Natural resource condition assessment: Haleakalā National Park

Krushelnycky, Paul; Chimera, Charles; VanderWerf, Eric

Natural Resource Condition Assessments (NRCAs) evaluate current conditions for a subset of natural resources and resource indicators in national park units. Haleakalā National Park (HALE), the unit that is the focus of this NRCA, is a 33,719 acre (13,645 ha) natural area on the island of Maui, Hawaiʻi. HALE includes lands from sea level to the summit of Haleakalā Volcano at 10,023 ft (3,056 m) elevation, and protects a remarkable diversity of biomes and ecosystem types. These include, but are not limited to: coastal strand and scrub; dry, mesic and wet lowland forests; montane mesic or wet forests and bogs; subalpine grasslands and mesic or dry shrublands, which grade into alpine desert; and freshwater ecosystems. The NRCA for HALE covers 16 focal resources that were chosen for assessment, split among three overarching categories: Life-Supporting Environment, Biological Integrity, and Landscape Condition Context. Current conditions for each of these resources, and for constituent indicators that were considered to be most relevant in characterizing the resources, were evaluated according to all available information and assigned to one of three broad categories: good, warranting moderate concern, and warranting significant concern. When sufficient temporal information was available, an increasing, stable, or declining trend in the condition was also assigned. When insufficient information was available, current conditions and/or trends were categorized as unknown. Of the three focal resources pertaining to the Life-Supporting Environment, Water Quality was judged to be in good current condition with an unknown trend, Air Quality was judged to be good with an improving trend, and Soil Quality was judged to warrant moderate concern. Water Quality is characterized by no or few known violations of state standards in levels of total phosphorus, total nitrogen, and turbidity, but somewhat more frequent exceedances for nitrate + nitrite. Air Quality is often very good, but is periodically impacted by volcanic emissions from Kīlauea Volcano on Hawaiʻi Island, which is a natural process. Visibility showed an improving trend as volcanic emissions decreased between 2010 and 2015, but it remains to be seen how the 2018 eruption will affect that trend. Soil Quality is generally good in most regions of the park with the exception of the newer Nuʻu Parcel, where severe erosion caused by large numbers of feral ungulates has long been a problem. This condition is currently stable, but is anticipated to improve in the future as large portions of the parcel are fenced to exclude the ungulates, and stabilizing vegetation recovers. Ten focal resources pertain to Biological Integrity, and their assessment comprised the bulk of the NRCA. Only three of these resources (Cave Ecosystems, Sub-alpine Grassland Ecosystems, and the Crater ecoregion) were judged to be in good condition. All three were assigned a stable trend. Cave Ecosystems support a number of unique cave-adapted invertebrate species, and these communities appear relatively undisturbed. Sub-alpine Grassland Ecosystems are currently minimally invaded, being characterized by native plant diversity, and especially cover, that is higher than that of non-native plants. The Crater also supports native plant diversity and cover that is substantially higher than that of non-native plants, a condition due in large part to the fencing and removal of ungulates. However, recent evidence indicates that changing climate is impacting at least some plants, like ‘āhinahina, and may be an important new influence in Crater ecosystems. A moderate fraction of shrubland arthropod communities is composed of non-native species, including the highly damaging Argentine ant and western yellowjacket. The distribution of the Argentine ant in the Crater is currently limited but expanding, and is contributing to a worsening condition of native invertebrate communities.

Natural resource condition assessment: Haleakalā National Park

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