Search USGS⌕ Search

SEARCH · Search USGS

Results for “Plant Ecology and Diversity”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 361 records · Page 20Linked to original sources
USGS2002

Molecular analysis of a 11 700-year-old rodent midden from the Atacama Desert, Chile

DNA was extracted from an 11 700-year-old rodent midden from the Atacama Desert, Chile and the chloroplast and animal mitochondrial DNA (mtDNA) gene sequences were analysed to investigate the floral environment surrounding the midden, and the identity of the midden agent. The plant sequences, together with the macroscopic identifications, suggest the presence of 13 plant families and three orders that no longer exist today at the midden locality, and thus point to a much more diverse and humid climate 11 700 years ago. The mtDNA sequences suggest the presence of at least four different vertebrates, which have been putatively identified as a camelid (vicuna), two rodents (Phyllotis and Abrocoma), and a cardinal bird (Passeriformes). To identify the midden agent, DNA was extracted from pooled faecal pellets, three small overlapping fragments of the mitochondrial cytochrome b gene were amplified and multiple clones were sequenced. These results were analysed along with complete cytochrome b sequences for several modern Phyllotis species to place the midden sequence phylogenetically. The results identified the midden agent as belonging to an ancestral P. limatus. Today, P. limatus is not found at the midden locality but it can be found 100 km to the north, indicating at least a small range shift. The more extensive sampling of modern Phyllotis reinforces the suggestion that P. limatus is recently derived from a peripheral isolate.

Molecular Ecology↗
USGS2002

Avian response to bottomland hardwood reforestation: The first 10 years

Bottomland hardwood forests were planted on agricultural fields in Mississippi and Louisiana predominantly using either Quercus species (oaks) or Populus deltoides (eastern cottonwood). We assessed avian colonization of these reforested sites between 2 and 10 years after planting. Rapid vertical growth of cottonwoods (circa 2–3 m/year) resulted in sites with forest structure that supported greater species richness of breeding birds, increased Shannon diversity indices, and supported greater territory densities than on sites planted with slower-growing oak species. Grassland birds ( Spiza americana [Dickcissel] and Sturnella magna [Eastern Meadowlark]) were indicative of species breeding on oak-dominated reforestation no more than 10 years old. Agelaius phoeniceus (Red-winged Blackbird) and Colinus virginianus (Northern Bobwhite) characterized cottonwood reforestation no more than 4 years old, whereas 14 species of shrub-scrub birds (e.g., Passerina cyanea [Indigo Bunting]) and early-successional forest birds (e.g., Vireo gilvus [Warbling vireo]) typified cottonwood reforestation 5 to 9 years after planting. Rates of daily nest survival did not differ between reforestation strategies. Nest parasitism increased markedly in older cottonwood stands but was overwhelmed by predation as a cause of nest failure. Based on Partners in Flight prioritization scores and territory densities, the value of cottonwood reforestation for avian conservation was significantly greater than that of oak reforestation during their first 10 years. Because of benefits conferred on breeding birds, we recommend reforestation of bottomland hardwoods should include a high proportion of fast-growing early successional species such as cottonwood.

Restoration Ecology↗
USGS2026

Long-term aridity shapes grassland drought resistance and modulates the roles of plant diversity and functional composition

Understanding the drivers of plant community stability is crucial for predicting ecosystem responses to extreme drought events. In grasslands, drought resistance supports the maintenance of key functions such as above-ground primary productivity, making the identification of resistance drivers essential to guide management under climate change. Proposed factors contributing to grassland stability include multiple diversity facets, functional traits and long-term climate, but most assessments focus on temporal invariability under historical disturbance regimes, leaving mechanisms of extreme drought resistance and their variation across climatic contexts relatively underexplored. Here, we analysed data from 54 grassland sites of the International Drought Experiment to examine the resistance of above-ground net primary productivity to a short-term (i.e. 1 year) extreme drought. We investigated the relative importance and joint influence of functional composition (i.e. community-weighted means of leaf and root traits), plant diversity facets (taxonomic, functional and phylogenetic) and climate (aridity and rainfall variability) on drought resistance. We used structural equation models to disentangle direct, indirect, and moderating pathways linking these drivers to drought resistance. Long-term aridity appeared as one of the most important drivers of grassland resistance to drought, with more arid sites showing lower resistance. Moreover, aridity impacted resistance through indirect effects by shaping functional composition and plant diversity, and by moderating the influence of plant diversity and functional composition. Functional composition related to dehydration avoidance and dehydration tolerance was also positively associated with resistance, while diversity had a weaker relationship with resistance, mostly through functional and phylogenetic facets. Interannual rainfall variability also influenced resistance, with different effects in more arid versus humid and less arid sites. Synthesis . Widely studied stability drivers such as plant diversity and functional composition have only partial explanatory power for short-term drought resistance of above-ground productivity in grasslands at a global scale. The abiotic context, particularly long-term aridity, is crucial for understanding ecosystem responses to rainfall variation and can improve predictive models for advancing the study of ecosystem resistance to drought. Along with management practices that target high species diversity or specific traits, restoration and conservation practices should support vulnerable sites experiencing high aridity

