Hawaii Volcanoes Research Articles

Reported fatal and non-fatal incidents involving tourists in Hawaii Volcanoes National Park, 1992–2002

Objectives. To examine fatal and non-fatal incidents involving tourists in Hawaii Volcanoes National Park. Methods. Official press releases from the public relations office at Hawaii Volcanoes National Park were examined for reports of fatal and non-fatal incidents involving tourists. Results. Between 1992 and 2002 there were 65 press releases reporting 40 fatalities, 45 serious injuries, 53 minor injuries, and 25 no injury events. Severity information was unavailable for four additional tourists. Aircraft and backcountry incidents each accounted for 30% of all incidents followed by road incidents (22%) and frontcountry incidents (17%). Aircraft incidents reported 17 fatalities, backcountry incidents accounted for 10 fatalities, frontcountry incidents reported seven fatalities, and road incidents totaled six fatalities. One fatality was classified as a suicide. Backcountry (23) and road (10) incidents had the highest number of serious incidents. Male tourists (62) were more frequently involved in incidents than female tourists (41) and tourists aged 20-29 years and 40-49 years accounted for the highest number of fatalities and total incidents. Conclusions. Helicopter tours, hiking in areas with active lava flows, falls into steam vents and earthcracks, and driving unfamiliar rental cars in unfamiliar locations are the major activities resulting in death and serious injury. Additional factors such as tourists ignoring warning signs, wandering off-trail or hiking at night, tourists misinformed by guidebooks and other tourists, and tourists with pre-existing heart and asthma conditions are contributing causes in many incidents. The findings of this study provide information that allows prospective tourists, tourism managers, and travel health providers make informed decisions that promote safe tourism and can aid future efforts in developing preventative strategies at tourist destinations with similar environments and activities. However, in order for preventative strategies to be most effective, future research using medical or emergency response records and employing an injury epidemiology framework that identifies the cause of fatal and non-fatal injuries is recommended.

Viewing Lava Safely: An Epidemiology of Hiker Injury and Illness in Hawaii Volcanoes National Park

To report the injuries and illnesses encountered by wilderness hikers in Hawaii Volcanoes National Park attempting to hike to active lava flows and to investigate the roles that demographics, prior hiking experience, hiking behavior, and preparedness play in hiker vulnerability to injury and illness. During an 8-week period, daily on-site exit interviews of lava hikers were conducted by a uniformed park ranger and park volunteer. Information about the hiker's home residence, wilderness hiking experience, preparedness, health status, and health problems encountered during the hike was collected from a total of 804 hikers. A high rate of injury and illness was found among the study population. Scrapes and abrasions (59%), blisters (51%), and muscle strains and sprains (47%) were the most common injuries. Dehydration (77%) and respiratory irritation (46%) were the most common illnesses. Lower extremities were the most common site of injuries, and beginning hikers were the most vulnerable to injury and illness. Many hikers were inexperienced tourists willing to disregard warning signs and enter high-risk areas. Hawaii Volcanoes National Park is one of 22 US national park units with volcanic resources. The injuries and illnesses reported by the study group identify the impact that this type of environment can have on the safety of wilderness users in areas with similar resources. Recreating in remote and severe areas has inherent risks, but the high rate of injuries and illnesses sustained by the hikers of this study can potentially be reduced through the development of more direct risk management methods.

A Field-Oriented Volcanology Course to Improve Earth Science Teaching

Volcanology for Earth Science Teachers (VEST), a teacher enhancement project conducted by the University of Hawaii at Hilo (UH-Hilo), was funded by the National Science Foundation from 1994 to 1996. During the project, a total of 75 middle- and secondary-school Earth science teachers from Hawaii, Alaska, Washington, Oregon, and California participated in the three-week summer workshop, which consisted of classroom sessions held at UH-Hilo and in Hawaii Volcanoes National Park plus field excursions to the five volcanoes that make up the island of Hawaii. In the VEST workshop, the teachers gained information and teaching ideas about volcanic processes, products, and features; volcanic and related hazards; and eruption monitoring and prediction. The teachers, who were selected through a competitive application process, were required to develop a lesson plan for a teaching activity related to volcanology, conduct an inservice program in their school district based on their VEST experiences, and contribute an article to the bi-monthly VEST newsletter. Project LAVA is a self-supporting educational program that continues to offer the VEST experience to all teachers.

