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We employed grass and forest versions of the CENTURY model under a range of N deposition values (0.02–1.60 g N m −2 y −1 ) to explore the possibility that high observed lake and stream N was due to terrestrial N saturation of alpine tundra and subalpine forest in Loch Vale Watershed, Rocky Mountain National Park, Colorado. Model results suggest that N is limiting to subalpine forest productivity, but that excess leachate from alpine tundra is sufficient to account for the current observed stream N. Tundra leachate, combined with N leached from exposed rock surfaces, produce high N loads in aquatic ecosystems above treeline in the Colorado Front Range. A combination of terrestrial leaching, large N inputs from snowmelt, high watershed gradients, rapid hydrologic flushing and lake turnover times, and possibly other nutrient limitations of aquatic organisms constrain high elevation lakes and streams from assimilating even small increases in atmospheric N. CENTURY model simulations further suggest that, while increased N deposition will worsen the situation, nitrogen saturation is an ongoing phenomenon.
Oil and gas development is changing the landscape in many regions of the United States and globally. However, the nature, extent, and magnitude of landscape change and development, and precisely how this development compares to other ongoing land conversion (e.g. urban/sub-urban development, timber harvest) is not well understood. In this study, we examine land conversion from oil and gas infrastructure development in the upper Susquehanna River basin in Pennsylvania and New York, an area that has experienced much oil and gas development over the past 10 years. We quantified land conversion in terms of forest canopy geometric volume loss in contrast to previous studies that considered only areal impacts. For the first time in a study of this type, we use fine-scale lidar forest canopy geometric models to assess the volumetric change due to forest clearing from oil and gas development and contrast this land change to clear cut forest harvesting, and urban and suburban development. Results show that oil and gas infrastructure development removed a large volume of forest canopy from 2006 to 2013, and this removal spread over a large portion of the study area. Timber operations (clear cutting) on Pennsylvania State Forest lands removed a larger total volume of forest canopy during the same time period, but this canopy removal was concentrated in a smaller area. Results of our study point to the need to consider volumetric impacts of oil and gas development on ecosystems, and to place potential impacts in context with other ongoing land conversions.
Landsat time series data sets were acquired for the Santa Fe National Forest in New Mexico. This area includes the San Pedro Parks Wilderness area, which was designated as an official wilderness in 1964. Eight autumnal Landsat Thematic Mapper (TM) scenes acquired from 1988 to 2006 were analyzed to determine whether significant changes have occurred throughout the region during the past 18 years and, if so, to assess whether the changes are long-term and gradual or short-term and abrupt. It was found that, starting in about 1995, many of the conifer stands within the Wilderness area showed consistently gradual and marked increases in the Shortwave Infrared/Near Infrared Index. These trends generally imply decreases in canopy greenness or increases in mortality. Other high-elevation conifer forests located outside of the Wilderness area showed similar spectral trends, indicating that changes are potentially widespread. The spatial patterns of forest damage as inferred from the image analyses were very similar to the general patterns of insect defoliation damage mapped via aerial sketch mapping by the United States Department of Agriculture Forest Service Forest Health Monitoring Program. A field visit indicated that zones of spectral change are associated with high levels of forest damage and mortality, likely caused by a combination of insects and drought. The study demonstrates the effectiveness of using historical Landsat data for providing objective and consistent long-term assessments of the gradual ecosystem changes that are occurring within the western United States.
The management of wildfire has long been controversial. The role of fire and fire-related management in terrestrial and aquatic ecosystems has become an important focus in recent years, but the general debate is not new. In his recent book, Stephen Pyne (2001 ) describes the political and scientific debate surrounding the creation of the U.S. Forest Service and the emergence of fire suppression as a central tenet of wildland management. Essentially, views in the first decade of the 20th century focused on fire as good or evil: a tool that might benefit other resources or interests (e.g. Indian burning) and mitigate larger more destructive fires, or a threat to the recruitment and productivity of newly designated forest reserves. The “great fires” in the Western USA in 1910 and the associated loss of human life and property largely forged the public and political will to suppress fire on a massive scale.
