skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


  • NSF Public Access
  • Search Results
  • Using a Hyperspectral Sensor Mounted on an Unoccupied Aircraft System to Detect Biological Soil Crust’s Spatial Distribution in the Chihuahuan Desert Ecosystem to Determine Their Annual Carbon Fixation Capacity
Title: Using a Hyperspectral Sensor Mounted on an Unoccupied Aircraft System to Detect Biological Soil Crust’s Spatial Distribution in the Chihuahuan Desert Ecosystem to Determine Their Annual Carbon Fixation Capacity
Biological soil crusts (BSCs) consist of cyanobacteria, algae, fungi, lichens, and mosses, which live within the uppermost millimeters of the soil’s surface where they influence soil stability, nitrogen, and carbon cycles. BSCs are only a few millimeters thick but cover large expanses of ground allowing for possibly significant contributions to the carbon cycle in arid environments. Remote sensing of these organisms has been used to study BCS in a non-destructive manner over the last 36 years. In this project, we aimed to quantify the abundance and distribution of BSCs and to estimate their annual carbon fixation rate at different community stages in two unique research sites (T-East and T-West) in the Chihuahuan desert of southern New Mexico, USA. We first investigated the utility of an unoccupied aircraft system (UAS)-mounted hyperspectral camera to measure the spatial cover of two BSCs functional groups (light and dark BSC) in a shrub-dominated vs. predominantly grassland site. Using a spectral angle mapper (SAM) algorithm we classified the hyperspectral imagery into five cover classes (light BSC, dark BSC, bare soil, grasses, and shrubs). With observations collected utilizing a line point intercept (LPI) method, we quantified the percent cover of BSCs and vegetation within the transects to validate the SAM estimates. Lastly, we incorporated C-fixation rates from local BSC communities to estimate the mean annual C-fixation rates for both BSCs within our research plots. The SAM algorithm overestimated light biocrust (LBC) in T-East by 17.7% when compared with the LPI estimates. Inversely, the SAM underestimated dark biocrust (DBC) for T-East by 9.3% as well as underestimating both Light and DBCs for T-west (23.9% and 6.7% respectively) when compared to the LPI estimates. This produced a higher annual fixed CO2 value for T-East’s LBC of 36.4% and a lower rate for DBC of 37.2% in comparison with the LPI’s observations. The T-West annual fixed CO2 was underestimated by the SAM algorithm by 66.1% for LBC and 42.9% for DBC when compared to the LPI observations. The results indicate the heavily shrub-encroached T-East site had a better accuracy rate than the T-West grassland site for the accurate classification of the five cover classes. It was believed that the vegetation's close proximity to the soil surface and sample timing negatively interfered with the detection rates of light and dark BSCs.  more » « less
Award ID(s):
2025166
PAR ID:
10556944
Author(s) / Creator(s):
Publisher / Repository:
ProQuest
Date Published:
Format(s):
Medium: X
Institution:
New Mexico State University
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; ; ; (, Frontiers in Microbiology)
    null (Ed.)
    Numerous studies have examined bacterial communities in biological soil crusts (BSCs) associated with warm arid to semiarid ecosystems. Few, however, have examined bacterial communities in BSCs associated with cold steppe ecosystems, which often span a wide range of climate conditions and are sensitive to trends predicted by relevant climate models. Here, we utilized Illumina sequencing to examine BSC bacterial communities with respect to climatic gradients (elevation), land management practices (grazing vs. non-grazing), and shrub/intershrub patches in a cold sagebrush steppe ecosystem in southwestern Idaho, United States. Particular attention was paid to shifts in bacterial community structure and composition. BSC bacterial communities, including keystone N-fixing taxa, shifted dramatically with both elevation and shrub-canopy microclimates within elevational zones. BSC cover and BSC cyanobacteria abundance were much higher at lower elevation (warmer and drier) sites and in intershrub areas. Shrub-understory BSCs were significantly associated with several non-cyanobacteria diazotrophic genera, including Mesorhizobium and Allorhizobium - Neorhizobium - Pararhizobium - Rhizobium . High elevation (wetter and colder) sites had distinct, highly diverse, but low-cover BSC communities that were significantly indicated by non-cyanobacterial diazotrophic taxa including families in the order Rhizobiales and the family Frankiaceae. Abiotic soil characteristics, especially pH and ammonium, varied with both elevation and shrub/intershrub level, and were strongly associated with BSC community composition. Functional inference using the PICRUSt pipeline identified shifts in putative N-fixing taxa with respect to both the elevational gradient and the presence/absence of shrub canopy cover. These results add to current understanding of biocrust microbial ecology in cold steppe, serving as a baseline for future mechanistic research. 