Magmatic precursors to the 18 May 1980 eruption of Mount St. Helens, USA

Research Article| February 01, 2004 Magmatic precursors to the 18 May 1980 eruption of Mount St. Helens, USA K.V. Cashman; K.V. Cashman 1Department of Geological Sciences, University of Oregon, Eugene, Oregon 97403-1272, USA Search for other works by this author on: GSW Google Scholar R.P. Hoblitt R.P. Hoblitt 2U.S. Geological Survey, Hawaiian Volcano Observatory, P.O. Box 51, Hawaii Volcanoes National Park, Hawaii 96718, USA Search for other works by this author on: GSW Google Scholar Geology (2004) 32 (2): 141–144. https://doi.org/10.1130/G20078.1 Article history received: 30 Jul 2003 rev-recd: 16 Oct 2003 accepted: 17 Oct 2003 first online: 03 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation K.V. Cashman, R.P. Hoblitt; Magmatic precursors to the 18 May 1980 eruption of Mount St. Helens, USA. Geology 2004;; 32 (2): 141–144. doi: https://doi.org/10.1130/G20078.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Perhaps the most difficult task facing volcanologists today is that of distinguishing between low-level volcanic restlessness and activity that presages a full-scale eruption. We illustrate these difficulties by reexamining the sequence of events that led to the 18 May 1980 eruption of Mount St. Helens, activity that is often presented as a classic example of early phreatic explosions leading to a magmatic eruption. This interpretation is problematic, however, given the known ascent of juvenile magma to within ∼250 m of the surface prior to the climactic event. Reexamination of ash samples from several precursory events shows that small amounts of juvenile material were erupted as early as 28 March 1980, just two weeks after the first seismic signals of reawakening, and that the juvenile content of the ash had probably increased by early May. The magmatic component of these eruptions was not recognized at the time because of the high crystallinity of the juvenile material—a signature of extensive degassing-induced crystallization during magma ascent. Identification of juvenile material in the precursory ash from Mount St. Helens has important implications for initiation of eruptive activity. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

The Effects of Exotic Grasses on Litter Decomposition in a Hawaiian Woodland: The Importance of Indirect Effects

Exotic grasses and grass-fueled fires have altered plant species composition in the seasonal submontane woodlands of Hawaii Volcanoes National Park. These changes have altered both structural and functional aspects of the plant community, which could, in turn, have consequences for litter decomposition and nitrogen (N) dynamics. In grass-invaded unburned woodland, grass removal plots within the woodland, and woodland converted to grassland by fire, we compared whole-system fluxes and the contributions of individual species to annual aboveground fine litterfall and litterfall N, and litter mass and net N loss. We assessed the direct contribution of grass biomass to decomposition and N dynamics, and we determined how grasses affected decomposition processes indirectly via effects on native species and alteration of the litter layer microenvironment. Grasses contributed 35% of the total annual aboveground fine litterfall in the invaded woodland. However, total litterfall mass and N were not different between the invaded woodland and the grass removal treatment because of compensation by the native tree Metrosideros polymorpha, which increased litter production by 37% ± 5% when grasses were removed. The 0.3 g N m−2/y−1 contained in this production increase was equal to the N contained in grass litter. Litter production and litterfall N was lowest in the grassland due to the loss of native litter inputs. Decomposition of litterfall on an area basis was highest in the grass-invaded woodland. We attributed this effect to increased inherent decomposability of native litter in the presence of grasses because (a) the microenvironment of the three vegetation treatments had little effect on decomposition of common litter types and (b) M. polymorpha litter produced in the invaded woodland decomposed faster than that produced in the grass removal plots due to higher lignin concentrations in the latter than in the former. Area-weighted decomposition was lowest in the grassland due to the absence of native litter inputs. Across all treatments, most litter types immobilized N throughout the incubation, and litter net N loss on an area basis was not different among treatments. Our results support the idea that the effects of a plant species or growth form on decomposition cannot be determined in isolation from the rest of the community or from the direct effects of litter quality and quantity alone. In this dry woodland, exotic grasses significantly altered decomposition processes through indirect effects on the quantity and quality of litter produced by native species.