Wood duck (Aix sponsa) populations have been increasing in the Central Flyway, but little is known about wood duck brood rearing in prairie ecosystems. We compared movements and habitat use of radiomarked female wood ducks with broods in South Dakota on 2 rivers with contrasting prairie landscapes. The perennial Big Sioux River had a broad floodplain and riparian forest, whereas the intermittent Maple River had emergent vegetation along the river channel. Movements between nest sites and brood-rearing areas were longer on the Maple River than on the Big Sioux River (P = 0.02) and were among the longest reported for wood duck broods. Movements on the Big Sioux River were longer in 1992 (P = 0.01), when the floodplain was dry, than in 1993 or 1994. Before flooding occurred on the Big Sioux River, broods used semipermanent wetlands and tributaries outside the floodplain; thereafter, females selected forested wetlands along the river. Broods on the Maple River used emergent vegetation along the river channel throughout the study. Because median length of travel to brood-rearing areas was 2-3 km we recommend maintenance of brood-rearing habitat every 3-5 km along prairie rivers. Wildlife managers should encourage landowners to retain riparian vegetation along perennial rivers and emergent vegetation along intermittent streams to provide brood-rearing habitat during wet and dry cycles.
The projected rapid changes in climate will affect the unique vegetation assemblages of the Northern Rockies region in myriad ways, both directly through shifts in vegetation growth, mortality, and regeneration, and indirectly through changes in disturbance regimes and interactions with changes in other ecosystem processes, such as hydrology, snow dynamics, and exotic invasions (Bonan 2008; Hansen and Phillips 2015; Hansen et al. 2001; Notaro et al. 2007). These impacts, taken collectively, could change the way vegetation is managed by public land agencies in this area. Some species may be in danger of rapid decreases in abundance, while others may undergo range expansion (Landhäusser et al. 2010). New vegetation communities may form, while historical vegetation complexes may simply shift to other areas of the landscape or become rare. Juxtaposed with climate change concerns are the consequences of other land management policies and past activities, such as fire exclusion, fuels treatments, and grazing. A thorough assessment of the responses of vegetation to projected climate change is needed, along with an evaluation of the vulnerability of important species, communities, and vegetation-related resources that may be influenced by the effects, both direct and indirect, of climate change. This assessment must also account for past management actions and current vegetation conditions and their interactions with future climates.
The environmental factors controlling soil biodiversity along resource gradients remain poorly understood in wet tropical ecosystems. Aboveground biodiversity is expected to be driven by changes in nutrient availability in these ecosystems, however, much less is known about the importance of nutrient availability in driving soil biodiversity. Here, we combined a cross-continental soil survey across tropical regions with a three decades' field experiment adding nitrogen (N) and phosphorus (P) (100 kg N ha −1 y −1 and 100 kg P ha −1 y −1 ) to Hawai'ian tropical forests with contrasting substrate ages (300 and 4,100,000 years) to investigate the influence of nutrient availability to explain the biodiversity of soil bacteria, fungi, protists, invertebrates and key functional genes. We found that soil biodiversity was driven by soil acidification during long-term pedogenesis and across environmental gradients, rather than by nutrient limitations. In fact, our results showed that experimental N additions caused substantial acidification in soils from Hawai'i. These declines in pH were related to large decreases in soil biodiversity from tropical ecosystems in four continents. Moreover, the microbial activity did not change in response to long-term N and P additions. We concluded that environmental filtering drives the biodiversity of multiple soil organisms, and that the acidification effects associated with N additions can further create substantial undesired net negative effects on overall soil biodiversity in naturally tropical acid soils. This knowledge is integral for the understanding and management of soil biodiversity in tropical ecosystems globally.
Riverine iron (Fe) derived from glacial weathering is a critical micronutrient source to ecosystems of the Gulf of Alaska (GoA). Here we demonstrate that the source and chemical nature of riverine Fe input to the GoA could change dramatically due to the widespread watershed deglaciation that is underway. We examine Fe size partitioning, speciation, and isotopic composition in tributaries of the Copper River which exemplify a long-term GoA watershed evolution from one strongly influenced by glacial weathering to a boreal-forested watershed. Iron fluxes from glacierized tributaries bear high suspended sediment and colloidal Fe loads of mixed valence silicate species, with low concentrations of dissolved Fe and dissolved organic carbon (DOC). Iron isotopic composition is indicative of mechanical weathering as the Fe source. Conversely, Fe fluxes from boreal-forested systems have higher dissolved Fe concentrations corresponding to higher DOC concentrations. Iron colloids and suspended sediment consist of Fe (hydr)oxides and organic complexes. These watersheds have an iron isotopic composition indicative of an internal chemical processing source. We predict that as the GoA watershed evolves due to deglaciation, so will the source, flux, and chemical nature of riverine Fe loads, which could have significant ramifications for Alaskan marine and freshwater ecosystems.
