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Accessible information on Galápagos soils is very limited. Much of the existing, although still scarce, information is several decades old and not easily retrieved. The aim of this paper is to present a critical synthesis. Three local soilforming factors (parent material, climate, and vegetation) are briefly highlighted, followed by a more detailed discussion of the hypsometric soil sequence on Santa Cruz, the only island where systematic information was recorded by a Belgian geopedological mission in 1962. Five zones are distinguished from the coast toward the top of the island: a dry coastal area, containing superficial and interstitial reddish, smectite-bearing soils between basalt blocks; a transition zone of brown, also smectite-bearing soils; and three subsequent higher zones covered by deeper, brown soils with probably andosolic characteristics. Trace element analyses point to a uniform composition of the parent material and a more progressed weathering on the higher slopes. Micromorphological characteristics of the soils are discussed. Soils of Santa Fé are comparable with those of the coastal zone of Santa Cruz but show higher amounts of P and S, probably of avian origin. Deeper, reddish clayey soils cover San Cristóbal and are at least partly pre- Holocene. On the younger islands, no soils seem to be present.
Considerable time and effort has been spent removing nonnative ungulates from sensitive subalpine and forest areas in Hawai'i, with less effort dedicated to documenting changes in plant community structure after feral animal removal. Abundance of native and nonnative vegetation was quantified in a study comparing plots both before (1994) and 14 yr after (2008) removal of feral animals from windward East Maui subalpine and forest habitat in Waikamoi Preserve. An analysis of changes in abundance in two vegetation layers documented increases in relative cover of native subalpine vegetation: bryophytes tripled and lichens increased over nine times in the subalpine shrubland habitat within the ground cover (0 to 1 m) layer, and alien grass cover was halved. In the understory (1 to 2 m) layer, native ferns increased significantly, and native shrub cover tripled. In the forest habitat, bryophytes increased in both layers, and lichens increased in the understory layer. Higher-elevation plots in 2008 more closely resembled the species composition and abundance of plots about 100 m lower in elevation sampled in 1994. Rainfall declined and temperatures increased during the study period; however, vegetation responses were more likely a result of release from ungulate damage than a response to climate. We conclude that goat and pig removal programs conducted in the late 1980s and early 1990s likely contributed to an overall increase in native vegetation cover in spite of a relatively dry 14-yr period since ungulate removal.
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.
A single strain of Puccinia psidii, the causal agent of rust disease on Myrtaceae, was recently reported on multiple myrtaceous hosts in Hawai'i, but this strain has caused only mild levels of damage to the state's predominant native forest tree, ‘ōhi‘a ( Metrosideros polymorpha). Multiple other strains of Puccinia psidii have been identified from Brazil and characterized via extensive sampling and microsatellite analyses. Potential effects of other Brazilian P. psidii strains on Hawai'i's ‘ōhi‘a were investigated with two inoculation experiments conducted in Brazil. The first, a split-plot experiment, was conducted to determine pathological impact of five Brazilian P. psidii strains on ‘ōhi‘a seedlings and to assess variation in susceptibility of seedlings from six different open-pollinated ‘ōhi‘a parent trees to each P. psidii strain. The second experiment was conducted to determine influence of the rust disease on growth and survival of ‘ōhi‘a seedlings. Three of the five P. psidii strains were highly virulent on most of the inoculated ‘ōhi‘a seedlings (93%–100% infection rates), and none of the ‘ōhi'a families used in this test showed significant resistance. The other two strains tested were much less virulent. Infection by the highly virulent strains of P. psidii resulted, on average, in a 69% reduction in height growth and 27% increase in mortality of ‘ōhi‘a seedlings at 6 months postinfection. These results have immediate implications for designing Hawai'i's quarantine barriers.
This study investigated cerambycid long-horned beetles in a lowland tropical forest in Fiji and produced 18 new records of beetle-tree associations along with data on beetle phenology and development times. Beetles were reared from timber baits exposed for 1 month to ovipositing females in the Savura Forest Park, Viti Levu. Twelve native, locally common tree species representing 10 families were examined. For each tree, two baits consisting of 16 kg of freshly cut branches were exposed in each of four time periods between June 2008 and May 2009. Eighteen cerambycid species and 557 individual beetles were reared from the 96 baits, with three of the beetle species probably being undescribed. Ceresium was the most abundant genus, representing almost 90% of all individuals reared, with most adults emerging between 4 and 6 months after the timber baits were exposed. Seventeen of the 18 beetle species each emerged from timber belonging to a single tree species, although more rearing records are required to support the high level of host-plant specificity reported here.
Wildlife species that have been translocated between temperate and tropical regions of the world provide unique opportunities to understand how disease processes may be affected by environmental conditions. European mouflon sheep (Ovis gmelini musimon) from the Mediterranean islands were introduced to the Hawaiian Islands for sport hunting beginning in 1954 and were subsequently hybridized with feral domestic sheep (O. aries), which had been introduced in 1793. Three isolated mouflon populations have become established in the Hawaiian Islands, but diseases in these populations have been little studied. The objective of this study was to evaluate and compare gross and histologic lesions in respiratory, renal, and hepatic systems of free-ranging sheep in two isolated volcanic environments on Hawai'i Island. Tissue and fecal samples were collected in conjunction with population reductions during February 2011. We found gross or histologic evidence of lungworm infection in 44/49 sheep from Mauna Loa that were exposed to gaseous emissions from Kīlauea Volcano. In contrast, only 7/50 sheep from Mauna Kea had lesions consistent with lungworm, but Mauna Kea sheep had significantly more upper respiratory tract inflammation and hyperplasia consistent with chronic antigenic stimulation, possibly associated with exposure to fine airborne particulates during extended drought conditions. We hypothesize that gases from Kīlauea Volcano contributed to severity of respiratory disease principally associated with chronic lungworm infections at Mauna Loa; however, there were numerous other potentially confounding environmental factors and interactions that merit further investigation.