Journal of Ecology↗
USGS2005

Patterns of plant species richness, rarity, endemism, and uniqueness in an arid landscape

Most current conservation literature focuses on the preservation of hotspots of species diversity and endemism, as if the two were geographically synonymous. At landscape scales this may not be the case. We collected data from 367 1000-m 2 plots in the Grand Staircase–Escalante National Monument, Utah, USA, to show that: (1) the vast majority of plant species are locally rare; (2) species-rich areas are generally in rare, mesic, or high-elevation habitats such as aspen stands or riparian zones high in soil N and P; (3) endemic species (to the Colorado Plateau and the Monument) were generally found in relatively species-rich, but low-elevation, xeric vegetation type areas low in soil P; (4) unique species assemblages were found in areas moderately high in endemism and species richness; and (5) nonnative plant species were widely distributed, but more prevalent in species-rich, mesic sites high in soil fertility or disturbed sites, and significantly less prevalent in plots with endemic species. We show that primary hotspots of species richness, high endemism, and unique species assemblages are not co-located on the landscape. Hence, conservation strategies may have to consider a much broader concept of “hotspots” to adequately preserve native plant species and the processes that foster persistence.

Ecological Applications↗
USGS2014

An ecological response model for the Cache la Poudre River through Fort Collins

The Poudre River Ecological Response Model (ERM) is a collaborative effort initiated by the City of Fort Collins and a team of nine river scientists to provide the City with a tool to improve its understanding of the past, present, and likely future conditions of the Cache la Poudre River ecosystem. The overall ecosystem condition is described through the measurement of key ecological indicators such as shape and character of the stream channel and banks, streamside plant communities and floodplain wetlands, aquatic vegetation and insects, and fishes, both coolwater trout and warmwater native species. The 13- mile-long study area of the Poudre River flows through Fort Collins, Colorado, and is located in an ecological transition zone between the upstream, cold-water, steep-gradient system in the Front Range of the Southern Rocky Mountains and the downstream, warm-water, low-gradient reach in the Colorado high plains. The City wanted to better understand the ecological response of the Poudre River ecosystem to potential changes in stream flow and other physical parameters through the conceptual framework of a multivariable integrated model. This goal was met through the use of a probabilistic model based on Bayesian concepts. This construct allowed the integration of a wide range of data and expert opinion (as informed by local data) to predict potential changes to ecosystem conditions under various flow scenarios. Nine flow scenarios representing past, present, and possible future hydrology were developed as the primary model input. Both reach-scale drivers such as stream channel conditions and pollutant loads, as well as ecological conditions, including species composition, interactions, and habitat requirements influenced model-predicted ecosystem outcomes. Model output consisted of probability distributions for eight ecological indicators collectively representing the physical setting, aquatic life, and riparian habitats of the river ecosystem. We are confident in model predictions related to probable trends, relative magnitude of changes and potential ecosystem responses to changing flow conditions, though data availability and the process of converting diverse data types into a common unit (probabilities) limit precision of individual results. Key findings suggest that: The present ecological function of the Poudre River is altered as a result of more than 150 years of human influences that include highly managed flows, urbanization, gravel mining, channelization and urban and industrial encroachment in the floodplain, underscoring the vulnerable and complex character of the Poudre River; A continuation of today’s flow management will lead to ongoing changes in ecosystem condition, and additional water depletions will compromise ecological conditions; High flows play an essential role in maintaining and improving the aquatic and riparian condition of the river; Adequate flows in base-flow periods are critical to desirable water quality, and thriving fish and insect populations; Improvement of native aquatic life is possible if issues related to channel modifications, siltation, invasive species, and base and high flow conditions are managed properly; The present confined river channel and modified flows has reduced the potential for a keystone and iconic species, plains cottonwood, to be self-sustaining in the study area; The streamside corridor retains the potential to support a functioning riparian forest that provides important ecological services if periodic floodplain inundation occurs. Environmental flows that combine stable and adequate flows in base-flow periods with occasional rejuvenating high flows that meet target levels defined in this study are likely improve all biological indicators across the system. ERM test scenarios that include both stable base flows and rejuvenating high flows indicate that substantial improvements in the river ecosystem can be achieved with improved management of flow volumes similar to those observed in the river during the last half century of intensive water development. These results underscore the possibility of improving the river ecosystem through active management while still maintaining the Poudre’s diverse economic benefits and role as a working river. The ERM was designed to represent the multi-dimensional ecological character of the contemporary urban Poudre River. It provides a scientific foundation that can serve as a decision support tool and foster a more informed community discussion about the future of the river as it provides a better understanding of the likely response of the Poudre River ecosystem to environmental flow management and other stewardship activities. In particular, model results can assist managers in developing specific management actions to achieve desirable goals for key indicators of river health.