EXOTIC GRASSES ALTER CONTROLS OVER SOIL NITROGEN DYNAMICS IN A HAWAIIAN WOODLAND

Exotic invasive grasses and fire have altered plant species composition in the seasonal submontane woodlands of Hawaii Volcanoes National Park. These changes have affected both structural and functional aspects of the plant community, which could have consequences for soil nitrogen (N) dynamics and N availability to plants. To determine if, when, and how soil N dynamics were altered by grass invasion, we measured net and gross N mineralization and nitrification during wet and dry seasons across three vegetation types: (1) experimental grass removal plots within unburned woodland created to simulate the native ecosystem that may have existed prior to invasion; (2) woodland invaded by grasses; and (3) invaded woodland converted to grassland by fire. Grass invasion into woodland shifted the timing, but not the amount, of N available. After conversion to grassland, N-cycling rates were 3.4 times greater. The wet season accounted for 35% of annual net N mineralization in the grass removal treatment, 75% in the...

Volcanically influenced iron and aluminum cloud water deposition to Hawaii

Fog or cloud water (CW) deposition plays an important role in particle scavenging and the delivery of trace constituents to the Earth's surface. In this study, CW concentrations of total dissolvable iron (Fe) and aluminum (Al) were measured in 60 samples spanning 26 individual CW events throughout 1999 in Hawaii Volcanoes National Park on the island of Hawaii. Al concentrations ranged from 8 to 10,489 nM, with a median of 344 nM while Fe concentrations ranged from < 1 to 6419 nM with a median of 32 nM. CW deposition fluxes for Fe and Al ranged from 0.15–0.52 mmol Fe m −2 yr −1 and 0.62 –1.35 mmol Al m −2 yr −1, depending on the estimation method used. The large range in concentrations is higher than expected for a relatively pristine ecosystem. It appears that this inconsistency is due to emissions from the currently active nearby volcano, Kilauea. Categorizing CW events into volcanically versus less or non-volcanically impacted events suggests that although volcanically impacted events only accounted for 12% of fog water deposition, Kilauea Volcano was responsible at least 42% of the measured CW Al deposition and 61% of the CW Fe deposition measured for 1999.

Dieback of Acacia koa in Hawaii: ecological and pathological characteristics of affected stands

