Geology topics

Jennifer A. Holmes

Publications and source records attributed to Jennifer A. Holmes.

5 recordsLinked to original sources

USGS2024

Tropical forests and global change: Biogeochemical responses and opportunities for cross-site comparisons, an organized INSPIRE session at the 108th Annual Meeting, Ecological Society of America, Portland, Oregon, USA, August 2023

Tropical forests play a critical role in the global carbon (C) cycle. These ecosystems maintain the highest rates of net primary production (NPP) on Earth (Hengl et al ., 2017 ), contain c . 30% of terrestrial C stocks (Jobbagy & Jackson, 2000 ), and have some of the largest stores of fine-root biomass globally (Jackson et al ., 1996 ), as well as higher fine-root production and turnover rates compared with other biomes (Cusack et al ., 2021 ). Tropical forest responses to projected warming, altered rainfall regimes, and elevated CO 2 concentrations (IPCC, 2021 ) are likely to be different from other ecosystems because of their unique characteristics (Box 1 ), making targeted research and model development important for understanding tropical forest–climate feedbacks. There is now a critical mass of long-term global change field experiments and modeling efforts in tropical forests, yet thus far there has been little synthesis, cross-site comparison, or multi-site standardized experimentation among tropical forests to help us understand how these biomes are changing. An organized INSPIRE session at the 108 th Annual Meeting of the Ecological Society of America set out to tackle just this. Speakers covered large-scale tropical forest field experiments and modeling efforts, with an emphasis on changes in ecosystem biogeochemistry under warming, drying, elevated atmospheric CO 2 , and changing nutrient status. In this Meeting report, we provide an overview of the large-scale global change experiments presented and highlight the main objectives and opportunities for tropical forest research that emerged, including cross-site comparisons and integration with ecosystem-scale models (Fig. 1 ).

New Phytologist↗

USGS2017

Identifying western yellow-billed cuckoo breeding habitat with a dual modelling approach

The western population of the yellow-billed cuckoo ( Coccyzus americanus ) was recently listed as threatened under the federal Endangered Species Act. Yellow-billed cuckoo conservation efforts require the identification of features and area requirements associated with high quality, riparian forest habitat at spatial scales that range from nest microhabitat to landscape, as well as lower-suitability areas that can be enhanced or restored. Spatially explicit models inform conservation efforts by increasing ecological understanding of a target species, especially at landscape scales. Previous yellow-billed cuckoo modelling efforts derived plant-community maps from aerial photography, an expensive and oftentimes inconsistent approach. Satellite models can remotely map vegetation features (e.g., vegetation density, heterogeneity in vegetation density or structure) across large areas with near perfect repeatability, but they usually cannot identify plant communities. We used aerial photos and satellite imagery, and a hierarchical spatial scale approach, to identify yellow-billed cuckoo breeding habitat along the Lower Colorado River and its tributaries. Aerial-photo and satellite models identified several key features associated with yellow-billed cuckoo breeding locations: (1) a 4.5 ha core area of dense cottonwood-willow vegetation, (2) a large native, heterogeneously dense forest (72 ha) around the core area, and (3) moderately rough topography. The odds of yellow-billed cuckoo occurrence decreased rapidly as the amount of tamarisk cover increased or when cottonwood-willow vegetation was limited. We achieved model accuracies of 75–80% in the project area the following year after updating the imagery and location data. The two model types had very similar probability maps, largely predicting the same areas as high quality habitat. While each model provided unique information, a dual-modelling approach provided a more complete picture of yellow-billed cuckoo habitat requirements and will be useful for management and conservation activities.