Colorado↗
USGS2019

An old tree and its many‐shaped leaves

Plant leaf shape is highly variable. The beauty of leaves can be purely aesthetic, but also derives from the mystery of adaptive significance. This mystery is especially compelling for species with strongly varying leaf shape on a single tree. The desert poplar (Populus euphratica Oliv.) is an ancient and protected species, and forms riparian forests in deserts of mid and west Asia, north Africa and southern Europe. More than half of all desert poplar forest is found along the Tarim River within the Taklamakan, a desert in northwest China. The Taklamakan is in the rain shadow of the Himalayas and the world’s second largest shifting sand desert. There, forest extent has been greatly reduced, mostly due to flow diversion for agriculture, but many old trees persist. The tree in the picture is the oldest recorded living desert poplar. The innermost ring in a core dates back to 1709 or earlier. The leaves on this tree vary widely in shape, from smooth to dentate, from narrow to broad, and from linear to lanceolate to ovate. Drought is a dominant stressor in this hyperarid environment with highly variable temperature and soil salinity. Leaf shape may relate to tradeoffs among water conservation, thermoregulation and growth rate. Is this extremely wide variation in leaf shape on a single tree an adaptation to the large temporal fluctuations in the environment? Alternatively, could leaf polymorphism be a neutral and thus non-adaptive consequence of variable gene expressions related to developmental stages. Answers to these questions can enrich the ecological and evolutionary understanding of trees and ecological drought.

Frontiers in Ecology and the Environment↗
USGS2015

Inundation and salinity impacts to above- and belowground productivity in Spartina patens and Spartina alterniflora in the Mississippi River Deltaic Plain: implications for using river diversions as restoration tools

Inundation and salinity directly affect plant productivity and processes that regulate vertical accretion in coastal wetlands, and are expected to increase as sea level continues to rise. In the Mississippi River deltaic plain, river diversions, which are being implemented as ecosystem restoration tools, can also strongly increase inundation in coastal wetlands. We used an in situ mesocosm approach to examine how varying salinity (two levels) and inundation rates (six levels) influenced end-of-season above- and belowground biomass of Spartina patens and Spartina alterniflora during the growing season (March–October) in 2011. Above- and belowground biomass was highest in both species at higher elevations when inundation was minimal, and decreased exponentially with decreased elevation and increased flood duration. This negative biomass response to flooding was more pronounced in S. patens than in S. alterniflora , and S. patens also showed stronger biomass reductions at higher salinities. This salinity effect was absent for belowground biomass in S. alterniflora . These findings suggest that even subtle increases in sea level may lead to substantial reductions in productivity and organic accretion, and also illustrate the importance of considering the inundation tolerance of co-dominant species in receiving areas when utilizing river diversions for delta restoration.

Louisiana↗
USGS2023

Genomes & islands & evolution: Oh my!