Light is a primary constraint on primary production and drives many ecological processes in stream ecosystems, yet light regimes have received considerably less attention than other factors of the stream environment, such as hydrology or nutrient cycling. Light received by streams can be highly heterogeneous in both space and time resulting from changes in topography, channel characteristics, and riparian vegetation. Both the structure and phenology of riparian vegetation can be important determinants of the seasonality and magnitude of light reaching the stream surface, particularly in smaller forested streams. Despite the importance of riparian phenology on temporal patterns of stream light availability, existing models do not account for the seasonal dynamics of canopies. We developed a dynamic, biophysically based model ( StreamLight ) that incorporates canopy structure and phenology to predict light reaching the stream surface. We compared StreamLight to an existing model at 21 sites across the USA and found that, across sites, our biophysically based model produced light estimates that were more strongly correlated to observations and reduced the magnitude of errors in comparison to the existing model, particularly for streams that were relatively narrow compared to the height of riparian vegetation. Because smaller streams represent most global stream length, we expect that, in many smaller forested streams, the inclusion of canopy structure and phenology will enhance our ability to predict light regimes. We also used model simulations to examine the importance of controls on stream light environments and found that channel width was the strongest control on light environments. StreamLight represents an important incremental step forward in developing mechanistic models of river network productivity and in linking shifts in terrestrial vegetation structure and phenology to aquatic ecosystem productivity and thermal regimes.
Context Mountaintop removal/valley fill (MTR/VF) mining in the central Appalachians is a major driver of landscape change within terrestrial ecosystems. Objective We quantified avian community and individual taxa thresholds in response to changing landscapes from MTR/VF using a Threshold Indicator Taxa Analysis approach. Methods We conducted 50-m fixed radius avian surveys (n = 707) within forest adjacent to mine lands in 2012–2013 and obtained data for additional surveys (n = 905) sampled using comparable methods during 2008–2013. We quantified positive and negative community, habitat guild, and species thresholds in abundance and occurrence for each of five landscape metrics within a 1-km radius of each survey point. Results Reclaimed mine-dominated landscapes (less forest and more grassland/shrubland cover) elicited more negative (57 %) than positive (39 %) species responses. Negative thresholds for each landscape metric generally occurred at lower values than positive thresholds, thus negatively responding species were detrimentally affected before positively responding species benefitted. Forest interior birds generally responded negatively to landscape metric thresholds, interior edge species responses were mixed, and early successional birds responded positively. The forest interior guild declined most at 4 % forest loss, while the shrubland guild increased greatest after 52 % loss. Based on random forest importance ranks, total amount of landscape grassland/shrubland had the most influence, although this varied by guild. Conclusions Because of little overlap in habitat requirements, managing landscapes simultaneously to maximally benefit both guilds may not be possible. Our avian thresholds identify single community management targets accounting for scarce species. Guild or individual species thresholds allow for species-specific management.
We measured CO 2 and CH 4 exchange from the center of a Sphagnum ‐dominated permafrost collapse, through an aquatic moat, and into a recently burned black spruce forest on the Tanana River floodplain in interior Alaska. In the anomalously dry growing season of 2004, both the collapse and the surrounding burned area were net sinks for CO 2 , with a mean daytime net ecosystem exchange of −1.4 μ mol CO 2 m −2 s −1 , while the moat was a CH 4 source with a mean flux of 0.013 μ mol CH 4 m −2 s −1 . Regression analyses identified temperature as the dominant factor affecting intragrowing season variation in CO 2 exchange and soil moisture as the primary control influencing CH 4 emissions. CH 4 emissions during the wettest portion of the growing season were four times higher than during the driest periods. If temperatures continue to warm, peatland vegetation will likely expand with permafrost degradation, resulting in greater carbon accumulation and methane emissions for the landscape as a whole.