Koa ( Acacia koa) is an endemic Hawaiian tree that serves as a keystone species in the upper elevation forests of all the main islands. In the Mauna Loa Strip area of Hawaii Volcanoes National Park, mature koa stands are suffering from an unexplained dieback that has increased in severity since it was first noticed approximately 25 years ago. The dieback is often evident in patches, and generally spreads within stands in a radial fashion from a localized infection center. Entire crowns of affected trees become wilted, with foliage gradually progressing from an apparent healthy to a completely chlorotic condition. Although most trees die soon after the onset of symptoms, some trees are able to survive crown death by producing epicormic shoots on the lower portions of the trunk. Previously published studies reported that a vascular wilt fungus ( Fusarium oxysporum f. sp. koae) was associated with koa seeds and the rhizosphere of healthy and dieback-affected koa stands. The purpose of this study was to characterize the stand structure, soil conditions, and physiological condition of dieback-affected trees, and to assess the possible role of F. oxysporum f. sp. koae in the current dieback stands. This fungus was isolated from branches of symptomatic koa in dieback-affected stands and roots from healthy and dieback-affected stands. Possible differences in the pathogenicity and virulence of F. oxysporum f. sp. koae isolates obtained from the roots of healthy koa in unaffected stands and those from branches of dieback-affected koa were determined by greenhouse inoculations of koa seedlings. Healthy koa saplings in stands unaffected by dieback were also inoculated to determine if disease symptoms could be induced by inoculation of injured roots in the field. Both branch and root isolates were pathogenic; with the percent mortality of inoculated seedlings ranging from 30 to 60% for all isolates. Disease severity between branch and root isolates was not significantly different. Wilt symptoms were not observed in field inoculations of koa saplings after 8 months. Investigation of the dieback stand structure determined that the larger size classes (i.e., DBH>3 cm ) were all affected equally, with the smallest size class (i.e., 0–3 cm DBH) having the lowest percentage of dieback at each site. Soil from dieback stands had higher water content and was more acidic than that from neighboring unaffected stands. Phyllodes on epicormic shoots of dieback trees had a reduced area, mass, and mass to area ratio. Phyllodes on dieback trees also had reduced stomatal conductance and higher (less negative) leaf water potential. Results from the greenhouse inoculations demonstrated that F. oxysporum f. sp. koae is pathogenic to koa, but the pathogen’s activity in the field may be influenced by predisposing factors such as temperature fluctuations, water availability, soil type, and interactions with other soil organisms. F. oxysporum f. sp. koae appears to play an important role in regulating koa stand dynamics, growth, and physiology under environmental and edaphic conditions favorable for disease development.

ALTERATION OF ECOSYSTEM NITROGEN DYNAMICS BY EXOTIC PLANTS: A CASE STUDY OF C4GRASSES IN HAWAII

Biological invaders can alter ecosystem processes via multiple pathways, yet few studies have compared the relative importance of these pathways. We assessed the impacts of exotic, invasive grasses on ecosystem nitrogen (N) cycling in the seasonal submontane woodlands of Hawaii Volcanoes National Park, where native grasses have been historically rare. Exotic grasses have become abundant over the past 30 yr and have altered two controls over N cycling: plant species composition and fire regime. Here we synthesize the results of a long-term investigation of species impacts in this system. To determine effects of grasses and fire on internal N cycling, we compared litterfall, decomposition, N mineralization from soil organic matter (SOM), and plant N uptake and production in invaded unburned forest, grass-removal plots within the forest, and woodland converted to grassland by fire. We measured ecosystem N loss via fire by comparing N pools among unburned, naturally burned, and experimentally burned sites. We...

Egg Parasitoids of Sophonia rufofascia (Homoptera: Cicadellidae) in Hawaii Volcanoes National Park

Abstract Parasitism of the leafhopper Sophonia rufofascia (Kuoh and Kuoh), a recent immigrant that has become a widespread pest in Hawaii, was examined in a 1-year survey in Hawaii Volcanoes National Park. Samples of young leaves of four plant species infested with eggs of S. rufofascia were collected at five sites ranging from 880 to 1190 m in elevation. Leafhopper eggs were parasitized principally by three species of Mymaridae (Hymenoptera): Polynema sp., Schizophragma sp. probably bicolor (Dozier), and Chaetomymar sp. Although parasitism by each species fluctuated at levels usually below 10%, all three were detected consistently across most host plants, sites, and sample periods. Total parasitism differed at a marginally significant level among host plants and sites, but not among sample periods. Total parasitism averaged 14.3% (maximum: 26.3%) on Dodonaea viscosa Jacquin, 10.6% (maximum: 17.5%) on Myrica faya Aiton, 8.7% (maximum: 29.5%) on Metrosideros polymorpha Gaudich-Beaupre, and 1.6% (maximum: 4.3%) on Vaccinium reticulatum Smith. Parasitism was generally higher at sites lower in elevation. Further monitoring is recommended to determine whether parasitism will increase to levels that can effectively suppress S. rufofascia populations. The efficacy of natural enemies already present in Hawaii is important because concern over nontarget impacts on endemic leafhoppers makes introduction of new biological control agents difficult.