A central question in evolutionary biology is how lineages quickly diversify to occupy different ecological niches, along with determining genomic factors that facilitate evolutionary change. Isolated, oceanic archipelagos are famous for adaptive radiations characterized by endemic, species-rich clades with substantial ecological variation, yet genome resources key to determining eco-evo processes are generally lacking. Here I present a comparison of the number of genome reference assemblies available (as of May 31, 2023) for three major eukaryotic lineages, briefly describe genome sequencing and benchmarking strategies, and highlight as a case study a genome assembly project for Bidens hawaiensis (Koʻokoʻolau, Asteraceae or Compositae; Coreopsidae), a member of a hexaploid Hawaiian plant adaptive radiation. The total number of plant genome references (1,394) was found to substantially lag the total number of genome references for animal (6,003) and fungi (4,400). Improvements to the quality of de novo assembled genomes are fueled by second- and third-generation long-read sequencing advancements, among other sequencing approaches. In conjunction, strategies to improve genome contiguity include optical maps, Hi-C chromatin capture, or trio binning. Continual improvements to genome sequencing and assembly algorithms have brought within reach telomere-to-telomere genome assemblies, albeit this level of sequencing has to date only been achieved in a few cases. With improvements in sequencing techniques and per-base pair costs that continue to trend downward, the number of high-quality genomes is anticipated to continue to increase, leading to the filling in of taxonomic gaps and sampling of groups of taxa from under sampled geographic areas. Increasing the number of plant genome resources available for the study of island endemism could help to shed light on genome-phenome relationships and genome characteristics that have produced the stunning biological diversity that we now observe across the globe.

Capitulum↗
USGS2019

Adaptive management assists reintroduction as higher tides threaten an endangered salt marsh plant

In theory, extirpated plant species can be reintroduced and managed to restore sustainable populations. However, few reintroduced plants are known to persist for more than a few years. Our adaptive‐management case study illustrates how we restored the endangered hemiparasitic annual plant, Chloropyron maritimum subsp. maritimum (salt marsh bird's beak), to Sweetwater Marsh, San Diego Bay National Wildlife Refuge, California, United States, and used monitoring and experimentation to identify the factors limiting the reintroduced population. After extirpation in 1988, reintroduction starting that year led to a resilient, genetically diverse population in 2016 (a “boom” of approximately 14,000) that rebounded from a “bust” (62 in 2014). Multiple regressions attributed 82% of the variation in population counts to tidal amplitude, rainfall, and temperature. Populations of salt marsh bird's beak crashed when the diurnal tide range peaked during the 18.6‐year lunar nodal cycle (a rarely considered factor that periodically added approximately 12 cm to tidal ranges). We explain booms as follows: During smaller tidal amplitudes , above‐average rainfall could desalinize upper intertidal soils and stimulate salt marsh bird's beak germination. Then, moderate temperature in May favors growth to reproduction in June. In addition, salt marsh bird's beak needs a short and open canopy of native perennial plants, with roots to parasitize (not non‐native annual grass pseudohosts) and nearby upland soil for a preferred pollinator, ground‐burrowing bees. Although our reintroduced salt marsh bird's beak population is an exceptional case of persistence, this rare species‐specific environmental and biological requirement makes it vulnerable to rising sea levels and global warming.

California↗
USGS2026

Evaluating seedling traits, maintenance and effective costs to support tropical forest restoration practices

While large-scale restoration is essential, tropical forest restoration often depends on small-scale practitioners and landowners who produce, plant and maintain trees. Their collective impact on restoring forest diversity and function is substantial, making it critical to address the constraints they face through efficient, effective techniques. We used generalized linear mixed models to evaluate how seedling traits, weeding maintenance and a fertilizer application influenced the 5-year survival of 1796 seedlings from 11 tree species planted in Monteverde, Costa Rica. Estimates of annual survival increased with seedling age (time after planting) and leaf count at planting. Weeding effects varied by species, improving survival in 7 of 10 species and reducing survival in one. All species reached >80% annual survival after 2 years regardless of maintenance, and seedlings planted with ≥25 leaves showed increased survival that decreased the need for weeding. Weeding is costly: all effective costs per 4-year surviving seedlings were higher with weeding than without and varied by species. Costs were calculated by species, treatment and seedling leaf counts when planted (5, 10, 15, 25, 35, 45). Beyond the 2-year threshold, where mortality is highest, weeding effort and costs no longer appear justified. A single fertilizer application did not improve survival in either of the species tested. Practical implications . These findings support landowner restoration by giving restoration technicians accessible tools to improve seedling survival—increasing leaf counts before planting—and reducing post-planting weeding costs by targeting only species for which it benefits and limiting weeding to 2 years.