The Hawaiian Euphorbia is an assemblage of 17 species, seven of which are endangered and four others rare. Euphorbia kuwaleana is an endangered species of small shrubs restricted to three small populations in West O'ahu, Hawai'i. The species has declined to fewer than 1,000 individuals largely due to habitat encroachment by alien plant species and the periodic fires that occur in the vicinity. Genetic variation was assessed among individuals in two populations to determine what impact small population size has had on genetic diversity within the species using RAPD markers. Results demonstrate that polymorphism within these populations is high (mean = 82.5%), equal to or exceeding that of many other nonendangered Hawaiian species. Genetic similarities within (0.741) and among (0.716) populations, FST (0.072), and PCO analysis all indicate differentiation among the populations although in close geographical proximity (<1 km apart). Conservation efforts for this species should focus on protection of existing populations from eminent threats and the establishment of new populations in suitable habitats on O'ahu.
Hybridization between alien plant species and their native congeners represents a major global threat to native floras. In Hawai'i, two introduced cotton species, Pima cotton (G. barbadense) and Upland cotton (G. hirsutum), have naturalized on the main Hawaiian Islands. Both species are capable of producing fertile hybrids with the native Hawaiian cotton (G. tomentosum). Hybrid populations between Pima and Hawaiian cotton were documented at Nanakuli on the Wai'anae coast of O'ahu in 1964 by the late Stanley G. Stephens. Extant populations of Pima and Hawaiian cotton in the vicinity of those documented by Stephens (1964) were screened using both morphological and molecular (microsatellite markers) techniques to assess persistence of the original hybrid population and potential gene flow that may have occurred between the two cotton species. We did not relocate the original hybrid populations described in Stephens (1964), although a herbarium voucher that was verified as a hybrid indicates that at least one hybrid plant occurred at a nearby site until as late as 1980. No hybrids between Pima and Hawaiian cotton were found in populations of either species, suggesting that no recent gene flow has taken place and that hybrid plants have not persisted or spread.
Detailed morphological and rbcL sequence analyses are presented for two species of Gelidium collected along the Pacific coast of Costa Rica. Although relatively well known in the tropical eastern Pacific, Gelidium sclerophyllum W. R. Taylor had previously been collected only once in Costa Rica. Four current G. sclerophyllum collections were found to have identical rbcL sequences and differed from a partial sequence for an isotype specimen at only one base pair. Phylogenetic analyses revealed that G. sclerophyllum and G. floridanum W. R. Taylor are geminate sister species. Development of the female reproductive system and cystocarps were observed to follow the usual patterns described for Gelidium species. Spermatangial development in G. sclerophyllum was also observed for the first time and revealed the cutting off of spermatia by transverse divisions as is characteristic of Gelidiales. The new species, Gelidium microglossum Grusz & Freshwater, was also collected and described. This is a small species with a prostrate habit, generally compressed axes of variable width, and clavate to obphyriform ultimate branches. Distinctive characteristics include spatulate tetrasporangial branchlets, medullary cells often forming a meshlike network, variably oriented rhizines, and an unusual attachment haptera structure. Phylogenetic analyses resolve G. microglossum within Gelidium, but placement within the genus remains uncertain.
Maesa canfieldiae Fosberg & Sachet was formerly recognized as a single- island endemic in the Palau archipelago with a potentially rare distribution warranting its listing on the IUCN Red List as Vulnerable. Here we synonymize M. canfieldiae into Maesa tetrandra (Roxb.) A. DC., a more widespread species native to Indonesia and New Guinea, and discuss its likely method of recent introduction to the Palau Islands. Because this particular species favors disturbance and is now considered naturalized in the Pacific, we have included a general description of the plant to aid in its identification by nonexperts and to allow monitoring of its invasive potential. We recommend the listing of M. tetrandra as Least Concern on the IUCN Red List.
Oceanic island ecosystems are particularly vulnerable to invasion by exotic species, and this vulnerability may be intensified by the effects of climate change, particularly if favorable climate conditions allow exotic invaders to spread to new areas. Effective management of such species requires knowledge of their potential distribution under current and future climate. This research examines the value of species distribution modeling in invasive species management in small island ecosystems using the specific case of Lantana camara L. invasion in Fiji. A niche model of L. camara was developed using CLIMEX species distribution modeling (SDM) software. Several sources of data were used to develop the model including phenological observations and geographic distribution records. The model was used to estimate its potential distribution under historical climate. The CSIRO Mk3.0 Global Climate Model (GCM) was used to explore impacts of climate change on its potential future distribution. The model was run with the A1B and A2 scenarios for 2030 and 2070. Large parts of both major islands of Fiji, Viti Levu and Vanua Levu, were shown to have high climatic suitability for L. camara. However, under future climate scenarios, climatic suitability for L. camara in Fiji was projected to contract. The results illustrate that SDMs can play a useful role in formulation of cost-effective invasive species management strategies and the resulting species distribution maps have broad applicability throughout the many islands of the South Pacific region.