Constraints on the energy and chemical balances of the modern TAG and ancient Cyprus seafloor sulfide deposits

The size, chemical composition, energy flux, and fluid composition of the TAG hydrothermal sulfide deposit at the Mid‐Atlantic Ridge and the size, chemical composition and reaction zone characteristics of the Skouriotissa volcanogenic massive sulfide deposit of the Troodos ophiolite in Cyprus are used to examine the energy requirements and chemical balances associated with the generation of a large volcanogenic massive sulfide deposit. We conclude that formation of large sulfide deposits from oceanic hydrothermal systems is a geologically rapid process and occurs on timescales of hundreds of years, with episodes of activity as short as a few tens of years separated by thousands of years of inactivity. About 2×1019 J of energy supplied at high temperature is required to form a deposit the size of the TAG mound. Metals (up to 4 times the mass of any element present in the sulfide deposit) are leached out of relatively small reaction zones most likely at the base of the sheeted dikes. Chemical balance can be struck for all elements except sulfur with a reaction zone 1–2 km3 in volume from which a small proportion of iron and large proportions of copper, zinc, and manganese are removed. A sulfur balance requires that a significant fraction of sulfur be derived from reduction of seawater sulfate, as suggested by stable isotope analyses. We argue that the principal source of energy that drives hydrothermal circulation is latent heat of crystallization of magma close to the top of the plutonic section. Furthermore, we speculate that activity of the TAG hydrothermal system is related to periods of more rapid magma supply from the mantle at magma supply rates similar to those observed in volcanoes in Hawaii and Iceland.

Variation in the impact of exotic grasses on native plant composition in relation to fire across an elevation gradient in Hawaii

AbstractThe impact that an exotic species can have on the composition of the community it enters is a function of its abundance, its particular species traits and characteristics of the recipient community. In this study we examined species composition in 14 sites burned in fires fuelled by non‐indigenous C4 grasses in Hawaii Volcanoes National Park, Hawaii. We considered fire intensity, time since fire, climatic zone of site, unburned grass cover, unburned native cover and identity of the most abundant exotic grass in the adjacent unburned site as potential predictor variables of the impact of fire upon native species. We found that climatic zone was the single best variable for explaining variation in native cover among burned sites and between burned and unburned pairs. Fire in the eastern coastal lowlands had a very small effect on native plant cover and often stimulated native species regeneration, whereas fire in the seasonal submontane zone consistently caused a decline in native species cover and almost no species were fire tolerant. The dominant shrub, Styphelia tameiameia, in particular was fire intolerant. The number of years since fire, fire intensity and native cover in reference sites were not significantly correlated with native species cover in burned sites. The particular species of grass that carried the fire did however, have a significant effect on native species recovery. Where the African grass Melinis minutiflora was a dominant or codominant species, fire impacts were more severe than where it was absent regardless of climate zone. Overall, the impacts of exotic grass‐fuelled fires on native species composition and cover in seasonally dry Hawaiian ecosystems was context specific. This specificity is best explained by differences between the climatic zones in which fire occurred. Elevation was the main physical variable that differed among the climatic zones and it alone could explain a large percentage of the variation in native cover among sites. Rainfall, by contrast, did not vary systematically with elevation. Elevation is associated with differences in composition of the native species assemblages. In the coastal lowlands, the native grass Heteropogon contortus, was largely responsible for positive changes in native cover after fire although other native species also increased. Like the exotic grasses, this species is a perennial C4 grass. It is lacking in the submontane zone and there are no comparable native species there and almost all native species in the submontane zone were reduced by fire. The lack of fire tolerant species in the submontane zone thus clearly contributes to the devastating impact of fire upon native cover there.