    more » « less
  2. ; ; (, Environmental Data Initiative)
    This dataset contains raw and calculated percent cover and frequency data for biological soil crust (hereafter biocrust) functional groups, vascular plant functional groups, and abiotic land surface features on and off gypsum soils in the northern Chihuahuan and eastern Mojave Deserts. Abundance data were obtained from 20 study sites total, 10 located on soils derived from gypsum parent material and 10 located on soils derived from non-gypsum parent materials. Sites were grouped into 10 pairs, in which every gypsum site was partnered with a non-gypsum site located in the same region. Apart from soil type, partnered-site characteristics (topography, climate, elevation, slope, aspect, and presence of biocrusts) were held relatively constant. At each site, cover and frequency assessments were made using the line-point intercept method (LPI) and frequency quadrats (1.0 m^2), respectively. Biocrust functional groups included the following crusts: lichen, moss, incipient algal, light algal, dark algal, unknown photosynthetic crust, and vagrant cyanobacteria. Vascular plant categories included: perennial forbs, perennial graminoids, annual forbs, annual graminoids, subshrub, shrub, Yucca, and cacti. Abiotic land surface features included: woody litter, herbaceous litter, bare soil, rock, bedrock, and animal feces. Moss crusts identified within cover and frequency analyses were sampled, and classified to species level via microscopy. The resulting percent cover and frequency data was used to understand differences in biocrust and moss species abundance and diversity on and off gypsum soils; furthermore, how biocrust and moss species abundance was associated with the measured environmental variables. Soil physical and chemical data from this study can be accessed at knb-lter-jrn.210616002. This study and dataset are complete. 
    more » « less
  3. ; ; ; ; ; ; ; ; ; ; et al (, Frontiers in Microbiology)
    Biological soil crusts (biocrusts) are critical components of dryland and other ecosystems worldwide, and are increasingly recognized as novel model ecosystems from which more general principles of ecology can be elucidated. Biocrusts are often diverse communities, comprised of both eukaryotic and prokaryotic organisms with a range of metabolic lifestyles that enable the fixation of atmospheric carbon and nitrogen. However, how the function of these biocrust communities varies with succession is incompletely characterized, especially in comparison to more familiar terrestrial ecosystem types such as forests. We conducted a greenhouse experiment to investigate how community composition and soil-atmosphere trace gas fluxes of CO2, CH4, and N2O varied from early-successional light cyanobacterial biocrusts to mid-successional dark cyanobacteria biocrusts and late-successional moss-lichen biocrusts and as biocrusts of each successional stage matured. Cover type richness increased as biocrusts developed, and richness was generally highest in the late-successional moss-lichen biocrusts. Microbial community composition varied in relation to successional stage, but microbial diversity did not differ significantly among stages. Net photosynthetic uptake of CO2by each biocrust type also increased as biocrusts developed but tended to be moderately greater (by up to ≈25%) for the mid-successional dark cyanobacteria biocrusts than the light cyanobacterial biocrusts or the moss-lichen biocrusts. Rates of soil C accumulation were highest for the dark cyanobacteria biocrusts and light cyanobacteria biocrusts, and lowest for the moss-lichen biocrusts and bare soil controls. Biocrust CH4and N2O fluxes were not consistently distinguishable from the same fluxes measured from bare soil controls; the measured rates were also substantially lower than have been reported in previous biocrust studies. Our experiment, which uniquely used greenhouse-grown biocrusts to manipulate community composition and accelerate biocrust development, shows how biocrust function varies along a dynamic gradient of biocrust successional stages. 
    more » « less
  4. ; ; ; (, Ecohydrology)
    ABSTRACT Water redistribution during rain events in drylands plays a critical role in the persistence and spatial pattern of vascular plants in these patchy ecosystems. Biological soil crusts (BSCs) form a membrane in the soil surface and mediate ecohydrological dynamics. However, little is known about their influence on dryland ecosystem state and spatial pattern under changing climate, which may alter total annual rainfall and intraannual rainfall regime. Building on existing models, we develop a model that considers BSC–vascular plant interactions and realistic ecohydrological dynamics under rainfall pulses. We find that the presence of BSCs often increases ecosystem resilience by promoting runoff to plants under high aridity. However, the benefit of BSCs comes at the cost of plant biomass under relatively wetter conditions; a threshold in BSC effect occurs when water losses from BSCs exceed the benefit by their surface water routing to plants. Increased resilience from BSCs, and their own persistence, can be promoted in finer soils and under rainfall regimes of less frequent events—projected for many drylands. Lastly, we find that BSCs alter feedbacks underlying plant spatial self‐organization and hence their formed patterns. In high aridity, BSCs likely ameliorate competition between plants through large scale runoff promotion, reducing plant spatial pattern regularity. Our analysis highlights that BSCs significantly shape drylands' response to climate change and their positive effects on resilience may be stronger and more pervasive in a drier future, but such benefits come at a cost of ecosystem biomass and productivity when aridity is outside a critical range. 
    more » « less
  5. ; ; ; ; ; ; (, Ecology Letters)
    Abstract Hysteresis is a fundamental characteristic of alternative stable state theory, yet evidence of hysteresis is rare. In mesic grasslands, fire frequency regulates transition from grass‐ to shrub‐dominated system states. It is uncertain, however, if increasing fire frequency can reverse shrub expansion, or if grass‐shrub dynamics exhibit hysteresis. We implemented annual burning in two infrequently burned grasslands and ceased burning in two grasslands burned annually. With annual fires, grassland composition converged on that of long‐term annually burned vegetation due to rapid recovery of grass cover, although shrubs persisted. When annual burning ceased, shrub cover increased, but community composition did not converge with a long‐term infrequently burned reference site because of stochastic and lagged dispersal by shrubs, reflecting hysteresis. Our results demonstrated that annual burning can slow, but not reverse, shrub encroachment. In addition, reversing fire frequencies resulted in hysteresis because vegetation trajectories from grassland to shrubland differed from those of shrubland to grassland. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email