Arthur C. Medeiros

Effects of the Argentine ant on arthropod fauna of Hawaiian high-elevation shrubland.

Human-caused biological invasions by an alien species are a worldwide phenomenon. They are particularly significant on isolated oceanic islands and represent a serious threat to endemic biota. The Argentine ant (Iridomyrmex humilis) has become established in portions of the high-elevation shrubland of Haleakala National Park, Maui, Hawaii, over the past 25 yr. This ecosystem lacks native ants but possesses many locally endemic and rare arthropod species. Pitfall trapping and under-rock surveys were conducted to determine the effects of I. humilis on the local arthropod fauna. More than 180 taxa were sampled, mostly Arthropoda. Presence of the Argentine ant is associated with reduced populations of many native and non-native arthropod species, including important predator species and major pollinators of native plants. Effects of ant invasion were particularly severe at higher elevations of Haleakala volcano where endemic species normally exist at low densities. Some taxa, primarily alien species, were more abundant in the presence of ants. Invasion of the Argentine ant has locally reduced the abundance of many endemic species in the shrubland ecosystem. Although the spread of this ant species is slow, I. humilis appears to have the potential to invade a much larger area of Haleakala National Park than it now occupies. Active management of Argentine ant populations will be nec- essary if the endemic fauna is to be preserved.

A Multiagency Containment Program for Miconia(Miconia calvescens)an Invasive Tree in Hawaiian Rain Forests

Invasiveness of a species in a particular part of the world can often be successfully predicted by the species’ invasive behavior in another part of the world with similar environmental conditions. When naturalized miconia(Miconia calvescens;Melastomataceae) was discovered on Maui, Hawaii, in 1990, biologists responsible for protecting native ecosystems paid attention because of the infamous reputation of this species in ecologically similar Tahiti (French Polynesia), where it has come to extensively dominate forests since its introduction there in 1937. This species was introduced to the Hawaiian Islands as an ornamental in the early 1960s without attracting any great attention and was sold at nurseries for 2 decades. As of 1996, miconia had aroused a battle cry throughout the state of Hawaii, and cooperative efforts for its control were underway on four islands.

Dry Forest Restoration and Unassisted Native Tree Seedling Recruitment at Auwahi, Maui

Abstract: Efforts to restore highly degraded but biologically significant forests draw from a limited toolbox. With less than 10% of their former distribution remaining, Hawaiian dry forests, though critically endangered, remain important biological and cultural refugia. At restoration onset (1997), vegetation of restoration and control areas of degraded Auwahi dry forest, Maui Island, was similar, dominated by nonnative graminoids (restoration 78.3%; control 75.4%), especially Cenchrus ( Pennisetum) clandestinus. In 2012, unrestored control area vegetation was basically unchanged. In contrast, in the restoration area in 2012, native shrub cover increased from 3.1% to 81.9%, and cover of nonnative graminoids declined from 75.4% to 3.3%. In 2012, nonplanted seedlings of 14 of 22 native tree species and six of seven native shrub species were observed in restoration plots; the majority (99%) were five native (Dodonaea viscosa, Coprosma foliosa, Osteomeles anthyllidifolia, Chamaesyce celastoides, Nestegis sandwicensis) and one nonnative species (Bocconia frutescens). By 2012, stem counts of native woody plants had increased from 12.4 to 135.0/100 m2, and native species diversity increased from 2.4 to 6.6/100 m2. By 2012, seven rare dry forest tree species, Charpentiera obovata, Nothocestrum latifolium, Ochrosia haleakalae, Pleomele auwahiensis, Santalum ellipticum, S. haleakalae, and Streblus pendulinus, had established seedlings and/or saplings within the restoration site, especially notable because natural reproduction is largely lacking elsewhere. Without development and implementation of appropriate management strategies, remaining Hawaiian dry forest will likely disappear within the next century. Multicomponent restoration incorporating ungulate exclusion, weed control, and outplanting as described here offers one strategy to conserve and restore tracts of high-value but degraded forests.

Conservation of Cloud Forests in Maui County (Maui, Moloka‘i, and Lana‘i), Hawaiian Islands

Cloud forests of the Hawaiian Islands are crucially important as watershed and as reservoirs of endemic biological diversity. This paper (1) sketches the environment and biology of the cloud forests of Maui County, Hawai’i, with emphasis on upper Haleakala volcano, East Maui, and (2) describes threats to these forests and management efforts under way to maintain biologically intact cloud forests. The islands of Maui County and the approximate location of the cloud forests are shown in Figure 1.

Geranium hanaense (Geraniaceae), a new species from Maui, Hawaiian Islands

Geranium hanaense, a new species endemic to two small montane bogs (20 ha total) on northeast Haleakala, Maui, Hawaiian Islands, is described. This new species is postulated to have evolved from the high elevation xeromorphic species,G. cuneatum, in a fashion similar to that of the two other bogGeranium species. The ecology and evolution of HawaiianGeranium species, includingG. hanaense, are discussed.