Los Llanos, Monteverde↗
USGS2020

Assessment of population genetics and climatic variability can refine climate‐informed seed transfer guidelines

Restoration guidelines increasingly recognize the importance of genetic attributes in translocating native plant materials (NPMs). However, when species‐specific genetic information is unavailable, seed transfer guidelines use climate‐informed seed transfer zones (CSTZs) as an approximation. While CSTZs may improve how NPMs are developed and/or matched to restoration sites, they overlook genetic factors that can diminish restoration success and/or deteriorate natural patterns of genetic diversity and environmental factors that may introduce unexpected variation. Here, we analyze molecular data and geographic patterns of environmental variability across the western United States and demonstrate how they can refine CSTZs. Using genetic data available for 13 relevant plant species, we found that the probability of mixing genetically differentiated individuals (i.e. from different evolutionary lineages, or populations) was approximately 8% when considering locations separated by 50 km and reached nearly 80% by 500 km, which are distances relevant to ecoregionally constrained CSTZs. Furthermore, climate analyses revealed that geographically proximate locations are likely to maintain environmental similarity, regardless of CSTZ or ecoregion assignment. These results suggest constraining CSTZ‐informed seed transfer decisions by distance may mitigate the opportunity for negative genetic outcomes. Furthermore, environmental variability and/or specificity of NPMs (depending upon the restoration strategy) should be achieved by sourcing NPMs from geographically proximate locations to avoid introducing excessive genetic differentiation. Our results highlight the utility of combining molecular genetic data with other genetic inferences (i.e. of adaptation) to determine how best to transfer seed across restoration species' ranges and develop new restoration materials.

Restoration Ecology↗
USGS2024

Predictor importance in habitat suitability models for invasive terrestrial plants

Aim Due to the socioeconomic and environmental damages caused by invasive species, predicting the distribution of invasive plants is fundamental for effectively targeting management efforts. A habitat suitability model (HSM) is a powerful tool to predict potential habitat of invasive species to help guide the early detection of invasive plants. Despite numerous studies of the predictors used in HSMs, there is little consensus about the most appropriate predictors to use in creating ecologically realistic predictions from HSMs. Location The contiguous United States. Methods We explore 220 invasive terrestrial plant species' existing HSMs constructed with consistent modelling algorithms, background generation methods, predictor resolution, and geographic extent, and calculate the relative importance of predictors for each species. We sort predictors into eight groups (topography, temperature, disturbance, atmospheric water, landscape water, substrate, biotic interaction, and radiation) and compare the importance of predictor groups by plant lifeforms and phylogenetic relatedness. Results Human modification and minimum winter temperature were generally the two highest performing individual predictors across the species studied. The highest-performing predictor groups were disturbance, temperature, and atmospheric water. Across lifeforms, there were minimal differences in the influences of predictor groups, although woody plant models exhibited the largest differences in predictor importance when compared with non-woody plant models. Additionally, we found no significant relationship between the importance of predictor groups and phylogenetic relatedness. Main Conclusions This study has implications for informing predictor selection in invasive plant HSMs, leading to more reliable and accurate models of invasive terrestrial plants. Our results emphasize the need to critically select predictors included in HSMs, with special consideration to temperature and disturbance predictors, to accurately predict habitat of invasive plant for detection and response of invasive plant species. With more accurate predictions, managers will be better prepared to address invasive species and reduce their threats to landscapes.