Ecological Modelling↗

USGS2016

Identifying bird and reptile vulnerabilities to climate change in the southwestern United States

Current and future breeding ranges of 15 bird and 16 reptile species were modeled in the Southwestern United States. Rather than taking a broad-scale, vulnerability-assessment approach, we created a species distribution model (SDM) for each focal species incorporating climatic, landscape, and plant variables. Baseline climate (1940–2009) was characterized with Parameter-elevation Regressions on Independent Slopes Model (PRISM) data and future climate with global-circulation-model data under an A1B emission scenario. Climatic variables included monthly and seasonal temperature and precipitation; landscape variables included terrain ruggedness, soil type, and insolation; and plant variables included trees and shrubs commonly associated with a focal species. Not all species-distribution models contained a plant, but if they did, we included a built-in annual migration rate for more accurate plant-range projections in 2039 or 2099. We conducted a group meta-analysis to (1) determine how influential each variable class was when averaged across all species distribution models (birds or reptiles), and (2) identify the correlation among contemporary (2009) habitat fragmentation and biological attributes and future range projections (2039 or 2099). Projected changes in bird and reptile ranges varied widely among species, with one-third of the ranges predicted to expand and two-thirds predicted to contract. A group meta-analysis indicated that climatic variables were the most influential variable class when averaged across all models for both groups, followed by landscape and plant variables (birds), or plant and landscape variables (reptiles), respectively. The second part of the meta-analysis indicated that numerous contemporary habitat-fragmentation (for example, patch isolation) and biological-attribute (for example, clutch size, longevity) variables were significantly correlated with the magnitude of projected range changes for birds and reptiles. Patch isolation was a significant trans-specific driver of projected bird and reptile ranges, suggesting that strategic actions should focus on restoration and enhancement of habitat at local and regional scales to promote landscape connectivity and conservation of core areas.

Open-File Report↗

USGS2014

Projecting climate effects on birds and reptiles of the Southwestern United States

We modeled the current and future breeding ranges of seven bird and five reptile species in the Southwestern United States with sets of landscape, biotic (plant), and climatic global circulation model (GCM) variables. For modeling purposes, we used PRISM data to characterize the climate of the Western United States between 1980 and 2009 (baseline for birds) and between 1940 and 2009 (baseline for reptiles). In contrast, we used a pre-selected set of GCMs that are known to be good predictors of southwestern climate (five individual and one ensemble GCM), for the A1B emission scenario, to characterize future climatic conditions in three time periods (2010–39; 2040–69; and, 2070–99). Our modeling approach relied on conceptual models for each target species to inform selection of candidate explanatory variables and to interpret the ecological meaning of developed probabilistic distribution models. We employed logistic regression and maximum entropy modeling techniques to create a set of probabilistic models for each target species. We considered climatic, landscape, and plant variables when developing and testing our probabilistic models. Climatic variables included the maximum and minimum mean monthly and seasonal temperature and precipitation for three time periods. Landscape features included terrain ruggedness and insolation. We also considered plant species distributions as candidate explanatory variables where prior ecological knowledge implicated a strong association between a plant and animal species. Projected changes in range varied widely among species, from major losses to major gains. Breeding bird ranges exhibited greater expansions and contractions than did reptile species. We project range losses for Williamson’s sapsucker and pygmy nuthatch of a magnitude that could move these two species close to extinction within the next century. Although both species currently have a relatively limited distribution, they can be locally common, and neither are presently considered candidates for prospective endangerment. We project range losses of over 40 percent, from its current extent of occurrence, for the plateau striped whiptail, Arizona black rattlesnake, and common lesser earless lizard. Currently, these reptile species are thought to be common or at least locally abundant throughout their ranges. The total contribution of plants in each distribution model was very small, but models that contained at least one plant always outperformed models with only physical variables (climatic or landscape). The magnitude of change in projected range increased further into the future, especially when a plant was in the model. Among bird species, those that had the strongest association with a landscape feature during the breeding season, such as terrain ruggedness and insolation, exhibited the smallest contractions in projected breeding range in the future. In contrast, bird species that had weak associations with landscape features, but strong climatic associations, suffered the greatest breeding range contractions. Thus, landscape effects appeared to buffer some of the negative effects of climate change for some species. Among bird species, magnitude of change in projected breeding range was positively related to the annual average temperature of their baseline distribution, thus species with the warmest breeding ranges exhibited the greatest changes in future breeding ranges. This pattern was not evident for reptiles, but might exist if additional species were included in the model. Our results provide managers with a series of projected range maps that will enable scientists, concerned citizens, and wildlife managers to identify what the potential effects of climate change will be on bird and reptile distributions in the Western United States. We hope that our results can be used in proactive ways to mitigate some of the potential effects of climate change on selected species.