Variation in the impact of exotic grasses on native plant composition in relation to fire across an elevation gradient in Hawaii

The impact that an exotic species can have on the composition of the community it enters is a function of its abundance, its particular species traits and characteristics of the recipient community. In this study we examined species composition in 14 sites burned in fires fuelled by non-indigenous C4 grasses in Hawaii Volcanoes National Park, Hawaii. We considered fire intensity, time since fire, climatic zone of site, unburned grass cover, unburned native cover and identity of the most abundant exotic grass in the adjacent unburned site as potential predictor variables of the impact of fire upon native species. We found that climatic zone was the single best variable for explaining variation in native cover among burned sites and between burned and unburned pairs. Fire in the eastern coastal lowlands had a very small effect on native plant cover and often stimulated native species regeneration, whereas fire in the seasonal submontane zone consistently caused a decline in native species cover and almost no species were fire tolerant. The dominant shrub, Styphelia tameiameia, in particular was fire intolerant. The number of years since fire, fire intensity and native cover in reference sites were not significantly correlated with native species cover in burned sites. The particular species of grass that carried the fire did however, have a significant effect on native species recovery. Where the African grass Melinis minutiflora was a dominant or codominant species, fire impacts were more severe than where it was absent regardless of climate zone. Overall, the impacts of exotic grass-fuelled fires on native species composition and cover in seasonally dry Hawaiian ecosystems was context specific. This specificity is best explained by differences between the climatic zones in which fire occurred. Elevation was the main physical variable that differed among the climatic zones and it alone could explain a large percentage of the variation in native cover among sites. Rainfall, by contrast, did not vary systematically with elevation. Elevation is associated with differences in composition of the native species assemblages. In the coastal lowlands, the native grass Heteropogon contortus, was largely responsible for positive changes in native cover after fire although other native species also increased. Like the exotic grasses, this species is a perennial C4 grass. It is lacking in the submontane zone and there are no comparable native species there and almost all native species in the submontane zone were reduced by fire. The lack of fire tolerant species in the submontane zone thus clearly contributes to the devastating impact of fire upon native cover there.

Near‐ridge seamount chains in the northeastern Pacific Ocean

High‐resolution bathymetry and side‐scan data of the Vance, President Jackson, and Taney near‐ridge seamount chains in the northeast Pacific were collected with a hull‐mounted 30‐kHz sonar. The central volcanoes in each chain consist of truncated cone‐shaped volcanoes with steep sides and nearly flat tops. Several areas are characterized by frequent small eruptions that result in disorganized volcanic regions with numerous small cones and volcanic ridges but no organized truncated conical structure. Several volcanoes are crosscut by ridge‐parallel faults, showing that they formed within 30–40 km of the ridge axis where ridge‐parallel faulting is still active. Magmas that built the volcanoes were probably transported through the crust along active ridge‐parallel faults. The volcanoes range in volume from 11 to 187 km3, and most have one or more multiple craters and calderas that modify their summits and flanks. The craters (&lt;1 km diameter) and calderas (&gt;1 km diameter) range from small pit craters to calderas as large as 6.5×8.5 km, although most are 2–4 km across. Crosscutting relationships commonly show a sequence of calderas stepping toward the ridge axis. The calderas overlie crustal magma chambers at least as large as those that underlie Kilauea and Mauna Loa Volcanoes in Hawaii, perhaps 4–5 km in diameter and ∼1–3 km below the surface. The nearly flat tops of many of the volcanoes have remnants of centrally located summit shields, suggesting that their flat tops did not form from eruptions along circumferential ring faults but instead form by filling and overflowing of earlier large calderas. The lavas retain their primitive character by residing in such chambers for only short time periods prior to eruption. Stored magmas are withdrawn, probably as dikes intruded into the adjacent ocean crust along active ridge‐parallel faults, triggering caldera collapse, or solidified before the next batch of magma is intruded into the volcano, probably 1000–10,000 years later. The chains are oriented parallel to subaxial asthenospheric flow rather than absolute or relative plate motion vectors. The subaxial asthenospheric flow model yields rates of volcanic migration of 3.4, 3.3 and 5.9 cm yr−1 for the Vance, President Jackson, and Taney Seamounts, respectively. The modeled lifespans of the individual volcanoes in the three chains vary from 75 to 95 kyr. These lifespans, coupled with the geologic observations based on the bathymetry, allow us to construct models of magma supply through time for the volcanoes in the three chains.