Diversity and Distributions↗
USGS2013

MODIS phenology image service ArcMap toolbox

Seasonal change is important to consider when managing conservation areas at landscape scales. The study of such patterns throughout the year is referred to as phenology. Recurring life-cycle events that are initiated and driven by environmental factors include animal migration and plant flowering. Phenological events capture public attention, such as fall color change in deciduous forests, the first flowering in spring, and for those with allergies, the start of the pollen season. These events can affect our daily lives, provide clues to help understand and manage ecosystems, and provide evidence of how climate variability can affect the natural cycle of plants and animals. Phenological observations can be gathered at a range of scales, from plots smaller than an acre to landscapes of hundreds to thousands of acres. Linking these observations to diverse disciplines such as evolutionary biology or climate sciences can help further research in species and ecosystem responses to climate change scenarios at appropriate scales. A cooperative study between the National Park Service (NPS), the U.S. Geological Survey (USGS), and the National Aeronautics and Space Administration (NASA) has been exploring how satellite information can be used to summarize phenological patterns observed at the park or landscape scale and how those summaries can be presented to both park managers and visitors. This study specifically addressed seasonal changes in plants, including the onset of growth, photosynthesis in the spring, and the senescence of deciduous vegetation in the fall. The primary objective of the work is to demonstrate that seasonality even in protected areas changes considerably across years. A major challenge is to decouple natural variability from possible trends—directional change that can lead to a permanent and radically different ecosystem state. Trends can be either a gradual degradation of the landscape (often from external influences) or steady improvement (by implementing long-term conservation plans). In either case, it is important to first grasp the magnitude of natural variation so that it is not confused with actual trends. This work used existing and freely available remote sensing data, specifically the NASA-funded 250-meter (m) spatial resolution land-surface phenology product for North America. This product is calculated from an annual record of vegetation health observed by NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS) instrument. The land-surface phenology product is, in essence, a method to summarize all the observations throughout a year into a few key, ecologically relevant “metrics”.

Open-File Report↗
USGS2000

The importance of ground water in the Great Lakes Region

Ground water is a major natural resource in the Great Lakes Region because it indirectly contributes more than 50 percent of the stream discharge to the Great Lakes. In addition, ground water is the source of drinking water for millions of people in the region, is an important source of supply for agriculture and many industries, and provides a relatively uniform supply of water in some ecologically sensitive areas to sustain plant and animal species. Therefore, to improve our understanding of water-resources issues in the Great Lakes Region, it is important to have a better understanding of the role that ground water plays in the overall hydrologic system of the lakes. The main ground-water resources issues in the Great Lakes Region are related to the amount of ground water, the interaction of ground water and surface water, changes in ground-water quality as development expands, and ecosystem health related to quantity and quality of water. Issues related to the amount of ground water Although the amount of water in the Great Lakes Region is vast, issues related to relatively small quantities of water are being raised more and more often. For example, even though the amount of ground water pumped in the region is small compared to the total amount of water present, ground water is an important source of public-water supply as well as an important source of supply for industrial, agricultural, and domestic needs. Less clearly understood, however, is the relation between the amount of streamflow discharging to the Great Lakes and the large portion of that flow that originates as ground water. The implications of this understanding for water- and land-use practices and, in turn, their effects on water quantity and quality, have not been fully incorporated into a policy framework. To help include information about the implications of the role that ground water plays in addressing regional water issues, a comprehensive analysis of indirect ground-water discharge to the Great Lakes is needed. Direct ground-water discharge to the Great Lakes is not a large factor in water-budget analyses for the Great Lakes. Locally, however, direct ground-water discharge to the Great Lakes may be important, even though the rates and places of discharge are not well known. A long-term evaluation of direct ground-water discharge to the Great Lakes would help place this hydrologic process in proper perspective. Near-shore areas with high rates of direct ground-water discharge may provide valuable habitat for aquatic organisms. Issues related to the interaction of ground water and surface water Withdrawal of ground water removes that water from the watershed when it is consumptively used or when the return flow is discharged to another drainage basin. Under these circumstances, pumping ground water constitutes a diversion of Great Lakes water. Alternatively, ground-water withdrawal could have the opposite effect of diverting ground-water flow into the watershed by altering the ground-water divides. In particular, as withdrawals associated with urban expansion increase, more accurate data on the amount and effects of ground-water use need to be collected. Data on the amounts of ground water pumped both within the watershed and outside, but near the watershed boundaries needs to be collected and evaluated for potential diversion of water to or from the Great Lakes. It is currently thought that both irrigation and ground-water withdrawals near the watershed boundaries constitute relatively small amounts of water; however, both rapidly changing farming practices and rapidly expanding urban communities could alter these amounts in a relatively short timeframe, especially during drought periods. At present, the effects of ground-water withdrawals have been quantified in detail at only a few urban locations. In addition to quantifying the amount of water pumped out of aquifers, it is also important to improve our knowledge of the amount of water that is recharging them. Ground-water recharge rates estimated in earlier studies cover only a small part of the Great Lakes Region. A comprehensive study of ground-water recharge rates for the entire watershed is needed to more completely determine the role of ground water in the hydrologic budget of the Great Lakes. Issues related to changes in ground-water quality as development expands Ground-water quality is as important as quantity for most water uses. As ground-water development proceeds, the possibility of altering the quality of ground water increases. The quality of ground water can be altered when water levels are drawn below the layer that confines the aquifer or by inducing water of lesser quality into an aquifer. Many local studies of these problems have been conducted, but few regional-scale analyses of changes in ground-water quality as a result of ground-water development have been done. Issues related to ecosystem health and quantity and quality of ground water Ground water is essential to maintain wetlands and to provide healthy habitat for other aquatic systems. Wetland hydrology is widely recognized as the primary influence on wetland ecology, development, and persistence, and information about hydrology is essential to understanding and quantifying wetland functions and processes. Studies of the role of ground water in selected wetlands in a range of physiographic settings throughout the Great Lakes watershed are needed to more fully understand the role of wetlands in the Great Lakes Region.