The Valles Caldera National Preserve is one of New Mexico’s natural wonders and a popular area for public recreation, sustainable natural resource production, and scientific research and education. Here, we provide a concise overview of the natural and cultural history of the Preserve, including descriptions of the ecosystems, flora and fauna. We note that, at the landscape scale, the Valles caldera appears to be spectacularly pristine; however, humans have extracted resources from the Preserve area for many centuries, resulting in localized impacts to forests, grasslands and watersheds. The Valles Caldera Trust is now charged with managing the Preserve and providing public access, while preserving and restoring these valuable public resources.
Under Section 404 of the Clean Water Act, the U.S. Environmental Protection Agency (EPA) has regulatory responsibilities related to the discharge of dredged or fill material into the Nation’s waters. In addition to its advisory role in the U.S. Army Corps of Engineers' permit program, EPA has a number of specific authorities, including formulation of the Section 404(b)(1) guidelines, use of Section 404(c) to prohibit disposal at particular sites, and enforcement actions for unauthorized discharges. A number of recent court cases focus on the geographic scope of Section 404 jurisdiction in potential bottomland hardwood (BLH) wetlands and the nature of landclearing activities in these areas that require a permit under Section 404. Accordingly, EPA needs to establish the scientific basis for implementing its responsibilities under Section 404 in bottomland hardwoods. EPA is approaching this task through a series of workshops designed to provide current scientific information on bottomland hardwoods and to organize that information in a manner pertinent to key policy questions. The first two workshops in the series were originally conceived as technically oriented meetings that would provide the information necessary to develop policy options at the third workshop. More specifically, the first workshop was designed to examine a zonation concept as a means of characterizing different BLH communities and describing variations in their functions along a soil moisture gradient. The second workshop was perceived as an attempt to evaluate the impacts of various activities on those functions. However, one conclusion of the first workshop, which was held in December 1984 in St. Francisville, Louisiana, was that the zonation approach does not describe the variability in the functions performed by BLH ecosystems sufficiently well to allow its use as the sole basis for developing a regulatory framework. That is, factors other than zone were considered critical for an effective characterization of the structure and functions of bottomland hardwoods. The approach to the second workshop, the results of which are described in this report, was therefore modified in response to the conclusions from the first workshop. The focus of the second workshop remained an analysis of the impacts of various activities or the functions of BLH ecosystems. However, as a prerequisite to this analysis, participants were also asked to develop a list of characteristics that determine the extent to which BLH sites perform the important functions. The workshop was organized such that alternating plenary and workgroup sessions allowed ample time for communication while still maintaining a focus on the overall goal. In the initial session, various individuals gave presentations concerning methodologies for evaluating the functions performed by wetlands, factors influencing the conversion of BLH forests to other uses, and the impacts of conversion activities. These were followed by a series of case study presentations designed to familiarize participants with the kinds of issues that are dealt with in the Section 404 program. These presentations are cited in this report as (author, workshop presentation). At the conclusion of these presentations, participants were divided into six workgroups to examine the functions of BLH ecosystems in the areas of hydrology, water quality, fisheries, wildlife, ecosystem processes, and culture/recreation/economics. Each workgroup was asked to undertake the following tasks. 1. Developed a list of functions performed by BLH ecosystems from the perspective of the workgroup's expertise and area of responsibility. 2. Identify those activities (e.g., impoundment construction, conversion to soybean farming) that impact the major functions (e.g., sediment retention, detrital export) performed by BLH ecosystems. 3. Develop a list of characteristics that determine the extent to which a BLH site performs each function and describe the relationship of each characteristic to the function. Develop, with supporting evidence where possible, an analysis of the impact of each activity (Task 2) on each characteristic (Task 3) and on each function as a whole. Upon completion of Task 2, in an effort to provide some uniformity in the analysis by the various workgroups, EPA personnel and several participants met and compiled a complete list of all the activities identified as having significant impacts in bottomland hardwoods (Table 1). From this list the group derived a set of seven activities, and a number of specific actions associated with each, for analysis by the workgroups (Table 2). These activities were selected on the basis of their perceived importance in BLH ecosystems and their interest from the perspective of EPA. Each workgroup was also encourage to ass any activities of particular important from its perspective. The workgroup reports that follow document the results of discussion concerning the above tasks. The WORKSHOP SUMMARY attempts to summarize these workgroup results, discuss availability of information, and identify some problems that must be addressed prior to the third workshop in this series.