The complex frequencies of long-period seismic events as probes of fluid composition beneath volcanoes

Summary Long-period (LP) events have been widely observed in relation to magmatic and hydrothermal activities in volcanic areas. LP waveforms characterized by their harmonic signature have been interpreted as oscillations of a fluid-filled resonator, and mixtures of liquid and gas in the form of bubbly liquids have been mainly assumed for the fluid. To investigate the characteristic properties of the resonator system, we analyse waveforms of LP events observed at four different volcanoes in Hawaii, Alaska, Colombia and Japan using a newly developed spectral method. This method allows an estimation of the complex frequencies of decaying sinusoids based on an autoregressive model. The results of our analysis show a wide variety of Q factors, ranging from tens to several hundred. We compare these complex frequencies with those predicted by the fluid-filled crack model for various mixtures of liquid, gas and ash. Although the oscillations of LP events with Q smaller than 50 can be explained by various combinations of liquids and gases, we find that ash-laden gases are required to explain long-lasting oscillations with Q larger than 100. The complex frequencies of LP events yield useful information on the types of fluids. Temporal and spatial variations of the complex frequencies can be used as probes of fluid composition beneath volcanoes.

An Evaluation of the Wilt-Causing Bacterium Ralstonia solanacearum as a Potential Biological Control Agent for the Alien Kahili Ginger (Hedychium gardnerianum) in Hawaiian Forests

Kahili ginger (Hedychium gardnerianum) is an invasive weed in tropical forests in Hawaii and elsewhere. Bacterial wilt caused by the ginger strain of Ralstonia (=Pseudomonas) solanacearum systemically infects edible ginger (Zingiber officinale) and ornamental gingers (Hedychium spp.), causing wilt in infected plants. The suitability of R. solanacearum as a biological control agent for kahili ginger was investigated by inoculating seedlings and rooted cuttings of native forest plants, ornamental ginger, and solanaceous species to confirm host specificity. Inoculation via stem injection or root wounding with a bacterial–water suspension was followed by observation for 8 weeks. Inoculations on H. gardnerianum were then carried out in ohia-lehua (Metrosideros polymorpha) wet forests of Hawaii Volcanoes National Park to determine the bacterium's efficacy in the field. No native forest or solanaceous species developed wilt or other symptoms during the study. The bacterium caused limited infection near the inoculation site on H. coronarium, Z. zerumbet, Heliconia latispatha, and Musa sapientum. However, infection did not become systemic in any of these species, and normal growth resumed following appearance of initial symptoms. All inoculated H. gardnerianum plants developed irreversible chlorosis and severe wilting 3–4 weeks following inoculation. Systemic infection also caused death and decay of rhizomes. Most plants were completely dead 16–20 weeks following inoculation. The destructiveness of the ginger strain of R. solanacearum to edible ginger has raised questions regarding its use for biological control. However, because locations of kahili ginger infestations are often remote, the risk of contaminating edible ginger plantings is unlikely. The ability of this bacterium to cause severe disease in H. gardnerianum in the field, together with its lack of virulence in other ginger species, contributes to its potential as a biological control agent.

The effects of aircraft overflights on visitors to U. S. National Parks

Aircraft overflights of public lands, and specifically of US National Parks, increasingly have become a source of sound intrusions into otherwise undisturbed natural environments. In response to both park management and public concern about the effects of these overflights, several studies have been conducted to examine the benefits and the impacts of aircraft flights over National Parks. This paper summarizes the methods and results of two such studies: 1) Dose-Response studies conducted at six sites in Grand Canyon, Hawaii Volcanoes, and Haleakala National Parks; 2) a Cognitive Survey conducted at a site in White Sands National Monument. In addition, this paper offers an approach for using the results of the Dose-Response studies to judge the relative impacts of aircraft overflights on visitors.

