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Chapter 4 Refuge Biology Chapter 1 Introduction and ... · PDF file Chapter 4. Refuge Biology and Habitat 4-1 Chapter 4. Refuge Biology and Habitats This chapter addresses the biological

Jun 21, 2020

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  • Chapter 4 Refuge Biology

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  • Kīlauea Point National Wildlife Refuge Draft Comprehensive Conservation Plan and Environmental Assessment

    Chapter 4. Refuge Biology and Habitat 4-1

    Chapter 4. Refuge Biology and Habitats This chapter addresses the biological resources and habitats of Kīlauea Point NWR; however, it is not an exhaustive overview of all species and habitats occurring within the Refuge. The chapter begins with a discussion of biological integrity; we then focus on the presentation of pertinent background information for the priority resources of concern and other benefitting species designated under the CCP. Background information includes descriptions, locations, conditions, trends, key ecological attributes, and threats (stresses and sources of stress) to the habitats and/or associated resources of concern. The information presented was used to develop goals and objectives for the CCP (see Chapter 2).

    4.1 Biological Integrity, Diversity, and Environmental Health

    The Improvement Act directs the Service to ensure that the biological integrity, diversity, and environmental health (BIDEH) of the Refuge System is maintained for the benefit of present and future generations of Americans. The Service’s policy on BIDEH (601 FW 3) also provides guidance for consideration and protection of the broad spectrum of fish, wildlife, and habitat resources found on refuges and associated ecosystems that represent BIDEH on each refuge. The Refuge Administration Act, as amended by the Improvement Act, clearly establishes that wildlife conservation is the singular Refuge System mission. House Report 105-106 accompanying the Improvement Act states “…the fundamental mission of our System is wildlife conservation: wildlife and wildlife conservation must come first.” BIDEH is a critical component of wildlife conservation. BIDEH policy defines biological integrity as “the biotic composition, structure, and functioning at genetic, organism, and community levels comparable with historic conditions, including the natural biological processes that shape genomes, organisms, and communities.” Biological diversity is defined as “the variety of life and its processes, including the variety of living organisms, the genetic differences among them, and communities and ecosystems in which they occur.” Environmental health is defined as the “composition, structure, and functioning of soil, water, air, and other abiotic features comparable with historic conditions, including the natural abiotic processes that shape the environment.” In simplistic terms, elements of BIDEH are represented by native fish, wildlife, plants, and their habitats, as well as those ecological processes that support them. Biological integrity lies along a continuum from a completely natural system to a biological system extensively altered by considerable human impacts to the landscape. No modern landscape retains complete BIDEH. However, we strive to prevent the further loss of natural biological features and processes. Maintaining or restoring biological integrity is not the same as maximizing biological diversity. Maintaining biological integrity may entail managing for a single species or community at some refuges and combinations of species or communities at other refuges. Maintaining critical habitat for a specific endangered species, even though it may reduce biological diversity at the refuge scale, helps maintain biological integrity and diversity at the ecosystem or national landscape scale. Historically, migratory and nonmigratory native birds and native coastal plant communities may have thrived in the Kīlauea Point area in some or most years and on multiple islands on much larger landscapes. This is supported by fossil and subfossil records of species in lowlands, previously thought to be restricted to higher elevations or other islands, including, ‘a‘o, ‘ua‘u, and nēnē (Burney et al. 2001). Native coastal ecosystems are among the most threatened ecosystems in the Hawaiian

  • Kīlauea Point National Wildlife Refuge Draft Comprehensive Conservation Plan and Environmental Assessment

    4-2 Chapter 4. Refuge Biology and Habitat

    Islands due to the long-term presence of humans and the negative effects of their actions— specifically, development, agriculture, fire, and the introduction of invasive species. Therefore, to conserve native plant and animal populations at larger landscape scales to support long-term regional conservation goals, we may manage habitats at the Refuge to maintain higher densities of native species than those that may have occurred historically at the Refuge level because of loss and degradation of surrounding habitat. On refuges, we typically focus our evaluations of biological diversity at the refuge scale; however, these refuge evaluations can contribute to assessments at larger landscape scales. We strive to maintain populations of breeding individuals that are genetically viable and functional. Evaluations of biological diversity begin with population surveys and studies of flora and fauna. The Refuge System's focus is on native species and natural communities such as those found under historical conditions. We evaluate environmental health by examining the extent to which environmental composition, structure, and function have been altered from historic conditions. Environmental composition refers to abiotic components, such as air, water, and soils, all of which are generally interwoven with biotic components (e.g., decomposers live in soils). Environmental structure refers to the organization of abiotic components, such as atmospheric layering, aquifer structure, and topography. Environmental function refers to the processes undergone by abiotic components, such as wind, tidal regimes, evaporation, and erosion. A diversity of abiotic composition, structure, and function tends to support a diversity of biological composition, structure, and function. We strive to manage in a holistic manner the combination of BIDEH. We balance all three by considering refuge purposes, Refuge System mission, and landscape scales. Where practical, we support the return of extirpated native species in the context of surrounding landscapes. The elements of BIDEH for Kīlauea Point NWR are summarized in Table 4.1 below. Table 4-1. Biological Integrity, Diversity, and Environmental Health. Habitats Historic habitat

    attributes Historic natural processes responsible for these conditions

    Current limiting factors

    Coastal mixed woodland- grassland

    Native-dominated coastal dry-mesic shrubland, mixed shrub and grassland, and mixed shrubland and forest communities with

  • Kīlauea Point National Wildlife Refuge Draft Comprehensive Conservation Plan and Environmental Assessment

    Chapter 4. Refuge Biology and Habitat 4-3

    Sea cliff Native-dominated coastal dry-mesic shrubland, mixed shrub and grassland, and mixed shrubland and forest communities with >45° slope. Potential conservation species: seabirds including ‘iwa, ‘ā, ‘ua‘u kani, koa‘e kea and rare native coastal plant communities supporting threatened and endangered plants and endemic insects.

    Shallow, well-drained, highly erodible, saline, phosphorus-rich soils; wind, wave, and water erosion; and low annual precipitation.

    Invasive species: ironwood, Christmasberry, lantana, haole koa, introduced mammalian and avian predators and scavengers and insect pests; climate change; human development; human trespass

    Beach strand Bare sand, gravel, or rock within or just above the tidal zone; sparsely vegetated by native- dominated coastal dry herbland and mixed communities. Potential conservation species: ‘ilio-holo-i-ka- uaua, honu, migratory shorebirds, ‘iwa, ‘ā, and rare native coastal plant communities.

    Well-drained, sandy to rocky substrates; wind and water erosion; wave inundation; saline environment; low annual precipitation.

    Invasive species: ironwood, Christmasberry, lantana, haole koa, introduced mammalian and avian predators and scavengers and insect pests; climate change; human trespass

    4.2 Priority Resources of Concern

    4.2.1 Analysis of Resources of Concern

    In identifying resources of concern (ROCs), the team followed the process outlined in the Service’s draft Identifying Refuge Resources of Concern and Management Priorities: A Handbook (USFWS 2010). As defined in the Service’s Policy on Habitat Management Plans (620 FW 1), ROCs are:

    “all plant and/or animal species, species groups, or communities specifically identified in refuge purpose(s), System mission, or international, national, regional, state, or ecosystem conservation plans or acts. For exa