We asked whether 3–5 kg N y −1 atmospheric N deposition was sufficient to have influenced natural, otherwise undisturbed, terrestrial and aquatic ecosystems of the Colorado Front Range by comparing ecosystem processes and properties east and west of the Continental Divide. The eastern side receives elevated N deposition from urban, agricultural, and industrial sources, compared with 1–2 kg N y −1 on the western side. Foliage of east side old-growth Englemann spruce forests have significantly lower C:N and lignin:N ratios and greater N:Mg and N:P ratios. Soil % N is higher, and C:N ratios lower in the east side stands, and potential net N mineralization rates are greater. Lake NO 3 concentrations are significantly higher in eastern lakes than western lakes. Two east side lakes studied paleolimnologically revealed rapid changes in diatom community composition and increased biovolumes and cell concentrations. The diatom flora is now representative of increased disturbance or eutrophication. Sediment nitrogen isotopic ratios have become progressively lighter over the past 50 years, coincident with the change in algal flora, possibly from an influx of isotopically light N volatilized from agricultural fields and feedlots. Seventy-five percent of the increased east side soil N pool can be accounted for by increased N deposition commensurate with human settlement. Nitrogen emissions from fixed, mobile, and agricultural sources have increased dramatically since approximately 1950 to the east of the Colorado Front Range, as they have in many parts of the world. Our findings indicate even slight increases in atmospheric deposition lead to measurable changes in ecosystem properties.
Human activities on floodplains have severely disrupted the regeneration of foundation riparian shrub and tree species of the Salicaceae family ( Populus and Salix spp.) throughout the Northern Hemisphere. Restoration ecologists initially tackled this problem from a terrestrial perspective that emphasized planting. More recently, floodplain restoration activities have embraced an aquatic perspective, inspired by the expanding practice of managing river flows to improve river health (environmental flows) . However, riparian Salicaceae species occupy floodplain and riparian areas, which lie at the interface of both terrestrial and aquatic ecosystems along watercourses . Thus, their regeneration depends on a complex interaction of hydrologic and geomorphic processes that have shaped key life-cycle requirements for seedling establishment . Ultimately, restoration needs to integrate these concepts to succeed. However, while regeneration of Salicaceae is now reasonably well-understood, the literature reporting restoration actions on Salicaceae regeneration is sparse, and a specific theoretical framework is still missing. Here, we have reviewed 105 peer-reviewed published experiences in restoration of Salicaceae forests, including 91 projects in 10 world regions, to construct a decision tree to inform restoration planning through explicit links between the well-studied biophysical requirements of Salicaceae regeneration and 17 specific restoration actions, the most popular being planting (in 55% of the projects), land contouring (30%), removal of competing vegetation (30%), site selection (26%), and irrigation (24%). We also identified research gaps related to Salicaceae forest restoration and discuss alternative, innovative and feasible approaches that incorporate the human component.
Agricultural production is a fundamental activity conducted on 45% of the U.S. land area, 55% of Mexico’s land area, and 7% of Canada’s land area (World Bank 2016). Because of this vast spatial extent and the strong role that land management plays in how agricultural ecosystems function, agricultural lands and activities represent a large portion of the North American carbon budget. Accordingly, improved quantification of the agricultural carbon cycle, new trends in agriculture, and added opportunities for emissions reductions provide a critical foundation for considering the relationships between agriculture and carbon cycling at local, regional, continental, and global scales. More than 145 countries have specifically included agriculture in their targets and actions for mitigating climate change (FAO 2016), and agriculture has featured particularly prominently in recent target and action commitments made by developing countries to reduce greenhouse gas (GHG) emissions (Richards et al., 2015). Conversion of vast native forest and prairie to agriculture across North America between 1860 and 1960 resulted in carbon dioxide (CO2) fluxes to the atmosphere from biota and soils that exceeded those from fossil fuel emissions over the same period (Houghton et al., 1983). Correspondingly, soil organic carbon (SOC) declined in many soils during the 50 years following conversion from native ecosystems to production agriculture (Huggins et al., 1998; Janzen et al., 1998; Slobodian et al., 2002). Crop yields and corresponding above- and belowground biomass have steadily increased since the 1930s due to genetic and management innovations, which