Lake Erie, Lake Huron, Lake Michigan, Lake Ontario↗
USGS2002

Rocky road in the Rockies: Challenges to biodiversity

To people worldwide, the Rocky Mountains of the United States and Canada represent a last bastion of nature in its purest and rawest form-unspoiled forests teeming with elk and deer stalked by mountain lions and grizzly bears; bald eagles nesting near lakes and rivers; fat, feisty native trout in rushing mountain streams; and dazzling arrays of wildflowers in lush meadows. In fact, the total biodiversity of the Rocky Mountains is considerable, with relatively high diversity in birds, mammals, butterflies, reptiles, and conifers (Ricketts et al. 1999) and with geographic variation in the flora and fauna of alpine, forest, foothill, and adjacent shortgrass prairie and shrub communities over more than 20 degrees of latitude and more than 10' of longitude. Although the biodiversity of most North American regions has declined because of anthropogenic influences, the perception remains that the biodiversity of the Rocky Mountains is intact. This view exists in part because the Rocky Mountains are remote from urban centers, in part because so much of the land comprises protected areas such as national parks and wilderness areas, and in part because of wishful thinking-that nothing bad could happen to the biodiversity that is so much a part of the history, national self-image, legends, nature films, and movies of the United States and Canada. Despite modern technology and the homogenization and globalization of their cities and towns, at heart North Americans still regard their land as the New World, with pristine nature and untamed landscapes epitomized by the Rockies. The reality is that the biodiversity of the Rocky Mountains has not been free of anthropogenic influences since the West was settled in the 1800s, and in fact it was altered by Native Americans for centuries prior to settlement. A number of escalating problems and consequences of management choices are currently changing Rocky Mountain ecological communities at a dizzying pace. In Order to maintain some degree of natural ecosystem processes and preserve natural biodiversity in light of these challenges, Americans and Canadians are faced with the need for intensive, hands-on management of both ecosystems and selected plant and animal populations. In this chapter, we first discuss the primary issues regarding the biodiversity of the Rocky Mountains, including the Rocky Mountain portions of Arizona, Colorado, Idaho, Montana, New Mexico, Utah, Wyoming, British Columbia, and Alberta. Next, we survey groups of organisms to examine their status and special problems. Finally, we touch on major challenges to biodiversity that loom in the near future. Given that entire books may be written on these issues, the discussion is brief and general, but with case histories for more detailed examples.

Book chapter↗
USGS2022

Flower plantings support wild bee reproduction and may also mitigate pesticide exposure effects

Sustainable agriculture relies on pollinators, and wild bees benefit yield of multiple crops. However, the combined exposure to pesticides and loss of flower resources, driven by agricultural intensification, contribute to declining diversity and abundance of many bee taxa. Flower plantings along the margins of agricultural fields offer diverse food resources not directly treated with pesticides. To investigate the potential of flower plantings to mitigate bee pesticide exposure effects and support bee reproduction, we selected replicated sites in intensively farmed landscapes where half contained flower plantings. We assessed solitary bee Osmia lignaria and bumble bee Bombus vosnesenskii nesting and reproduction throughout the season in these landscapes. We also quantified local and landscape flower resources and used bee-collected pollen to determine forage resource use and pesticide exposure and risk. Flower plantings, and their local flower resources, increased O. lignaria nesting probability. Bombus vosnesenskii reproduction was more strongly related to landscape than local flower resources. Bees at sites with and without flower plantings experienced similar pesticide risk, and the local flowers, alongside flowers in the landscape, were sources of pesticide exposure particularly for O. lignaria . However, local flower resources mitigated negative pesticide effects on B. vosnesenskii reproduction. Synthesis and applications . Bees in agricultural landscapes are threatened by pesticide exposure and loss of flower resources through agricultural intensification. Therefore, finding solutions to mitigate negative effects of pesticide use and flower deficiency is urgent. Our findings point towards flower plantings as a potential solution to support bee populations by mitigating pesticide exposure effects and providing key forage. Further investigation of the balance between forage benefits and added pesticide risk is needed to reveal contexts where net benefits occur.