Colorado Plateau;Sonoran Desert↗

USGS2007

Yellow-Billed Cuckoo Distribution, Abundance, and Habitat Use Along the Lower Colorado and Tributaries, 2006 Annual Report

Executive Summary This 2006 annual report details the first season of a 2-year study documenting western yellow-billed cuckoo (Coccyzus americanus occidentalis) distribution, abundance, and habitat use throughout the Lower Colorado River Multi-Species Conservation Plan boundary area. We conducted cuckoo surveys at 55 sites within 17 areas, between 11 June and 13 September. The 243 visits across all sites yielded 180 yellow-billed cuckoo detections. Cuckoos were detected at 27 of the 55 sites, primarily at the Bill Williams River National Wildlife Refuge AZ sites (n = 117 detections) and the Grand Canyon National Park-Lake Mead National Recreation Area AZ delta sites (n = 29 detections). There were also cuckoos at the Gila River-Colorado River Confluence, AZ (n = 9), Overton Wildlife Management, NV area (n = 7), and Limitrophe Division North, AZ (n = 6); however, at these sites the numbers were much lower and very few of these birds were considered to be paired or breeding. The greatest number of detections (n = 79) occurred during the second survey period (3-23 July). In 2006, we confirmed five breeding events, including one nesting observation and sightings of four juveniles; all confirmed breeding was at the Bill Williams River NWR and Grand Canyon NP-Lake Mead NRA delta sites. The breeding status of most of our detections were unknown, however, we observed 17 adult cuckoos carrying nest material or food and 40 cuckoo detections were detected while counter-calling occurred in same area during repeated surveys. We used playback recordings to survey for western yellow-billed cuckoos. Compared to simple point counts or surveys, this method increases the number of detections of this secretive, elusive species. It has long been suspected that cuckoos have a fairly low response rate, and that the standard survey method of using playback recordings may fail to detect all birds present in an area. In 2006, we found that the majority (72%) of cuckoo detections were solicited through playback at all study sites. The number of solicited detections peaked during the first half of July and then declined as the breeding season progressed, while the number of unsolicited detections (cuckoos heard calling before playback was initiated) remained fairly constant. The majority (64%) of cuckoo detections, solicited or unsolicited, were aural; 27 percent were both heard and seen and nine percent were visual detections only. Cuckoos in areas with the largest populations had the highest rate of vocalizations before playback or after the first broadcast. In contrast, more than half the responses at sites with fewer cuckoos (with < 10 detections per site) first occurred after three or more playback recordings. This type of baseline information will be used to help refine the survey protocol for 2007, and to create hypotheses that can serve as the foundation for a full-scale evaluation and optimization of this survey technique. Our preliminary analysis of vegetation data from occupied and unoccupied sites in 2006 focused on general patterns in the distribution and abundance of woody species. The density and composition of woody riparian vegetation varied considerably among the study areas. Much of the variation in tree density was due to the patterns of abundance of trees in the smallest size class (< 8 cm dbh). The dominant tree species at the cuckoo survey sites were cottonwood, willow, and tamarisk. Tamarisk was the most common tree, due to the abundance of small (< 8 cm dbh) individuals. When occupied and unoccupied sites were compared, occupied sites tended to have higher average canopy cover, attributable to higher average cover of the mid and low canopy. The dominant canopy at occupied sites most often consisted of cottonwood or willow trees. In addition, occupied sites in most areas had lower than average total tree density whereas unoccupied sites were denser than average. When densities of trees in different size classes were com

Open-File Report↗