landscape science in practice on public lands in the western United States

“…The Bureau of Land Management (BLM) has directed its staff to ''incorporate appropriately-scaled metrics in monitoring plans that clearly indicate if landscape and habitat conditions are trending toward, or away from, desired outcomes'' (BLM 2018). The National Park Service and U.S. Forest Service now organize their monitoring and, in the case of the U.S. Forest Service, their planning (36 CFR 219 [2012]), around the concept of ecological integrity, which requires identifying the natural range of variability of multiple ecological indicators across large spatial and temporal extents (Wurtzebach and Schultz 2016;Carter et al 2019).…”

Informing conservation decisions to target private lands of highest ecological value and risk of loss

“…The ecological metrics are summarized below and in Table 1. The resolution of all the layers was 30 m except for Protection‐weighted Range‐size Rarity of Imperiled Species, which was 990 m. Various other metrics and/or data sources could have been used (see e.g., Carter et al, 2019; Hansen, Noble, et al, 2021; Tierney et al, 2009; Walston & Hartmann, 2018), and we selected these metrics because in our judgment they best meet the criteria above.…”

The Ecosystem Integrity Index: a novel measure of terrestrial ecosystem integrity

“…The concept was further developed by Parrish et al (2003), who proposed that 'an ecological system has integrity when its dominant ecological characteristics (e.g., elements of structure, composition, function, and ecological processes) occur within their natural ranges of variation'. Carter et al (2019), simplified this further to define ecosystem integrity as 'the extent to which the composition, structure, and function of an ecosystem fall within their natural range of variation'. Structure comprises the three-dimensional aspect of ecosystems -the biotic and abiotic elements that form the heterogeneous matrix supporting the composition and functioning.…”

“…(2003), who proposed that ‘an ecological system has integrity when its dominant ecological characteristics (e.g., elements of structure, composition, function, and ecological processes) occur within their natural ranges of variation’. Carter et al . (2019), simplified this further to define ecosystem integrity as ‘the extent to which the composition, structure, and function of an ecosystem fall within their natural range of variation’.…”