California↗
USGS2025

DNA metabarcoding and video camera collars yield different inferences about the summer diet of an arctic ungulate

The diets of wild ungulates are a foundational component of their ecology, influencing their behavior, body condition, and demography. With changing environmental conditions, there is a significant need to identify important forage items for ungulates, but this has often proved challenging. Declines in several barren-ground caribou herds across the North American Arctic have raised concerns about the influence of climate change on caribou forage conditions. Shifts in plant phenology, biomass, quality, and composition may be influencing caribou diets and subsequently affecting their body condition and demographic rates. Although forage is a primary driver of barren-ground caribou behavior and population dynamics, there is limited recent information about the specific foods they consume, and uncertainty about appropriate methods for identifying those foods. Investigators are increasingly using fecal DNA metabarcoding and video camera collars to assess ungulate diets, but comparative studies of these approaches are lacking. To examine the summer diets of barren-ground caribou, we used both fecal metabarcoding and video camera collars to identify forage used by the Porcupine caribou herd, which spans the Alaska–Yukon border. In 2021, we sampled the diets of adult females by collecting fecal samples and observing collar videos during 4 sampling occasions. We found that caribou consumed very specific forage items, and those items varied markedly across the growing season. Caribou predominantly consumed graminoids and lichens during early summer, and shrubs and forbs later in the season. Metabarcoding and video data provided significantly different estimates of diet for all taxonomic levels we evaluated, and inferences from the two approaches were often disparate. Metabarcoding failed to detect some items frequently consumed in videos, such as lichens, and indicated high use of other items rarely consumed, such as mosses. We found that video data provided greater taxonomic diversity and resolution for vascular plants and lichens, and more closely aligned with past research and biological expectations than data from fecal metabarcoding. Additional research is needed to be able to use these methods to identify the biomass of different forage items consumed.

Alaska, Yukon↗
USGS2025

Metabarcoding analysis of arthropod pollinator diversity: A methodological comparison of eDNA derived from flowers and DNA derived from bulk samples of insects

Limitations of traditional insect sampling methods have motivated the development and optimisation of new non-lethal methods capable of quantifying diverse arthropod communities. Environmental DNA (eDNA) metabarcoding using arthropod-specific primers has recently been investigated as a novel way to characterise arthropod communities from the DNA they deposit on the surface of plants. This sampling method has had demonstrated success, but pollinators—especially bees—are oddly underrepresented in these studies. To evaluate this inconsistency, we investigated the limitations of eDNA metabarcoding for bees and other pollinators. We compared pollinator diversity derived from eDNA extracted from flowers and DNA extracted from pulverised bulk samples of insects collected from vane traps deployed at the same sites using three metabarcoding primers, two of which target arthropods generally (COI-Jusino and 16S-Marquina) and one that targets bumblebees ( Bombus spp., COI-Milam). Across methods, we detected 77 insect families from 9 orders. The COI-Jusino marker amplified the highest taxonomic diversity compared to 16S-Marquina and COI-Milam. More amplicon sequence variants (ASVs) were recovered from vane traps (blue: 1357, yellow: 1542) than flowers (245), but only 23% of families and 13% of genera were shared among methods, indicating that flowers and blue and yellow vane traps may each sample different parts of the available arthropod community. Of 29 flower samples with known bee visitations, only 10 samples had bee detections from eDNA, and incomplete reference databases hindered assignment to species. Although our study provides additional evidence for the usefulness of eDNA metabarcoding for characterising arthropod communities, significant challenges remain when using eDNA metabarcoding methods to identify and quantify pollinator communities, especially bees.

Molecular Ecology↗