provide more organic input from which to build SOC ( Johnson et al., 2006; Hatfield and Walthall 2015). This, coupled with improved input-use efficiencies may reduce GHG-emissions per unit yield (GHG intensity), with additional improvements possible through management optimization (Grassini and Cassman 2012; Pittelkow et al., 2015). Options include reducing tillage, integrating perennials onto the landscape, reducing or eliminating bare-fallow land (i.e., land without living plants), adding cover crops, and enrolling lands in conservation easement programs. These options, originally proposed to control erosion, have potential co-benefits in terms of increased soil health, plant productivity, and soil carbon stabilization (Lehman et al., 2015). Conversely, returning lands previously enrolled in conservation easements (e.g., the Conservation Reserve Program [CRP] and other land set-aside efforts) to row-crop production, tillage, or aggressive harvesting of crop residues all risk degrading soil quality and exacerbating SOC loss. Of note is that the net results of land use and land management practices in an agricultural setting vary according to many factors, such as crop or production system type, soil type, climate, and the collection of practices at any given site. For example, many traditional practices followed by Indigenous people on tribal lands are based on an integrated approach to natural resource management and response to environmental change that may provide agricultural options uniquely suited to varied environmental settings (see Ch. 7: Tribal Lands, p. 303). Agricultural land in the United States totaled 408.2 million hectares (ha) in 2014, of which 251 million ha were in permanent meadows and pastures, 152.2 million ha were in arable land, and 2.6 million ha were in permanent crops (FAOSTAT 2016). Compared with the distribution in 2007, these numbers reflect a 4.7 million ha decline in total agricultural lands, driven by declines in arable land and permanent crops but partially offset by a modest increase in permanent meadows and pastures. Although arable lands have been declining, the combined acreage of the four major crops (corn, wheat, soybeans, and cotton) has risen slightly, with increases in land planted in corn and soybeans and decreases in cotton and wheat (see Figure 5.1, p. 232). Despite the overall slight decline in agricultural land area, the value of U.S. agricultural production rose over the past decade as a result of increased production efficiency and higher prices (USDA 2017a; see also www.ers.usda.gov). Canada has about 65 million ha of agricultural land, of which about 46 million ha are arable, accounting for only about 7% of the country’s total land area (FAOSTAT 2017). Prominent crops on Canada’s arable lands include cereals (e.g., wheat, barley, and maize), oilseeds (e.g., canola and soybeans), and pulses (e.g., peas and lentils). Natural and seeded pastures available for grazing in Canada make up about 20 million ha (Legesse et al., 2016). Agricultural land in Mexico makes up 107 million ha, of which 23 million ha are arable land, 2.7 million ha are permanent crops, and 81 million ha are permanent meadows and pastures (FAOSTAT 2017). Mexico’s major crops are fruits, corn, grains, vegetables, and sugarcane.
The invasive rust Austropuccina psidii was detected in the Hawaiian Islands in 2005 and has become widely established throughout the archipelago in both native and introduced species of Myrtaceae. Initial predictions about the impacts of the fungus on native ʽōhiʽa lehua ( Metrosideros polymorpha ), a keystone native tree, have not materialized, but there is ongoing concern that introductions of new genotypes of the fungus could lead to widespread mortality with catastrophic effects on native ecosystems. By contrast, two recently emergent Ascomycete pathogens, Ceratocystis lukuohia ( Ceratocystis wilt of ‘ōhi‘a) and C. huliohia ( Ceratocystis canker of ‘ōhi‘a), collectively known to cause Rapid ʽŌhiʽa Death (ROD), are causing significant mortality in native forests on Hawaiʻi and Kauaʻi Islands, but pathways of spread are still incompletely understood. We used a network of passive environmental samplers for collecting windblown urediniospores of Austropuccina to evaluate the effectiveness of environmental monitoring to detect seasonal and landscape-scale differences in airborne propagules of this rust on Hawai`i Island. The samplers were also used to determine if windborn ambrosia beetle frass or spores of Ceratocystis can spread long distances. We found frequent detections and regional and seasonal differences in numbers of samplers that were positive for urediniospores of Austropuccinia , but little evidence of long-distance airborne dispersal of the ROD-causing fungi. The simple, inexpensive platform for sampling airborne fungal spores that we used may have value as a monitoring tool for detecting spread of airborne fungal pathogens, evaluating habitats for suitability for restoration efforts, and for detecting new pathogen introductions, particularly new Austropuccinia genotypes both in Hawaiʻi and other parts of the world.