The response of native species to removal of invasive exotic grasses in a seasonally dry Hawaiian woodland

Abstract. Non‐native perennial grasses form 30% of the live understory biomass in seasonally dry, submontane forests in Hawaii Volcanoes National Park, yet their effects on native species are unknown. We removed these grasses from plots of 20 m × 20 m in 1991 and maintained removal and control areas over the next three years. Two fast growing shrub species, Dodonaea viscosa and Osteomeles anthylidifolia, increased in size significantly more in removal areas than in controls. Individuals of the most abundant shrub species, Styphelia tameiameia showed no net growth response to grass removal. They did, however, change their architecture: many branches along the mid and upper sections of the main trunk died and a proliferation of new leaves and shoots occurred in the lower 40 cm of trunk. Basal diameter increase was very small in Metrosideros polymorpha, the dominant tree species in these sites.All species except Styphelia had significantly increased leaf tissue nitrogen in removal plots by 18 months after removal when compared to shrubs in control areas suggesting that removal plot shrubs had greater access to soil nitrogen. Available soil‐N pools, which were generally higher in the removal plots, support this interpretation. Light levels near the soil surface were also higher where grasses were removed than where they were present which may have contributed to increased shrub growth. By contrast, soil moisture was consistently lower where grasses were removed than where they were still present. Shrub tissue carbon isotope values were consistent with the interpretation that shrubs in removal plots had less rather than more water available to them. Hence, the increased growth observed in removal plot shrubs could not be due to release from moisture competition.Lastly, our results showed that seedlings of all woody species except Metrosideros were significantly more abundant in removal plots at both one and three years after removal and initially high sapling mortality was balanced by high recruitment into the sapling class. We believe that over time this will result in increased densities of native shrubs if grasses are kept out. With the presence of grasses, shrub growth in these woodlands is reduced and biomass is shifting towards grasses.

Use of “virtual” field trips in teaching introductory geology

We designed a series of case studies for Introductory Geology Laboratory courses using computer visualization techniques integrated with traditional laboratory materials. These consist of a comprehensive case study which requires three two-hour long laboratory periods to complete, and several shorter case studies requiring one or two, two-hour laboratory periods. Currently we have prototypes of the Yellowstone National Park, Hawaii volcanoes and the Mid-Atlantic Ridge case studies. The Yellowstone prototype can be used to learn about a wide variety of rocks and minerals, about geothermal activity and hydrology, about volcanic hazards and the hot-spot theory of plate tectonics. The Hawaiian exercise goes into more depth about volcanoes, volcanic rocks and their relationship to plate movements. The Mid-Atlantic Ridge project focuses on formation of new ocean crust and mineral-rich hydrothermal deposits at spreading centers. With new improvements in visualization technology that are making their way to personal computers, we are now closer to the ideal of a “virtual” field trip. We are currently making scenes of field areas in Hawaii and Yellowstone which allow the student to pan around the area and zoom in on interesting objects. Specific rocks in the scene will be able to be “picked up” and studied in three dimensions. This technology improves the ability of the computer to present a realistic simulation of the field area and allows the student to have more control over the presentation. This advanced interactive technology is intuitive to control, relatively cheap and easy to add to existing computer programs and documents.

Microclimate Change and Effect on Fire Following Forest‐Grass Conversion in Seasonally Dry Tropical Woodland1

ABSTRACTWe tested the hypothesis that, where fire has historically been infrequent, wooded areas that have been invaded by grasses and converted to grassland by fire are predisposed to future fire compared to adjacent areas that remain wooded; thus, an initial forest fire may promote future fires. We compared microclimate between a grass‐dominated burned area and a nearby grass‐invaded woodland that has not burned in recent history, both located in the submontane dry forest of Hawaii Volcanoes National Park. The results were used to parameterize BEHAVE, a fire behavior prediction model developed by the USDA Forest Service. The model's predictions include probability of ignition, intensity, rate of spread, and tree mortality. Contrary to expectations, daytime hourly mean temperatures were higher and relative humidity was lower in the woodland site. However, the differences in temperature and humidity were not great enough to affect spread rate or probability of ignition. Wind speeds were substantially greater in the grassland, and this was most important in driving differences in modeled fire spread. Given similar synoptic conditions, a fire started in the grassland can be expected to spread an order of magnitude faster than one started in the woodland.